How does gravity work?

Question

How does Earth know there is a Sun or a moon out there and it should be attracted to it? How does gravity work?

I read your answers. I want to let you know that I have studied this subject to some depth and though there are models to explain the effect of gravity on celestial objects (the space time model) but my question was more about how does it work. Gravitons seem to be a partial answer, but it is only a proposed particle, not proved yet. The next part of the question would be like this. If we can stop/ deflect/ refract/ reflect all kinds of EM waves and particles including photons. Then is there a way to make a wall (hypothetical) that can reflect / deflect these gravitons. Also if say the light from the Sun takes 8 min to reach earth at the velocity of C, then will earth still keep revolving around the sun for 8 minutes after it explodes (hypothetical) or disintegrates. Answers, anyone??

Answer 1

The real answer to your question is: we do not know... yet.

Newton simply stated that the force depends on the masses and the distance between them. He did not even try to explain why it was that way. (Mind you, it was enough that he gave us an equation because, before him, we didn't even have that).

Then was the graviton, an exchange particle between masses.

Einstein proposed that gravity is a change in the 'shape' of space-time. The mass changes the shape of space-time. The shape tell the masses how to move.

The analogy that is often used involves a rubber sheet that is horizontal (and supported only at the edges).

Place a massive object at the centre, and the rubber sheet is deformed: the sheet is pulled downwards by the weight of the mass.
Place a smaller objects onywhere on the sheet and it will tend to 'fall' down the slope towards the bigger object.

Now twist your mind to imagine this deformation in 3 dimensions of space and one of time.

The Sun deforms the "big rubber sheet" of the solar system. The Earth, rolling along this rubber sheet, simply curves according to the slope. It does not need to know where the Sun is; it only needs to know what the slope is at its own position.
Mathematically, this representation of gravity as a slope, is called a field.

But how it words (why is there a field, or why are there gravitons), we do not know yet.
Instant Nobel prize if you find out.

Answer 2

The best explanation thus far is from General Relativity. A mass in space will displace the very properties of the space it is in..so imagine a planet with a field of space imploding all around it. Space will curve at a rate directly proportional to an object's mass...any smaller masses within proximity of the larger mass shall be forced towards the larger mass due to the mutual displacement fields of space crossing each other...which is just a fancy way of describing how things "fall"!
They're still working on the gravity of subatomic particles...the closest "culprit" being String Theory...so the answer isn't entirely complete yet.

ps to asker's follow-up: What would the wall be made of?? Gravitons (theoretical, and IMO doubtful) would generally pass right through any possible wall that could be constructed. Any such wall would need to have MORE than subatomic "building blocks"..it would need to be one of the elements on the aromic table. That said, apart from the protons, nuetrons, and electrons, the atom consists MOSTLY of empty space. The graviton (if real) is so small, it would most likely pass through that space, since hitting it's constructs would be like hitting a needle in a haystack...one of which is orbitting it's other parts near light speed!

Answer 3

Please don't listen to ayumi_hakushin
HERE ON EARTH, ALL OBJECTS FALL AT THE SAME RATE REGARDLESS OF THEIR WEIGHT!!!!!!!!!! Atmospheric pressure has nothing to do with it

So whats gravity?
Matter is attracted to other matter. That attraction is what we call gravity. Yep thats right all matter has gravity, even me and you.

How does the earth know there is a sun or moon out there?
One way scientists model gravity is to picture that each massive body projects a gravitational field. The earth feels the sun's gravitational field.

What is a gravitational field?
Einstein porposed with his theory of general relativity (GR)that gravity is the curvature of space-time. In GR the presence of a massive body curves the shape of space-time. The explanation within GR for why the earth orbits the sun is because it follows a straight path in a curved space. Try this simple demonstration:

You'll need 3 other people, a bed sheet, a bowling ball(basketball or any big ball will work), and a marble( any small ball will work). The sheet will be the fabric of space-time, the bowling ball will be the sun and the marble will be the earth.

Have each person hold a corner of the sheet so it is stretched out. Place the bowling ball in the center. Notice how the presence of the Bowling ball has curved the sheet. Place the marble on the sheet. Notice it moves toward the bowling ball. Now, take the marble and roll it (fast) along the outside of the sheet. You rolled it straight but it curved becuase the space it taveled in (the sheet) is curved. If you rolled it hard enough it probly made a complete circle around the bowling ball before falling toward the center. So it orbited the bowling ball just like earth orbits the sun. Why did the marble fall toward the center and hit the bowling ball? The earth doesn't crash into the sun? Well the marble was slowed down by friction with the sheet and didnt have enough speed to stay in orbit. Space is a vacuum. In other words there is no friction and nothing to slow the earth down. So it just stays in orbit.

Hope this demo helped!!

Answer 4

Hoo boy! Where do I start? One of your responders is somewhere in the pre_Newtonian Middle Ages, claiming that the acceleration of a falling object depends upon its mass, while another seems to be a New Age pseudoscientist, claiming that gravity is a "vibrational frequency" (as opposed to a non-vibrational frequency?) and that time is a constant. Ouch! My brain!

Many responders use the rubber sheet analogy, which is a good way to picture the distortion of spacetime by massive objects. This is accurate, but my problem with that picture is that it relies on gravity to work by "pulling down" on the masses arranged on the 2 dimensional sheet .

I like to think about gravity in terms of the windowless rocket analogy. If you are standing inside a windowlesss rocket that is accelerating upward in empty space at 1 G, then you will feel the force of 1 G acting against the soles of your feet.

If the rocket is standing "still" on the surface of the earth with the engines not running, you will also feel 1G against the soles of your feet due to the Earth's gravity.

What Einstein said was that, inside the rocket, you cannot tell the difference between these two cases. And that is because there is no difference. Think of it this way: any time you accelerate (in a car, in an aircraft during takeoff, etc) you feel the effects of the forces that are causing that acceleration. You are pressed back in your seat, it's a lttle harder to lean forward, etc. . But if you are above the Earth's surface and falling, you are accelerating at a higher rate (~9.8 m/sec^2) but you don't feel any forces on you at all; you are in free fall and weightless. Why? How can you accelerate without being "pushed?" Newton (giant that he was) had no response, other than the gravitational constant, which is basically a fudge factor to make the numbers work out. In fact, he acknowledged as much. Einstein figured out that it was because the spacetime of the universe is locally curved in such a way that the "path of least resistance" is skewed toward the center of Earth's mass. Gravity and acceleration are equivalent. So, with no forces acting on you, you will move through spacetime in that direction. In order to keep from falling in that direction, a force must be applied by the solid surface of the Earth against the soles of your feet. This force does not accelerate you upward in space as it does with running engines out in empty space, it "accelerates" you in spacetime while you stand on the surface. In Newtonian space, it just keeps you from falling any further.

This is not terribly intuitive, but I think it's correct.

Answer 5

Gravity is the attraction of masses. Only large masses such as a planet will have enough gravity to cause other objects to be drawn to it. You can picture space as a large flat sheet. These large masses cause the sheet to dip and cause objects such as a sattelite or moon to orbit around them. The sun is magnitudes larger than the earth so its dip will force the earth and other planets to orbit around it. We can measure gravity with units of distance and time i.e. m/s^2 basically this states that gravity causes objects to accelerate. On earth the metric number is about 9.8 m/s^2 but the moon will have a different number and so does everything else.

Answer 6

Gravitation is a natural phenomenon by which all objects attract each other. In everyday life, gravitation is most familiar as the agency that endows objects with weight. Gravitation is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth; for the formation of tides; for convection (by which hot fluids rise); for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe. Gravitation is also the reason for the very existence of the Earth, the Sun, and most macroscopic objects in the universe; without it, matter would not have coalesced into these large masses, and life, as we know it, would not exist.

Modern physics describes gravitation using the general theory of relativity, but the much simpler Newton's law of universal gravitation provides an excellent approximation in most cases.

In scientific terminology gravitation and gravity are distinct. "Gravitation" is the attractive influence that all objects exert on each other, while "gravity" specifically refers to a force which all massive (objects with mass) objects are theorized to exert on each other to cause gravitation.

Answer 7

It works by the interaction of the graviton with other particles in it's proximity! According to B. Heim gravity has limits in both the macro universe and the micro levels as well! If we were to reach out to the edge of the known universe we may find that gravity is weaker or doesn't have the same effect. Gravity is limited by distance! It is also limited by very short distances as well!

Answer 8

God makes it work. How dare you doubt Him and His glory!
Also, what goes up must come down. The larger an object's weight or mass, the faster it falls. Simply put, gravity is the process of pressure in the atmosphere forcing an object to fall. Pressure in the Atmosphere + Object (weight) = Gravity (Force). For example, a dictionary will fall faster than a sheet of plain paper because it has a greater weight or mass.

Answer 9

Gravity is a vibrational frequency dependent on the total mass of an object. The Earth vibrates at 7.83 Hertz (Hz) which is cycles per second. At about 20Hz of sinewave frequency our ears can begin to pick up the frequency as sound. Our hearing falls off at 20,000Hz. Dogs can hear higher, as well as other animals. At 40 octaves above sound is where the visible light spectrum begins (infrared) which becomes 'heat'. After the visible spectrum of light and the UltraViolet frequencies, we begin to go into the radio frequency spectrum (kHz, MHz, GHz), which can go extensively above 6Ghz which is approaching microwave frequencies. At this point the frequency becomes vibratory to atomic molecules and we have microwaves and radiation, which can burn our skin. Plutonium is one example of a highly vibrational element that is toxic to life. You pass into X-rays, Gamma Rays, and other forms of high radiation. At some point in quantum physics, the 'sub-quark' is the smallest form of 'mass' that we have observed, which is actually energy as well according to Einstein's Theory of Relativity stating that Mass or Energy can neither be created nor destroyed according to E=Mc2 where c equals the speed of light (squared). Although the speed of light is a constant, it is this squaring of the speed (times itself) that is 'akin' to gravity, which is 9.8m/s squared (on this planet). At these highest frequencies of vibration, energy becomes self-sustaining, and builds upon itself relative to the lower frequencies, like a giant pyramid. So because all mass has energy, and all energy has mass due to the atoms, molecules, or 'sub-quarks' making up the structure, the 'bigger' something is, the more total energy force it exerts outward into the universe due to the sum total of the vibrations of its entire mass. Gravity therefore is one of the highest forms of energy we recognize because it is involved with the space-time continuum. Time for example vibrates at such a high frequency that it remains constant. There is actually no past or future (for real) but only the present, which is experienced by everyone at the same time. Gravity is somewhat less of an influence, since the rate at which objects accelerate towards each other increases as they continue to fall under the influence of their vibrational-mass frequency. Magnets are good tools to work with for gravitational experiments since the magnetic attraction they have on each other and magnetic metals like iron can show the invisible forces of vibrational attraction for like objects. The metal core of the earth is so massive, that its rate of like attraction creates so much energy that the metal becomes molten and liquid. Volcanoes spew out a much less 'dense' (and therefore less hot as well) magma that forms the earth's crust. It is this total density of the earth that exerts 'gravitational' force on all mass, pulling the total mass of atomic weight with an ever increasing strength dependent on the distance between the two objects, thus gravity is a squared constant dependent on mass like Einstein's theory shows the Matter and Energy are related by the squared speed of light.

Answer 10

suposedly, there is an unknown particle called a graviton that has a high gravitational energy which keeps us on earth