research work on gravity

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General relativity and gravity articles from across Nature Portfolio

General relativity describes gravitation in a geometrical framework generalizing special relativity and classical mechanics. This term includes theoretical studies of gravity, experimental studies of gravitational waves and observational studies of gravitational lensing, as well as tests of general relativity and laboratory experiments.

Latest Research and Reviews

Pinpointing gravitational waves via astrometric gravitational wave antennas

• Mariateresa Crosta
• Mario Gilberto Lattanzi
• Alberto Vecchiato

Correlation between birefringence and absorption mapping in large-size Sapphire substrates for gravitational-wave interferometry

• Simon Zeidler
• Marc Eisenmann
• Matteo Leonardi

Precessing jet nozzle connecting to a spinning black hole in M87

This study analyses radio observations of the jet in galaxy M87, from which the existence of a spinning black hole that induces Lense–Thirring precession of a misaligned accretion disk is inferred.

• Kazuhiro Hada
• Weiye Zhong

Astrophysics with continuous gravitational waves

Continuous gravitational waves represent an exciting new frontier for multi-messenger astrophysics. This overview discusses their origins and the results obtained in the LIGO–Virgo–KAGRA O3 observing run, highlighting their potential for future studies.

Quantum reference frames for an indefinite metric

Finding a way to combine quantum mechanics and gravity is a longstanding issue in physics. While there are different approaches to quantum gravity, there are many challenges in making concrete predictions for scenarios at the interface of these two theories. Here, the authors propose a first-principles strategy to determine the dynamics of objects in the presence of mass configurations in superposition, which enables predictions where the gravitational source is in a quantum superposition rather than a classical configuration.

• Anne-Catherine de la Hamette
• Viktoria Kabel
• Časlav Brukner

Three-dimensional wormhole with cosmic string effects on eigenvalue solution of non-relativistic quantum particles

• Faizuddin Ahmed

News and Comment

Strong evidence for the discovery of a gravitational wave background

In 2023, pulsar timing arrays announced what could become the first ever discovery of a stochastic gravitational wave background: the random superposition of gravitational waves permeating the cosmos — a vestige of cosmic processes in the Universe.

• Chiara Caprini

Forty days and forty-five nights at space’s edge

The SuperBIT telescope spent more than a month being carried through the stratosphere by a scientific balloon, imaging space from above 99.5% of the Earth’s atmosphere.

• Richard Massey
• C. Barth Netterfield
• William C. Jones

The persistent ring of M87* confirms predictions

• Morgan Hollis

Why even specialists struggle with black hole proofs

Mathematical proofs of black hole physics are becoming too complex even for specialists.

• Alejandro Penuela Diaz

The black hole revolution needs you!

The NANOGrav collaboration has found light-years long gravitational waves from, most likely, the mergers of millions of supermassive black holes. To keep watching this cosmic dance, we need sustained funding for black hole research.

• C. M. F. Mingarelli

Charles Gammie and colleagues wrote the HARM code to tackle the extreme physics close to a spinning black hole. Twenty years later, it is performing a similar task in three dimensions in 1/10,000th of the time.

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Daniel Jafferis’ team has for the first time conducted an experiment based in current quantum computing to understand wormhole dynamics.

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One small step toward understanding gravity

Alice McCarthy

Harvard Correspondent

Quantum computing simulation reveals possible wormhole-like dynamics

Complete understanding of many of the most fundamental forces at play in our world has proven slippery. A new experiment by a group of researchers, including Daniel Jafferis of Harvard’s Department of Physics and peers from Caltech, represents a small step in advancing our view of the relationship between gravity, which shapes the universe, and quantum mechanics, the theoretical framework governing the motion and interaction of subatomic particles.

For more than 100 years, the common description of gravity has stemmed from Albert Einstein’s theory of general relativity — that gravity relates to the curvature of space-time. In the last 25 years scientists have discovered there is an intimate connection between gravity and quantum mechanics. Among these connections are wormholes, also known as bridges or tunnels of space, which Einstein described in 1935 as passages through space-time that could connect two black holes.

Jafferis’ team has for the first time conducted an experiment based in current quantum computing to understand wormhole dynamics. “It is a quantum simulation of an extraordinarily tiny wormhole,” said Jafferis. “Before this, it was not clear with the devices we have now if one could do it at all.” The research was published in Nature .

Einstein’s general relativity theory described wormholes as two black holes whose interiors are joined, where something could jump in each side, meet in the middle, but neither could get out again — the proverbial trap in a black hole.

“It’s a beautiful idea from the 1930s that wormhole interiors are joined, but it has not been known if this concept is an operationally meaningful statement,” Jafferis said. “But now we know that wormhole configuration does indeed have a physical interpretation; it corresponds to the two separate black holes in a highly entangled space.”

In recent years, scientists have built physical devices like quantum computers to create simulations in which they can manipulate the entanglements of quantum states in a controlled way. Jafferis’ team wanted to see whether they could create a simplified model that would emulate the gravitational aspects of a wormhole. Could they make a quantum system where the pattern of space entanglement is structurally of the right sort so that it looks like sending something through a wormhole?

In lab experiments, the researchers introduced a connection between the two sides, making the wormhole traversable. Signals could be sent in one side and come through the other, maybe not quickly, but without getting stuck. In the quantum language this is called “quantum teleportation,” a way of sending quantum information using shared entanglement. “The information is not sent through the direct signal, but in a more subtle way that uses entanglement,” Jafferis added.

The team started with a qubit, the simplest kind of quantum space, in one area of their device. They released other qubits in another fixed entangled space within the computer for a total of nine qubits. The two spaces were then mixed using the gate operations of the quantum computer.

Next, they used data operations that interpreted the evolving system according to certain dynamics. The final step was looking at the qubit once it reached the other side of the computer. “We asked if it was the same as the one we sent in or if it looked different,” said Jafferis. “It was the simplest possible quantum circuit we could create to see if we could simulate wormhole dynamics.”

The team’s ultimate goal is to learn all the details about the gravitational description of quantum systems. “We know how that works through theoretical mathematics in limited cases, but we don’t know all the answers,” said Jafferis. “Using this very small quantum system, we see it as a first step toward making bigger ones where we can discover more.”

This research was funded the U.S. Department of Energy Office of Science.

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Einstein's Theory of Gravitation

Our modern understanding of gravity comes from Albert Einstein’s theory of general relativity, which stands as one of the best-tested theories in science. General relativity predicted many phenomena years before they were observed, including black holes , gravitational waves , gravitational lensing , the expansion of the universe , and the different rates clocks run in a gravitational field. Today, researchers continue to test the theory’s predictions for a better understanding of how gravity works.

Center for Astrophysics | Harvard & Smithsonian astrophysicists research the predictions of general relativity in many ways:

Capturing the first image of a supermassive black hole using the Event Horizon Telescope (EHT). This image of the black hole at the center of the nearby galaxy M87 reveals how gravitation affects the matter in orbit and the light that material emits, providing a novel test of general relativity in a regime where gravity is very strong. CfA Plays Central Role In Capturing Landmark Black Hole Image

Using gravitational lensing to search for the earliest galaxies in the universe. While they’re too faint to be seen directly, closer-by galaxies and clusters sometimes magnify their light, allowing us to learn about the ancestors of the Milky Way and other modern galaxies. Discovering Distant Radio Galaxies via Gravitational Lensing

Reconstructing the location of most of the mass in the universe using gravitational lensing. Next-generation observatories like the Large Synoptic Survey Telescope (LSST) will provide a census of millions of galaxies from their gravitational distortions. Mapping Dark Matter

Performing follow-up observations of gravitational wave events, to confirm the nature of the source. Collisions between neutron stars produce a lot of light in the form of short duration gamma ray bursts in addition to gravitational waves. Astronomers observed such a collision in 2017 using Dark Energy Camera on the Blanco Telescope in Chile, providing complementary data to the observation from LIGO. Astronomers See Light Show Associated With Gravitational Waves

Studying gravitational wave sources that aren’t visible to LIGO, but will be to future gravitational observatories. Using visible light telescopes, astronomers have observed that white dwarf binaries are relatively common in the galaxy, and some of them are in sufficiently tight orbits to be emitters of gravitational waves. One pair in particular orbits every 12.75 minutes, which will make it the strongest source for the future Laser Interferometer Space Antenna (LISA). Space-Warping White Dwarfs Produce Gravitational Waves

Determining whether black holes are actually what GR predicts. While GR is very clear that black holes exist, alternative theories propose different objects that behave in different ways. The challenge is that black holes appear very small in our telescopes, so it’s hard to observe their behavior. However, researchers have ruled out a number of alternative explanations, based on many observations of black holes. Do Stars Fall Quietly into Black Holes, or Crash into Something Utterly Unknown?

Testing general relativity’s prediction about the shape of a black hole. The Event Horizon Telescope is designed to take a picture of the “shadow” of the Milky Way’s supermassive black hole, which is the dark region through which no light passes. The shape of this shadow is predicted by GR, so the EHT will provide the first precision measurement of a fundamental property of a black hole. Event Horizon Telescope Reveals Magnetic Fields at Milky Way's Central Black Hole

A Century of Relativity

Albert Einstein published his full theory of general relativity in 1915, followed by a flurry of research papers by Einstein and others exploring the predictions of the theory. In general relativity (GR), concentrations of mass and energy curve the structure of spacetime, affecting the motion of anything passing near — including light. The theory explained the anomalous orbit of Mercury, but the first major triumph came in 1919 when Arthur Eddington and his colleagues measured the influence of the Sun’s gravity on light from stars during a total solar eclipse.

Physicists made many exotic predictions using general relativity. The bending of light around the Sun is small, but researchers realized the effect would be much larger for galaxies, to the point where gravity would form images of more distant objects — the phenomenon now called gravitational lensing. GR also predicted the existence of black holes: objects with gravity so intense that nothing getting too close can escape again, not even light.

General relativity showed that gravitation has a speed, which is the same as the speed of light. Catastrophic events like collisions between black holes or neutron stars produce gravitational waves. Researchers finally detected these waves in 2015 using the Laser Interferometer Gravitational Observatory (LIGO), a sensitive laboratory that took decades to develop.

For many aspects of astronomy — the motion of planets around stars, the structure of galaxies, etc. — researchers don’t need to use general relativity. However, in places where gravity is strong, and to describe the structure of the universe itself, GR is necessary. For that reason, researchers continue to use GR and probe its limits.

Black holes are extremely common in the universe. Stellar-mass black holes, the remnants of massive stars that exploded, are sometimes the source of powerful X-ray emissions when they are in binary systems with stars. In addition, nearly every galaxy harbors a supermassive black hole at its center, some of which produce powerful jets of matter visible from across the universe. GR is essential to understanding how these objects become so bright, as well as studying how black holes form and grow. The Event Horizon Telescope (EHT) is a world-spanning array of observatories that captured the first image of a supermassive black hole, providing a new arena for testing GR’s predictions.

Gravitational waves are a new branch of astronomy, providing a complementary way to study astrophysical systems to the standard light-based observations. Researchers use GR to provide “templates” of many possible gravitational wave signals, which is how they identify the source and its properties. Gravitational wave astronomy combines with light-based astronomy to characterize some of the most extreme events in the cosmos: collisions of black holes and neutron stars .

Astronomers use gravitational lensing to locate some of the earliest galaxies in the universe, which are too faint to be seen without the magnification provided by gravity. In addition, the distortion created by lensing allows researchers to study dark matter , and map the structure of the universe on the largest scales.

Not long after Einstein published GR, researchers realized the theory predicts that the universe changes in time. Observations in the 1920s found that prediction was true: the universe is expanding, with galaxies moving away from each other. Using GR, cosmologists found the cosmos had a beginning, and was once hotter and denser than it is today. GR provides the mathematical framework for describing the structure and evolution of the universe from its beginnings 13.8 billion years ago, and into the future.

This artist’s illustration depicts two merging neutron stars and the gravitational waves they emit. As the LIGO and Virgo gravitational wave observatories have confirmed, collisions of black holes and neutron stars emit enough gravitational waves to be seen billions of light-years away.

• Why do we need an extremely large telescope like the Giant Magellan Telescope?
• What happens to space time when cosmic objects collide?
• Black Holes
• Gravitational Lensing
• Gravitational Waves
• Very Long Baseline Interferometry
• High Energy Astrophysics
• Optical and Infrared Astronomy
• Theoretical Astrophysics

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What Is Gravity?

Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun.

What else does gravity do?

Why do you land on the ground when you jump up instead of floating off into space? Why do things fall down when you throw them or drop them? The answer is gravity: an invisible force that pulls objects toward each other. Earth's gravity is what keeps you on the ground and what makes things fall.

An animation of gravity at work. Albert Einstein described gravity as a curve in space that wraps around an object—such as a star or a planet. If another object is nearby, it is pulled into the curve. Image credit: NASA

Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is.

Earth's gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. That's what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here.

Image credit: NASA

You exert the same gravitational force on Earth that it does on you. But because Earth is so much more massive than you, your force doesn’t really have an effect on our planet.

Gravity in our universe

Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made.

Gravity not only pulls on mass but also on light. Albert Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it. You can't see the change with your eyes, but scientists can measure it.

Black holes pack so much mass into such a small volume that their gravity is strong enough to keep anything, even light, from escaping.

What is a black hole?

Watch this video to find out more about these areas of immense gravity!

Gravity on Earth

Gravity is very important to us. We could not live on Earth without it. The sun's gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun's light and warmth. It holds down our atmosphere and the air we need to breathe. Gravity is what holds our world together.

However, gravity isn’t the same everywhere on Earth. Gravity is slightly stronger over places with more mass underground than over places with less mass. NASA uses two spacecraft to measure these variations in Earth’s gravity. These spacecraft are part of the Gravity Recovery and Climate Experiment (GRACE) mission.

The GRACE mission helps scientists to create maps of gravity variations on Earth. Areas in blue have slightly weaker gravity and areas in red have slightly stronger gravity. Image credit: NASA/University of Texas Center for Space Research

GRACE detects tiny changes in gravity over time. These changes have revealed important details about our planet. For example, GRACE monitors changes in sea level and can detect changes in Earth’s crust brought on by earthquakes.

More about gravity!

What is a gravitational wave?

What is a barycenter?

If you liked this, you may like:

William H. Miller III Department of Physics & Astronomy

• Cosmology and Gravity

• Astrophysics
• Atomic, Molecular, and Optical Physics
• Biological Physics
• Condensed Matter Physics
• Information and Complexity
• Particle Physics
• Physics and Machine Learning

The Physics & Astronomy Department is engaged in a broad range of research that explores the nature of gravity and the origin and evolution of the Universe.  Theoretical research is conducted on general relativity, alternative-gravity theories, gravitational-wave physics and astrophysics, physical and early-Universe cosmology, and dark matter and dark energy.  Relevant experimental/observational work includes direct searches for dark matter, measurements of the cosmic expansion history, galaxy surveys, and cosmic-microwave-background measurements.

Nima Arkani-Hamed

A professor at the Institute for Advance Study, Arkani-Hamed is also a Visiting Professor in the Department of Physics and Astronomy at Johns Hopkins. Arkani-Hamed is a particle theorist with broad interests, among them the physics behind inflation and the nature of dark matter. Arkani-Hamed is also currently pursuing fundamental new paradigms that may ultimately supplant our notions of space and time.

Ibrahima Bah

Bah is a theoretical physicist with a general research interest is in theoretical high-energy physics and cosmology. He explores the relations between quantum field theories, string theory and gravity via the framework of holography. Bah is also interested in fundamental aspect of black holes and their role in nature. His research work is part of a larger research program in high-energy physics whose main goal is to understand a quantum theory of gravity.

Charles Bennett

Bennett is an experimental cosmologist perhaps best known for his role as Principal Investigator of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), the satellite experiment that transformed our view of the Universe and the nature of its contents. Bennett is now co-leading (with Prof. Toby Marriage) the CLASS (Cosmology Large-Angular-Scale Surveyor) experiment which provides a unique avenue toward extracting information about inflation from the polarization of the cosmic microwave background. He is also building up to study the properties of the dark Universe as a member of the Euclid science consortium and of the Subaru Prime Focus Spectrograph (SPFS).

Emanuele Berti

Berti is a theoretical physicist who specializes in gravitational physics and gravitational-wave astronomy. His research interests include the structure, stability, dynamics and formation of black holes and neutron stars; gravitational-wave signatures of modified theories of gravity and physics beyond the Standard Model; using gravitational waves to understand black hole binary astrophysics and cosmology; and preparing for the challenge of detecting gravitational waves in space with LISA.

Sean Carroll

Sean Carroll is the Homewood Professor of Natural Philosophy, teaching in both Physics and Philosophy. He is interested in foundational questions in quantum mechanics, spacetime, statistical mechanics, complexity, and cosmology. His current research focuses on two main themes. First, quantum mechanics and the emergence of spacetime: how spacetime and the laws of physics can emerge from basic quantum ingredients. Second, entropy and complexity: how the arrow of time arises from an initial low-entropy condition, and how complex structures originate and interact over cosmic time.

Marc Kamionkowski

Kamionkowski is a theoretical cosmologist with interests in inflation, dark energy, dark matter, and beyond. He is known largely for his work on dark matter and for the development of ideas that have motivated several generations of cosmic microwave background experiments. He is currently exploring new ideas for dark energy, dark matter, and inflation and news ways to test these ideas with a variety of astronomical observations and laboratory tests.

David Kaplan

David Kaplan is a particle theorist whose wide interests include several subjects in cosmology. He is responsible for some of the most inventive and influential recent ideas for dark matter, including several that relate the origin of dark matter to that of the ordinary atomic matter of which we are composed. Kaplan is also known for his role as producer (and co-star) of “Particle Fever,” a feature-length documentary that follows the discovery of the Higgs boson at the Large Hadron Collider. Kaplan is currently exploring several new ideas for dark matter and new strategies for dark-matter detection.

Jared Kaplan

Jared Kaplan is a particle theorist of remarkably broad interests that extend from condensed-matter theory to the early Universe.  He is known in the world of cosmology as co-creator of the effective field theory of inflation, a novel and powerful way to look at inflation, and for his work on dark matter.  His current work on black-hole physics in unusual spacetimes holds promise to elucidate the fundamental physics that may underlie inflation.

Toby Marriage

Marriage is an experimental cosmologist who before arriving at Johns Hopkins played a central role in the development, fielding, analysis pipeline, and science results from the Atacama Cosmology Telescope.  Chief among the results that he contributed to are measurements of cosmological parameters and studies of galaxy clusters.  He is currently co-leading (with Chuck Bennett) the CLASS (Cosmology Large-Angular-Scale Surveyor) experiment which provides a unique avenue toward extracting information about inflation from the polarization of the cosmic microwave background.

Brice Ménard

Ménard is an observational cosmologist who specializes in distilling novel and important science results from large astronomical data sets.  This work has led to major advances in our ability to determine the distribution of dark matter in the Universe and the discovery of vast reservoirs of interstellar dust in galactic halos.  Ménard is currently developing a new approach to determine cosmic distances, a technique that is likely to considerably augment how science is done with future cosmic surveys.  He will also study the properties of the dark Universe as a member of the Euclid science consortium and of the Subaru Prime Focus Spectrograph (SPFS).

Surjeet Rajendran

Rajendran’s scholarly interests are in theoretical physics with a strong focus on physics beyond the standard model. Prior to coming to Hopkins, he was the Henry Shenker Professor of Physics at the University of California, Berkeley. He holds a PhD in physics from Stanford University.

Riess is an observational cosmologist interested in measurements of the cosmic expansion history.  He was one of the key players in the 1998 discovery of accelerated cosmic expansion, which suggests that the Universe is filled with some negative-pressure “dark energy” that drives galaxies away from each other.  His work since then has placed important constraints on the nature of this dark energy.  He has also been leading an array of projects that provide the most stringent constraints to the Hubble constant, the parameter that measures the expansion rate of the Universe today.

Joseph Silk

Silk, who splits his time between Johns Hopkins, Oxford University, and the Institut d’Astrophysique in Paris, is one of the grey eminences of cosmology, with nearly half a century of contributions to a stunning variety of subjects in cosmology, physics, and astronomy.  This includes pioneering work on the cosmic microwave background and ideas that have motivated a variety of the most significant current experimental efforts to detect dark matter.  Silk currently works on a broad array of subjects, including dark matter, the physics of black holes, inflation, and galaxy formation.

Danielle Speller

Speller is a researcher in experimental nuclear and particle astrophysics. Her work centers on understanding the nature of matter and mass through low-energy, cryogenic searches for physics beyond the standard model. Professor Speller is a collaborator on both the Cryogenic Underground Observatory for Rare Events (CUORE) and the Haloscope at Yale Sensitive to Axion Cold dark matter (HAYSTAC), as well as related R&D projects. Her graduate work was with the Super Cryogenic Dark Matter Search experiment (SuperCDMS).

Alex Szalay

Szalay’s career has spanned an enormous range, beginning with important early theoretical contributions to particle astrophysics and cosmic statistics.  He was the chief architect of the Sloan Digital Sky Survey Data Archive and has become known as one of the chief pioneers of big-data astronomy.  His interests in big data have evolved into an array of subjects within computational astrophysics and to areas of science well beyond astrophysics.  His current research includes work on the large-scale structure of the Universe, data-archiving and data-mining techniques, and the mechanisms for doing science with future cosmology surveys

Image source: ESO/M. Kornmesser (artist concept).

• Space & time

Understanding gravity—warps and ripples in space and time

Gravity allows for falling apples, our day/night cycle, curved starlight, our planets and stars, and even time travel ...

Expert reviewers

Professor Tamara Davis

School of Mathematics and Physics

The University of Queensland

Professor Dean Rickles

Professor of History and Philosophy of Modern Physics

The University of Sydney

Professor Susan Scott FAA

Professor of Theoretical Physics

Australian National University

• Isaac Newton described the effects of gravity, but didn’t propose a mechanism for how it worked
• Albert Einstein proposed that massive objects warp and curve the universe, resulting in other objects moving on or orbiting along those curves—and that this is what we experience as gravity
• This theory, general relativity, has led to a number of predictions that have held up to experimental testing
• One prediction of this theory is that ‘gravitational waves’ ripple through the universe, but Einstein thought they would be too small to detect
• In February 2016 the direct measurement of gravitational waves was announced. This provides us with a new method for exploring the universe
• In its current form, general relativity is incompatible with quantum mechanics—signalling that a shift in our understanding may be on the horizon

Take a moment to observe the effects of gravity. Lift your arm and feel how you are compelled to drop it again. Gravity is always there—it’s stable, it’s permanent, it’s unchanging. Or is it?

For hundreds of years we’ve been able to predict the effects of gravity. But we had no idea how it worked until Einstein stepped in, painting a strange and unintuitive picture. In Einstein’s view, gravity is far from a static, unchanging force—it is a fundamental part of the structure of the universe, which curves and twists and ripples as objects move and rotate and jostle about.

The predictions of Einstein’s theories have been validated time and time again. And now, 100 years after the formulation of his theory of gravity, another one of its predictions—gravitational waves—has been directly measured, despite Einstein’s belief that we’d never be able to do this.

In this topic we’ll explore Einstein’s dynamic vision of gravity, including the recently measured phenomenon of gravitational waves. If you’re unfamiliar with relativity GLOSSARY relativity The general idea that the results of experiments do not depend on the states of motion of observers , some of these concepts may boggle your mind. If so, we encourage you to keep pushing onwards, as it’s one of the greatest journeys in the history of science.

Let’s begin by looking at why Newton’s laws didn’t provide a complete picture of gravity.

Newton and the laws of gravity

Newton published one of the most celebrated works of science, the Principia , in 1687. In it, he described that the force that pulls objects towards the ground is the very same force that underlies the motion of the planets and stars.

To come to this conclusion, Newton imagined taking an object far from the surface of Earth, and throwing it. If you throw it with too little momentum, it will fall towards Earth, captured by gravity like we are ourselves. If you throw it with too much momentum, it will speed away from the planet, beginning its journey into the reaches of space. But with exactly the right momentum, you can throw it so that it falls continuously around Earth, around and around in an eternal tug-of-war. The object tries to continue in the path you threw it, but gravity keeps on pulling it back in. With the right balance, the object is now in orbit around Earth—just like the moon, or like Earth around the sun.

Newton formulated this insight into a mathematical equation, known today as the law of universal gravitation. When combined with knowledge of geometry and Newton’s other equations of motion, we can use it to make predictions about the movement of the planets, or the paths of comets, or how much force is needed to get a rocket to the moon.

We acknowledge Newton not just because of his idea, but because he formulated that idea into an equation that made predictions with greater accuracy than ever before. But it wasn’t perfect—Newton’s equations produced some incorrect predictions, and, more importantly, he didn’t describe how gravity works the way it does. Newton was well aware of this when he said,

Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers. Isaac Newton

Distortions in space and time

More than 200 years after the  Principia was published, the world was still without an understanding of gravity’s mechanism. Enter Albert Einstein—a man who was to change the world in so many ways. But before we get to his work, we’ll have to take one more detour.

You can’t tell if you’re moving (at a constant rate)

In 1632, even before Newton published his now-famous work, Galileo Galilei wrote about the relative motion of objects familiar in his time: ships. 

If you are in a closed room on a ship sailing at a constant speed and the ride is perfectly smooth, objects behave as they would on land. There’s no physical experiment you could conduct to tell whether you’re moving or stationary (assuming you’re not peeking out of a porthole). This is the core idea behind relativity, and is the same reason why we don’t feel our planet’s movement around the sun, or our solar system’s movement through the galaxy.

Space and time are linked

Almost 300 years after Galileo, Einstein pondered the consequences of relativity in the context of an important factor: the speed of light. He wasn’t the only person who was pondering these topics—other physicists at the time were aware that there were unanswered questions on this front. But it was Einstein who formulated a theory—his theory of special relativity GLOSSARY special relativity Einstein’s theory regarding the relationship between space and time, the constancy of the speed of light, and the fact that physics must be the same in all uniform states of motion —to explain existing phenomena and create new predictions. At first, special relativity may  not seem to have much to do with gravity, but it was an essential stepping stone for Einstein for understanding gravity.

Moving clocks tick more slowly

Experiments during Einstein’s time had shown that the speed of light appeared to be constant. No matter how fast you try and catch up, light always appears to zip away from you at almost 300,000,000 metres per second.

Why is this important? Well, let’s imagine constructing a clock out of light itself. Two mirrors are placed opposite each other, and a “tick” of the clock is the time it takes for a particle of light to travel from one side to the other and back.

Imagining a light clock

(in slow motion)

“Ticks” of the clock

Now let’s imagine that your friend, who’s on a spaceship zipping past Earth, has one of these clocks. For your friend, the clock seems to be working normally—the particles of light travel up and down, as expected, and time proceeds in its usual fashion. But from your perspective, watching the ship pass by, the light is moving both up and down and to the side, with the ship. The light travels a longer distance with each tick.

Stationary vs moving light clocks

As seen from inside the spaceship, as seen by a stationary observer.

So if, for the space traveller, light travels at 300,000,000 m/s but only has to travel up and down; and to the Earthbound observer, light travels at 300,000,000 m/s, but must travel a longer, diagonal distance; then for the Earthbound observer, the clock takes longer to “tick”. 

This effect is called time dilation GLOSSARY time dilation The slowing down of time for one observer relative to another . The faster you travel through space, the slower you travel through time.

Perspective matters

But whose time is really slowed down? Is it the person on Earth, watching his friend zip past in her spaceship? Or the astronaut, who argues she ’ s staying still while the Earth flies by?

Strangely enough, both viewpoints are valid—but only while both are in constant motion.

To illustrate, let’s assume that when the astronaut left Earth, she and her friend were the same age. When she leaves, the spaceship accelerates away from Earth. When she returns, the spaceship decelerates to avoid a crash landing. In both leaving and returning, the spaceship changes its frame of reference GLOSSARY frame of reference The physical environment of an observer that involves their state of motion. A person travelling in one car is in a different frame of reference than someone travelling in a car going a different speed or direction, or a pedestrian at the side of the road, or someone travelling overhead in a plane, etc. , and our astronaut can feel the change of motion. Experiments conducted inside the spaceship during acceleration and deceleration would show that something’s changing. This breaks the symmetry of the situation, and when the spaceship lands back on Earth, our astronaut really will be younger than her Earthbound counterpart. 

The effects are only noticeable if they were travelling really, really fast—but it’s still true to say that when today’s astronauts and fighter pilots return from a high-speed mission, they will have aged a teeny-tiny bit less than the rest of us did during that mission.

The four dimensions of spacetime

Following from this, rather than thinking of three dimensions of space and one separate dimension of time, we can consider them as four dimensions of “spacetime”. The faster you travel through space, the slower you travel through time, and vice versa.

Moving objects contract in space

Another consequence of special relativity is that fast-moving objects appear to contract in size, in the direction of their motion. (And again, this gets flipped around depending on whose perspective you’re looking from.)

This follows from the distortion of time—after all, you can measure the length of something by the amount of space something travels through time (e.g. light-years, light-seconds). And while it’s tricky to imagine measuring the length of a moving object from someone else’s perspective, length contraction is a real, physical effect, and not just an outcome of imprecise measurements.

Unlike the age differences that can arise from time dilation, there are no residual effects due to length contraction once the moving object and the observer are reunited.

Understanding gravity

Einstein’s description of gravity leads to situations just as bizarre as special relativity—time travel included!

Acceleration and gravity can be indistinguishable

Imagine waking up in a spaceship, accelerating through space. Just as you’re pushed back in the seat of an accelerating car, the accelerating spaceship pushes you to the side opposite the one it’s accelerating towards. At a certain rate of acceleration, a set of scales could tell you that you weigh exactly the same as you do when you’re at home on Earth.

Is there any physical experiment you could do within the confines of your spaceship to tell whether you really were accelerating through space (assuming there were no windows to look out from), or if, instead, you were inside a spaceship stationary on the surface of Earth? Einstein said no—just as Galileo imagined the indistinguishability between a person inside a smooth-sailing ship (confined without windows) and a person on land, Einstein realised that the effects of acceleration and gravity were indistinguishable too. This is called the equivalence principle GLOSSARY equivalence principle The effects of being in a gravitational field are indistinguishable from the effects of being in an accelerated frame of reference .

Space warps under accelerated motion

Once Einstein had formulated the equivalence principle, gravity became less mysterious. He could apply his knowledge of acceleration to better understand gravity.

You may know that acceleration doesn’t always mean a change in speed, like when you speed up in a car, pushing you to the back of your seat. It can also mean a change in direction, like when you go round a roundabout, causing you to lean towards the side of the car. 

To extend this further, let’s imagine a cylindrical carnival ride where you and your fellow passengers are pinned to the outer surface. The cylinder is rotated faster and faster until the acceleration eases and the movement stays constant. But even once the speed is constant, you still feel the accelerated motion—you feel yourself being pinned to the outer edge of the ride.

If this spinning ride was large enough and moving at a fast enough rate, you’d start to notice some bizarre effects inside the ride itself, not just from the point of view of someone standing outside it. 

With every rotation, those at the edge of the ride travel the full circumference of the cylinder—while at the very centre, there’s hardly any movement at all. So if someone stood in the very centre of the ride (perhaps held by a brace, stopping them from falling to the edge), they would notice all those weird effects we saw under special relativity—that those on the edge will contract in length, and their clocks will tick at a slower rate.

Gravity is the curvature of spacetime

The equivalence principle tells us that the effects of gravity and acceleration are indistinguishable. In thinking about the example of the cylindrical ride, we see that accelerated motion can warp space and time. It is here that Einstein connected the dots to suggest that gravity is the warping of space and time. Gravity is the curvature of the universe, caused by massive bodies, which determines the path that objects travel. That curvature is dynamical, moving as those objects move.

This theory,  general relativity GLOSSARY general relativity Einstein’s theory of gravity , predicts everything from the orbits of stars to the collision of asteroids to apples falling from a branch to the earth—everything we have come to expect from a theory of gravity.

Spacetime grips mass, telling it how to move... Mass grips spacetime, telling it how to curve Physicist John Wheeler

The success of general relativity

Just as Newton’s formulation of the laws of gravity were valuable because of their predictive power, the same goes for those of Einstein. To date, his predictions—as strange as they may sound—have all stood the test of time. 

Gravity bends light

Although light seems to be pretty unfazed by gravity, Einstein predicted that this is not always the case. Light travels through spacetime, which can be warped and curved—so light should dip and curve in the presence of massive objects. This effect is known as gravitational lensing GLOSSARY gravitational lensing The bending of light caused by gravity .

This effect was first observed in 1919, analysing starlight during a solar eclipse. Astronomers found that starlight that passed very close to the sun was very slightly offset in position compared to the same starlight when measured at night. Today, with more powerful telescopes, we ’ve found evidence of gravitational lensing all over the place—including entire galaxies that distort the light of other galaxies.

Gravity slows the passage of time

Similar to how the passage of time is changed under special relativity, general relativity predicts that massive objects will also dilate time. The more massive the object, the more noticeable the effect.

This was used as a plot device in the 2014 science-fiction film Interstellar, but it’s not fiction. Gravitational time dilation has been confirmed via experiments of extremely precise atomic clocks that lose sync with other clocks depending how close or far away they are from the Earth’s surface. So while we’re yet to send a crew of astronauts near a black hole GLOSSARY black hole Extremely massive and dense objects with so much gravity that not even light can escape , we know that being in the vicinity of such a massive object would mean that when they’d return, they will have aged noticeably less than the rest of us.

GPS technology needs offsetting

While the application of Einstein’s theories may seem so far from everyday experience, consider this: satellite positioning technology—whether used on your phone, or by pilots in planes, or for logistics and industry the world over—would not work without our understanding of relativity.

The Global Positioning System (GPS) consists of satellites that orbit Earth 20,000 km above ground at a speed of around 14,000 km/h. On board each satellite is an atomic clock, and your position on the planet can be determined by checking the time broadcast by the satellites above you and comparing those times against the known position of each satellite. Relativity tells us that these clocks will tick more slowly than those on Earth—so if we weren’t able to correct for these differences, we wouldn’t be able to pinpoint our location on Earth to an accuracy down to a few metres. Seen another way, the accuracy of GPS acts as further proof of Einstein’s theories.

Moving and rotating objects make additional twists and warps in spacetime

Two more predictions of general relativity are the geodetic effect GLOSSARY geodetic effect The additional distortion of spacetime caused by moving objects and the frame-dragging effect GLOSSARY frame-dragging effect The additional distortion of spacetime caused by rotating objects . Both effects have been confirmed by a range of experiments , including the Gravity Probe B satellite. Equipped with extremely sensitive gyroscopes, this satellite measured the tiny twists and warps in spacetime made by Earth as it moves and rotates through space.

The universe ripples as objects move and collide

Since the curvature of spacetime is dynamical, moving objects should create ripples in space that permeate through the universe. Most of these ripples are too small to notice, but the more extreme the event, the higher the chance we can detect it. These ripples have been named gravitational waves, and we’ve found them.

Gravitational waves

Echoes of cataclysm from far away.

Imagine two very massive objects, such as black holes. If those objects were to collide, they could potentially create an extreme disturbance in the fabric of spacetime, moving outwards like the ripples in a pond. But how far away could such waves be felt? Einstein predicted that gravitational waves existed, but believed they would be too small to detect by the time they reached us here on Earth.

So it was with great excitement that on February 11 2016, the scientific community was abuzz with the announcement that a gravitational wave GLOSSARY gravitational wave Ripples in spacetime that propagate outwards like waves had been detected. We needed instruments capable of detecting a signal one-ten-thousandth the diameter of a proton (10 -19 meter). That’s exactly what the Laser Interferometer Gravitational-Wave Observatory (LIGO) equipment, operated by the California Institute of Technology and the Massachusetts Institute of Technology, can do. 

The LIGO experiment

In the LIGO experiment, a laser is directed into a large tunnel structure. The laser beam is split so that half of it travels down one of the 4-kilometre-long ‘arms’, and the other half travels down the other 4-kilometre arm at the exact same time. At the end of each arm, a mirror reflects the light from the laser back to where it came from, and the two beams merge back into one. 

Normally, the laser beams should recombine at exactly the same time. But if a gravitational wave comes rippling through space while the detectors are switched on, that ripple will stretch one arm of the L-shaped structure before stretching the other. The gravitational wave distorts the passage of the light, resulting in a particular kind of interference light pattern detected at the end.

On 11 February 2016, the LIGO teams announced the direct discovery of a gravitational wave matching the signal predicted from the collision of two black holes.

If the February 2016 news of the discovery of gravitational waves caused you to feel a sense of déjà vu, it’s probably because of a similar announcement in March 2014. Astronomers at the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope had supposedly discovered evidence of gravitational waves, but that evidence was later recalled, as it did not pass closer scrutiny.

The methods used in in the BICEP2 study were very different from those used in the LIGO experiment. Rather than listening for the direct signal of a gravitational wave as it rolled past our planet (the setup at LIGO), the BICEP2 team analysed swirls of light within the cosmic microwave background GLOSSARY cosmic microwave background The faint remnant of light that permeates the whole universe, left over from the heat of the big bang . They theorised that during the early expansion of the universe, tiny gravitational waves would have disturbed the light around them, which would have been amplified into a larger pattern as the universe expanded, coalescing into these patterns in the cosmic microwave background.

The announcement was made before the BICEP2 data went through more rigorous analysis and feedback from their colleagues. The experiment’s claims were questioned, and then, later, retracted. Instead, it looked likely that the patterns of light were not caused by gravitational waves, but instead by the dust inside our own galaxy as it interacted with magnetic fields.

Gravitational wave astronomy

The successful LIGO experiment has ushered in a new era of astronomy. Before now, astronomers have largely focused on the study of the electromagnetic spectrum (including light and radio waves). We’ve been able to discover a huge amount about our universe through that work, but now we have a brand new way to study the universe. 

The discovery of gravitational waves gives astronomers a new ‘sense’ with which to explore the universe, and so there will almost certainly be surprises ahead. What we do know is that this technique will allow us to better understand the most massive objects in the universe such as black holes, neutron stars, and supernovae; and it will provide us with a new window to study how the universe formed.

Is our understanding complete?

While Einstein’s theory of gravity has been validated by experiment after experiment, this does not mean our understanding is complete. In fact, we know that something’s not quite right. 

One unanswered question is whether or not gravity is propagated by the graviton—the proposed (but so-far undetected) particle responsible for gravitational interactions. Even more pressing, we know that general relativity is, in its current form, incompatible with the other pillar of modern physics: quantum mechanics GLOSSARY quantum mechanics A branch of physics that explains how the universe works on incredibly tiny scales (atomic and subatomic) . This is an indication that one or both theories are incomplete, or that we’re missing some other key component.

Whether or not Einstein’s theory of gravity will remain unchanged is not known. But it has produced many unexpected, unintuitive predictions that have been confirmed again and again for over a hundred years. That’s the sign of a great scientific theory—it makes predictions that may not be able to be proven at the time, but stand up to rigorous testing. This has been one of the greatest journeys in the history of science, involving not just Newton and Einstein, but thinkers and doers all around the world who have worked to put these theories to the test.

Even so, the schism between relativity and quantum mechanics remains. As for what’s next, no one knows with certainty. However, there are a few theories—stringy, loopy, multi-dimensional theories—unproven but with promise of becoming the next milestone in understanding our cosmos.

The dark stuff of our universe

Exploring the unknown with the square kilometre array, is earth safe from asteroids and comets.

• solar system

How (and why) do NASA researchers simulate microgravity on Earth?

All aspects of our lives are affected by gravity. Muscles develop to push against the force of gravity. Sports rely on balls being pulled back to Earth. Cyclists fight against it to climb mountains.

What if we didn’t have to contend with gravity? And what can we learn by studying phenomena unencumbered by it? That’s what NASA researchers aim to find out.

Removing the effects of gravity can enable researchers to answer important scientific questions and study how humans can safely stay longer in space. For example, the shape of flames on Earth is formed by heated, less dense air rising, which is due to gravity. In space, flames burn as spheres . To better understand the core principles of combustion on Earth and learn how to keep crews safe on deep space missions, NASA’s Biological and Physical Sciences (BPS) Division studies flames in microgravity. While the International Space Station provides a platform for long-duration microgravity studies, BPS scientists can also simulate short-term microgravity on Earth.

Why simulate microgravity?

Although platforms like the space station have made long-duration microgravity accessible, launching research into orbit still takes a significant investment of time and money. Researchers often only have one shot at success and not much control over the study once it is loaded onto the rocket.

Simulating microgravity on Earth is much lower cost and risk. Researchers can easily perform many versions of an experiment and be more hands on with the work, enabling them to gather data quickly.

While simulated microgravity can only last for a short time and does not perfectly replicate the space environment, it is a great testing grounds for studies that might later fly aboard the International Space Station. Experiments can be refined on Earth before committing to launching it to the orbiting laboratory. For example, the BPS-sponsored Ring Sheared Drop investigation, which studies amyloids and fibrils associated with diseases such as Alzheimer’s, used parabolic flights to test its equipment before launching the experiment to station.

How to simulate microgravity

Important tools for simulating microgravity close to Earth include drop towers, parabolic flights, and suborbital flights.

Drop Towers

Time in microgravity: ~5 seconds

These ground-based Towers support the dropping of experiments with low drag from air, due to creating a vacuum in the tower before the drop and enable a few seconds of microgravity.

Parabolic Flights

These plane flights — also known as “vomit comets” — follow a steep up and down pattern, creating a microgravity environment at the top of the hills of the flight. This is the same effect as when a rider temporarily feels weightless on a roller coaster and is experiencing reduced gravity.

Suborbital Flights

Time in microgravity: 3-4 minutes

Rockets carrying science experiments follow the same parabola as the airplane, but because they fly much higher, the microgravity time is extended.

NASA employs a variety of microgravity platforms to advance scientific research efficiently and cost-effectively.

There is, however, no substitute for launching research to space. Space stations allow for “unlimited” access to microgravity, which enables researchers to study phenomena for longer periods of time and gather critical data that could lead to transformational discoveries. Together, these research platforms ensure NASA possesses the information needed to go farther and stay longer in deep space.

Learn more:

Why Do Science in Microgravity?

Parabolic Flights Advance Space Technologies for Gesture Control, Propellant Gauging, and Mars Sample Return Capabilities

5 Hazards of Human Spaceflight

NASA’s Biological and Physical Sciences Division pioneers scientific discovery and enables exploration by using space environments to conduct investigations not possible on Earth. Studying biological and physical phenomenon under extreme conditions allows researchers to advance the fundamental scientific knowledge required to go farther and stay longer in space, while also benefitting life on Earth.

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Science News

Galileo’s famous gravity experiment holds up, even with individual atoms.

Different types of atoms fall with the same acceleration due to gravity

Individual atoms fall at the same rate due to gravity, scientists report, reaffirming a concept called the equivalence principle.

vchal/iStock/Getty Images Plus

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By Emily Conover

October 28, 2020 at 6:00 am

According to legend, Galileo dropped weights off of the Leaning Tower of Pisa, showing that gravity causes objects of different masses to fall with the same acceleration. In recent years, researchers have taken to replicating this test in a way that the Italian scientist probably never envisioned — by dropping atoms.

A new study describes the most sensitive atom-drop test so far and shows that Galileo’s gravity experiment still holds up — even for individual atoms. Two different types of atoms had the same acceleration within about a part per trillion, or 0.0000000001 percent, physicists report in a paper in press in Physical Review Letters .

Compared with a previous atom-drop test, the new research is a thousand times as sensitive. “It represents a leap forward,” says physicist Guglielmo Tino of the University of Florence, who was not involved with the new study.

Researchers compared rubidium atoms of two different isotopes, atoms that contain different numbers of neutrons in their nuclei. The team launched clouds of these atoms about 8.6 meters high in a tube under vacuum. As the atoms rose and fell, both varieties accelerated at essentially the same rate, the researchers found.

In confirming Galileo’s gravity experiment yet again, the result upholds the equivalence principle, a foundation of Albert Einstein’s theory of gravity, general relativity. That principle states that an object’s inertial mass, which determines how much it accelerates when force is applied, is equivalent to its gravitational mass, which determines how strong a gravitational force it feels. The upshot: An object’s acceleration under gravity doesn’t depend on its mass or composition.

So far, the equivalence principle has withstood all tests. But atoms, which are subject to the strange laws of quantum mechanics, could reveal its weak points. “When you do the test with atoms … you’re testing the equivalence principle and stressing it in new ways,” says physicist Mark Kasevich of Stanford University.

Kasevich and colleagues studied the tiny particles using atom interferometry, which takes advantage of quantum mechanics to make extremely precise measurements. During the atoms’ flight, the scientists put the atoms in a state called a quantum superposition, in which particles don’t have one definite location. Instead, each atom existed in a superposition of two locations, separated by up to seven centimeters. When the atoms’ two locations were brought back together, the atoms interfered with themselves in a way that precisely revealed their relative acceleration.

Many scientists think that the equivalence principle will eventually falter. “We have reasonable expectations that our current theories … are not the end of the story,” says physicist Magdalena Zych of the University of Queensland in Brisbane, Australia, who was not involved with the research. That’s because quantum mechanics — the branch of physics that describes the counterintuitive physics of the very small — doesn’t mesh well with general relativity, leading scientists on a hunt for a theory of quantum gravity that could unite these ideas. Many scientists suspect that the new theory will violate the equivalence principle by an amount too small to have been detected with tests performed thus far.

But physicists hope to improve such atom-based tests in the future, for example by performing them in space, where objects can free-fall for extended periods of time. An equivalence principle test in space has already been performed with metal cylinders , but not yet with atoms ( SN: 12/4/17 ).

So there’s still a chance to prove Galileo wrong.

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Quantum Gravity Unveiled – Scientists Crack the Cosmic Code That Baffled Einstein

By University of Southampton March 8, 2024

Researchers have developed a method to measure gravity at a microscopic level, marking a significant advancement in understanding quantum gravity. Credit: SciTechDaily.com

Physicists successfully measure gravity in the quantum world, detecting weak gravitational pull on a tiny particle with a new technique that uses levitating magnets, putting scientists closer to solving mysteries of the universe.

Scientists are a step closer to unraveling the mysterious forces of the universe after working out how to measure gravity on a microscopic level.

Experts have never fully understood how the force discovered by Isaac Newton works in the tiny quantum world.

Even Einstein was baffled by quantum gravity and, in his theory of general relativity, said there is no realistic experiment that could show a quantum version of gravity.

A Breakthrough in Quantum Gravity

However, physicists at the University of Southampton, working with scientists in Europe, have now successfully detected a weak gravitational pull on a tiny particle using a new technique.

They claim it could pave the way to finding the elusive quantum gravity theory.

The experiment, published in the Science Advances journal, used levitating magnets to detect gravity on microscopic particles – small enough to border on the quantum realm.

Artist impression of the quantum experiment. Credit: University of Southampton

Pioneering Gravity Research

Lead author Tim Fuchs, from the University of Southampton, said the results could help experts find the missing puzzle piece in our picture of reality.

He added: “For a century, scientists have tried and failed to understand how gravity and quantum mechanics work together.

“Now we have successfully measured gravitational signals at the smallest mass ever recorded, it means we are one step closer to finally realizing how it works in tandem.

“From here we will start scaling the source down using this technique until we reach the quantum world on both sides.

“By understanding quantum gravity, we could solve some of the mysteries of our universe – like how it began, what happens inside black holes, or uniting all forces into one big theory.”

The rules of the quantum realm are still not fully understood by science – but it is believed that particles and forces at a microscopic scale interact differently than regular-sized objects.

Academics from Southampton conducted the experiment with scientists at Leiden University in the Netherlands and the Institute for Photonics and Nanotechnologies in Italy, with funding from the EU Horizon Europe EIC Pathfinder grant (QuCoM).

Their study used a sophisticated setup involving superconducting devices, known as traps, with magnetic fields, sensitive detectors, and advanced vibration isolation.

It measured a weak pull, just 30aN, on a tiny particle 0.43mg in size by levitating it in freezing temperatures a hundredth of a degree above absolute zero – about minus-273 degrees Celsius .

Expanding the Horizons of Quantum Research

The results open the door for future experiments between even smaller objects and forces, said Professor of Physics Hendrik Ulbricht also at the University of Southampton.

He added: “We are pushing the boundaries of science that could lead to new discoveries about gravity and the quantum world.

“Our new technique that uses extremely cold temperatures and devices to isolate the vibration of the particle will likely prove the way forward for measuring quantum gravity.

“Unravelling these mysteries will help us unlock more secrets about the universe’s very fabric, from the tiniest particles to the grandest cosmic structures.”

Reference: “Measuring gravity with milligram levitated masses” by Tim M. Fuchs, Dennis G. Uitenbroek, Jaimy Plugge, Noud van Halteren, Jean-Paul van Soest, Andrea Vinante, Hendrik Ulbricht and Tjerk H. Oosterkamp, 23 February 2024, Science Advances . DOI: 10.1126/sciadv.adk2949

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31 comments on "quantum gravity unveiled – scientists crack the cosmic code that baffled einstein".

Unravelling these mysteries will help us unlock more secrets about the universe’s very fabric, from the tiniest particles to the grandest cosmic structures. Please answer: 1. Is what was observed in the experiment the physical reality of quantum mechanics? 2. Are topological vortices and their antivortices gravitational fields? 3. Does a topological vortex have mass? 4. What is the physical essence of mass? 5. Isn’t it ugly to face the spin of topological vortices like an ostrich with its back to do? 6. Are so-called academic journals (such as Physical Review Letters, Nature, Science, etc.) scientific and honest? 7. Why are opposed and hated the following statements by some people and so-called academic journals? and so on.

Today, we have already entered the era of the internet. With the help of artificial intelligence and big data, discussions on scientific knowledge have become open and transparent. However, a group of editors of so-called academic journals (such as Physical Review Letters, Nature, Science, etc.) are mystifying themselves. They only care about their own so-called sufficiently high priority rating, general significance, discipline, novelty, etc., and do not care about what science and pseudoscience are.

Science and pseudoscience are not determined by a publication, an organization or a person, nor by you or me, but by mathematics the final say. Physical models must be based on mathematics or mathematical models in order to be scientific, convincing, and in accordance with natural laws.

The branch of mathematics known as topology has become a cornerstone of modern physics. The perpetually swirling topological vortices defy traditional physics’ expectations. A physical properties of topological vortices is their to spontaneously begin to change periodically in time, even though the system does not experience corresponding periodic interference. Therefore, in the interaction of topological vortices, time is both absolute and relative，and physics often requires treating space and time at the same level.

Low-dimensional spacetime matter is the foundation of high-dimensional spacetime matter. Low-dimensional spacetime matter (such as topological vortex) can form new material structures and derive more complex physical properties via interactions and self-organization. It is extremely wrong and irresponsible to imagine low dimensional spacetime matter using high-dimensional spacetime matter.

Science must follow mathematical rules. For example, the Standard Model (SM) is considered to be one of the most significant achievements of physics in the 20th century. However, the magnetic moment of μ particle is larger than expected, revealed by a g-2 experiment at Fermilab, suggests that the established theory (such as SM) of fundamental particles is incomplete. Furthermore, the SM omitting gravitation, it not involved the time problem and when the particle movement starts. Mathematics is the foundation of science. Physics must respect the scientific nature of mathematics and mathematical models. The SM must be based on mathematical models in order to be scientific, convincing, and in line with natural laws.

I hope researchers are not fooled by the pseudoscientific theories of the Physical Review Letters (PRL), and hope more people dare to stand up and fight against rampant pseudoscience. The so-called academic journals (such as Physical Review Letters, Nature, Science, etc.) firmly believe that two high-dimensional spacetime objects (such as two sets of cobalt-60) rotating in opposite directions can be transformed into two objects that mirror each other, is a typical case of pseudoscience rampant. If researchers are really interested in Science and Physics, you can browse https://zhuanlan.zhihu.com/p/643404671 and https://zhuanlan.zhihu.com/p/595280873 .

The simplest explanation is that your ideas are crankery. Occam’s razor and all that. As Pauli once put it, you aren’t even wrong.

BTW, math is not the foundation of science. That is the mistake the ancient Greeks made, that you can start from self evident axioms and logically deduce your way to understanding the entire universe.

It didn’t work and for a good reason. Math is a description. It can describe things that are right as well as things that are not. The decider is observation and experiment. Nature will tell you who she is. But if you try to tell nature who she is supposed to be, that’s the short road to exploding space shuttles.

If you’re looking at math, you already missed the physics. Physical reasoning is what you use to get to the right representation and that is always based on a deep knowledge of the existing data on the phenomena.

Very good! If you’re looking at math, you already missed the physics. The pride of today’s physics. A proud pupil of Physics Review Letters (PRL).

You can go home now. Please follow the advice of the Physical Review Letters (PRL) to have your father and mother rotate in opposite directions, so that they can be observed as two things that mirror each other. You don’t have to tell me if your observation is laughing or crying.

@Bao-hua ZHANG: pjcamp is correct, you are not even wrong. You make claims on science which is wrong (say, that “topological vortices” are relevant for quantum field theory as such).

And then that general claim is made you don’t try to point to counter examples (but how could you), you simply resort to pleading for a stop of criticism and to name calling. (Your parents would be ashamed of you. :-/)

Sorry! It’s just a simple children’s game. Your understanding goes beyond the thinking of adults.

Why does anything quantum bring out the crazies over here at scitech? It’s a simple experiment with simple to understand results. The interesting but wi) be as they progress down to truly quantum sizes and scales, if the theories hold up or not. No need to bring in quantum vortecies and to question all of reality – yet.

Please answer: 1. What is the difference between science and pseudoscience? 2. What is the basis for mathematics to become the language of science? 3. Does mathematical models have guiding significance for physical reality? 4. What is the difference between mathematical models and physical reality in two-dimensional spacetime? 5. Are topological vortices two-dimensional spacetime matter? 6. Is the spin and symmetry of topological vortices scientific? 7. Is the result always the same when observing the same object from different perspectives? 8. Is the pattern observed by color blindness the same as that of a normal person? 9. Is scientific experimentation omnipotent? 10. Are the quantum scales described by quantum mechanics necessarily a high-dimensional spacetime object? 11. Is the spin of a topological vortex left-handed or right-handed? and so on.

If you are really interested in science and physics, you can browse https://zhuanlan.zhihu.com/p/479457051 and the comments on the https://scitechdaily.com/quantum-revolution-redefining-physics-with-fractional-charges/ .

Please don’t post pseudoscience links.

I’ll admit though that your reaction of reposting your initial conspiracy theory on science (regarding the publishing system) in a more rational form is two steps removed from your earlier attacks on the messenger.

But it doesn’t respond to the observation of crankery.

[The summary answer to that series of questions is testing, including that science as a tool is well tested.]

Very good! Outstanding students and talents in contemporary physics.

Every practical with a charge state has gravity, gravity is the electric field energy produced, that’s why dark matter has no signature for display.

Sorry I mean Particle

No it isn’t.

Electromagnetism can either attract or repel. Gravity only attracts. Electromagnetism is a vastly stronger force than gravity. I could go on. They aren’t even close to being the same thing.

WRONG!!! Only stupid people say the Gravity is the weakest of the 4 forces (now 3 cause Einstein says gravity isn’t a force LMAO) based on the illogical and nonsensical reasoning that wheneva u lift up off a chair, thats u overcoming the full gravitational force of the earth LMAO HAHAHAHAHA!!! Whoeva says this is a moron!!! U CANNOT OVERCOME A FORCE THAT U R COMPLETELY IMMERSED INSIDE OF!!!! But physicts aren’t always the most logical as they rely on theoretical math instead of logical/rational reasoning skills to determine truth!

Anyone who even TRIES to make such a bold claim that is backed up by nothing and can only respond with “WRONG”, clearly has no idea how science works. Care to try again, with something that even remotely takes the form of science or a real hypothesis?

Gravity has to be the weakest force since it embeds all other interaction energy in a larger system (of gravity).

But we can just note that the reason why dipole forces do not rule the larger scale of the universe is because they cancel out (since the universe has zero net charge). Gravity curving space has to be unipolar – no antigravity mass “charge” – and so can sum to larger forces and eventually create black holes. (Though they need electromagnetism for it, dark matter do not collapse to black holes.)

Note though that space is on average flat, testifying to gravity weakness.

> “now 3 cause Einstein says gravity isn’t a force” This guy is my new favorite quack because he implies Einstein’s opinions on gravity are recent. Like Einstein popped up with his newfangled opinion on gravity earlier this month to weigh in. Maybe he read about it on CNN.

Measuring such a small gravitational force is certainly a technical accomplishment, but I have seen nothing in stories about this that demonstrate gravity exists in discrete quanta.

There’s no theory here, only an observation. Meaning the title is a lie when it claims scientists to have “Cracked the Cosmic Code” That means this article is click bait and scitechdaily has sold their integrity for a dirty buck.

No, it just means the site has a less than ideal title editor.

I don’t get it. 0.43 mg is huge, about the size of a fruit fly. A dead fruit fly will fall to the ground, demonstrating gravity’s effect on it. What does this experiment show that is different?

They are using a new tech ique to measure the gravitational force down to the smallest amount, yet. The point, as stated in the article, is not that they detected gravity, but that they even COULD detect the gravitational signal. Next step is making it smaller and refining the analysis until it truly does reach the quantum scale.

“Scientists Crack the Cosmic Code That Baffled Einstein”

Not really, all they offer observationally is MOND and no quantum gravity anomalies are due to MOND, that’s for sure.

? I don’t think you read the paper. It starts:

“Einstein’s theory of general relativity (GR), our widely accepted theory of gravity, has seen different experimental confirmations (1, 2) by observing massive astronomical objects and their dynamics, most recently by the direct observation of gravitational waves from the merger of two black holes (3) and the imaging of a black hole by the event horizon telescope (4), as well as dedicated satellite missions for testing the basic principle of GR—the equivalence principle (5) and frame dragging effects (6).”

MOND and similar alternatives died long since with the first multimessenger observation of a neutron binary merger. [“Troubled Times for Alternatives to Einstein’s Theory of Gravity”, Katia Moskvitch, Quanta Magazine, 2018] They shouldn’t be mentioned except when fringe scientists float a theory most consider rejected by observation.

Comment was about the sellout crazy article title. Your GR sales PR is likewise always unreadable.

GR significantly underestimates frame dragging effects because (as is well-known) GR is not quantizable and says nothing reasonable about quantizing gravity.

GR fails to express emergence of cooled nucleonic gravitational retro-reflectivity and fails to conserve an ultralow rate of angular momentum. because, again, GR is not quantizable. Nonetheless there’s clearly an over-controlling global gravity pride cartel that among other things pretends GR’s gravitational time-rate shifting is validated in GPS when actually it’s not but of course most military people won’t mind that popularizers are funded to get it wrong all the time.

Unfortunately the experiment is not very convincing yet. They use a small mass and get 35 % of the modeled signal with lots of noise. It would be more convincing if they started at larger masses for both test and outside mass and run a series of experiments to see how the huge discrepancy scales.

The article does not discuss development of the field much. But a straightforward effective quantum field theory has been developed long ago and is consistent with general relativity except on highest energy Planck scales (where both theories break down). http://www.scholarpedia.org/article/Quantum_gravity_as_a_low_energy_effective_field_theory

The potential problem with these theories seem to lie elsewhere. They are both effective and so need observations to pin down parameters, instead of being independent on observation as some would like to see. (But that is an odd requirement on scientific theories.)

The scale (size ) is the important part of the experiment.

This is one of the best Gravity formula using M theory. 2019 Meeting of the Division of Particles & Fields of the American Physical Society Author: John Brandenburg The GEMS ( GEM Super) Unification Theory is based on simple physical models yet appears to validate the well-known mathematical path of beginning with the Hilbert Action principle and then expanding it to include first 1 hidden dimension after KK ( Kaluza-Klein), going from 4 dimensional Minkowski space where the Hidden 5th dimension is assumed to “deploy”to some much larger ideal size from the Planck length, M -> MxS1 and then in a similar process , acquiring a new dimension, proposed by Wolfgang Pauli, so that the result is M x S2 satisfying a SO(3) symmetry. The hidden dimensions in this theory are associated physically with electric charge and finally quark “color”charge in the S2 phase. The theory begins with a physical model of Gravity fields based on the “ExB” drift of plasma physics [1] and results in the covariant formula. Notably, the theory results in a formulas for “G”, the Newton Gravitation constant , and the proton mass, that are highly accurate and easily derived from the requirement that the deployment of the K-K hidden dimension separates both EM and gravity and electrons and protons from each other and the Planck Mass, MP, with the 5th dimension deployment from the Planck scale. A crucial parameter in the GEM theory is the Lepton-Baryon end-member (proton-electron) mass ratio :σ = (mp/me)1/2 = 42.8503…

Measuring a gravitational effect at the quantum level may be an impressive achievement. But it still leaves us a long way from having a comprehensive quantum theory that includes gravitation. It does not even guarantee that there can be such a theory. I regard the title of this article as being rather extravagant clickbait.

Note also that the effect they measured was not even close to the quantum level.

Portable quantum gravitometers are apparently available on the market now, as far as I know, and they measure the difference between entangled atoms divided into taking different paths, which some people apparently like to pretend means the atoms are individually split, Young’s particle-style (particle count/energy non-accountant version), into two parts to follow two different gravitational paths for comparisons. A lot of people apparently would also like to memory-hole that little quantum gravitometer reality but all they’ve been able to do so far is spook it up with entanglement woo, although it’s nothing more than a gravity field path difference that is slowing different individual phase-synced atoms differently.

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Artificial gravity: Definition, future tech and research

Artificial gravity could revolutionize space exploration and off-Earth tourism.

Creating artificial gravity

• Health effects
• Voyager space hotel

Additional resources

Bibliography.

Artificial gravity is the creation of an inertial force in a spacecraft, in order to emulate the force of gravity. This concept is often seen in but is not limited to science-fiction shows like "Star Trek", and researchers are currently working on methods to create artificial gravity in space. 

Not only would the creation of artificial gravity simplify the next era of space exploration, making tasks more straightforward, but it would also be crucial for potential space tourism.

The effects of microgravity in space can actually be harmful to humans, so as we look at longer crewed missions, including journeying to Mars , artificial gravity could be essential to our astronauts' health. 

Related: Is the origin of dark matter gravity itself?

In his 1905 theory of special relativity , Albert Einstein wrote that gravity and acceleration are actually indistinguishable. That means that in a rocket travelling at 31.19 feet per second (9.81 meters per second ) squared —  the downward acceleration of gravity here on Earth —  an astronaut would feel their body anchored to the floor just like it is on their home planet.

The problem is you can’t always be accelerating at this rate in space, especially in an orbiting space station. Fortunately, there is more than one form of acceleration — and by using centrifugal force we can generate something equivalent to gravity on Earth.

One possible way of creating artificial gravity in space is by utilizing a technology called an O’Neill cylinder. Named after the physicist who proposed them, Gerard O’Neill, this consists of a pair of massive cylinders that rotate in opposite directions, allowing them to be permanently directed toward the sun , replicating gravity.

Jeff Bezos , the owner of space exploration company Blue Origin , has proposed O’Neill cylinders as the basis of floating space colonies, enabling trillions of humans to live in orbit. 

Aside from being a long way from any kind of practical application, at 20 miles (32.2 kilometers) long and 4 miles (6.4 km) in diameter — designed to house several million people — O'Neill cylinders are way too big for most applications smaller than colonies in space.

Researchers at the University of Boulder Colorado have a smaller scale suggestion — rotating systems that could fit inside the rooms of spacecraft. 

While this wouldn’t provide artificial gravity for the whole craft or station, it would enable space travellers to retreat to a specific area and spend some time experiencing a gravitational field more like that of Earth. 

The system also uses centrifugal acceleration, replicating a gravitational field of 1G — the same as that on Earth — with astronauts lying down on a short-radius centrifuge for a quick spin. 

– China's Tiangong space station

– Is the origin of dark matter gravity itself?

– Laika the space dog: First living creature in orbit

Spinning astronauts might not be the ideal solution, however. As anyone who has ridden the teacups one too many times can tell you, this method comes with its own health effects. 

Another potential design for creating artificial gravity is a long spinning stick-like vehicle around 328 feet (100 metres) across with a nuclear reactor on one end and a crew compartment on the other for journeys to Mars. However, these have had engineering issues preventing their application. 

The health effects of microgravity

Establishing artificial gravity could be key to protecting the health of astronauts on long-term space missions. For five decades NASA’s Human Research Program (HRP) has studied the effects of microgravity on the human body.

They have found that deprived of the gravity of Earth weight-bearing bones lose on average 1 to 1.5% of mineral density every month of spaceflight. Muscle mass is lost more rapidly under microgravity conditions than on Earth.

In addition to these factors, during spaceflight, fluids in the human body can shift upwards putting pressure on the eyes that potentially lead to vision issues. 

The Voyager space hotel

The Voyager space station is a planned rotating wheel space station set to begin construction in 2025. Pioneered by the Orbital Assembly Corporation (OAC) Voyager will differ from the International Space Station in two key ways; it will be open to the public, and it will have artificial gravity.

Placed in a low-Earth orbit, the space hotel will rotate rapidly enough to generate artificial gravity for its 400 occupants. If the station is completed as currently planned it will become the largest man-made structure ever placed into orbit. 

The first steps of the project will include the creation of a prototype gravitational ring to improve that artificial gravity in space is viable. The 200-foot (61-meter) diameter ring will generate gravity equivalent to roughly 40% that of Earth's, or about the same as the gravity of Mars. 

For more information about artificial gravity check out " Artificial Gravity " by Gilles Clément and Angie Bukley. Check out more artificial gravity designs at the Orbital Assembly Corporation (OAC) .

• NASA, " Artificial Gravity ", March 2021. 
• NASA, " The Human Body in Space ", February 2021
• Theodore W. Hall, " Artificial Gravity in Theory and Practice ", 46th International Conference on Environmental Systems, July 2016. 
• National Space Society, " O’Neill Cylinder Space Settlement ", accessed May 2022. 
• National Space Society, " Stanford Torus Space Settlement ", accessed May 2022.
• Orbital assembly, " The Space Gravity Experience Is Here ", accessed May 2022. 
• Nikolas Martelaro, " Powering the Stanford Torus ", Stanford University, May 2017. 

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Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

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The quantum theory of gravitation, effective field theories and strings: Past and present

by Clare Sansom, SciencePOD

Gravity is one of four fundamental interactions. The most precise description of this force is still provided by Einstein's General Theory of Relativity, published in 1915, an entirely classical theory. This description sets gravity apart from the other three forces—strong, weak, and electromagnetism—all described by quantum fields. Therefore, any attempt to unify the four forces must depend on a description of gravity that uses the principles of quantum mechanics.

This has been an active area of theoretical physics since the 1930s. A historian and a physicist, Alessio Rocci from VUB in Brussels and Thomas Van Riet from KU Leuven in Belgium have set out a historical overview of the development of quantum theories of gravity to explain our current view on a future unified theory of the four forces. This work has been published in The European Physical Journal H .

Physicists began to investigate the quantum theory of gravitation in the 1930s, taking a perturbative approach, convinced that there should be no fundamental difference between the gravitational force and the other interactions. However, finding a description of the gravitational interaction according to the laws of quantum mechanics is still a very complex task.

Later in the century, Steven Weinberg, a pioneer of both effective field theory and the standard model of particle physics , began a process of cross-fertilization between these areas and the research area of quantum gravity that produced our current view on Einstein's theory. From the mid-1980s, string theory set up a possible framework to approach quantum gravity using a 'top-down' approach. The effective field theory approach to strong forces drove the development of the 'bottom-up' perspective, culminating in the mid-1990s.

Recently, physicists have started a new program called Swampland to overcome the criticism of string theory that arose in the 2000s. Van Riet says, "The ultimate hope is that the Swampland program can lead to general patterns with observational consequences."

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What Is Gravity, and How Does It Work?

Legend has it that Isaac Newton had the moment of inspiration that would lead to his theory of gravity when, on a warm afternoon, he saw an apple fall from a tree and wondered why it should fall down instead of up. (Some versions of the story have the apple falling and hitting poor Newton on the head.) He named his new hypothesis after the Latin gravitas , for "weight." The tale of Newton's bruised noggin may be apocryphal, but his interest in what makes things move—and especially what makes them fall —was very real. Newton had come home to stay when his university closed down due to a bout of bubonic plague, and he was looking for something to occupy his mind. In 1665, he found it, apple or no apple.

It took Newton, one of the world's greatest mathematical minds and, by all accounts, an irascible jerk, 20 years to articulate his thoughts on gravity to his satisfaction. His biggest problem? The question of whether the Earth's gravitational influence could extend all the way to the Moon.

Two hundred years later, the calculations that took humanity to the Moon were based on Newton's mechanics. But how does gravity work in the first place? What did Newton understand that was such a revolution?

Gravity: The Basics

Can someone just... explain gravity to me?

Let's start with a definition. Gravity, or gravitational attraction, is the tendency of mass to gather toward itself, drifting together even across great distances due to curvature in spacetime. This tendency allows the formation of stars, planets, galaxies, and black holes.

Standing on Earth's surface, the planet's mass creates a gravitational force sufficient to accelerate any object downward (toward the core of the planet, or perpendicular to the planet's surface) at 9.8 m/s²—that is, an additional 9.8 meters per second, each second. Everything experiences the same amount of gravity, but if you take a hammer in one hand and a feather in the other and drop them at the same time, the hammer will hit the ground first. Why? Drag (air resistance) opposes acceleration due to gravity. In a vacuum, such as on the Moon, both objects will hit the ground at the same time.

How does gravity work?

Gravity applies an effective force of mutual attraction to things with inertial mass, including physical matter and photons. The force of gravity is transmitted through spacetime at the speed of light, which creates wavefronts we can detect with special equipment like the LIGO gravitational wave detectors.

In classical (or "Newtonian") mechanics, which describes the motion of macroscopic objects (i.e., things larger than an atom, such as planets), gravity is sometimes called a central force . A central force is directed towards or away from a point called the center of force . Gravity, electrical charge, and magnetism are three examples of central forces. Centers of electromagnetic energy radiating inward or outward are known as poles.

Newton used a mathematical approach to gravity not unlike Coulomb had done with electrostatics, with a field that falls off as the inverse square of the distance between two objects. Looking at it this way, the gravitational force at a point can be expressed as a vector, with magnitude and direction.

How is gravity transmitted?

Christian Huygens, a contemporary of Isaac Newton, discovered that light carries energy. This suggests a force-carrying graviton as an obvious theoretical parallel to a photon. But where photons are the force carrier of the electromagnetic field, relativity frames gravity as an emergent consequence of the way inertial mass warps spacetime. Instead of requiring a force carrier, according to general relativity, what we think of as gravity is more like the idea of "downhill."

Massive or high-energy objects warp the mesh of spacetime, dragging it in toward themselves and creating a gravitational field of influence or "gravity well" from which it can be difficult to escape.

Central Forces

When matter is collected in one place, it forms a center of mass from which its inward-pointing field of gravitational influence extends. The force of attraction between two objects falls off as distance increases from the center of mass.

Objects under the influence of a gravitational field will move toward the field's center of gravity . Sometimes, as with the Sun and Jupiter, their mutual center of gravity or barycenter lies slightly outside one of the bodies; Jupiter is large enough that it drags the Sun in a little circle, centered slightly outside of the Sun's radius, as Jupiter makes each orbit.

On Earth, we have to contend with our own gravity well when we launch rockets and spacecraft; if a rocket isn't powerful enough to escape its gravity well, it will fall back to Earth. As matter becomes more and more dense, that effect becomes more pronounced. Black holes create a gravity well so deep that there's a threshold around black holes called an event horizon, a boundary in space marking the point of no return. Nothing inside the event horizon can escape from a black hole. Indeed, it's thought that the only thing that can ever escape a black hole's gravity is a frisson of virtual particles called Hawking radiation, thrown off every so often when subatomic symmetries align.

Sacred Geometry

Astronomers in ancient Greece noticed that the planets sometimes seem to move in retrograde across the sky, backward with respect to their normal orbits. This offended some astronomers' sense of cosmos , the orderliness of the universe. In a universe perfectly ordered by the hands of their gods, there was little room for irrational numbers or eccentric orbits.

In their attempt to reconcile their geocentric models with their empirical observations, they proposed the idea of epicycles: complex orbits that were neither circular nor elliptical, with planets dancing around the Earth in paths that look like geometric lace.

Geocentrism reigned unchallenged for more than two thousand years. Despite the repeated proposal of a heliocentric solar system over the millennia by scholars as respected as Leonardo da Vinci, heliocentrism wasn't taken seriously until the medieval era. However, the scientific consensus began to change in the 1500s. Nicolaus Copernicus developed a heliocentric model, backing up his argument with astronomical observations—and predictions that would confirm his model as correct or invalidate it. Galileo Galilei, using the newly invented refracting telescope, made and published observations showing that the planet Venus went through phases just like the Moon, and that Jupiter was orbited by its own moons.

Music of the Spheres

Then, Johannes Kepler put forth a solution to the problem of retrograde planets that would have satisfied even the strictest Pythagorean. Even with their orbits taking the "imperfect" shape of an ellipse, Kepler showed, a planet swept out an equal geometric area of its orbit over the same length of time, no matter where in its elliptical orbit it might be, nor how eccentric that ellipse. Kepler was a big believer in musica universalis , the music of the spheres; the idea that an inaudible mathematical harmony existed between the orbits of the planets was central to his Mysterium Cosmographicum .

In 1687, Isaac Newton published his opus, Philosophiæ Naturalis Principia Mathematica (Latin for Mathematical Principles of Natural Philosophy , but many affectionately call it just Principia for short), which combined his laws of motion with a new mathematical analysis—calculus!—that could replicate Kepler's empirical observations of the planets and their moons. In Principia , Newton proposed a law of universal gravitation that now bears his name. Newton's law of universal gravitation holds that any two bodies, no matter how far they may be separated in space, are attracted by a force proportional to their mass and inversely proportional to the square of the distance between them.

'Spooky Action at a Distance'

Yet the question remained: How could one planet affect another at such a great distance? Newton considered action at a distance to be, in his own words, "so great an Absurdity that I believe no Man who has in philosophical Matters a competent Faculty of thinking can ever fall into it." Familiar as he was with electrostatics, Newton's theory of gravitation didn't require what he viewed as an exotic, unnecessary transmission mechanism when the inverse-square law modeled gravitational attraction entirely well enough.

Newton was by no means in the scientific minority on the topic of action at a distance. Albert Einstein operated under some assumptions of aether theory when developing his theory of relativity. Einstein would eventually dismiss the notion of quantum entanglement between two particles as spukhafte Fernwirkungen (translated as "spooky action at a distance"). Likewise, Newton and others of his day believed there must be a transmission medium, such as the luminiferous aether, through which electromagnetic or gravitational forces could exert a force on bodies separated in space.

Quantum Gravity

What Einstein knew that Newton didn't is that the universe is permeated not by an aetheric substance made of molecules of some kind but by an invisible warp and weft of field lines along which forces such as gravity are transmitted. No aether is required to produce the effects described in Maxwell's laws of electromagnetism or to produce gravity as we understand it. Today, it looks like the graviton will go the way of the aether.

On the deepest level, our cosmos is governed by four fundamental forces or fundamental interactions: electromagnetism and gravity, whose reach appears unlimited, and the weak and strong nuclear forces, which constrain themselves to the smallest scale, the inner workings of the atom. We call them fundamental forces because when we try to answer how spacetime works under the hood, these four forces appear not to be reducible to simpler interactions.

The human understanding of gravity still has some problems. Chief among them is the difficulty of applying current models to the subatomic scale or to extremely high-energy environments such as black holes or the very early universe.

As technology advances, scientists' understanding of what the laws of physics will permit stays in a state of flux. Once fusion, which must surmount the Coulomb barrier, was an exotic fiction; now, it's an engineering problem. It may be the same with gravity and other phenomena on the quantum scale. Until then, we can all enjoy the view from where we stand—on the shoulders of giants.

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Resultados científicos revolucionarios en la estación espacial de 2023

What is microgravity.

Gravity is a force that governs motion throughout the universe. It holds us to the ground, and it keeps the moon in orbit around Earth and Earth in orbit around the sun. Many people mistakenly think that gravity does not exist in space. However, typical orbital altitudes for human spaceflight vary between 120 – 360 miles above Earth’s surface. The gravitational field is still quite strong in these regions, since this is only about 1.8 percent the distance to the moon. Earth’s gravitational field at about 250 miles above the surface is 88.8 percent of its strength at the surface. Therefore, orbiting spacecraft, like the space shuttle or space station, are kept in orbit around Earth by gravity. The nature of gravity was first described by Sir Isaac Newton, more than 300 years ago. Gravity is the attraction between any two masses, most apparent when one mass is very large (like Earth). The acceleration of an object toward the ground caused by gravity alone, near the surface of Earth, is called “normal gravity,” or 1g. This acceleration is equal to 32.2 ft/sec2 (9.8 m/sec2). If you drop an apple on Earth, it falls at 1g. If an astronaut on the space station drops an apple, it falls too. It just doesn’t look like it’s falling. That’s because they’re all falling together: the apple, the astronaut and the station. But they’re not falling towards Earth, they’re falling around it. Because they’re all falling at the same rate, objects inside of the station appear to float in a state we call “zero gravity” (0g), or more accurately microgravity (1×10-6 g.) Creating Microgravity The condition of microgravity comes about whenever an object is in free fall. That is, it falls faster and faster, accelerating with exactly the acceleration due to gravity (1g). As soon as you drop something (like an apple) it is in a state of free fall. The same is true if you throw something; it immediately starts falling towards Earth. But how does something fall around Earth? Newton developed a thought experiment to demonstrate this concept. Imagine placing a cannon at the top of a very tall mountain. Once fired, a cannonball falls to Earth. The greater the speed, the farther it will travel before landing. If fired with the proper speed, the cannonball would achieve a state of continuous free-fall around Earth, which we call orbit. The same principle applies to the space shuttle or space station. While objects inside them appear to be floating and motionless, they are actually traveling at the same orbital speed as their spacecraft: 17,500 miles per hour (28,000 km per hour)! Objects in a state of free fall or orbit are said to be weightless. The object’s mass is the same, but it would register “0” on a scale. Weight varies depending on whether you are on Earth, the moon or in orbit. But your mass stays the same, unless you go on a diet! NASA uses a variety of facilities to create microgravity conditions. The most famous way is by aircraft flying in parabolic arcs to create microgravity for tests and simulations that last 20-25 seconds. NASA’s Johnson Space Center, for example, operates a C-9 Low-G Flight Research aircraft also known as the “Vomit Comet.” It can make several trips each year to NASA Glenn in support of ground-based microgravity research. It’s predecessor, a KC-135 aircraft, was used to shoot the weightless scenes in the movie Apollo 13. The facilities most likely to be misconstrued as “anti-gravity chambers” are NASA’s drop towers. Specifically, NASA Glenn has the Zero Gravity Research Facility . It is a large shaft some 500 feet deep that allows test packages to free fall in a vacuum for just over 5 seconds. In this state of free fall, weightlessness (at or near microgravity) can be obtained. NASA Glenn also has a 2.2 second drop tower . You may have experienced weightlessness yourself without realizing it. Many amusement park rides create brief periods of free fall. Some rides that operate vertically without any applied forces are actually classified as free fall rides. Most roller coasters have a set of parabolic (rolling) hills that also create brief periods of weightlessness. For less adventurous people, a car ride on the rolling hills of a country road or jumping on a trampoline also create brief experiences of weightlessness.  

Meet our team

Our diverse team of deeply curious, analytic, and results-focused researchers are here to help.

Kevin Turpin

President of National Journal Group

Kevin Turpin II is president of National Journal Group, a research and information services portfolio company. Since Turpin took over the role of president in 2016, he has led the organization through a complete transformation from a traditional media company to its current enterprise, which includes founding a new portfolio company, Gravity Research. The company has experienced double digit revenue growth every year since he took the helm Turpin has a deep passion for mentorship of young people and serves as chair of the board of City Year DC; a non-profit dedicated to mentoring young people during their primary and secondary years of education. He is also the board chair of Gracism Global, a non-profit focused on equipping leaders that have decided to bridge the deep divides of color, class, and culture in their industries. In addition, Turpin serves as a member of the Economic Club of Washington and the Council on Foreign Relations. A proud Hoya, Turpin is a graduate of Georgetown University.

Luke Hartig

President, Gravity Research

Luke Hartig is President of Gravity Research. He leads Gravity’s research and consulting businesses, including the Stakeholder Influence Analysis, Societal and Reputational Intelligence service, and the Political and Reputational Vetting Service. Prior to joining National Journal, Luke served as a senior director at the National Security Council (NSC) in the Obama White House. He previously served in a range of government roles at the Pentagon, State Department, Office of Management and Budget, and Government Accountability Office. Luke began his career as a Peace Corps volunteer in Guatemala. Luke holds a master’s in public policy from the Harvard Kennedy School and a B.A. in international relations from Boston University. He is an adjunct fellow at New America, an executive editor of Just Security, and a member of the advisory councils for Hostage US and the James W. Foley Legacy Foundation. Luke lives in Washington, D.C. with his wife and two sons.

Kendall VanHoose Seketa

Vice President, New Products

Kendall Seketa currently serves as the Vice President of New Products at Gravity Research. In this role, Kendall leads Gravity Research's evolving support for corporations managing reputation concerns associated with a wide range of societal issues. In her time with National Journal, Kendall has supported the launch and operations of multiple product lines, collaborating closely with executives of Fortune 500 companies to understand both their reputational risk and policy challenges and creating strategic Stakeholder Influence Analysisghts products to solve them. This has included the launch of National Journal Research's Societal and Reputational Intelligence work, Corporate IStakeholder Influence Analysisders Survey, Political and Reputational Vetting analysis, and business development support for federal contractors. Prior to joining National Journal, Kendall served as a consultant at Booz Allen Hamilton, supporting clients in the federal healthcare market. Originally from Virginia, Kendall graduated from the College of William and Mary and currently lives in Washington, DC.

Daniel Thomas

Vice President, Research

Daniel Thomas is Vice President of Research at Gravity Research. Prior to this position, Daniel worked at Meta as a User Experience Research Manager, leading a team of researchers that were helping to build new business messaging products in Facebook, Instagram and WhatsApp. Daniel has also worked as a Research Director in Gartner’s financial services team and was a Managing Director in Hanover Research’s higher education practice. He holds a B.A. in History from King’s College, London, an M.St. in Historical Research from the University of Oxford and a Ph.D. in Modern History from the University of St Andrews. Originally from Dorset in the UK, Daniel now resides In Silver Spring, MD with his wife and two children.

Joanna Piacenza

Vice President of Thought Leadership

Joanna Piacenza is Vice President of Thought Leadership at Gravity Research, where she oversees all public-facing research and thought leadership. Prior to this role, Piacenza served as vice president and head of industry analysis at Morning Consult, where she built and oversaw the company’s public-facing industry research arm. She was also the editor of the Public Religion Research Institute, where she edited public opinion research at the intersection of religion, culture and public policy. Piacenza graduated from the University of Wisconsin-Madison with a bachelor’s degree in journalism and mass communications and holds a master’s degree in religious studies from the University of Colorado Boulder.

Aidan Mallon

Senior Government Business Analyst

Aidan Mallon is a Senior Government Business Analyst with Gravity Research. Aidan attended Boston College where he received a B.A. in Political Science with minors in Asian Studies, Theatre, and Management for Social Impact & the Public Good. Prior to joining National Journal, Aidan interned at the U.S. Department of State. Originally from Long Island, Aidan now resides in Washington, D.C.

Amelia D’Agaro

Public Policy Research Analyst

Amelia D’Agaro is a Public Policy Research Analyst for the Stakeholder Influence Analysis team at Gravity Research. She received her B.A. in Public Policy from Duke University. During her time at Duke, Amelia worked in various policy-oriented industries, including internships in government affairs, public sector consulting, and public service at a district congressional office. She also spent a semester studying abroad in Florence, Italy. Originally from the Chicago area, Amelia now resides in Washington, DC.

Andrew Swick

Managing Director, Political and Reputational Vetting

Andrew Swick is the Managing Director of the Political and Reputational Vetting service, responsible for managing the service and its research team. Prior to joining National Journal/Gravity Research, he worked as an analyst with the National Commission on Military, National, and Public Service and at the Center for a New American Security, focusing on military policy and defense issues. Andrew is a graduate of Georgetown University and the United States Military Academy, and previously served as an Army infantry officer.

Anuradha (Anu) Bhatt

Associate Research Director, Stakeholder Influence Analysis

Anu Bhatt is an Associate Research Director with the Stakeholder Influence Analysis team. Prior to joining National Journal, Anu worked at the Association of Immunization Managers as a Program/Policy Analyst for 7 years. She completed her undergraduate degree in Political, Legal, Economic Analysis at Mills College in Oakland, CA. Anu also holds an MPH in Health Policy from the George Washington University School of Public Health. She grew up in the Washington DC area, and currently resides in Chevy Chase.

Research Associate for Political and Reputational Vetting

April Liu is an Associate on the Political and Reputational Vetting team. She graduated from Mount Holyoke College in 2022, with a double major in Economics and International Relations. She joined Gravity Research in July 2023 after working in the think tank space for a year. April was born and raised in Vancouver, BC, Canada, and currently resides in Arlington, VA.

Benjamin Elias

Senior Stakeholder Influence Analysis Research Analyst

Benjamin Elias is a Senior Research Analyst at Gravity Research. Benjamin is a recent graduate of the University of Chicago where he majored in philosophy and minored in statistics. Before joining National Journal, Benjamin worked on various network mapping projects as a research assistant at the Chicago Project on Security and Threats. In addition to the various research projects he has been a part of, Benjamin helped found a healthy snack brand called Quevos, which is still in operation. Originally from Teaneck, New Jersey, Benjamin plans on moving to Washington D.C in the near future.

Blake Vieira

Senior Political and Reputational Vetting Research Associate

Blake Vieira is a Senior Research Associate with the Political and Reputational Vetting team. He joined National Journal in 2021 after graduating from American University with a BA in International Studies, where he focused on the Middle East, North Africa, and national security policy. He previously interned with Sen. Michael Bennet and Del. Eleanor Holmes Norton and most recently served as a research assistant for Wall Street Journal reporter Michael Gordon on his book "Degrade and Destroy: The War Against the Islamic State from Barack Obama to Donald Trump." Born in Riverside, CA and raised between there, Bellevue, WA and Castle Rock, CO, he currently lives in Washington, DC.

Caitlin Fischer

Social Impact and Reputational Risk Analyst

Caitlin is a Social Impact and Reputational Risk Analyst with Gravity Research. Prior to joining the Societal and Reputational Intelligence team, they performed research in fields ranging from nuclear nonproliferation to black hole astrophysics, including assessing the readiness of nuclear disarmament verification technologies as a Fulbright-Schuman Scholar to the European Union. They also have experience as a consultant specialising accessibility and community management. Caitlin graduated from MIT with a degree in Physics and a minor in Political Science. They grew up in Hong Kong and are now based in Washington, DC.

Chantal Elias

Associate Research Director, Societal and Reputational Intelligence

Chantal Elias is an Associate Research Director with Gravity Research. She graduated from Dartmouth College with a degree in International Relations and Climate Science in June 2022. Prior to joining National Journal, Chantal worked at a number of human rights and global affairs organizations, such as CARE USA, The Political Violence Fieldlab, Journalists for Human Rights, and the G20 Research Group. She also has spent several years working as a climate science researcher focused on Greenland. Originally from Toronto, Canada, Chantal now resides in Washington, D.C.

Chinelo Njubigbo

Senior Survey Analyst

Chinelo is a Senior Survey Analyst at Gravity Research. She holds a Master of Science degree in Epidemiology from Harvard University and a Bachelors degree in Public Health from Wayne State University. Chinelo has a passion for research and has held roles at Brown University and Charles R. Drew University of Medicine and Science, where she focused on the impact of discrimination on reproductive health care and HPV-related health disparities, respectively. Prior to joining Gravity Research she worked as a Global Market Access Associate at Johnson and Johnson supporting projects centered on patient needs and clinical trials. Originally from Detroit, Michigan, she now calls DC home.

Crystal Styron

Senior Director of Societal and Reputational Intelligence

Crystal Styron is Gravity Research's Senior Director of Societal and Reputational Intelligence. In this role, Crystal leads Gravity Research's work with Fortune 500 companies in understanding, assessing, and addressing their key sociopolitical risk factors. Immediately prior to joining Gravity Research, Crystal served as DEI research team leader and senior principal at Gartner. Crystal originally hails from North Carolina. She graduated with a BA from Princeton University and an MA from Johns Hopkins School of Advance International Studies. She resides in Alexandria, VA.

Daniel O'Rourke

Daniel O’Rourke is a Public Policy Research Analyst for the Stakeholder Influence Analysis team at Gravity Research. He graduated from Cornell University with a B.S. in Information Science and a concentration in Information Law & Policy. Prior to joining National Journal, Daniel worked as a consultant for Deloitte for several years. He has also worked as a research analyst for a nonprofit organization focused on election transparency and civic participation. Originally from Westchester County, New York, Daniel currently lives in New York City and plans to relocate to Washington D.C. in the near future.

Emma is a Social Impact and Reputational Risk Analyst with Gravity Research. She graduated from U.C. Berkeley in 2022 with a double degree in Political Economics and Sociology. She has experience working at several non-profit organizations and conducting research for the Human Rights Investigations Lab at the U.C. Berkeley School of Law. Before Gravity Research she was doing market research and expert sourcing for private equity in San Francisco. Emma is originally from Falls Church, VA and currently resides in San Francisco.

Emma Hopler

Emma Hopler is a Public Policy Research Analyst for the Stakeholder Influence Analysis team at Gravity Research. She graduated from the George Washington University with a BA in International Affairs and a concentration in Gender. She also studied at the University of Amsterdam, where she focused on human trafficking prevention. Prior to Gravity Research, she held a number of politically focused internships including ones with EMILY’s List and The White House. Originally from Reading, Pennsylvania, Emma now lives in Washington D.C.

Gage Grispino

Health Policy Research Analyst

Gage Grispino is a Health Policy Research Analyst for the Stakeholder Influence Analysis team at Gravity Research. He graduated with a B.S. in Biochemistry and a certificate in American Constitutional Democracy from the University of Missouri’s Kinder Institute on Constitutional Democracy. Prior to Gravity Research, he worked within health policy research and health data analytics within the consulting and nonprofit spaces. Originally from Maryville, Missouri, Gage now lives in Washington D.C.

Hannah Cohen

Associate Research Director, Political and Reputational Vetting

Hannah Cohen is an Associate Research Director with Gravity Research's Political and Reputational Vetting team. She graduated from Davidson College in 2020 with a B.A. in History and Political Science. Prior to joining National Journal as a research associate in 2022, Hannah worked at a government affairs and strategic communications firm specializing in transportation and infrastructure policy. She grew up in New Jersey and currently resides in Washington, D.C.

Hannah Cohn

Social Impact and Reputational Risk Research Associate

Hannah Cohn is a Social Impact and Reputational Risk Research Associate for Gravity Research. She graduated from Rutgers University- New Brunswick with a degree in Environmental Policy and a double minor in Political Science and Psychology. Prior to joining the National Journal, she worked for various political campaigns as well as environmental nonprofits and advocacy organizations. Although she is from New Jersey, she has been residing in California for the past two years and is currently in the process of relocating to Washington, D.C.

Senior Health Policy Research Analyst

Ian Schurr is a Senior Health Policy Research Analyst at Gravity Research's Stakeholder Influence Analysis team. Having joined National Journal in 2022, Ian handles a portfolio of cross-sector health clients focused on a wide range of policy topics. Ian completed his Master’s in Public Policy from the University of Virginia’s Batten School of Leadership and Public Policy. He also holds a Bachelor’s degree in Economics and Government from the University of Virginia. Previously, Ian has interned for the Office of Management and Budget and the House Committee on Appropriations. Originally from Alexandria, Virginia, Ian now resides in Washington, DC.

Jaimee Simwinga

Jaimee Simwinga is a Social Impact and Reputational Risk Analyst with Gravity Research. She graduated from Princeton University in 2023 with a degree in Anthropology and a certificate in African American Studies. Prior to joining the National Journal, Jaimee worked at the Field Museum, the Princeton University Art Museum, and Westside Housing, an affordable housing organization. She has also served as a qualitative researcher for a group focused on young adult relational health. Originally from Kansas, Jaimee currently resides in Washington, D.C.

Jamada Garner

Government Business Analyst

Jamada Garner is a Government Business Analyst for Gravity Research. Jamada was an intern for the Congressional Black caucus foundation where he interned under Representative Steve Cohen. Originally from Tennessee, Jamada graduated from Vanderbilt University, where he earned his Bachelor's in Public Policy. During his time he studied political science and French and interned with local campaigns during midterms. He currently resides in Knoxville, TN.

Research Director, Stakeholder Influence Analysis

James Ween is a Research Director for the Stakeholder Influence Analysis team at Gravity Research. He received a dual BA in Economics and Political Science from the University of Washington in Seattle. While an undergraduate, James wrote his senior thesis examining private sector influence on monetary policy decisions at the Federal Reserve and the Bank of Canada. Prior to joining National Journal, James worked in market research for a private equity firm focused in the energy sector. A proud Pacific Northwesterner, James currently resides in Washington, DC.

Jane Ann Langford

Jane Ann Langford is a Senior Research Associate with the Political and Reputational Vetting team. She joined National Journal in 2023 after graduating from the University of Virginia with her Master’s in Public Policy and a B.A. in Foreign Affairs. Prior to joining the National Journal, Jane Ann completed internships in research and non-profit organizations. She grew up in Birmingham, Alabama and currently lives in Washington, DC.

Research Director, Societal and Reputational Intelligence

Jena Kanji is a Research Director for the Societal and Reputational Intelligence team at Gravity Research. Prior to joining National Journal, Jena worked as a Management Consultant Associate for L.E.K. Consulting. Jena graduated from Georgetown University in 2019 where she majored in International Political Economy & Business with a minor in Arabic and a certificate in Entrepreneurship. She is originally from Long Island, New York, but currently resides in Washington, D.C.

Jessica Copenhaver

Jessica Copenhaver is an Associate Research Director with Gravity Research’s Political and Reputational Vetting team. She graduated from the Georgia Institute of Technology with a B.S. in Public Policy. Jessica has worked as a policy researcher with non-profits, academic institutions, and private entities. She is from Houston, Texas, and currently resides in North Carolina.

Joseph Andersen-Stanley

Joseph Andersen-Stanley is a Senior Research Associate with the Political and Reputational Vetting Team. He graduated from Utah Valley University with a B.S. in Political Science and minors in Philosophy and Constitutional Studies. Before coming to National Journal, Joseph worked on the Quill Project, a digital humanities project based at Pembroke College, where he researched negotiations made by US constitutional conventions in the late 1800's. He is also an award-winning songwriter. Originally from Provo, Utah, he currently lives with his wife in Arlington, Virginia.

Kamaan Richards

Senior Social Impact and Reputational Risk Analyst

Kamaan is a Senior Social Impact and Reputational Risk Analyst on Gravity Research's Societal & Reputational Intelligence team. He served in the United States Marine Corps from 2012-2017, then went on to graduate from the University of Minnesota with a bachelor’s of Political Science. He recently completed a master’s degree in Security Studies at Georgetown University. Originally from Houston, TX, Kamaan currently lives and works in Minneapolis, MN. Prior to joining Gravity Research, Kamaan served as the Multimedia Editor for the Minnesota Daily, and supported the Minnesota State Legislature.

Kelly Bruner

Social Impact & Reputational Risk Analyst

Kelly Bruner is a Social Impact & Reputational Risk Analyst with Gravity Research. She joined National Journal from Forward Risk, a boutique corporate risk and political opposition research firm. Previously, she worked for a non-profit in Austin, TX analyzing consumer experience of the international remittance market. Kelly is a graduate of Georgetown University’s School of Foreign Service with a degree in International Political Economy. Though she originally hails from Northern California, Kelly now considers Washington D.C. as home.

Kevin Pollack

Kevin Pollack is an Associate Research Director for the Stakeholder Influence Analysis team at Gravity Research. He graduated from Georgetown University with a degree in International Politics and a minor in Music. Before joining National Journal, Kevin worked at an environmental advocacy group, where he monitored federal legislation and contributed to lobbying efforts. Originally from Fort Lauderdale, Florida, Kevin now resides in Washington, DC.

Luke Benson

Luke is excited to join the team as a Social Impact and Reputational Risk Research Associate. He studied Psychology at UC Berkeley with an emphasis on political psychology and research. He previously worked as a student researcher for the UC Center Sacramento and interned at the Fair Political Practices Commission where he conducted research on campaigns and elections. This past year he studied abroad in Berlin where he completed a research project on political polarization. He just moved from the Bay Area to Washington DC and is excited to explore!

Madison Greenhall

Madison Greenhall is a Social Impact and Reputational Risk Research Associate for Gravity Research. She graduated from the University of North Carolina at Chapel Hill with a degree in Exercise and Sports Science and subsequently, recently completed an MSc from King’s College London in Global Health and Social Justice. Prior to joining the National Journal, she completed an internship at a specialist think tank and is a published researcher. Madison is from Charlotte, NC, but currently resides in Washington, D.C.

Mary Banks is a Social Impact and Reputational Risk Analyst with Gravity Research. She graduated from the University of Southern California with a Masters of Public Policy degree in May 2023. Originally from Salt Lake City, Utah, she now resides in Los Angeles, California.

Michael Decker

Michael Decker is a Research Director for the Stakeholder Influence Analysis team. Prior to joining National Journal, Michael served as a Director within the Stand Together philanthropic community leading research for policy campaigns. He worked directly with nonprofits and foundations on advocacy efforts focused on healthcare, fiscal policy, and criminal justice reform. He received his Master’s of Science degree in Applied Economics from the University of Maryland and holds a Bachelor’s degree from The George Washington University. Originally from Savannah, GA, Michael currently resides in Washington, DC.

Peter Kaufmann

Senior Social Impact & Reputational Risk Analyst

Peter Kaufmann is a Senior Social Impact & Reputational Risk Analyst with the Stakeholder Influence Analysis. He obtained a B.A. in Anthropology and an M.A. in Public Anthropology from American University, the latter of which he completed in the summer of 2022. Prior to joining the National Journal, Peter worked at the media nonprofit The Institute for Public Accuracy, and also served as a Research Assistant under two anthropologists within his graduate department. Originally from Silver Spring, Maryland, Peter has recently moved to the Woodley Park neighborhood of Washington, D.C.

Ripley Hunter

Associate Research Director, Procurement Influence Mapping

Ripley Hunter is an Associate Research Director with Gravity Research's Procurement Influence Mapping team. Before joining National Journal, Ripley worked as a Researcher at the Center for a New American Security and previously interned at the U.S. Department of Defense’s Near East South Asia Center for Strategic Studies. Ripley holds an M.A. in Security Policy Studies from the George Washington University and a B.A. in International Security from San Diego State. Originally from Northern California, he currently resides in Washington, DC.

Sarah Adkins

Sarah Adkins is a Social Impact and Reputational Risk Research Associate with Gravity Research. She graduated from Johns Hopkins University in the spring of 2022 with a B.A. in Political Science and a minor in history. Prior to joining National Journal, Sarah interned for U.S. Congressman Dutch Ruppersberger (MD-02). She has also spent time working and volunteering with various organizations that promote the rights of women and the prevention of gender violence. Sarah has an interest in human rights, especially political violence and international law. She is originally from Baltimore, Maryland and currently resides in Northern Baltimore County.

Sophia Dinman

Social Impact and Reputational Risk Research Analyst

Sophia Dinman is a Social Impact and Reputational Risk Research Analyst with Gravity Research. She obtained a B.A. in Political Science with minors in History and Environmental Studies from Seton Hall University. Additionally, she earned a certificate in Leadership from the Buccino Leadership Institute where she was also employed as the Institute’s Director of Strategic Communications. Her prior work experience involves internships with Senator Cory Booker, the Office of the Secretary of the Senate, and a New York City based political consulting firm. Sophia currently resides in the Northern Virginia area.

Troy Looper

Troy Looper serves as a Senior Social Impact and Reputational Risk Analyst for Gravity Research. Before joining the National Journal, Troy was a public school teacher with Teach for America in Hawaii where he completed his Master's in Education through Chaminade University. He earned his B.S. from Brigham Young University where he majored in Sociology with minors in Business Management and International Development. He has previously interned for several corporations helping to improve their corporate social responsibility efforts, including Microsoft and as a program evaluator in Malawi for Nu Skin Enterprises. Troy is a native of Jacksonville, Florida and currently resides in Arlington, VA.

Taylor Amey

Senior Public Policy Research Analyst

Taylor Amey is a Senior Public Policy Research Analyst with the Stakeholder Influence Analysis team. Prior to joining National Journal, Taylor worked for Blue Compass Strategies, a political consulting firm where he performed opposition and political research. He was raised in Davenport, Iowa, before attending George Washington University, where he double majored in Political Science and Communication. His senior thesis was a rhetorical analysis on the public debate surrounding the 2013 immigration reform bill. Taylor lives in Arlington, Virginia.

Tyler Jones

Strategic Executive Advisor

Tyler Jones is the Strategic Executive Advisor with Gravity Research. Prior to this, Tyler was Director of Middle East & North Africa with Edelman Global Advisory (EGA), the corporate strategy and political risk consultancy arm of Edelman. In this position, Tyler led an international team of government affairs, communications, and policy practitioners and advised executive leadership teams on market access, strategic communications, regulatory navigation, and geopolitical risk. Before EGA, Tyler spent over a decade with the US Government as a senior Middle East policy advisor with a specialization in diplomatic affairs and national security. He worked in Baghdad, Iraq where he directed strategic US policy objectives during a period of government transition and heightened political and military tension across the region. Tyler subsequently worked in Amman, Jordan, during which time he managed a variety of US policy programs focused on regional security and senior diplomatic engagements. Originally from Michigan, Tyler earned his master’s degree in international security from Georgetown University’s School of Foreign Service and his bachelor’s in Middle Eastern studies from the University of Michigan.

Tyson Rhodes

Tyson Rhodes is a Senior Social Impact and Reputational Risk Analyst with Gravity Research. Prior to joining the National Journal, Tyson worked at the Congressional Black Caucus Foundation. During that same time he received his Master's in Public Policy from Pepperdine University. He is originally from California and still resides there.

Katie Collins

Chief Revenue Officer

Katie Collins is the Chief Revenue Officer at Gravity Research. In this role, she manages the company’s relationships with heads of government affairs at Fortune 500 companies and leaders of industry trade associations and oversees business development strategy. In her previous role as vice president of development, Katie successfully launched the Stakeholder Influence Analysis and managed National Journal’s strategic advertising relationships. She also helped lead the transition of National Journal’s client base from individual subscriptions to organizational memberships as National Journal shifted from a media company to a consulting model providing research and advisory services. Katie’s prior experience spans nearly 15 years in business development and advocacy at National Journal, Corporate Executive Board, and the U.S. Chamber of Commerce. Katie is a graduate of Georgetown University. She lives in Washington, D.C. with her husband.

Allyson Grennille

Executive Director of Partnerships and Strategy

Allyson Grennille is the Executive Director of Partnerships and Strategy. In this role, she oversees partnership development and account management across Stakeholder Influence Analysis's portfolio of clients. Allyson has worked in the research and advisory services space for more than a decade and is passionate about building strategic, insghts-driven partnerships with clients to help them realize their goals. Prior to National Journal, Allyson was a Senior Managing Director at Hanover Research, where she oversaw the company's Corporate practice, including both research and revenue operations. She has an M.A. in Sociology from the University of Chicago and currently resides in New Jersey with her husband and daughter.

Anjali Varma

Director of Partnerships and Strategy

Anjali Varma is the Director of Partnerships and Strategy for Gravity Research. Anjali is an adjunct professor at American University Kogod School of Business where she teaches a class which she co-created, Women In Organization Leadership and has served as a women's leadership consultant. Anjali is a former small business owner and entrepreneur. Prior to entrepreneurship, she worked at American Express in a variety of roles including partnerships, sales and marketing. Anjali is a graduate of New York University Stern School of Business and the University of Michigan. She lives in Bethesda, Maryland with her husband and two sons.

Anne Koloski

Client Engagement and Operations Associate

Anne Koloski is a new Client Engagement and Operations Associate joining the Gravity Research revenue team. She is a recent graduate of Appalachian State University, where she studied political science with a concentration in pre-law and a minor in criminal justice. She previously worked as a legal assistant for a family law firm. She grew up in Charlotte, North Carolina, and has just moved to Washington DC.

Isabella Newell

Client Engagement Associate

Bella Newell serves as a Client Engagement Associate on the Gravity Research Revenue Team. She recently graduated from Boston University with Bachelors of Arts in Political Science and International Relations, and concentrations in African Politics and Security Studies. She is a two-time State Department intern, having previously interned with the Africa Regional Media Hub and U.S. Embassy, Kinshasa. She has also worked in education, helping students, administrators, and BOE officials to advance K-12 international relations education in the U.S. and abroad. Originally from Bethesda, Maryland, she is very happy to once again reside in Washington, D.C.

Jackie Breuer

Jackie Breuer is the executive director, partnering with clients of the Societal and Reputational Intelligence and government affairs work. Jackie has been working with government affairs and corporate affairs professionals for almost a decade. Originally, hailing from Northern California, she moved to DC to attend American University and has called it home ever since.

Jimmy Howard

Client Partnership Associate

Jimmy Howard serves as a Client Partnership Associate on the Gravity Research Revenue team. In this role, he specializes in building and cultivating partnerships for clients involved in Societal Reputational Intelligence as well as Stakeholder Influence Analysis. He graduated from the University of Colorado in 2023 with a bachelor’s degree in History. In recent years, Jimmy has interned in the Colorado House of Representatives as a Legislative Assistant and at The Heritage Foundation on the Development team. Jimmy is originally from Maryland but has lived a majority of his life in Colorado. He currently resides in Washington DC and is grateful to call this area his home once again.

Lizzy Andrew

Director of Strategic Partnerships

Lizzy Andrew serves as the Director of Strategic Partnerships for Gravity Research. In her role she leads engagement and relationship building for Stakeholder Influence Analysis's existing Core Government Affairs and Societal Issues clients. Her previous roles at National Journal have included working as the Capitol Hill liaison and managing a portfolio of client revenue for National Journal's subscription services. You can also occasionally catch Lizzy voicing the advertisements for the National Journal Radio Podcast. Prior to National Journal, she worked as the Student Engagement Specialist for the Rome School of Music, Drama, and Art at her alma mater and as a professional actress performing at a number of theaters across the DC area. Originally from Holland, MI, she graduated from the Catholic University of America with a Bachelor of Music in Musical Theatre.

Kira Bannister

Manager of Strategic Partnerships

Kira Bannister is a Manager of Strategic Partnerships on the Gravity Research revenue team working on the Societal and Reputational Intelligence work. She graduated from the University of Virginia (Wahoowa!) with a BA in Foreign Affairs and a BA in English Literature. Previously she has interned with the Treasury Department, Mines Advisory Group, the Be Good Foundation, and worked on a campaign in the VA-05. She currently lives in Washington, D.C. and is originally from San Antonio, TX.

Masih Khybari

Director of Partnership and Strategy

Masih Khybari is the Director of Partnership and Strategy for Gravity Research. Prior to joining the National Journal, Masih served as Counselor at the Friends of the American University of Afghanistan, a 501(c)(3) dedicated to higher education and economic development in Afghanistan. Masih holds an MSc from the London School of Economics in International Relations Theory and a LL.B. from Staffordshire University, where he focused on International Law. Masih serves on the Advisory Board of Women Forward International (WFI) and lives in Washington, D.C.

Molly Donnelly

Senior Manager, Partnerships and Strategy

Molly Donnelly serves as Senior Manager, Partnerships and Strategy on the Revenue Team for Gravity Research. In this role, she is primarily responsible for client onboarding and revenue operations for the Societal and Reputational Intelligence service as well as coordination of Gravity Research's virtual and in-person events. Prior to joining National Journal, Molly worked in corporate event management organizing and hosting conferences for C-suite executives across the US. Molly is a graduate of the University of Maryland, where she obtained a BA in Communications, and she currently lives in Bethesda, MD.

Nimna Gabadage

Manager, Partnerships & Strategy

Nimna Gabadage is a Manager, Partnerships & Strategy with Gravity Research's Revenue Team. Nimna joined Gravity from a consulting firm in Virginia where he supported the execution of data-driven public affairs strategies for a range of clients from Fortune 500 companies to non-profits and trade groups. He attended Florida State University's Honors College, where he received a BS in Finance and served as Student Body President and a university trustee. He was also elected Chairman of the Florida Student Association, a role in which he represented the state's 500,000 public university students as a Governor on the Florida Board of Governors. Nimna is currently a National Advisor to the non-profit Young Invincibles, where he weighs in on nonpartisan strategies for boosting civic engagement amongst young people in America, particularly within the key policy areas of the economy, healthcare, and higher education. A lifelong Floridian, he now resides in Washington, D.C.

Ryan DeRosa

Ryan DeRosa serves as a Client Engagement Associate on the Gravity Research Revenue Team. He recently graduated from the University of Delaware with a Dual Bachelors of Arts in Environmental Studies and Public Policy, with minors in Sustainable Infrastructure, Planning and Design and Historic Preservation. Over the past few years, Ryan interned for NYC Council Member Gale Brewer, the New Castle County Land Use Department, and recently finished up as a legislative intern in the office of U.S. Senator Tom Carper (D-DE). Originally from Long Island, New York, he currently resides in Washington, D.C.

Wyatt Hudgens

Revenue Operations Manager and Executive Assistant to the Chief Revenue Officer

Wyatt Hudgens is the Revenue Operations Manager and Executive Assistant to the Chief Revenue Officer. He previously supported the president of National Journal, the president of National Journal Membership, and the president of National Journal Research as the Executive Assistant. Prior to joining National Journal, Wyatt interned for Protegrity, a cybersecurity and data protection company in Salt Lake City, Utah. Additionally, Wyatt interned for the U.S. Department of State in the Bureau of Legislative Affairs. Wyatt graduated from the University of Utah with a B.S. in Political Science and a B.S. in Economics. Originally from Park City, UT, Wyatt currently resides in Washington, D.C.

Marketing and Design

Lesley Martinez

Vice President, Marketing

Lesley Martinez is Vice President of Marketing and Product where she is responsible for developing Gravity Research's marketing strategy and vision as well as overseeing marketing operations, events, and creatives. Prior to National Journal, Lesley spent six years at CEB where she managed demand generation, acquisition marketing, and retention strategies for their finance clients both in the large enterprise and SMB space. Before that, she was at The Chronicle of Higher Education/The Chronicle of Philanthropy managing marketing efforts for corporate advertisers and new product launches. Lesley is a D.C. native and attended James Madison University in Harrisonburg, VA. She lives in Virginia with her husband and two daughters.

Audrey Williams

Marketing Manager

Audrey Williams is a Marketing Manager at National Journal Group. Prior to joining the marketing team, Audrey worked as the government and external affairs coordinator at the Cato Institute. She also served in Rep. Justin Amash’s D.C. office for four years, starting as an intern and departing as legislative correspondent. Audrey graduated from Taylor University with a degree in political science and international studies. She grew up in Canton, Ohio, and currently lives in Washington, D.C.

Brian Tourellas

Graphic Design Associate

Brian Torruellas is a Graphic Design Associate for National Journal. He graduated from Maryland Institute College of Art, where he earned a degree in Graphic Design. After spending 15 years as a Pastry Chef, he pivoted careers to pursue his passion for art and design. Originally from Yonkers, New York, Brian moved to Washington DC in 2010 where he currently resides with his wife and son.

Chris Holden

Marketing Operations Specialist

Chris Holden is the Marketing Operations Specialist for National Journal Group. He manages marketing automation software and executes a variety of campaigns that serve the team’s overall goal of attracting and retaining members. Prior to this role, Chris worked at strategy firms, PACs and established his own start-up consulting firm in marketing and research roles. He graduated from George Mason with a degree in Government and International Politics, and currently lives in Arlington, VA.

Jesse Chimes

Senior Director of Marketing

Jesse Chimes is the Senior Director of Marketing for National Journal Group. He helps develop and implement strategies to expand National Journal’s membership base and strengthen its brand positioning. Jesse graduated from American University and lives in Washington, DC.

Katherine Bennett

Events and Marketing Specialist

Katherine Bennett is an Events and Marketing Specialist at the National Journal Group. She graduated from St. Mary’s College of Maryland in 2022 with a degree in Political Science and Public Policy. Prior to this role, she worked as a staff assistant for a Maryland based lobbying firm and has experience in the Maryland General Assembly. Originally from Annapolis, MD, she now lives in Washington, DC where she enjoys going to museums, and trying new restaurants with friends.

Sara Stanton

Creative Lead

Sara Stanton is the creative lead at National Journal Group. Prior to joining National Journal, Sara led their own graphic design studio specializing in data visualization and social impact. Sara holds a masters degree from the Maryland Institute College of Art and an undergraduate degree from the University of Vermont. Originally from New Hampshire, Sara lives in Virginia with their wife and dog

Talent and Culture

Rebecca Katona

Chief Administrative Officer

Rebecca Katona is the Chief Administrative Officer, leading National Journal Group's human resources team. Since joining NJ in 2013 to run Membership Events, Rebecca has served in a half dozen people operations-focused roles, including as NJ's Chief of Staff, Atlantic Media's Director of Talent & Culture, and AtlanticLIVE's Executive Director. Previously, Rebecca led a nonprofit higher education forum for promising domestic and international undergraduates. A native of Columbus, OH, and proud graduate of The Ohio State University, Rebecca lives on Capitol Hill with her husband Joey and their three sons: Calvin, Winston, and Truman.

Elli Miller

Employee Experience and Wellness Manager

Elli Kennedy Miller is the Employee Experience and Wellness Manager on the Talent and Culture team. Previous to this role, she worked for 2 years in people operations for a Utah based tech start up called Chatbooks. Elli is a Colorado native and a proud graduate of Brigham Young University. She is currently attending graduate school at Georgetown University alongside her husband. They reside in downtown DC.

Isabel Levatino

Executive Assistant

Isabel Levatino is the Executive Assistant to the President of Gravity Research and the COO/CFO of National Journal. She recently graduated from the University of Delaware with a degree in Psychology and Criminal Justice, and a minor in Spanish. During her time in Delaware, Isabel interned for the Federal U.S. Attorney’s Office and the Delaware State Chamber of Commerce, as well as was involved in many activities on campus. Isabel graduated as a McNair Scholar and was awarded the UD Benjamin McLuckie award for her commitment to Diversity, Equity and Inclusion. She is excited to start her professional career with National Journal and explore Washington D.C.

Kevin Ponder

Associate Director of Operations

Kevin Ponder is the Associate Director of Operations at National Journal Group. He manages the onsite operations and responsibilities that are required to run the National Journal offices. Prior to National Journal, he worked in both Human Resources and Facilities Management roles at Spire Energy in St. Louis, MO. He received his B.S. in Psychology from the Missouri University of Science and Technology, and his M.A. in Industrial/Organizational Psychology from Southern Illinois University - Edwardsville. Originally from St. Louis, Missouri, Kevin now lives in Washington, DC.

Shaly Joseph

Associate Director of Recruiting

Shaly Joseph is the Associate Director of Recruiting for National Journal Group. Prior to joining the team, Shaly served as the Assistant Director of Membership and Intern Operations at NASPA-Student Affairs Administrators in Higher Education. During her tenure at NASPA, Shaly managed membership initiatives, implemented strategic renewals campaigns, and developed short and long term data reporting solutions. In addition, she launched a robust internship program providing students with professional development opportunities that support their particular career interests/goals. Earlier, she worked in the Professional & Liberal Studies admissions office at Saint’s Joseph’s University, planning orientation and other recruitment events. Originally from Pennsylvania, Shaly earned a B.A from Saint Joseph’s University in Political Science with concentrations in History, Asian Studies and European Politics.

Chief Financial Officer and Chief Strategy Officer

Afzal Bari serves as CFO and CSO for National Journal Group. Afzal previously held roles at Bloomberg Government, Corporate Executive Board, Capco Consulting, and several startups. Afzal holds an MBA from Duke University's Fuqua School of Business, undergraduate degrees from the University of Maryland College Park, and is a CFA Charterholder. He lives in Chevy Chase, Md. with his wife and two children.

Edgard Lacayo

Accounts Receivable Specialist

Edgard Lacayo serves as the Accounts Receivable Specialist on the Finance team. Originally from Managua, Nicaragua, he graduated from Roanoke College with a BBA and a concentration in Finance and another concentration in Latin American and Caribbean Studies. In his previous position, he worked as an accounting assistant in Nicaragua. During his time at Roanoke College, he served as a research assistant to multiple professors in the Modern Languages and History departments as well as a staff reporter for the college’s student run newspaper, The Brackety Ack. He currently resides in Annandale, Virginia.

Michael Breton

Assistant Controller

Michael Breton serves as Assistant Controller for both National Journal Group and Bradley Media Holdings. Prior to joining the company in 2018 as a staff accountant, he worked at Plex Systems in Reston, VA and Wedding Wire in Chevy Chase, MD. A Marylander at heart, Michael attended The Fashion Institute of Technology (FIT) in NY, New York due to his love of Society, the fashion industry, European history and literature, pop culture and the arts, majoring in Advertising and Marketing Communications. Realizing that his home and heart belonged in the DMV area, he then moved back to the DC metropolitan area to be close with his family and to pursue a career in business and accounting. He earned his Bachelors of Science degree in Accounting and Business Management from the University of Maryland, University College. Michael lives in Bethesda, MD and enjoys a buttered lobster roll in Annapolis, MD once in a while.

Chris Dornfeld

Senior Vice President, Technology

Chris Dornfeld is senior vice president of technology at National Journal, where he’s responsible for crafting and executing the vision for NJ’s interactive offerings and overseeing information technology. Prior to National Journal, Chris held senior leadership roles in engineering and analytics at Manifest and co-founded a DC-based web development firm. Chris holds a B.S. in computer science from Carnegie Mellon and is widely recognized for typing very fast and very loud. He lives in Washington.

Andrew Littler

Senior Web Developer

Andrew Littler is a Senior Web Developer with National Journal Group. He graduated from University of St. Thomas in Minnesota with a B.A. in Computer Science. Prior to joining National Journal, Andrew worked in various IT related roles at different companies. He currently lives in Minnesota.

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