# what is gravitational force?

Gravitational force is particle or wave? I know that gravitation depend of the mass and the rotation speed but what is the transmission medium of this wave the same like transmission medium of the light ?

• Gravitational force is mediated by a massless spin-2 field that couples to energy, similarly to how electromagnetic force is mediated by a massless spin-1 field that couples to electric charge. That much has been understood for quite a long time now. Beyond that, I'm not sure what you're intending to ask. – Stan Liou Feb 6 '16 at 1:33
• @TheVoid What are you on about? Gravity has been described by a massless spin-2 field since 1915. I recommend you check e.g. Feynman's Lectures on Gravitation (initially done in 1962), which includes an argument that a massless spin-2 field implies the equivalence principle (the pillar of general relativity) for point particles or bulk unpolarized matter. This was shown more rigorously using quantum field theory by Weinberg in 1972. These things are well-known features of gravity. – Stan Liou Feb 6 '16 at 2:51
• @TheVoid Of course it would (as strange as such taking such a shape or being able to hold it against its own gravity would be). But your question is such a bizarre non-sequitur that I suspect you're just trolling me, so I won't bother replying to you further. – Stan Liou Feb 6 '16 at 2:59
• @TheVoid General Relativity describes gravity not as a force, but as a consequence of the curvature of spacetime caused by the uneven distribution of mass/energy. By the way, GR has proven incredibly accurate and calling it "just a theory" is extremely misleading. Theories are what science is based upon; there are no certainties. GR is the closest thing to reality that we have right now, since it's so precise. – Sir Cumference Feb 6 '16 at 19:49
• My question is what is the transmission medium of the gravity and do its have some name ? – sytolk Feb 6 '16 at 21:55

As a hobbyist, I'll give a limited answer.

Gravitational force is particle or wave?

Until we actually find out what gravity is, the safe answer here is that we don't know, but it's probably a wave and a particle. Most (perhaps all) fundamental particles in quantum physics are waves and particles. Light for example, Electrons too, though we might think of an electron as a particle, it's wave properties are easily demonstrated, and wave properties of protons can be demonstrated as well. There's a ton of stuff that can be googled on the wave-particle duality. Here's one.

It's unclear exactly what fundamental particles "are" so saying a fundamental particle is "this or that" is a bit iffy since we can't see them. We can only study how they behave. Gravity, if it's a fundamental particle, which it probably is, it should be both a wave and a particle, and a field. I know, that's a little hard to think about. We don't get to have many tangible answers in quantum physics.

I know that gravitation depend of the mass and the rotation speed

Gravity depends on mass. Period. Rotation speed can creates a centrifugal force opposing gravity and making things lighter, but that isn't gravity. The gravity is still 100% governed by mass.

what is the transmission medium of this wave the same like transmission medium of the light ?

Light (as far as I know) doesn't require a transmission medium. Gravity shouldn't either. Sound waves require a medium but light and gravity can pass through empty space.

If you have more specific questions, you might have better luck on Physics rather than Astronomy. Also, my 2 cents, Stan Liou has made some intelligent comments well worth reading.

• @userLTK- Great way to answer the unanswerable, No deception or fictional facts.Everything doesn't have to be written in stone. – user5434678 Feb 6 '16 at 5:55
• @userLTK if the light and gravity is a wave they have transmission medium like the wave in the sea have transmission medium -water. In the water wave the particles have rotation direction too and one wave reaches the beach on the principle of domino (the same particles hit the beach many times) we see that wave is moving but the particles not moving with wave they only hit the other particles and continue with rotation direction. – sytolk Feb 6 '16 at 21:34
• "Rotation speed can create a centripetal (centrifugal??) force opposing gravity and making things lighter," Rotation also stores energy, and energy is mass, per $E=mc^2$. A body spinning sufficiently fast will exert higher gravity, e.g. a slowly-spinning neutron star will have a weaker gravitational pull than equivalent neutron star that spins very fast. – SF. Feb 6 '16 at 23:52
• @user3252198 I understand what you're saying about the behavior of a water wave but I'm not sure how that applies to a light wave. I'm also not sure that light passes through a medium at all, or if it does, it's a "field", which is a different kind of medium. . That gets a little complicated physics.stackexchange.com/questions/109982/… – userLTK Feb 7 '16 at 2:29
• @SF, Relativistic mass to rotational energy. :-) I like that, but it's mostly quite small. I'm also not sure that what you suggest is realistic. Probably better for a separate question though. Oh, and it's centrifugal. I looked bhoffert.faculty.noctrl.edu/HST263/… I've edited my post. – userLTK Feb 7 '16 at 2:59