gravitons

Originally posted by @metal-brain
"I think of gravity as mass having an effect on the time part of space-time,"

I agree. Time dilation is gravity, not a result of gravity. I think of time dilation in the same way as a low pressure area. Things move toward a slower passage of time because it is the shortest path in time.

Time dilation is the result of bent spacetime because space is malleable like taffy, it flows and that will effect the flow of time. High gravity well, time slows down. Same as high velocity, time slows down.

Originally posted by @sonhouse
Time dilation is the result of bent spacetime because space is malleable like taffy, it flows and that will effect the flow of time. High gravity well, time slows down. Same as high velocity, time slows down.

Bent spacetime is the result of time dilation. You had it backwards.

Originally posted by @metal-brain
Bent spacetime is the result of time dilation. You had it backwards.

If all of time is present..all past..all future is here at once..how can it be bent/ So that proves that space cant bend either !!

Originally posted by @ogb
If all of time is present..all past..all future is here at once..how can it be bent/ So that proves that space cant bend either !!

I don't follow your chain of reasoning. You have if A then not B. If not B then not C. Where A is all of time is present simultaneously, B is time is bent, C is space is bent. There seems to be something of a synthetic argument going on. First it's not obvious to me what you mean by "all of time is present simultaneously", I'm assuming you mean a picture where space and time form a manifold and past and future are just words for what is ahead of us and behind us in the time-like direction. The second problem I have is the claim that because of the eternalist picture time cannot be "bent" - I assume you mean curved - a one dimensional space has no intrinsic curvature it is only curved when embedded in a higher dimensional space - I don't think that follows at all from an eternalist picture, so I'd like to see more of an argument there. The third statement, that time not being "bent" implies that space cannot be either also seems to lack some justification. So I don't think that you have demonstrated anything very much.

Originally posted by @metal-brain
Bent spacetime is the result of time dilation. You had it backwards.

So write up your Phd thesis and prove it. Of course all you have is opinion, having no science in your background.

Originally posted by @sonhouse
So write up your Phd thesis and prove it. Of course all you have is opinion, having no science in your background.

It is my opinion. So what?
Prove me wrong if you are so sure that is the case.

Had it ever occurred to you that I may be onto something? If accelerating at high speed causes time dilation and a gravity like force why shouldn't the time dilation cause objects to accelerate while falling? Gravity does that. When objects fall.they accelerate.
Can you show me that a future rocket ship accelerating with a certain time dilation would not have the same g-force as the gravity of a planet or moon with the same time dilation? If you can do that you can prove me wrong.

Originally posted by @metal-brain
It is my opinion. So what?
Prove me wrong if you are so sure that is the case.

Had it ever occurred to you that I may be onto something? If accelerating at high speed causes time dilation and a gravity like force why shouldn't the time dilation cause objects to accelerate while falling? Gravity does that. When objects fall.they accelerate.
Can y ...[text shortened]... vity of a planet or moon with the same time dilation? If you can do that you can prove me wrong.

The rate at which a clock runs in the absence of a gravitational field depends on the instantaneous velocity of the observer, not their acceleration, this is known as the Clock Hypothesis and is experimentally confirmed. In a gravitational field the rate a clock runs depends on where in the gravitational field one is. So I don't think you can make a simple identification between time dilation and acceleration. What's causing me some problems is that my argument does some real damage to the principle of equivalence, so I need to think about this.

Originally posted by @deepthought
The rate at which a clock runs in the absence of a gravitational field depends on the instantaneous velocity of the observer, not their acceleration, this is known as the Clock Hypothesis and is experimentally confirmed. In a gravitational field the rate a clock runs depends on where in the gravitational field one is. So I don't think you can make a s ...[text shortened]... y argument does some real damage to the principle of equivalence, so I need to think about this.

Equivalence to what? Is my statement wrong that time dilation is an effect, not a cause like he is suggesting?

Originally posted by @sonhouse
Equivalence to what? Is my statement wrong that time dilation is an effect, not a cause like he is suggesting?

The Principle of Equivalence is that an observer in a small test volume cannot distinguish between a gravitational field and an acceleration. The difficulty I have is that the Clock Hypothesis seems to contradict this. I'm not sure how much of a problem it is as the observer in the test volume cannot tell that their clock is running slowly without consulting a second observer in an inertial frame and away from a gravity well - or on a planet with a non-varying clock rate. If the first observer is in an accelerated frame because they are accelerating in a flat background then their clock should be running slower and slower relative to the external observer.

Within the standard theory, yes time dilation is explained by curvature and not the other way round, I think metal-brain realizes that he is advocating a non-standard theory.

One difficulty with this discussion comes back to what we mean by cause and effect within the explanatory framework of a theory. There are two things, time-dilation and curvature, they are both there and it is normal to consider time-dilation as being a consequence of curvature, but since one never sees one without the other one needs a little more to decide that time-dilation is the consequence. That curvature is a tensor quantity with 20 independent components seems to indicate that time-dilation cannot provide a full account of it.

Consider two metal balls connected by a spring - is the compression of the spring caused by the motion of the balls or the motion of the balls caused by the compression in the spring?

Originally posted by @deepthought
The Principle of Equivalence is that an observer in a small test volume cannot distinguish between a gravitational field and an acceleration. The difficulty I have is that the Clock Hypothesis seems to contradict this. I'm not sure how much of a problem it is as the observer in the test volume cannot tell that their clock is running slowly without con ...[text shortened]... d by the motion of the balls or the motion of the balls caused by the compression in the spring?

I'm thinking that you could test for accel V gravity if you have say, an elevator, or spacecraft, accelerating, Vs the spacecraft on top of a tall tower, that if you had sensitive enough gravitometers there would a slight curvature of the gravity field because you would be above a round planet so it would seem the exact center of the elevator or whatever would have a tiny slightly greater gravity field V the edges of the elevator and that effect would be more noticeable the wider the craft, there would be more divergence of the field from edge to center. If you had a rocket shoving under the craft undergoing acceleration it would seem to me the same set of gravitometers would show equal 'gravity' at the center and the edge. I don't see how it would be possible to see the same thing with sensitive enough detectors, also don't know how many digits of scale you would have to have to see the difference in the case of an elevator on a high tower but it seems to me that would show the difference. Of course if it was humans in the elevator they would never be able to detect such a small change from center to edge of the elevator so in that sense the equivalence principle would be valid. I just think with sensitive enough instrumentation you could suss out which field you were in, acel or gravity.

If you had a spring with balls at each end and were in deep space and compressed the balls together as close as the springs would allow, it would turn into a cyclical affair, springing out as the energy of the spring gets converted to kinetic energy to the balls which of course would go further than neutral unstressed length of the spring thus causing the balls to cycle inwards and outwards and of course in this case the oscillations would die down because of friction inside the spring itself so it would eventually stop bouncing in and out. I know that was not on topic but thought I would point that out. Of course that would be assuming the balls were solidly connected to the ends of the spring.

It's funny that if the balls were spinning on the common axis the cycling of the springs would stop but the spinning would go on forever since there would be no force to stop it, unless you would consider the small number of atoms hitting the balls as a force to slow it down. In any event the spinning would go on long after the ball/spring cycle stopped.

Originally posted by @sonhouse
I'm thinking that you could test for accel V gravity if you have say, an elevator, or spacecraft, accelerating, Vs the spacecraft on top of a tall tower, that if you had sensitive enough gravitometers there would a slight curvature of the gravity field because you would be above a round planet so it would seem the exact center of the elevator or whatever w ...[text shortened]... to slow it down. In any event the spinning would go on long after the ball/spring cycle stopped.

Who knows, someday in the future we might develop the balls to confirm this.

... and the spring

Originally posted by @sonhouse
I'm thinking that you could test for accel V gravity if you have say, an elevator, or spacecraft, accelerating, Vs the spacecraft on top of a tall tower, that if you had sensitive enough gravitometers there would a slight curvature of the gravity field because you would be above a round planet so it would seem the exact center of the elevator or whatever w ...[text shortened]... to slow it down. In any event the spinning would go on long after the ball/spring cycle stopped.

The volume of space in which the principle of equivalence is expected to be rigourously true is infinitesimal, which sorts out the problem of divergence of the field. I used the word small to allow a realistic observer.

Originally posted by @deepthought
The volume of space in which the principle of equivalence is expected to be rigourously true is infinitesimal, which sorts out the problem of divergence of the field. I used the word small to allow a realistic observer.

So if the elevator was one micron wide that would make it impossible for small gravitation meters to make out a difference between left and right V an acceleration. Seems like it would have to apply to something more like a picometer wide.

Originally posted by @sonhouse
So if the elevator was one micron wide that would make it impossible for small gravitation meters to make out a difference between left and right V an acceleration. Seems like it would have to apply to something more like a picometer wide.

In the limit that the volume goes to zero...

Originally posted by @deepthought
The Principle of Equivalence is that an observer in a small test volume cannot distinguish between a gravitational field and an acceleration. The difficulty I have is that the Clock Hypothesis seems to contradict this. I'm not sure how much of a problem it is as the observer in the test volume cannot tell that their clock is running slowly without con ...[text shortened]... d by the motion of the balls or the motion of the balls caused by the compression in the spring?

"the observer in the test volume cannot tell that their clock is running slowly without consulting a second observer in an inertial frame and away from a gravity well - or on a planet with a non-varying clock rate. If the first observer is in an accelerated frame because they are accelerating in a flat background then their clock should be running slower and slower relative to the external observer. "

Are you talking about background dependence vs. background independence?

"That curvature is a tensor quantity with 20 independent components seems to indicate that time-dilation cannot provide a full account of it."

What 20 independent components? Please explain.