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

PeterDonis

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?

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".

Sure it does. See above.

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.

DaleSpam

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

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

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

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

That's exactly what I show. The red clocks do not move in red frame (world)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

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?

DaleSpam

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

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

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.

DaleSpam

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.

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

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

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.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

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

That is not what he said !!! Troll tactic.

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

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.

DaleSpam

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.

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

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

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.