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Thread: Is time contracted for massive objects?

  1. #1 Is time contracted for massive objects? 
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    We all know that massive objects exert a gravitational influence on other nearby objects. This obviously means that gravity works across space. Should the same not be true of time? I've heard it said once that there's a principle that states that space and time are analogues of each other, meaning that whatever is true of the one is also true of the other.

    But what does it mean for an object to exert gravity across time? To me, it could mean nothing other than that an object exerts a gravitational force on itself in its future and past states. But what does that mean? To me, it seems it could only mean the same thing that it would mean in terms of space. In terms of space, it means that the object exerting gravity will pull other objects closer to itself, or that it will shorten the distance between them. Therefore, in terms of time, it means the object will shorten the amount of time between its past and future states. And this can only mean that it goes through all its temporal states faster than less massive objects. The more massive the object, the speedier it lives its life in the universe.

    So what I'd like to know is whether this makes sense theoretically, and whether there is any evidence for it. If the answer to either of these is 'no', why wouldn't it be true (I mean, it does seem to have a certain logic to it, doesn't it)?


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    Your Mama! GiantEvil's Avatar
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    Let's consider a massively gravitational object, a black hole! Russian physicists call them, "Frozen Stars". Why is this? Because, according to Einstein's General Relativity, space, and time, are a single entity. And in the presence of mass, the stuff of the existential, this space-time becomes geometrically warped.

    Now let's imagine a very simple model for space time, a rubber band. Let's imagine a tennis ball for a gravity source. Our model will still exist in "normal" 3-space. Holding one end of the rubber band some distance, oh a foot or so, from the tennis ball. Stretch the other end of the rubber band toward the tennis ball. Our gravity source is now bending space-time. What is the condition of the rubber band? It is longer, and since it represent's space-time, that mean's that time is longer in gravitational fields. That is, that the distance between temporal moment's has increased, and it takes longer to travel between them.

    Temporal dilation has been absolutely proven. The U.S Dept. of Def. uses temporal dilation calculations to synchronize signals between satellite and ground units in military GPS.

    A simple but crude analogy is this. If we place one clock next to a big rock, and another clock next to a little rock. The clock next to the big rock will run more slowly. The clock next to the little rock will run more fast.

    According to General Relativity, within the event horizon of a black hole, the geometric warping of space time becomes infinite. For the black hole, time is stopped. That is why the Russian's call them, "Frozen Stars".


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    Quote Originally Posted by GiantEvil
    Stretch the other end of the rubber band toward the tennis ball. Our gravity source is now bending space-time. What is the condition of the rubber band? It is longer, and since it represent's space-time, that mean's that time is longer in gravitational fields. That is, that the distance between temporal moment's has increased, and it takes longer to travel between them.
    Oh, I see, so time is stretched, not contracted.
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  5. #4 Re: Is time contracted for massive objects? 
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    Quote Originally Posted by gib65
    We all know that massive objects exert a gravitational influence on other nearby objects. This obviously means that gravity works across space. Should the same not be true of time? I've heard it said once that there's a principle that states that space and time are analogues of each other, meaning that whatever is true of the one is also true of the other.

    But what does it mean for an object to exert gravity across time? To me, it could mean nothing other than that an object exerts a gravitational force on itself in its future and past states. But what does that mean? To me, it seems it could only mean the same thing that it would mean in terms of space. In terms of space, it means that the object exerting gravity will pull other objects closer to itself, or that it will shorten the distance between them. Therefore, in terms of time, it means the object will shorten the amount of time between its past and future states. And this can only mean that it goes through all its temporal states faster than less massive objects. The more massive the object, the speedier it lives its life in the universe.

    So what I'd like to know is whether this makes sense theoretically, and whether there is any evidence for it. If the answer to either of these is 'no', why wouldn't it be true (I mean, it does seem to have a certain logic to it, doesn't it)?
    No. You have the theory all fouled up.

    Newtonian gravity does indeed predict instantaneous "action at a distance". That is a problem with the theory. It is good enough as an approximation for many purposes, but iti is wrong.

    The best available theory of gravity is general relativity, and in general relativity what we call gravity is the curvature of space-time. Curvature here is notion taken from differential geometry, and requires quite a bit of study and mathematical background to be understood.

    However, the gist is that gravitational "forces" do not propagate instantaneously.

    Relativity is a theory of space and time. They are part of a single manifold, called spacetime, and are intertwined so that space and time are distinguishable as separate things only locally. As with curvature, this requires some study and mathematical background in order to be made precise and understood.

    I suggest that you read books on the theory of relativity. One that is written for a general audience, and that requires little mathematics is Kip Thorne's Black Holes and Time Warps, Einstein's Outrageous Legacy. A more technical treatment is Wolfgang Rindler's Essential Relativity, Special, General and Cosmological which still is not highlymathematical. For the real deal see Gravitation by Misner, Thorne and Wheeler.
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