# Time Dilation. The faster you travel the longer I have to wait for you to return?

Tags: dilation, faster, return, time, travel
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P: 15,587
 Quote by Vandam That's mathematical mumbo jumbo with no physical sygnificance.
I agree. And yet, there is no experimental evidence which can select the LET mumbo jumbo over the block universe mumbo jumbo.

 Quote by Vandam You are lucky Einstein does not read you.
As long as we are channleing Einstein and pretending to know what he would say, I think that he would strongly object to your idea that any coordinates are physical. Certainly by the time GR was well established it was understood that coordinates are not physical, they are just mathematical conveniences.
P: 126
 Quote by DaleSpam I agree. And yet, there is no experimental evidence which can select the LET mumbo jumbo over the block universe mumbo jumbo.
I wonder what you exactly mean by 'experimental evidence'. That includes observation and measurements. We then have to agree on what you observe. Without observer independent events you only will end up in some bizarre philosophical interpretations such as solipsism. And if you do accept observer independent events as Einstein saw it (he was a realist and not a solipsist) it leads automatically to block universe.

Lorentz admitted that LT time-coordinates can not work in an ether (LET) context. LET with LT is a contradiction in terms. If you think you know better than Lorentz himself you have to do more work to convince me.
 P: 126 Here is what I mean. Green is the ether world. If you put green's coordinates of event A (0.5, 0.5) in the LT it gives you the red coordinates (Lorentz' local time) (0,289, 0,289). The red coordinates (time and space dimensions) have no meaning at all in the green ether context. Not even if you consider the green ether through event R3. In LET only the green coordinates have a physical meaning. Not the red ones. For the red ones you have to consider a physical red 3D world through R3 and A, which Einstein's SR allowed, but not Lorentz' LET. That's why Lorentz said: <> The LT only have a full physical meaning in SR, not LET.
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P: 15,587
 Quote by Vandam I wonder what you exactly mean by 'experimental evidence'. That includes observation and measurements.
Yes, exactly. And LET predicts the exact same observations and measurements in all situations as does the block universe. Thus there can never be any experimental evidence distinguising the two, regardless of your philosophical preferences and arguments.
P: 846
 Quote by DaleSpam Yes, exactly. And LET predicts the exact same observations and measurements in all situations as does the block universe.
How do you square that with the obvious: A 3-D universe evolving in time is physically not the same as a 4-D universe that is "...just all there." Or, "...things do not happen, they are just there."

 Quote by DaleSpam Thus there can never be any experimental evidence distinguising the two, regardless of your philosophical preferences and arguments.
Except that LET is not consistent with the results of entanglement experiments, whereas the block universe is.

And again, the block universe is more fundamental as compared to the ad hoc LET. It's a little bit like the difference between the heliocentric model of our solar system vs. the mathematical model of the earth centered solar system with cycles and epicycles, etc.
P: 1,162
 Quote by Vandam Here is what I mean. Green is the ether world. If you put green's coordinates of event A (0.5, 0.5) in the LT it gives you the red coordinates (Lorentz' local time) (0,289, 0,289). The red coordinates (time and space dimensions) have no meaning at all in the green ether context. Not even if you consider the green ether through event R3. In LET only the green coordinates have a physical meaning. Not the red ones. For the red ones you have to consider a physical red 3D world through R3 and A, which Einstein's SR allowed, but not Lorentz' LET. That's why Lorentz said: <> The LT only have a full physical meaning in SR, not LET.
It is true that Lorentz considered "the idea that the variable t only can be considered as the true time and that my local time t' must be regarded as no more than an auxiliary mathematical quantity. And SR considers both equivalent. But what that means is that SR considers BOTH t and t' as simply mathematical quantities with no implication that either one was "true" time or defining actual or physical simultaneity.

So your implication that SR considers t and t' as absolute in the sense Lorentz meant is not logically valid and in fact is antithetical to SR as it depends on the idea of an absolute scale or reference.

You can interpret Einsteins thoughts as meaning conventionally synchronized clocks define actual or absolute simultaneity , which is the basis of your interpretation of Block Time but I don't think you can back up that interpretation with Einstein's actual statements and I flatly don't believe it. It seems fundamental to SR that simultaneity is totally indeterminate and relative with the exception of co-located events.

It is true that SR denies the classical concept of a universal or absolute now but it does not replace it with a set of many universal or absolute "nows" . One for every velocity.

In actuality SR does not explicitly negate the possibility of a universal "now" it simply shows that any such instant is indeterminate and thus superfluous. Like an ether, or absolute motion.

Even given a hypothetical persistent and pre-created 4-d continuum , it is clear that consciousness exists in a limited slice of time and so in effect moves. SO there is neither any objection to the possibility that all consciousness is absolutely simultaneous. I.e a single slice of awareness progressing through the continuum nor any means of empirically falsifying such a concept.
It is self evident that the various clocks throughout the universe would not correspond to this simultaneity but how could this be observed or measured within the structure???

There may be a number of people who are open to the possibility of Block time in some form ( I don't completely reject it) but I would be surprised if there are many people who understand SR who consider conventionally synchronized clocks to be absolutely simultaneous.
WHich is exactly what you are claiming wouldn't you agree???
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P: 15,587
 Quote by bobc2 How do you square that with the obvious: A 3-D universe evolving in time is physically not the same as a 4-D universe that is "...just all there." Or, "...things do not happen, they are just there."
It isn't obvious to me. If a 3D evolving universe were physically different from a 4D universe then I would expect there to be some testable consequences, which there aren't. So I think they are philosophically different but physically identical.

 Quote by bobc2 Except that LET is not consistent with the results of entanglement experiments, whereas the block universe is.
Please provide a mainstream scientific reference for this claim. Since both LET and QFT use the LT your claim seems patently false to me.

 Quote by bobc2 And again, the block universe is more fundamental as compared to the ad hoc LET.
I agree completely, but this is a philosophical or aesthetic preference.
P: 846
 Quote by DaleSpam No, LET is consistent with entanglement since the LT is used by modern QFT.
That does not imply that LET is consistent with results of entanglement experiments. On the contrary, LET specifically requires light cone causality--that's the basis of Lorentz's derivations. That's why LET is tied directly to a 3-D universe evolving in time model. Entanglement experimental results violate light cone causality. Violation of light cone causality is not a problem for the block universe model. Thus, results of entanglement experiments provide the distinction you are looking for.
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P: 4,770
 Quote by bobc2 Entanglement experimental results violate light cone causality.
No, they don't. You can't send signals faster than light by using entanglement. The statistical correlations between results *appear* to "travel faster than light", but that's only an appearance; when you work out the underlying quantum field theory, the field operators commute at spacelike separations, so light cone causality is obeyed.

 Quote by bobc2 Violation of light cone causality is not a problem for the block universe model.
It would be if it actually happened; the block universe model still depends on a well-defined light cone structure that determines causal relationships between events.
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P: 15,587
 Quote by bobc2 That does not imply that LET is consistent with results of entanglement experiments.
Yes, it does. Entanglement follows the LT, just as predicted by LET. That is the epitome of consistency.

 P: 126 Austin0, Thanks for your reaction, I read it 4 times, but I am unable to understand what you exactly mean. I especially do not understand your 'absolute' and universal' terminology in the context what I mean. I think you didn't understand what I mean. If my spacetime diagram is wrong , tell me where it is wrong. How would you draw the spacetime diagram showing the Lt time coordinates? Same advice for Dalespam. If my spacetime diagram is wrong , tell me where it is wrong. How would you draw the spacetime diagram showing the Lt time coordinates? You just keep on telling me that the LT transformations give the same result in LET and SR, but if you can not tell me where the primed time coordinates should be read on a simple ether space and time diagram I am not impressed with your statement.
P: 846
 Quote by PeterDonis No, they don't. You can't send signals faster than light by using entanglement. The statistical correlations between results *appear* to "travel faster than light", but that's only an appearance; when you work out the underlying quantum field theory, the field operators commute at spacelike separations, so light cone causality is obeyed.
You are missing the whole point of my comments. I didn't say that signals are sent faster than light with entangled particles. It is for exactly that reason that LET fails with entanglement experiments. LET was developed specifically for explaining related events via the model of a fixed ether through which all processes evolve as a result of signals transmitting at the speed of light as ether waves.

Processes involving entangled particles at a distance (not local) simply do not fit that model. LET is inconsistent with that. A fixed ether medium does not work with quantum field theory. However, the block universe model is not at all inconsistent with that.

 Quote by PeterDonis It would be if it actually happened; the block universe model still depends on a well-defined light cone structure that determines causal relationships between events.
It certainly does not. The worldlines of the elementary particles are all there in the 4-dimensional structure. They can begin anywhere and end anywhere QM and QFT would like. It has no constraints by a fixed ether which includes only light cone causal influences.
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P: 4,770
 Quote by bobc2 I didn't say that signals are sent faster than light with entangled particles. It is for exactly that reason that LET fails with entanglement experiments. LET was developed specifically for explaining related events via the model of a fixed ether through which all processes evolve as a result of signals transmitting at the speed of light as ether waves.
I don't understand your point. You agree that entanglement doesn't send signals faster than light; and you say LET doesn't involve sending signals faster than light. So where's the discrepancy?

 Quote by bobc2 entangled particles at a distance (not local)
If entanglement can't be used to send signals faster than light, then it *is* local. That's the whole point. "Local" in a relativistic theory is indistinguishable from "causal". In the quantum version, "local" means "field operators commute at spacelike-separated events", which is the same as "causal".

 Quote by bobc2 A fixed ether medium does not work with quantum field theory.
Sure it does. See above.

 Quote by bobc2 The worldlines of the elementary particles are all there in the 4-dimensional structure. They can begin anywhere and end anywhere QM and QFT would like.
Which means they can only embody causal relationships permitted by QM and QFT. You seem to have a misconception that QM and QFT somehow relax the rules about causal relationships between events. They don't. The observed worldline of a particle with nonzero rest mass can still only be a timelike worldline. You can have "virtual" worldlines for the particle which are not timelike (at least, that's how the "sum over histories" view of QFT would describe it), but their amplitudes will always cancel out in the observable; the observed worldline can only be timelike.
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P: 15,587
 Quote by Vandam If my spacetime diagram is wrong , tell me where it is wrong.
I never said your diagram was wrong. Do you think that I did?

Regarding impressing you, frankly it isn't a requirement for being right.
P: 126
 Quote by DaleSpam I never said your diagram was wrong. Do you think that I did?
If you accept my diagram you can not say that the LT make sense in LET.
So there's a contradction in terms.
Don't you see that?
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P: 1,366
 Quote by Vandam Here is what I mean. Green is the ether world. If you put green's coordinates of event A (0.5, 0.5) in the LT it gives you the red coordinates (Lorentz' local time) (0,289, 0,289). The red coordinates (time and space dimensions) have no meaning at all in the green ether context. Not even if you consider the green ether through event R3. In LET only the green coordinates have a physical meaning. Not the red ones. For the red ones you have to consider a physical red 3D world through R3 and A, which Einstein's SR allowed, but not Lorentz' LET. That's why Lorentz said: <> The LT only have a full physical meaning in SR, not LET.
The red sentence is wrong.

Red coordinates provide valid account of measured time and distance with rulers and clocks (brought) at rest in that coordinate time. In green coordinate system we have to add specific law in order to predict elapsed time on a moving clock (given we know elapsed time on the same clock when it is brought at rest in green coordinate system).
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P: 1,366
 Quote by bobc2 Except that LET is not consistent with the results of entanglement experiments, whereas the block universe is.
As long as there are no loophole free Bell test there is no confirmed conflict with relativity.

But if you mean that block universe is consistent with QM predictions about entanglement then I would like to see how you arrived at that. Because you see block universe by itself does not tell anything. You have to equip it with physical laws that are consistent with know experimental results. And as you do that you effectively restrict what types of patterns are allowed in your block universe. And you can't model QM predictions using these allowed patterns.
P: 126
 Quote by zonde The red sentence is wrong. Red coordinates provide valid account of measured time and distance with rulers and clocks (brought) at rest in that coordinate time.
That's exactly what I show. The red clocks do not move in red frame (world)
 In green coordinate system we have to add specific law in order to predict elapsed time on a moving clock (given we know elapsed time on the same clock when it is brought at rest in green coordinate system).
Sorry, but where do copied this nonsense from? Do you understand yourself what you wrote there?

Please show me on the ether space and time diagram in which green ether space the red time coordinates are valid!

Let me elaborate a bit on my diagram to be sure the message gets across.
(It would have been better if I had sketched a loedel diagram in which the time and space units are equal, but I doubt most forum members are familiar with loedel diagrams...).

When the green ether observer has 0,5 on his wristwatch, the Red traveler's clock shows 0,433. Red clok runs slow. Red is at planet Q. The distance between the red traveler and event A (light at the star) is O,25.

The LT transfomation (event A's time and space coordinates for red) tells us what red observer will experience: at 0,289 on his wristwatch event A (light at the star) is located (3D space distance) at 0,289 from him.

How can red's scenario work in the ether? It cannot.

Do you perhaps want to replace the content of R4 wit that of content R3? red's wristwatch time indication of event R4? That's impossible: at R4 Red traveler with wristwatch 0,289 is at planet Q and not at planet P.
Red's wristwatch on 0,289 is in the green ether through that event R3, but in that ether Red traveler still can not measure the 3D space distance to A. Event A is not (yet) part of that green ether world!
The LT result only works in SR: Red traveler has his own 3D world 'in which' he measures 0,289 space dimension between the simultaneous events R3 and A.

(You might (but I doubt) get LT to work in a LET context if you question the existence of observer independent events, etc, but then you slide into solipsim or other bizarre philosophical approaches that are not necessary in SR.)

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