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what is gravity and how does gravity work/effect certain things

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what is gravity and how does gravity work/effect certain things

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gravitational pull is one of the many elements that makes the universe possible but how does this happen you may ask? in this slideshow I will show you everything there is about gravitational pull including a few unexplainable things and some theory's of them such as black holes!

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gravitational pull is one of the many elements that makes the universe possible but how does this happen you may ask? in this slideshow I will show you everything there is about gravitational pull including a few unexplainable things and some theory's of them such as black holes!

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one of the most widespread theory's on gravitational pull is that it is caused by the bending of the fabric of the universe causing a planet to go into orbit as it slowly circles around it like a funnel.

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one of the most widespread theory's on gravitational pull is that it is caused by the bending of the fabric of the universe causing a planet to go into orbit as it slowly circles around it like a funnel.

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here is a little experiment to show one of the most famous explanations on how gravity works

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here is a little experiment to show one of the most famous explanations on how gravity works

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step 1, create a 2ft-2ft box frame step 2, attach a blanket or smooth large cloth like a table cloth over the top of the frame until it is tight but still slightly manipulatable step 3, get several spherical-ish objects, each with different density's then put the most dense one in the center and then put the less-dense objects on the outside with a little push to represent the momentum and orbit and it should circle around it like a funnel goodbye! :)

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funny enough the concept of gravity is much different on earth than in space, on earth it rely's on both the concept we heard about in space and a new concept which is caused a planets rotation this will be explained below

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funny enough the concept of gravity is much different on earth than in space, on earth it rely's on both the concept we heard about in space and a new concept which is caused a planets rotation this will be explained below

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now because we sit on the crust we are the furthest from the outer core which is what causes the Earth's rotation, lets imagine it like this, imagine we are all some dirt in a plastic bag, as the outer core spins at insane speeds it slows down as we reach the crust, it spins slower making a sense of g-force keeping you on the surface so put something in a bag and spin it around and watch it stay in place on the surface inside the bag.

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science 1001, absolutely everything that matters in science in 1001 bite sized explanations by Dr Paul parsons

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science 1001, absolutely everything that matters in science in 1001 bite sized explanations by Dr Paul parsons

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spaghettification is one of the most popular theory's on what happens when you approach a black hole, the main explanation behind this is when you approach a black hole the gravity is to strong making it to where you hit max velocity the black hole try's to pull you faster stressing your body and stretching it out as the black hole try's to pull you closer.

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the great attractor is an anomaly in intergalactic space pulling over 100,000 galaxies towards it, this region is called the laniakea supercluster.

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well one theory about the great attractor is that it is caused by a supermassive black hole in the center of our universe pulling everyone and everything towards it and that this is why we are accelerating our movement in space. but this is highly unlikely for one reason. this reason is that if a black hole that strong enough did occur it would likely appear large enough to see with our highly advanced telescopes.

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The Great Attractor: Uncovering the Mystery of the Invisible Force

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The universe is filled with cosmic mysteries that continue to fascinate and intrigue astronomers and astrophysicists alike. One of the most puzzling and fascinating phenomena in the universe is the Great Attractor. The Great Attractor is a mysterious, massive object located in the direction of the Centaurus constellati

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the most likely theory is that it is an extremely dense supercluster counteracting the expansion of the universe with the gravity provides this is also more likely because if it were a supermassive black hole most of the surrounding supercluster would be gone in an instant but the fact that there is almost no disturbance in that area it makes it highly unlikely for a black hole making a supercluster the most likely.

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the scalar tensor theory's are theories based off of the concept of modifying general relativity by introducing a scalar feild alongside the existing tensor feild this represents gravity. the scalar the scalar tensor theories also have multiple ways of calculating. the main formuli will be shown in the images below. this theory was made by John moffat in 1979.

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this is one of the main ways to calculate a scalar tensor theory 

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this is one of the main ways to calculate a scalar tensor theory 

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this image shows some of the other ways to calculate them

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this image shows some of the other ways to calculate them

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In theoretical physics, a scalar-tensor theory is a field theory that includes both a scalar field and a tensor field to represent a certain interaction. For example, the Brans-Dicke theory of gravitation uses both a scalar field and a tensor field to mediate the gravitational interaction.

Modern physics tries to derive all physical theories from as few principles as possible. In this way, Newtonian mechanics as well as quantum mechanics are derived from Hamilton's principle of least action. In this approach, the behavior of a system is not described via forces, but by functions which describe the energy of the system. Most important are the energetic quantities known as the Hamiltonian function and the Lagrangian function. Their derivatives in space are known as Hamiltonian density and the Lagrangian density. Going to these quantities leads to the field theories.

Modern physics uses field theories to explain reality. These fields can be scalar, vectorial or tensorial. An example of a scalar field is the temperature field. An example of a vector field is the wind velocity field. An example of a tensor field is the stress tensor field in a stressed body, used in continuum mechanics.

In physics, forces (as vectorial quantities) are given as the derivative (gradient) of scalar quantities named potentials. In classical physics before Einstein, gravitation was given in the same way, as consequence of a gravitational force (vectorial), given through a scalar potential field, dependent of the mass of the particles. Thus, Newtonian gravity is called a scalar theory. The gravitational force is dependent of the distance r of the massive objects to each other (more exactly, their centre of mass). Mass is a parameter and space and time are unchangeable.

Einstein's theory of gravity, the General Relativity (GR) is of another nature. It unifies space and time in a 4-dimensional manifold called space-time. In GR there is no gravitational force, instead, the actions we ascribed to being a force are the consequence of the local curvature of space-time. That curvature is defined mathematically by the so-called metric, which is a function of the total energy, including mass, in the area. The derivative of the metric is a function that approximates the classical Newtonian force in most cases. The metric is a tensorial quantity of degree 2 (it can be given as a 4x4 matrix, an object carrying 2 indices).

Another possibility to explain gravitation in this context is by using both tensor (of degree n>1) and scalar fields, i.e. so that gravitation is given neither solely through a scalar field nor solely through a metric. These are scalar-tensor theories of gravitation.

The field theoretical start of General Relativity is given through the Lagrange density. It is a scalar and gauge invariant (look at gauge theories) quantity dependent on the curvature scalar R. This Lagrangian, following Hamilton's principle, leads to the field equations of Hilbert and Einstein. If in the Lagrangian the curvature (or a quantity related to it) is multiplied with a square scalar field, field theories of scalar-tensor theories of gravitation are obtained. In them, the gravitational constant of Newton is no longer a real constant but a quantity dependent of the scalar field.

Mathematical formulation

An action of such a gravitational scalar-tensor theory can be written as follows:

where is the metric determinant, is the Ricci scalar constructed from the metric , is a coupling constant with the dimensions , is the scalar-field potential, is the material Lagrangian and represents the non-gravitational fields. Here, the Brans-Dicke parameter has been generalized to a function. Although is often written as being , one has to keep in mind that the fundamental constant there, is not the constant of gravitation that can be measured with, for instance, Cavendish type experiments. Indeed, the empirical gravitational constant is generally no longer a constant in scalar-tensor theories, but a function of the scalar field . The metric and scalar-field equations respectively write:

and

Also, the theory satisfies the following conservation equation, implying that test-particles follow space-time geodesics such as in general relativity:

where is the stress-energy tensor defined as

The Newtonian approximation of the theory

Developing perturbatively the theory defined by the previous action around a Minkowskian background, and assuming non-relativistic gravitational sources, the first order gives the Newtonian approximation of the theory. In this approximation, and for a theory without potential, the metric writes

with satisfying the following usual Poisson equation at the lowest order of the approximation:

where is the density of the gravitational source and (the subscript indicates that the corresponding value is taken at present cosmological time and location). Therefore, the empirical gravitational constant is a function of the present value of the scalar-field background and therefore theoretically depends on time and location. However, no deviation from the constancy of the Newtonian gravitational constant has been measured, implying that the scalar-field background is pretty stable over time. Such a stability is not theoretically generally expected but can be theoretically explained by several mechanisms.

The first post-Newtonian approximation of the theory

Developing the theory at the next level leads to the so-called first post-Newtonian order. For a theory without potential and in a system of coordinates respecting the weak isotropy condition (i.e., ), the metric takes the following form:

with

where is a function depending on the coordinate gauge

It corresponds to the remaining diffeomorphism degree of freedom that is not fixed by the weak isotropy condition. The sources are defined as

the so-called post-Newtonian parameters are

and finally the empirical gravitational constant is given by

where is the (true) constant that appears in the coupling constant defined previously.

Current observations indicate that , which means that . Although explaining such a value in the context of the original Brans-Dicke theory is impossible, Damour and Nordtvedt found that the field equations of the general theory often lead to an evolution of the function toward infinity during the evolution of the universe. Hence, according to them, the current high value of the function could be a simple consequence of the evolution of the universe.

Seven years of data from the NASA MESSENGER mission constraints the post-Newtonian parameter for Mercury's perihelion shift to .

Both constraints show that while the theory is still a potential candidate to replace general relativity, the scalar field must be very weakly coupled in order to explain current observations.

Generalized scalar-tensor theories have also been proposed as explanation for the accelerated expansion of the universe but the measurement of the speed of gravity with the gravitational wave event GW170817 has ruled this out.

Higher-dimensional relativity and scalar-tensor theories

After the postulation of the General Relativity of Einstein and Hilbert, Theodor Kaluza and Oskar Klein proposed in 1917 a generalization in a 5-dimensional manifold: Kaluza-Klein theory. This theory possesses a 5-dimensional metric (with a compactified and constant 5th metric component, dependent on the gauge potential) and unifies gravitation and electromagnetism, i.e. there is a geometrization of electrodynamics.

This theory was modified in 1955 by P. Jordan in his Projective Relativity theory, in which, following group-theoretical reasonings, Jordan took a functional 5th metric component that led to a variable gravitational constant G. In his original work, he introduced coupling parameters of the scalar field, to change energy conservation as well, according to the ideas of Dirac.

Following the Conform Equivalence theory, multidimensional theories of gravity are conform equivalent to theories of usual General Relativity in 4 dimensions with an additional scalar field. One case of this is given by Jordan's theory, which, without breaking energy conservation (as it should be valid, following from microwave background radiation being of a black body), is equivalent to the theory of C. Brans and Robert H. Dicke of 1961, so that it is usually spoken about the Brans-Dicke theory. The Brans-Dicke theory follows the idea of modifying Hilbert-Einstein theory to be compatible with Mach's principle. For this, Newton's gravitational constant had to be variable, dependent of the mass distribution in the universe, as a function of a scalar variable, coupled as a field in the Lagrangian. It uses a scalar field of infinite length scale (i.e. long-ranged), so, in the language of Yukawa's theory of nuclear physics, this scalar field is a massless field. This theory becomes Einsteinian for high values for the parameter of the scalar field.

In 1979, R. Wagoner proposed a generalization of scalar-tensor theories using more than one scalar field coupled to the scalar curvature.

JBD theories although not changing the geodesic equation for test particles, change the motion of composite bodies to a more complex one. The coupling of a universal scalar field directly to the gravitational field gives rise to potentially observable effects for the motion of matter configurations to which gravitational energy contributes significantly. This is known as the "Dicke-Nordtvedt" effect, which leads to possible violations of the Strong as well as the Weak Equivalence Principle for extended masses.

JBD-type theories with short-ranged scalar fields use, according to Yukawa's theory, massive scalar fields. The first of this theories was proposed by A. Zee in 1979. He proposed a Broken-Symmetric Theory of Gravitation, combining the idea of Brans and Dicke with the one of Symmetry Breakdown, which is essential within the Standard Model SM of elementary particles, where the so-called Symmetry Breakdown leads to mass generation (as a consequence of particles interacting with the Higgs field). Zee proposed the Higgs field of SM as scalar field and so the Higgs field to generate the gravitational constant.

The interaction of the Higgs field with the particles that achieve mass through it is short-ranged (i.e. of Yukawa-type) and gravitational-like (one can get a Poisson equation from it), even within SM, so that Zee's idea was taken 1992 for a scalar-tensor theory with Higgs field as scalar field with Higgs mechanism. There, the massive scalar field couples to the masses, which are at the same time the source of the scalar Higgs field, which generates the mass of the elementary particles through Symmetry Breakdown. For vanishing scalar field, this theories usually go through to standard General Relativity and because of the nature of the massive field, it is possible for such theories that the parameter of the scalar field (the coupling constant) does not have to be as high as in standard JBD theories. Though, it is not clear yet which of these models explains better the phenomenology found in nature nor if such scalar fields are really given or necessary in nature. Nevertheless, JBD theories are used to explain inflation (for massless scalar fields then it is spoken of the inflaton field) after the Big Bang as well as the quintessence. Further, they are an option to explain dynamics usually given through the standard cold dark matter models, as well as MOND, Axions (from Breaking of a Symmetry, too), MACHOS,...

A generic prediction of all string theory models is that the spin-2 graviton has a spin-0 partner called the dilaton. Hence, string theory predicts that the actual theory of gravity is a scalar-tensor theory rather than general relativity. However, the precise form of such a theory is not currently known because one does not have the mathematical tools in order to address the corresponding non-perturbative calculations. Besides, the precise effective 4-dimensional form of the theory is also confronted to the so-called landscape issue.

P. Jordan, Schwerkraft und Weltall, Vieweg (Braunschweig) 1955: Projective Relativity. First paper on JBD theories.

C.H. Brans and R.H. Dicke, Phys. Rev. 124: 925, 1061: Brans-Dicke theory starting from Mach's principle.

R. Wagoner, Phys. Rev. D1(812): 3209, 2004: JBD theories with more than one scalar field.

A. Zee, Phys. Rev. Lett. 42(7): 417, 1979: Broken-Symmetric scalar-tensor theory.

H. Dehnen and H. Frommert, Int. J. Theor. Phys. 30(7): 985, 1991: Gravitative-like and short-ranged interaction of Higgs fields within the Standard Model or elementary particles.

H. Dehnen et al., Int. J. Theor. Phys. 31(1): 109, 1992: Scalar-tensor-theory with Higgs field.

C.H. Brans, June 2005: Roots of scalar-tensor theories. arXiv:gr-qc/0506063. Discusses the history of attempts to construct gravity theories with a scalar field and the relation to the equivalence principle and Mach's principle.

P. G. Bergmann (1968). "Comments on the scalar-tensor theory". Int. J. Theor. Phys. 1 (1): 25-36. Bibcode:1968IJTP....1...25B. doi:10.1007/BF00668828. S2CID 119985328.

R. V. Wagoner (1970). "Scalar-tensor theory and gravitational waves". Phys. Rev. D1 (12): 3209-3216. Bibcode:1970PhRvD...1.3209W. doi:10.1103/physrevd.1.3209.

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einstein's general theory of general relativity

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einstein's general theory of general relativity

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einstein's general theory of relativity Is a simple but complex theory at the same time. this theory is consisted mainly off of the ideas of special relativity and equivalence. you may be asking what even is special relativity. well the answer is that special relativity is the relationship and correlation between space and time its self. this can be put into the equation e=mc squared. this simply just means that energy and mass are equivalent and can be converted into each other. this theory was developed in 1915 by Albert Einstein.

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The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction.

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E = mc². It's the world's most famous equation, but what does it really mean? "Energy equals mass times the speed of light squared." On the most basic level, the equation says that energy and mass (matter) are interchangeable; they are different forms of the same thing. Under the right conditions, energy can become mass, and vice versa. We humans don't see them that way-how can a beam of light and a walnut, say, be different forms of the same thing?-but Nature does.

So why would you have to multiply the mass of that walnut by the speed of light to determine how much energy is bound up inside it? The reason is that whenever you convert part of a walnut or any other piece of matter to pure energy, the resulting energy is by definition moving at the speed of light. Pure energy is electromagnetic radiation-whether light or X-rays or whatever-and electromagnetic radiation travels at a constant speed of 300,000 km/sec (186,000 miles/sec).

Why, then, do you have to square the speed of light? It has to do with the nature of energy. When something is moving four times as fast as something else, it doesn't have four times the energy but rather 16 times the energy-in other words, that figure is squared. So the speed of light squared is the conversion factor that decides just how much energy lies within a walnut or any other chunk of matter. And because the speed of light squared is a huge number-90,000,000,000 (km/sec) ² -the amount of energy bound up into even the smallest mass is truly mind-boggling.

Here's an example. If you could turn every one of the atoms in a paper clip into pure energy-leaving no mass whatsoever-the paper clip would yield 18 kilotons of TNT. That's roughly the size of the bomb that destroyed Hiroshima in 1945. On Earth, however, there is no practical way to convert a paper clip or any other object entirely to energy. It would require temperatures and pressures greater than those at the core of our sun.

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E = mc2 . It's the world's most famous equation, but what does it really mean? "Energy equals mass times the speed of light squared." On the most basic level, the equation says that energy and mass (matter) are interchangeable; they are different forms of the same thing.

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The elevator, the rocket, and gravity: the equivalence principle « Einstein-Online

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Information about the principle that Einstein took as a starting point for developing his general theory of relativity

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General relativity is physicist Albert Einstein's understanding of how gravity affects the fabric of space-time.

The theory, which Einstein published in 1915, expanded the theory of special relativity that he had published 10 years earlier. Special relativity argued that space and are inextricably connected, but that theory didn't acknowledge the existence of .

Einstein spent the decade between the two publications determining that particularly massive objects warp the fabric of , a distortion that manifests as gravity, according to NASA.

Related: The hunt for wormholes: How scientists look for space-time tunnels

How does general relativity work?

To understand general relativity, first, let's start with gravity, the force of attraction that two objects exert on one another. Sir Isaac Newton quantified gravity in the same text in which he formulated his three laws of motion, the " Principia."

The gravitational force tugging between two bodies depends on how massive each one is and how far apart the two lie, according to NASA Glenn Research Center. Even as the center of the is pulling you toward it (keeping you firmly lodged on the ground), your center of mass is pulling back at the Earth. But the more massive body barely feels the tug from you, while with your much smaller mass, you find yourself firmly rooted thanks to that same force. Yet Newton's laws assume that gravity is an innate force of an object that can act over a distance.

Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels, according to Wired.

As a result, he found that space and time were interwoven into a single continuum known as space-time. And events that occur at the same time for one observer could occur at different times for another.

Related: What would happen if the speed of light was much lower?

As he worked out the equations for his general theory of relativity, Einstein realized that massive objects caused a distortion in space-time. Imagine setting a large object in the center of a trampoline. The object would press down into the fabric, causing it to dimple. If you then attempt to roll a marble around the edge of the trampoline, the marble would spiral inward toward the body, pulled in much the same way that the gravity of a planet pulls at rocks in space.

In the decades since Einstein published his theories, scientists have observed countless of phenomena matching the predictions of relativity.

General relativity FAQs answered by an expert

We asked Elena Giorgi, an assistant professor of mathematics at Columbia University a few commonly asked questions about general relativity.

Image credit: ​April Renae, Columbia University.

Assistant Professor

What is general relativity?

What force is explained by general relativity?

When was the theory of general relativity established?

Is general relativity proven?
Related: What Is Quantum Gravity?

(Image credit: NASA and European Space Agency (ESA))

Gravitational lensing

Light bends around a massive object, such as a black hole, causing it to act as a lens for the things that lie behind it. Astronomers routinely use this method to study stars and galaxies behind massive objects.

The Einstein Cross, a in the Pegasus constellation, according to the European Space Agency (ESA), and is an excellent example of gravitational lensing. The quasar is seen as it was about 11 billion years ago; the that it sits behind is about 10 times closer to Earth. Because the two objects align so precisely, four images of the quasar appear around the galaxy because the intense gravity of the galaxy bends the light coming from the quasar.

In cases like Einstein's cross, the different images of the gravitationally lensed object appear simultaneously, but that isn't always the case. Scientists have also managed to observe lensing examples where, because the light traveling around the lens takes different paths of different lengths, different images arrive at different times, as in the case of one particularly interesting .

Changes in Mercury's orbit

The orbit of is shifting very gradually over time due to the curvature of space-time around the massive sun, according to NASA.

As the closest planet to the sun, Mercury's perihelion (the point along its orbit that it's closest to the sun) is predicted to follow a slightly different direction over time. Under Newton's predictions, gravitational forces in the solar system should advance Mercury's precession ( change in its orbital orientation) is measured to be 5,600 arcseconds per century (1 arcsecond is equal to 1/3600 of a degree). However, there is a discrepancy of 43 arcseconds per century, something Einstein's theory of general relativity accounts for. Using Einstein's theory of curved space-time, the precession of Mercury's perihelion should advance slightly more than under the predictions of Newton, since planets don't orbit the sun in a static elliptical orbit.

Sure enough, several research papers published since the mid 20th century have confirmed Einstein's calculations of Mercury's perihelion precession to be accurate.

In a few billion years, this wobble could even cause the innermost planet to collide with the sun or a planet.

Frame-dragging of space-time around rotating bodies

The spin of a heavy object, such as Earth, should twist and distort the space-time around it. In 2004, NASA launched the Gravity Probe B (GP-B). The axes of the satellite's precisely calibrated gyroscopes drifted very slightly over time, according to NASA, a result that matched Einstein's theory.

"Imagine the Earth as if it were immersed in honey," Gravity Probe-B principal investigator Francis Everitt, of Stanford University, said in a NASA statement about the mission.

"As the planet rotates, the honey around it would swirl, and it's the same with space and time. GP-B confirmed two of the most profound predictions of Einstein's universe, having far-reaching implications across astrophysics research."

Gravitational redshift

The electromagnetic radiation of an object is stretched out slightly inside a gravitational field. Think of the sound waves that emanate from a siren on an emergency vehicle; as the vehicle moves toward an observer, sound waves are compressed, but as it moves away, they are stretched out, or redshifted. Known as the Doppler Effect, the same phenomena occurs with waves of light at all frequencies.

In the 1960s, according to the American Physical Society, physicists Robert Pound and Glen Rebka shot gamma-rays first down, then up the side of a tower at Harvard University. Pound and Rebka found that the gamma-rays slightly changed frequency due to distortions caused by gravity.

Gravitational waves

Einstein predicted that violent events, such as the collision of two black holes, create ripples in space-time known as gravitational waves. And in 2016, the Laser Interferometer Gravitational Wave Observatory ( LIGO) announced that it had detected such a signal for the first time.

That detection came on Sept. 14, 2015. LIGO, made up of twin facilities in Louisiana and Washington, had recently been upgraded, and were in the process of being calibrated before they went online. The first detection was so large that, according to then-LIGO spokesperson Gabriela Gonzalez, it took the team several months of analysis to convince themselves that it was a real signal and not a glitch.

Related: Phantom energy and dark gravity: Explaining the dark side of the universe

(Image credit: NASA/JPL-Caltech)

"We were very lucky on the first detection that it was so obvious," she said during the 228 American Astronomical Society meeting in June 2016.

Since then, scientists have begun quickly catching gravitational waves. All told LIGO and its European counterpart Virgo have detected a total of 50 gravitational-wave events, according to program officials, according to the Laser Interferometer Gravitational-wave Observatory.

Those collisions have included unusual events like a collision with an object that scientists can't definitively identify as a black hole or neutron star, merging neutron stars accompanied by a bright explosion, mismatched black holes colliding and more.

Observing neutron stars

In 2021 research published in the journal Physical Review X, challenged several of Einstein's predictions by observing a double-pulsar system around 2,400 light-years from Earth. Each of the seven predictions of general relativity was confirmed by the study.

Pulsars are a type of neutron star that appears to pulse due to beams of electromagnetic radiation and that are emitting from their magnetic poles.

The pulsar test subjects spin very fast - around 44 times a second - and are 30% more massive than the sun but are only 15 miles (around 24 kilometers) in diameter, making them incredibly dense. This means that their gravitational pull is immense, for example, on the surface of a neutron star gravity is around 1 billion times stronger than its pull on Earth. This makes neutron stars a great test subject to challenge predictions in Einstein's theories, such as the ability of gravity to bend light.

"We follow the propagation of radio photons emitted from a cosmic lighthouse, a pulsar, and track their movements in the strong gravitational field of a companion pulsar," Professor Ingrid Stairs from the University of British Columbia at Vancouver said in a statement.

"We see for the first time how the light is not only delayed due to a strong curvature of spacetime around the companion but also that the light is deflected by a small angle of 0.04 degrees that we can detect. Never before has such an experiment been conducted at such a high spacetime curvature" Stairs adds.

Additional resources

Read more about general relativity in the book Relativity: The Special and the General Theory - 100th Anniversary Edition. Explore the Nature of Space and Time (Isaac Newton Institute Series of Lectures, 3) and The Physics Book: Big Ideas Simply Explained.

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Albert Einstein's theory of general relativity is based on the idea that massive objects cause a distortion in space-time, which is felt as gravity