Reconciling relativity of simultaneity with causal reality

[bascule]

So it seems to me that relativity of simultaneity in GR really speaks to the irrelevance of actual simultaneity as opposed to a true sense of events occuring simultaneously as the causal structure of reality, at least within GR models, is bounded by the speed of light.

 

But the immeasurability of simultaneity aside, haven't things like quantum entanglement and the Aspect experiment shown us that through non-locality things can be causally linked which aren't bound by the speed of light? Wouldn't that paint a picture of a universal 'now' in which events are truly simultaneous throughout all frames of reference, and that the apparent effect of relative simultaneity is merely due to maximum velocity and thus propagation of events through the causal structure, in most instances, being bound to c?

 

That's not to say that QM doesn't appear to undermine causal determinism in other ways (although I don't believe it does through any other means than incomplete understanding), but relativity of simultaneity appears to me more to be a problem of observation and not an inherent property of the universe itself...

 

Or perhaps I'm just scared to discard the idea of "now"

[geistkiesel]

So it seems to me that relativity of simultaneity in GR really speaks to the irrelevance of actual simultaneity as opposed to a true sense of events occuring simultaneously as the causal structure of reality' date=' at least within GR models, is bounded by the speed of light.

 

But the immeasurability of simultaneity aside, haven't things like quantum entanglement and the Aspect experiment shown us that through non-locality things can be causally linked which aren't bound by the speed of light? Wouldn't that paint a picture of a universal 'now' in which events are truly simultaneous throughout all frames of reference, and that the apparent effect of relative simultaneity is merely due to maximum velocity and thus propagation of events through the causal structure, in most instances, being bound to c?

 

That's not to say that QM doesn't appear to undermine causal determinism in other ways (although I don't believe it does through any other means than incomplete understanding), but relativity of simultaneity appears to me more to be a problem of observation and not an inherent property of the universe itself...

 

Or perhaps I'm just scared to discard the idea of "now"[/quote']

Bascule,

your understanding of simultaneity is just fine. I used the gedanken Einstein used in his book "Relativity" to see through the simultaneity problem. It took me some time to see that AEs example included an almost hidden reference that the passengers were looking at the photon motion assuming the train was at rest and the embankment moving. There are some obvious flaws in AEs conclusion.

. The assumption that the frame is at rest and the embankment moving is not justified by any laws of physics, even the equivalence principal. The assumption of the rest state is arbitrary and the observer on the moving frame could just as well have assumed he was moving.

 

The Observer O is at the midpoint of the photons just as the photons are emitted. Then O moves and sees the photon coming from in front first, then passengers behind O see the photons arrive simultaneously at the stationary midpoint, then the photon catches up from nehind. All thsi sequence coul dhave been plotted out by the moving observer as a schematic of a possible resolution of he problem.

.

Once the First photon has been detected the rest is predictable, the midpoint is known to O . The A photon from behind is moving symmetrically with the forward photon. O claims that despite the information that the photons were emitted simultaneously, O insists that from his frame the photons were emitted sequentially.

 

When O sees the data collected by two moving observers at the A and B position just as the photons were emitted, both clocks are synchronized and the data is made availabkle to O, who must now conlcude the photons were emitted simultaneoulsy in the moving frame of reference other wise the photons would not have arived simultaneously at the midpoint as verified by passengers at the location on the train giving them a view of the photon arrival at the midpoint. If the photons were emmitted sequentually they wouldn't arrive at the midpoint at the same instant

I don't see how Einstein got away with the gibbrish for so long.

 

"Now" is a three letter word. There are events ocurring all over the universe right now, that doesn't mean that all the events are open to us for scrutiny, but the negation of simultraneity is not implied for this lack of inforamtion.

 

I see SRT as a negation of the concept of motion. Set the frame motion to zero,and then measure the speed of light wrt the frame, wow set the frame to zero motion and the relative velodity of frame and photon will always be c.

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