Q: "Time Dilation: Faster = Longer Wait?

[bobc2]

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.

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.

 

[PeterDonis]

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?

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".

A fixed ether medium does not work with quantum field theory.

Sure it does. See above.

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.

 

[Dale]

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.

 

[Vandam]

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?

 

[zonde]

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 chief cause of my failure was my clinging to 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. In Einstein's theory, on the contrary, t' plays the same part as t; if we want to describe phenomena in terms of x'; y'; z'; t' we must work with these variables exactly as we could do with x; y; z; t.>>
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).

 

[zonde]

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.

 

[Vandam]

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.)

 

[Vandam]

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.

I think Bob means this.
How can an observation of a particle, causing the collapse of the wavefunction, have an immediate impact on a simultaneous space-like event: (the twin 'entangled') particle?
LET can not give an answer because you need faster than light communication (even immediate communication!). Hence LET is not compatible with QM.
Block Universe solves that problem, because ALL the events, future, space-like or not, pre-exist. We only discover them as time goes by. So there has not to travel any information at all beween the entangled particles or events. Causal relationship between entangled particles is not necessary in Block Universe. (In Block universe the events are not 'caused' by (a) previous event(s); the causal relationschip is deducted from discovering a sequence of pre-existing events. But QM tells us that apparently (some?) QM events have no causal relationships. Bock universe can deal with that. Not LET (altough a 'Block ether universe' (!) might work, but that's still not compatible with SR.)
Block universe does not work with 'probabilities' or collapsing of wavefunctions'. These are only manmade tools to calculate, predict, or 'guess' the future 3D worlds. And because we do not know (yet?) precisely why Block Universe has those 'QM' entangled space-like events located there where they are, we do our best with the probabilities and wavefunctions to predict which QM events our 3D world will encouter.
Bob, I hope I didn't shake too much your QM line of thought with all this?

 

[Dale]

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?

No, I don't see that. Your diagram seems to follow the LT.

Do you believe your diagram violates the LT? If so, please point out the offending feature because I missed it.

 

[zonde]

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.

Okay I think I see where is your problem. You see we learn about event A only when light from that event have reached us.

So it is of little importance that this event has not yet happened because it can't affect us before some future point R5 where our worldline crosses future light cone of A.

 

[Vandam]

No, I don't see that. Your diagram seems to follow the LT.

Do you believe your diagram violates the LT? If so, please point out the offending feature because I missed it.

Haha. That's the best one! You make my day!

Can you at least recognize the ether in my drawings. Can you?

I'm afraid I may draw 100 diagrams and write 100 pages of text, it won't help you.

Hopeless. Really hopeless.

Please show me where on an ether'space and time' diagram (for the ether scenario a real 'spacetime' diagram doesn't make sense) the LT time (and space) coordinates make sense.

 

[Dale]

Can you at least recognize the ether in my drawings. Can you?

Yes, you clearly labeled it.

Please show me where on an ether'space and time' diagram (for the ether scenario a real 'spacetime' diagram doesn't make sense) the LT time (and space) coordinates make sense.

Exactly how you showed them. The green coordinates are the aether coordinates and the red coordinates are the local coordinates, related to the aether coordinates by a Lorentz transform.

Look, you may not like it, but LET is an interpretation of the LT. Specifically, it is the interpretation of the LT where one frame is uniquely designated as the aether frame and the other frames (all related to the aether frame by the LT) are designated as "local coordinates" instead. So your diagram cannot violate LET without drawing something contrary to the LT, which I don't see drawn.

You appear to be committing a strawman fallacy (http://www.fallacyfiles.org/strawman.html). There exists an interpretation of the LT wherein one frame (the aether frame) is singled out as uniquely representing the state of the 3D universe which is evolving in time, and other coordinate systems (local frames), not representing the state of the 3D universe, are related to the aether frame via the LT. If you are addressing some other theory which does not use the LT for its predictions then you are addressing a strawman that you have set up and not my argument.

 

[zonde]

So there has not to travel any information at all beween the entangled particles or events. Causal relationship between entangled particles is not necessary in Block Universe. (In Block universe the events are not 'caused' by (a) previous event(s); the causal relationschip is deducted from discovering a sequence of pre-existing events. But QM tells us that apparently (some?) QM events have no causal relationships. Bock universe can deal with that. Not LET (altough a 'Block ether universe' (!) might work, but that's still not compatible with SR.)

Causality is not absent from block universe. It is present as certain pattern in events.

Well of course you can claim that there can appear about anything you fancy in block universe but in that case you are not talking science. In order for your ideas to be scientific they should follow certain rules. And concept of block universe that follows these rules does not allow just anything you fancy in it.

 

[Vandam]

Okay I think I see where is your problem. You see we learn about event A only when light from that event have reached us.

I think not I but you have a problem: you insinuate that event A doesn't exist before we see it! Be careful. That leads to solipsism. That's metaphysics.

So it is of little importance that this event has not yet happened because it can't affect us before some future point R5 where our worldline crosses future light cone of A.

What you tell here has nothing to do with SR.
It has nothing to do with 'what can affect us or not'. That's not what SR is about.
You are too much concentrated on your lightcone.

Do you believe in an observer independent simultaneous space-like event before you see anything of it?
Do you believe in a 3D world made of observer independent events?

SR works with observer independent events.
Einstein was a realist, not a solipsist:

Einstein quotes:
"Belief in an external world independent of the perceiving subject is the basis of all natural science."

"Physics is an attempt conceptually to grasp reality as something that is considered to be independent of its being observed. In this sense one speaks of 'physical reality.'”

“I am not a positivist. Positivism states that what cannot be observed does not exist. This conception is scientifically indefensible, for it is impossible to make valid affirmations of what people 'can' or 'cannot' observe. One would have to say 'only what we observe exists', which is obviously false."

<As always the conception of the existence of the real world is fundamental in physics. Without is there would be no borderline between psychology and physics. ... Modern developments have changed nothing in this respect."

"The belief in an external world independent of the perceiving subject is the basis of all natural science."

 

[Vandam]

Yes, you clearly labeled it.

Exactly how you showed them. The green coordinates are the aether coordinates and the red coordinates are the local coordinates, related to the aether coordinates by a Lorentz transform.

Look, you may not like it, but LET is an interpretation of the LT. Specifically, it is the interpretation of the LT where one frame is uniquely designated as the aether frame and the other frames (all related to the aether frame by the LT) are designated as "local coordinates" instead. So your diagram cannot violate LET without drawing something contrary to the LT, which I don't see drawn.

I do not have to like it either.
Designating one frame as the ether frame and not the other is exactly what Lorentz mistake was. And he admited he was wrong:

<<The chief cause of my failure was my clinging to 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. In Einstein's theory, on the contrary, t' plays the same part as t; if we want to describe phenomena in terms of x'; y'; z'; t' we must work with these variables exactly as we could do with x; y; z; t.>>

The LT only have a full physical meaning in SR, not LET.

You simply do not get the essence of SR.

 

[Mentz114]

Okay I think I see where is your problem. You see we learn about event A only when light from that event have reached us.

I think not I but you have a problem: you insinuate that event A doesn't exist before we see it! Be careful. That leads to solipsism. That's metaphysics.

That is not what he said ! Troll tactic.

So it is of little importance that this event has not yet happened because it can't affect us before some future point R5 where our worldline crosses future light cone of A.

What you tell here has nothing to do with SR.
It has nothing to do with 'what can affect us or not'. That's not what SR is about.
You are too much concentrated on your lightcone.

What rubbish. Of course SR is a about causality and what can affect us.

You simply do not get the essence of SR.

Once again your claim is rubbish. You are not the only person who understands these things. In your case I use the word 'understanding' with reservation.

 

[Dale]

Designating one frame as the ether frame and not the other is exactly what Lorentz mistake was. And he admited he was wrong:

Perhaps he was wrong in a philosophical sense, but there isn't any empirical evidence that he was wrong. That is the thing that you seem unable to understand, the distinction between philosophy and evidence.

The LT only have a full physical meaning in SR, not LET.

Having "a full physical meaning" is another unnecessary philosophical consideration. As long as the predictions agree with experiments then it is scientifically irrelevant if local coordinates do not have "a full physical meaning". The evidence simply cannot distinguish between the block universe interpretation and the aether interpretation of the LT.

 

[zonde]

Do you believe in an observer independent simultaneous space-like event before you see anything of it?
Do you believe in a 3D world made of observer independent events?

Yes. I might be open to other possibilities but I consider them quite exotic.

SR works with observer independent events.
Einstein was a realist, not a solipsist:

Einstein quotes:
"Belief in an external world independent of the perceiving subject is the basis of all natural science."

"Physics is an attempt conceptually to grasp reality as something that is considered to be independent of its being observed. In this sense one speaks of 'physical reality.'”

“I am not a positivist. Positivism states that what cannot be observed does not exist. This conception is scientifically indefensible, for it is impossible to make valid affirmations of what people 'can' or 'cannot' observe. One would have to say 'only what we observe exists', which is obviously false."

<As always the conception of the existence of the real world is fundamental in physics. Without is there would be no borderline between psychology and physics. ... Modern developments have changed nothing in this respect."

"The belief in an external world independent of the perceiving subject is the basis of all natural science."

Yes. Quite natural position for physicist.


After a bit of thinking - maybe you equate coordinate system with simultaneity of that coordinate system?
In that case it would make sense to say that simultaneity of non aether frame has no physical meaning.

But if that is the case I would like drop out of discussion because while I privately might prefer to model the world as having one "right" simultaneity I like to keep out of discussions that can't be resolved by means of experiments and observations.

 

[Vandam]

Having "a full physical meaning" is another unnecessary philosophical consideration.

Of course. You call everything that does not apprear on your calculator a philosophical consideration.
Nice physics!
Look, I am not prepared to discuss physics on that bases. I consider this discussion closed. Good luck.

 

[PeterDonis]

How can an observation of a particle, causing the collapse of the wavefunction, have an immediate impact on a simultaneous space-like event: (the twin 'entangled') particle?

Why do you think it does? First of all, you're assuming that there is a collapse of the wavefunction; there is at least one QM interpretation, the many worlds interpretation, which has no collapse of the wavefunction. (And I think you will find that many physicists who believe in the "block universe" also believe in the MWI.) Second, even on a "collapse" interpretation, you're assuming that the collapse is "something real" that travels faster than light between the two entangled particles; but as I noted and bobc2 agreed, you can't send signals faster than light using entanglement, so the only thing that actually "travels faster than light" is a statistical correlation, which is not a "real thing". All causal influences still travel at the speed of light or slower.

LET can not give an answer because you need faster than light communication (even immediate communication!).

No, you don't. Entanglement doesn't let you communicate faster than light. See above.

Block Universe solves that problem, because ALL the events, future, space-like or not, pre-exist.

In your *model*, yes. In the *real world*, you don't know that this is true.

Causal relationship between entangled particles is not necessary in Block Universe.

If by "block universe" you just mean "a 4-D manifold with no constraints", then yes, I suppose this is correct. But if by "block universe", you mean "a 4-D manifold that obeys the laws of Special Relativity", which is the only kind of "block universe" that is consistent with experiments, then no, this is not correct. Causal relationships still exist between events in a block universe that is consistent with SR; if they didn't, it wouldn't be consistent with SR.

Have you read Julian Barbour's writings on time? He has done a *lot* of work on thinking out exactly what a "timeless" view of physics, which is basically the kind of "block universe" viewpoint you are advocating, involves. I think you would find his writings on this subject very interesting.

http://www.platonia.com/papers.html

In Block universe the events are not 'caused' by (a) previous event(s); the causal relationship is deducted from discovering a sequence of pre-existing events. But QM tells us that apparently (some?) QM events have no causal relationships.

No, QM does not tell us that. A causal relationship is a geometric relationship between events; events that are timelike separated or null separated are causally related, and events that are spacelike separated are not. QM, or more properly quantum field theory, does not change anything about causal relationships; QFT is still set in 4-D spacetime and events are still either timelike, null, or spacelike separated.

 

[PeterDonis]

Do you believe in a 3D world made of observer independent events?

I find it interesting that you keep insisting that the "block universe" does *not* involve a 3-D space evolving in time, and yet you also keep insisting on a "3D world" as a fundamental concept.

To me, the whole point of relativity of simultaneity is that a "3D world" is *not* a fundamental concept, because it's not frame-invariant. The key lesson of relativity is that all the physics in a theory is contained in the invariants: the things that *don't* change when you change reference frames. Light cones are invariant, so they are part of the physics of the theory. "3D worlds" are *not* invariant, so they are *not* part of the physics of the theory; they're just convenient abstractions to make calculations easier.

 

[bobc2]

..."3D worlds" are *not* invariant, so they are *not* part of the physics of the theory...

It's the observed continuous sequence of 3-D cross-sections of the 4-D universe that present reality to us. It's the objects we observer. It's processes involving objects that we observe--tracks in elementary particle experiments, rays of light, etc. That's not part of the physics?

These continuous sequence of 3-D worlds are not just any sequence--they are very special--the laws of physics are the same for any of the 3-D worlds identified through the use of some member of the group of Lorentz transformations. And these worlds are so special that a measurement of the speed of light is the same for each of them.

I guess your view would be that physics is not concerned with an external reality--perhaps just the rules of engagement for the objects.

 

[Dale]

Of course. You call everything that does not apprear on your calculator a philosophical consideration.

No, I call everything that cannot be tested experimentally philosophy. Experimental evidence is the key difference between philosophy and science. There is no experiment which can distinguish between the LT in a 3D universe evolving in time and the LT in a 4D universe.

I am not prepared to discuss physics on that bases.

That much is certainly clear. When you have prepared yourself sufficiently, then please return and we can carry on the discussion.

 

[PeterDonis]

It's the observed continuous sequence of 3-D cross-sections of the 4-D universe that present reality to us.

No, it isn't. It's the succession of past light cones along our worldline that presents reality to us. The 3-D cross sections are logical constructions from the data we get from our past light cones; we don't perceive them directly. Perceiving them directly would require signals to travel faster than light.

It's the objects we observer. It's processes involving objects that we observe--tracks in elementary particle experiments, rays of light, etc. That's not part of the physics?

The worldlines of objects are invariants, so yes, they are part of the physics. But 3-D cross-sections are not made up of worldlines of objects.

These continuous sequence of 3-D worlds are not just any sequence--they are very special--the laws of physics are the same for any of the 3-D worlds identified through the use of some member of the group of Lorentz transformations.

I have two answers to this. The first is, supposing I agree with this as you state it, so what? There are an infinite number of such sequences of 3-D worlds that all are "special" in this sense. There's nothing that picks out any particular sequence of 3-D worlds as special compared to any other such sequence.

The second answer is that you've stated it wrong. The laws of physics are not written in terms of 3-D worlds. They are written in terms of local invariants at each spacetime point. You can express all of the physics and all of the laws without ever mentioning 3-D worlds at all. So everything you say about sequences of 3-D worlds, even if it's correct mathematically, is not necessary for the actual physics; it's just a convenience for calculation.

I guess your view would be that physics is not concerned with an external reality--perhaps just the rules of engagement for the objects.

My view is that our physics does not tell us everything about external reality, so taking any particular theory of physics and trying to parlay it into a blanket statement about external reality is going way beyond what's justified by our knowledge of the physics.

 

[PeterDonis]

It's the observed continuous sequence of 3-D cross-sections of the 4-D universe that present reality to us.

In addition to what I said in my previous post, I also have the same comment here as I had for Vandam: I find it interesting that you, who are defending the "block universe" viewpoint, insist on talking about 3-D worlds and 3-D cross sections, instead of 4-D spacetime and invariant objects within it, like worldlines; while I, who am saying the "block universe" is not the only possible viewpoint, am talking in terms of invariants in 4-D spacetime.

 

[bobc2]

In addition to what I said in my previous post, I also have the same comment here as I had for Vandam: I find it interesting that you, who are defending the "block universe" viewpoint, insist on talking about 3-D worlds and 3-D cross sections, instead of 4-D spacetime and invariant objects within it, like worldlines; while I, who am saying the "block universe" is not the only possible viewpoint, am talking in terms of invariants in 4-D spacetime.

I figured that I had already beat the 4-D objects to death. Of course you are probably willing to acknowledge the mathematical worldlines without the physical 4-D objects that they represent.

It's probably a good time for ZapperZ to shut this one down.

 

[Vandam]

It's probably a good time for ZapperZ to shut this one down.

I agree.

 

[Dale]

bobc2 and Vandam,

If you have a line y=mx+b you can write it as y(x)=mx+b and interpret it as a 0D point in a 1D space, y, which evolves as a function of x. Alternatively, you can write it as (x,mx+b) and interpret it as a parameterized 1D line in a non-evolving 2D space. But no matter how many points on the line you collect they will never identify which is the "right" expression or interpretation.

You both have every right to prefer the block universe interpretation, for any reason or no reason at all.

You are both wrong to assert that there is any empirical evidence favoring that interpretation over any mathematically equivalent interpretation. If you would stop pretending that your position is based on evidence rather than personal preference then you would find much more support for it.