Constant Time

[Physman]

I think it is more reasonable to think that all time is constant. As in moves at the same rate at all times, although when viewed from differnet refference frames it can appear slower or faster. So what if all time was passing at a constant rate, but appeared different to another observer (as in faster or slower).I think it is similar to if I ride a bike past someone they appear to be accelerating in the opposite direction of me, but when looked at through a different perspective it is quite obvious that I am the only one accelerating.

Thoughts?

[StringJunky]

The rate of Time does not appear to be different depending on your position or viewpoint, It is a measurable fact that the rate of time changes according to your position (in the gravitational field) and motion. The GPS system proves this everyday.

 

The people that work on this system have to compensate for time rate differences between the satellite clock and the ground clocks due to relativistic effects i,e, the clocks tick faster on the satellites than the ground clocks, when viewed from the ground. If they didn't do this then the accuracy of the system would get progressively worse for determining the position of an object, linked to the system, on Earth over time.

 

Check this out:

 

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html

 

If there was no such thing as gravity and everything in the universe was stationary relative to each other, then there would be a constant time.

[Physman]

I am sorry I think we had a misunderstanding, when two devices seperatley synchronized 'tick', they might not tick as fast as eachother they are still meauring the same time. Also, not a position or view point so to speak, but a perspective based on a realtive velocity. Every device is measuring the SAME time Inconsequential of their refference of time measurement. I hope this clear things up.

thanks for the input though.

[StringJunky]

Ok. I'm new to physics and what I wrote is as far as I understand so far.

 

I'll have to take a back seat on this one, observe and see where it leads to.

[asprung]

I believe there is a universal time at which the universe ages. Clocks may run at different rates in different time frames but this would not put a single event in the future in one frame and the past in another.

[iNow]

I believe there is a universal time at which the universe ages.

 

Relative to what? Some other universe?

Your comment (to borrow from swansont) is like saying "What's the difference between a duck?" It's senseless.

[ajb]

People have worked on the idea of a universal time. One possible way is via Einstein aether theory in which general relativity is coupled to a time-like unit vector field. (didn't this come up in another post recently?)

 

This should not be confused with the luminiferous aether.

[Physman]

I must agree with asprung here, the universe ages at the same rate with different refference frames of perspective. two devices may not be synchronized but they measure the same time.

[swansont]

I must agree with asprung here, the universe ages at the same rate with different refference frames of perspective. two devices may not be synchronized but they measure the same time.

 

How?

 

Two identical clocks will measure different intervals between two events if the clocks are in different reference frames. You get two answers. How is that the "same time?"

[Physman]

because tell me this Swansanot if I stand next to clock A which ticks add a different (slower) rate than clock B, will I be in the past no. It will only appear to be going slower from the reference frame of clock B, in truth they may tick out of synch but there is only one time now. I can not go into one frame of the future or one frame of the past.

[swansont]

because tell me this Swansanot if I stand next to clock A which ticks add a different (slower) rate than clock B, will I be in the past no. It will only appear to be going slower from the reference frame of clock B, in truth they may tick out of synch but there is only one time now. I can not go into one frame of the future or one frame of the past.

 

No, you won't be in the past. You can never be in the past, because now is tautological. It is always "now," hence the term is not meaningful. This argument sounds circular, because it only makes sense if there is an absolute time, but you can't assume what you are trying to prove.

 

You can do this if you want to disprove the notion of absolute time, and since you can't exist in someone else's past, perhaps you've done that.

[Janus]

because tell me this Swansanot if I stand next to clock A which ticks add a different (slower) rate than clock B, will I be in the past no. It will only appear to be going slower from the reference frame of clock B, in truth they may tick out of synch but there is only one time now. I can not go into one frame of the future or one frame of the past.

 

But consider this: I'm standing next to clock A, and you are standing next to Clock B. Clocks A and B are moving with respect to each other. According to me, your clock is running slower than mine. But according to you, it is my clock that is running slower than yours.

 

For the sake of argument we'll assume that there is some point where we both agreed that each other's clock read 12:00 (At the exact instant we passed each other).

 

So, now, 1hr later by my clock, according to me, my clock reads 1:00 and yours reads 12:30.

 

But according to you, when your clock reads 12:30, mine reads 12:15. Or conversely, when my clock reads 1:00, your clock reads 2:00.

 

So for instance there is no way for us to arrange it so that we both shout the word "NOW" such that we both agree that we both said it at the same time. If you shout NOW when your clock reads 12:30, and I shout NOW when mine reads 1:00, I will say that we shouted at the same time, but according to you, You will have shouted NOW 45 min before I did.

 

So how can you and I share the same "Now", when we can't agree when "Now" is?

[Physman]

First;

Swansonot, I agree with you that you can not be in the past or future, the only time tat exists is now, it is like saying there is no tommorow we can only live today. I think we are arguing for the same cause:D.

 

Second;

This is a very plausable situation you have proposed, but what you are trying to say is disproven by Simultaenity. Consider this; If to boats are a distance away from eachother (x), and they each have a clock onboard where one ticks at 2 per second, and the other at 1 per second, (and they both record the elapsed time). And then we use light as a measurement of the exact time we are speaking of, and one clock records 200 ticks and the other only one hundred, and we us light for the EXACT point for when the clocks read, it is still the same time for both of us our measuremnet devices just measured time at a faster or slower rate. So we share the same time although our devices do not. the same circumstances would hold just to differnet magnitudes if we had a relative velocity to oneanother.

[swansont]

First;

Swansonot, I agree with you that you can not be in the past or future, the only time tat exists is now, it is like saying there is no tommorow we can only live today. I think we are arguing for the same cause:D.

 

Second;

This is a very plausable situation you have proposed, but what you are trying to say is disproven by Simultaenity. Consider this; If to boats are a distance away from eachother (x), and they each have a clock onboard where one ticks at 2 per second, and the other at 1 per second, (and they both record the elapsed time). And then we use light as a measurement of the exact time we are speaking of, and one clock records 200 ticks and the other only one hundred, and we us light for the EXACT point for when the clocks read, it is still the same time for both of us our measuremnet devices just measured time at a faster or slower rate. So we share the same time although our devices do not. the same circumstances would hold just to differnet magnitudes if we had a relative velocity to oneanother.

 

 

I have a problem with "we share the same time although our devices do not." The devices measure the time. If what we are "sharing" is not measured by them, then I don't know what it is, but it isn't time.

[Sisyphus]

We're clocks too. Just not nearly as precise as artificial ones.

[Physman]

Ok Swansont, if the circumsatnces we have already discuse hold, where two devices measure time differently (from their perspective). Then we do not share the same time according to the clocks, although if I were to stand next to your clock (running slower) would I be in your past, no and vice versa. When you rely on machines to estimate time it is true that they might measure differently and there for indicate that we do not share time, you must then ask yourself; Are these two devices in the future orr past of one another? and the answer would be no.

[Klaynos]

If you were to stand next to it you would be in the same frame and they would measure the same time.

 

If you had perfect clocks, clocks in different frames would still measure the time differently to each other, it is a result of the universe NOT of measurement methods.

[Physman]

Exactly Klaynos, the two devices would need to have a relative velocity to sho a difference in time frames.

[Klaynos]

Exactly Klaynos, the two devices would need to have a relative velocity to sho a difference in time frames.

 

But once you have that velocity difference the two clocks will never agree, nor will they agree which clock is slower. It is impossible for either clock to be right, or wrong they are just different.

[swansont]

Ok Swansont, if the circumsatnces we have already discuse hold, where two devices measure time differently (from their perspective). Then we do not share the same time according to the clocks, although if I were to stand next to your clock (running slower) would I be in your past, no and vice versa. When you rely on machines to estimate time it is true that they might measure differently and there for indicate that we do not share time, you must then ask yourself; Are these two devices in the future orr past of one another? and the answer would be no.

 

Future and past lose meaning when you examine multiple reference frames as time is relative. You can only talk about future and past from the point of view of a single frame of reference.

[Physman]

Although you must realize that, that single refference frame is what we call now. WHich indicates that it is impossible for there to be another time, regardless of measuring devices.

[asprung]

If we look at it from the standpoint of events,all observers should view an event as it occurs,the events "now", though the observers clocks may differ.

[Physman]

Exactly Swansont although this single time fraim is what we call 'now', and it is always now regardless of how a relative velocity may affect two measuring devices, as asprung commented.

[Klaynos]

There is no single frame, there is no right time frame.

 

Two frames moving with a relativistic speed relative to each other. An observer in each one will never agree how much time has passed, there is no prefered reference frame from which you can decide which is right.

[swansont]

Exactly Swansont although this single time fraim is what we call 'now', and it is always now regardless of how a relative velocity may affect two measuring devices, as asprung commented.

 

"it is always now" is the problem. It is a tautology. It does not answer the question "when will X happen? or "What time is it?"