Trekkie With a Phaser

I don't know if this question has ever been brought up before (or if it will even make sense) but what exactly is the relationship between gravity and time? I know that gravitational fields bend time as well as space, so it would seem that gravity is a force distinct and seperate from time. The thing is, gravity exerts a force on everything and everyone and we're all contained within time, thus gravity must be acting within the confines of spacetime. So, how can a force acting within spacetime (gravity) warp one of the things (time) that it's dependent on for its existence? Or am I completely wrong?

Abacus

Hmm. I'm not a physicist. But I'll give your question a shot.

It is my understanding that gravity is the curvature (or warping) of space-time. That is, the bending of both space and time, since they are part of the same entity, called space-time.

To quote Hermann Minkowski:

Space and time are not independent of each other. Therefore, the warping of space necessarily entails the warping of time.

So I guess the simple answer is, that's just what gravity is. The bending of space and time.

My apologies if this is not clear. It's really damn hard to explain (for me anyways).

Trekkie With a Phaser

Abacus,
Thanks for your reply. If I understand you correctly, you're saying that I'm making a mistake by thinking of space, time, and gravity as seperate entities. Space and time are inseperable (hence the term "spacetime") and gravity is just the warping of spacetime. This makes a lot more sense than what I had originally thought. Thanks for your help.

HeatherD

I'm not a physicist, but I'm pretty sure that gravity is not really dependent on time for its existence.

The other thing to remember is that while gravity does exert a force on everything, it doesn't do so equally. It's actually:

So gravity is affected by mass and distance. The most important thing is that gravitational force falls off as a square of the distance. If you double the distance the force is reduced by 1/4.

How does this effect time? While this might not be scientifically accurate, space is "warped" by gravity. We don't see this warping because it's in the temporal dimension.

In a universe (hypothetically) without gravity, space-time would be flat. The "distance" between point a and b is simply the space like dimension's distance. In our universe gravity warps space-time so that what was a just a straight line is now stretched.

I'm probably way off, it's been some time since I read about this stuff. The book I have refers to geodetic lines and such that explain the why a "straight" line in warped space is still straight, or something like that. It all has to do with geometry on curved spaces.

If you are really interested there are dozens of good books that explain these things. My favorite book, Einstein's Theory of Relativity by Max Born, was printed in 1962. It might be a little old but it's still pretty good.

fando

You mean in the context of General Relativity, right? You could ask the same question in the context of Quantum Mechanics or M-theory or even the new fangled Loop Quantum Gravity. What is gravity and its relationship to time? The answer, my friend, depends very much on how you frame it.

Trekkie With a Phaser

eh, what?,
Thanks for the book recommendation. I'm trying to get over my scientific illiteracy and I'm always up for anything that can help.

I knew that gravity is inversely proportional to the square of the distance between two masses and that that results in a stronger force the closer together the two masses are and a lesser force the farther apart they are. The problem I was having though was in thinking of gravity as a force that both affects time from without and as something that exists within time. Abacus's post made me realize that I was trying to divorce space, time, and gravity, which was creating my dichotomy. I have to think of gravity not as a seperate entity, but instead as the curvature of space time. Thinking of it this way removes the question of how it can be seperate from time and still function the way it does, because it's NOT actually seperate from time.

Anyway, thanks for giving it a shot. Believe me, I'm a lot less confused now than when I asked the question.

fando,
Yep, I do mean in the context of General Relativity. As little as I know about it I know even less about Quantum Mechanics and absolutely nothing about the last two that you mentioned.

Mr. Sammi

This invisible force of gravity does have itz source. What is itz source? Is it mass as understood as matter or is it energy?

At the infinitesimal plateau there are forces which bind particles together. Particles which endure existence have intrinsic time built/folded into them ELSE they would not be recognisable as particles in existence.

Gravity is like a force which tries to fuse particles together except the particles are large masses and mostly the grav force is not strong enough for the masses to meld.

What role is TIME playing in this scheme of things. Seeing there is intrinsic time, something to which we normally pay no heed, since this is the given of existence, AND there is extrinsic time, which is the manner in which existence itself plays out itself, we can surmise that the effects of mass(es) through time (extrinsic) when showing up as gravitational fields, plays out in existence, which corresponds to mass and extrinsic time in existence.

Summarily this means the emergent force of mass through time is effective in existence which exixts as mass in time. It is like two humans speaking to each other and the result is two humans affecting each other IFF they are close enough.

Does this lead us to think that there can be some massive gravitational force which can crush the intrinsic time of some mass AND therby removing the mass from existence.

Goodnight Irene...


Sammi Na Boodie ()

Philosoft

In that case, the space-time warping already mentioned is the common interpretation under GR.

Quote:

As little as I know about it I know even less about Quantum Mechanics and absolutely nothing about the last two that you mentioned.

Quantum mechanics predicts gravity will maifest as a force particle, as do the other forces, nuclear (bosons) and electromagnetic (photon). M[embrane]-Theory is basically a unification of the various superstring theories. M-Theory, among other things, predicts the existence of strings (branes) of greater than one dimension.

Friar Bellows

Both, sort of. The source of the gravitational field is the stress-energy tensor.

crocodile deathroll

I just did an illustration what my preferred model of time.
I favor the block time universe where all events are all equally real.
Some through in possibilism, but to me that is just an enhanced version of block time.