All undergraduate physics majors are shown how the counterintuitive aspects (“mysteries”) of time dilation and length contraction in special relativity (SR) follow from the light postulate, i.e., that everyone measures the same value for the speed of light c, regardless of their motion relative to the source (see this Insight, for example). And, we can understand the light postulate to follow from the principle of relativity, sometimes referred to as “no preferred reference frame” (NPRF). Simply put, if the speed of light from a source was only equal to ##c=\frac{1}{\sqrt{\epsilon_o \mu_o}}## (per Maxwell’s equations) for one particular velocity relative to the source, that would certainly constitute a preferred reference frame. Borrowing from Einstein , NPRF might be stated (see this...

• phoenix95, kurt101, Jimster41 and 1 other person

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I enjoyed this, esp the image of other universal constants working the same as c.

it seems like a chicken and egg problem a little (QM superselection rules and NPRF physical constants) but at least they are both chickens.

I enjoyed this, esp the image of other universal constants working the same as c.

it seems like a chicken and egg problem a little (QM superselection rules and NPRF physical constants) but at least they are both chickens.
Thnx. Would you mind expanding on that second comment for me? A referee said something similar, so I'm curious what exactly brought that to mind Which comes first, the partition that provides the correct equivalence relation on average for (c,h,G, b?) or the equivalence relation that dictates partition?

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Which comes first, the partition that provides the correct equivalence relation on average for (c,h,G, b?) or the equivalence relation that dictates partition?
Which is the superselection rule as you see it?

I’m going to go with “partition”, and venture even further... that is what physical chemistry sort of is.

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I’m going to go with “partition”, and venture even further... that is what physical chemistry sort of is.
Let's look at SR. Here is the explanatory hierarchy as we present it in our paper:

NPRF --> everyone measures c --> time dilation and length contraction --> relativity of simultaneity (different partitions of spacetime).

So, NPRF is not the equivalence relation, but it is the ultimate basis for our equivalence relation, which is strictly speaking the synchronized proper time of the comoving observers for either Alice or Bob (or ... ). Here we have NPRF/equivalence relation leading to the partition. Now let's flip it:

Relativity of simultaneity --> time dilation and length contraction --> everyone measures c --> NPRF.

For QM we have:

NPRF --> everyone measures h --> average-only conservation and Bell state correlations --> relativity of data partition (different partitions of Bell state data).

Again, NPRF isn't the equivalence relation, but it is the ultimate basis for it. Now let's flip it:

Relativity of data partition --> average-only conservation and Bell state correlations --> everyone measures h --> NPRF.

If you go with the equivalence relation as fundamental, you have one and the same rule leading to two different consequences. If you go the other way, you have two different rules with the exact same consequence. I think physicists would prefer the former, since they tend to be reductionists (explain more and more with less and less" per Weinberg). The other way makes NPRF look like an amazing coincidence.

hmm. I sort of read the table in the article up and down and that's why "at least both are chickens" aha. And I guess I see NPRF as exactly that pretty neat coincidence between relativity of simultaneity and the discrete partitioning of information for Bell observers in different frames.

to me these sound like accurate historical accounts of "what happened"
Relativity of simultaneity --> time dilation and length contraction --> everyone measures c --> NPRF.
Relativity of data partition --> average-only conservation and Bell state correlations --> everyone measures h --> NPRF.
So, I guess I see NPRF as a statement of "connected fact" rather than pejorative "amazing coincidence".

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hmm. I sort of read the table in the article up and down and that's why "at least both are chickens" aha. And I guess I see NPRF as exactly that pretty neat coincidence between relativity of simultaneity and the discrete partitioning of information for Bell observers in different frames.

to me these sound like accurate historical accounts of "what happened"

So, I guess I see NPRF as a statement of "connected fact" rather than pejorative "amazing coincidence".
That could be true • Jimster41
Actually, I prefer

“Time dilation and length contraction --> Relativity of simultaneity -->everyone measures c --> NPRF.”

“Average-only conservation and Bell state correlations --> Relativity of data partition --> everyone measures h --> NPRF.”

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