[BearInThere (OP)]

Is the 3 body problem caused by gravity being limited to the speed of light, therefore meaning you have to know the position of all objects prior to T0.

[Halc]

Is the 3 body problem caused by gravity being limited to the speed of light, therefore meaning you have to know the position of all objects prior to T0.

Gravity doesn't have a speed, so it isn't that.
Yes, one cannot predict even the position of a single body if the positions of the one body is not known at T0 or some starting point. The 3 body problem has to do with the fact that there is no formula to predict the future position of any of 3 bodies in a system, given an initial state.

[evan_au]

Another aspect of the 3-body problem is that the general case often exhibits chaotic behavior.
- This means that the future behavior depends critically on the initial conditions. Tiny errors in the initial measurements (at T=0) grow exponentially over time, and eventually overwhelm any prediction.
- So the future behavior cannot be predicted in detail, no matter how accurately you measure the initial mass, position (X, Y, Z) and velocity (V_X, V_Y, V_Z) of all 3 bodies. 

At least the 3-body problem has a couple of stable solutions, eg L4 & L5 identified by Lagrange (which only work if one of the bodies has a negligible mass).

This initial conditions problem is even more extreme for the very realistic n-body problem, eg our Solar System.
- The n-body problem has no stable solutions
- but for now, the Solar System has settled into some quasi-stable orbits
- unlike some of the extrasolar planetary systems we have discovered...

See: https://en.wikipedia.org/wiki/Lagrangian_point

[BearInThere (OP)]

Exuse me if I post this wrong but I am a newbie.

Halc
I'm surprised by your response, are you saying that the effects of gravity travel faster than the speed of light? I'm not saying you are wrong but entanglement is the only idea that I've heard of that could break the speed limit. (please do not go off topic about that)
What I was saying is that if I have P1, P2 and P3 in a static environment then at T0 the instantaneous attraction between any of the three can be known.
But who ever heard of a static environment. So at T0 P1 is not attracted to P2 but to where P2 was at T0 - (P1 - P2 * c)
If gravity travels at the speed of light then 3 body becomes self explanatory because you can never find a starting point for the equation.
If on the other hand gravity is instantaneous then I want proof.

[Halc]

Halc
I'm surprised by your response, are you saying that the effects of gravity travel faster than the speed of light?

It doesn't travel at all.  Gravity is a field, not an object that moves like light.  Gravity waves travel (as graviton 'objects'), but gravity waves are not what cause a pair of masses to attract.

I'm not saying you are wrong but entanglement is the only idea that I've heard of that could break the speed limit. (please do not go off topic about that)

Gravity doesn't break the speed limit since it is always there.  You can't turn it on and off.  You can turn gravity waves on and off, but again, that's something else.

What I was saying is that if I have P1, P2 and P3 in a static environment then at T0 the instantaneous attraction between any of the three can be known.
But who ever heard of a static environment.

If they're held in place somehow, then it's a static environment with calculable stress.  Otherwise it is an initial condition of some dynamic system.

So at T0 P1 is not attracted to P2 but to where P2 was at T0 - (P1 - P2 * c)

No, that's pretty easy to prove wrong.  If that were true, a pair of identical orbiting bodies would be attracted to a place not perpendicular to their motion, but to a place somewhere forward of that.  Both objects would spiral out, a violation of energy conservation.
The attraction is to where the mass is now.  This works in any frame.

If on the other hand gravity is instantaneous then I want proof.

See above.
Here's a site that illustrates the concept:
http://www.flight-light-and-spin.com/proof/instant-gravity.htm

[BearInThere (OP)]

Halc, thanks for the link. I’ll take a look at the math a bit later.
Yeah I get that gravity is a field not an object, hence my dislike of the term graviton.
And you nearly had me convinced. But Ligo’s first observation was of an event that took place 1.4 billion light years away and 1.4 billion years ago.  It validate Einstein’s POV that gravity is distortion in space caused by mass, and the propagation of that distortion is at the speed of light.

[evan_au]

I get that gravity is a field not an object, hence my dislike of the term graviton.

Electromagnetism is also a field, not an object.
But photons are very real - a disturbance on the electromagnetic field, which propagates at c.

Most physicists expect that gravitons also exist, as a disturbance on the gravitational field, which propagates at c.

It's just that the force of gravity is about 10⁴⁰ times weaker than electromagnetism;
- Astronomers regularly detect individual photons of visible light (and higher energies) - but it often takes cryogenically cooled detectors
- But we know of no existing technology that would allow us to detect individual gravitons; their individual energy is just too small
- A detailed understanding of what happens really close to the event horizon of a black hole will probably require an understanding of the graviton

[BearInThere (OP)]

I get the whole wave particle duality, but thinking of gravity as a particle just don't feel right to me.
 

Most physicists expect that gravitons also exist, as a disturbance on the gravitational field, which propagates at c.

Regardless of my previous comment regarding gravity waves, you've just tied gravity to c which was my whole point to begin with.

[Halc]

Halc, thanks for the link. I’ll take a look at the math a bit later.
Yeah I get that gravity is a field not an object, hence my dislike of the term graviton.
And you nearly had me convinced. But Ligo’s first observation was of an event that took place 1.4 billion light years away and 1.4 billion years ago.  It validate Einstein’s POV that gravity is distortion in space caused by mass, and the propagation of that distortion is at the speed of light.

LIGO detects gravity waves, and those very much do travel, and at light speed.  A quanta of gravity waves is the graviton.  Gravity does not exert its force via gravity waves.  It doesn't take a super sensitive device to measure gravity, but it takes one to detect gravity waves.
Changes (disturbances) to the gravitational field cause gravity waves, and change is information, and information travels at light speed, so yes, LIGO is expected to detect gravity waves at the same time that light comes from some distant event, assuming there is any light.

Regardless of my previous comment regarding gravity waves, you've just tied gravity to c which was my whole point to begin with

Gravity and gravity waves are two different things: A field (that does not travel), and quanta of wave energy, which does.

Gravity is an acceleration field (not even a force without a 2nd object).  It can expressed as A=Gm/r² where A is the acceleration at the current (not recent past) radius r from mass m.  This is not a force since there is no 2nd mass in the equation.

thinking of gravity as a particle just don't feel right to me.

Doesn't feel right to me either.  Gravity is a field, not moving particles.

[jeffreyH]

The solar system orbits the galaxy and is not static. Therefore the sun is moving. If the planets were not attracted to where the sun is 'now' then the solar system would be so unstable it would drift apart over time.

Never mind being chaotic. It would cease to exist as a system. This is just one of those things that we learn from observation. We might not think it makes sense but the universe doesn't care. It just does what it does. Some things you just have to accept.

[jeffreyH]

Oh, and by the way, if you think I'm wrong, explain tidal locking using your scenario.

[yor_on]

You could think of it as a spiders net Bear, that's what I do sometimes :)
If something disturbs this net the 'wave' will propagate at 'c'. When it comes to it being particles then that's one theory, The Higgs 'particle / boson' doesn't cover 'gravity', just a part of it. But if we assume gravity to be 'particles' then what we have in this 'net' is a constant shower of them, increasing with a disturbance. If it's not 'particles' or a combination?