Is time contracted for massive objects?

[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)?

[Spyman]

According to the Theory of Relativity, time will pass slower for a more massive body relative a less massive one.

 

"Gravitational time dilation is the effect of time passing at different rates in regions of different gravitational potential; the lower the gravitational potential (closer to the center of a massive object), the more slowly clocks run. Albert Einstein originally predicted this effect in his theory of relativity and it has since been confirmed by tests of general relativity."

http://en.wikipedia.org/wiki/Gravitational_time_dilation

[gib65]

Seems counterintuitive after considering my reasoning above, doesn't it? Any way of reconciling this?

[swansont]

Seems counterintuitive after considering my reasoning above, doesn't it? Any way of reconciling this?

 

Yes.

 

We do experiments. Time runs slower in a gravitational field created by other objects, and scales with the gravitational potential. GR wins.

[Spyman]

Seems counterintuitive after considering my reasoning above, doesn't it? Any way of reconciling this?

 

 

1.

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.

The connection between space and time is the speed of light, which is constant for all observers, this gives us the relation that when space is compressed then time is equally slowed down.

 

2.

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?

Gravity itself progress with the speed of light and is not able to exert force through time like you think. Forces can be caused in the past and might act upon us in the future, but right now here in the present there are only present forces acting on present space and time.

 

If the Sun would suddenly vanish it wold take ~8 minutes before the last photon in the stream of light already released from it would reach us and we would be in the dark, similar it would also take the same time before Earth would be free from the last of the gravitational grip and instead of orbiting would take off in a straight path.

 

But we are not able to measure a force of gravity from the Sun where it was 1 hour ago or from where it will be in 1 hour from now and if there are no forces emerging through time from no longer present Suns or from possible future Suns acting on us, then there are not any such forces acting on the Sun itself either.

 

A past object is not pulling or being pulled by its present self and neither is the future self of the same object.

 

Otherwise, if gravity would work across time, it would be possible to build a device that uses gravity as an agency for transfer of information to communicate with both the past and the future.

Edited May 11, 2010 by Spyman
Grammar

[michel123456]

the lower the gravitational potential , the more slowly clocks run.

 

And the higher gravitational potential, the more quick clocks run.

That is not counter-intuitive, that is the same thing that gib65 proposed.

 

A low gravitational potential is a photon: no time passes for a photon.

A high gravitational potential is matter: time passes for matter.

 

It reminds me an old idea that proposed that gravity & time are the one and same thing.

[ajb]

It reminds me an old idea that proposed that gravity & time are the one and same thing.

 

I don't know how one can understand gravity and time as being the same thing, but for sure they are not completely independent things. Or really, we should say that the best (classical) theory of gravity that is general relativity describes the structure of space and time.

[michel123456]

I don't know how one can understand gravity and time as being the same thing.

 

It is thought provocative.

[Spyman]

the lower the gravitational potential , the more slowly clocks run.

And the higher gravitational potential, the more quick clocks run.

That is not counter-intuitive, that is the same thing that gib65 proposed.

Hmm, the text I quoted from the Wiki article is phrased somewhat confusing...

 

This is what I quoted:

"Gravitational time dilation is the effect of time passing at different rates in regions of different gravitational potential; the lower the gravitational potential (closer to the center of a massive object), the more slowly clocks run."

http://en.wikipedia.org/wiki/Gravitational_time_dilation

 

What they mean to say is that for an object deeper down in a gravity well, where the intensity of the gravity field is greater, the clock will run slower relative for an object at higher altitude, where the intensity is lesser.

 

Further down this is written:

"Clocks which are far from massive bodies (or at higher gravitational potentials) run faster, and clocks close to massive bodies (or at lower gravitational potentials) run slower."

http://en.wikipedia.org/wiki/Gravitational_time_dilation

 

The wording with "gravitational potentials" is tricky because it is defined to be zero in empty flat space and then grow greater negative closer to and deeper inside massive bodies.

 

"By convention, the gravitational potential is defined as zero infinitely far away from any mass. As a result it is negative elsewhere."

http://en.wikipedia.org/wiki/Gravitational_potential

 

Thus "lower gravitational potential" is not where gravity itself is lower or weaker, instead it's where the potential gets MORE negative which is a larger negative value farther from zero, overturned it turns out to be where the gravitational potential is greater. Reversely "higher gravitational potential" is where the gravitational potential is lesser or closer to zero.

 

 

So it is actually the opposite of what gib65 is saying.

Edited May 12, 2010 by Spyman

[michel123456]

That was tricky, indeed. I completely forgot the negativeness of gravitational potential.

It is counter-intuitive.

 

Pity. I liked gib's idea.

It should be improved.

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From another old thread in a Forum forgotten by all gods:

 

Originally Posted by Michel

O sorry, I almost forgot: Gravity and time are 2 expressions of the same phenomena. That was my conclusion, but there is a missing part, because you cutted me off.

 

after being quoted , B. answers:

I've been giving this a bit more thought. Perhaps it was a bit unkind to dismiss it so readily. Let me rephrase your sentence in a way which I can see as sensible:

"A gravitational field is the spatial consequence of the intrinsic motion of time".

Now if that is what you are saying then you have had a pretty deep insight and are on to something.....

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Or

"A gravitational field is the spatial consequence of the intrinsic motion of objects through time".

 

because I consider the word "intrinsic" as abusive

and because the word "object" is redundant

we could say

 

"A gravitational field is the spatial consequence of motion through time".

Edited May 13, 2010 by michel123456
Consecutive posts merged.