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by Nthringas 921 days ago
IMO, the fact that GR is time-symmetric is actually a quality of the math underlying the physics

i.e. the theory, not reality, is where time symmetry comes from. and this is also exactly why those theories have predictive capabilities

but reality is still asymetric in the temporal dimension
2 comments
fnordpiglet 921 days ago
A wonderful aspect of using math to describe physics is the things admitted as possibly by the math might describe things possible in the physical reality but are very hard to observe given our frame of reference. The fact we’ve really found absolutely nothing observable that contradicts going backwards in time hints that it might in fact be possible under the right conditions. Our sense from our frame of reference that it isn’t doesn’t prove anything, just that we have only observed an asymmetry so far.

Sabine made a great episode on this recently, fwiw, and it’s worth watching if the subject interests you.

https://youtu.be/4ICIObFtWjM?si=XJ2t0P_I6XCWTl1Q

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chowells 921 days ago
> reality is still asymetric in the temporal dimension

That's an interesting claim. Do you have any evidence of it?

Oh, wait. Do you actually believe time passes? You're going to need to start by proving we're not in a block universe, then.

As far as I know, there is no such thing as an experiment that can disprove either assertion. As such, they're more claims of faith than claims about reality.

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Nthringas 921 days ago
my argument is more philosophical than scientific, so I can offer no evidence

time is asymmetric BY definition. if time weren't asymmetric I would have to call it space instead. (seems like I'm using asymmetry and monotonicity as synonyms)

in my definition, passing is all time can ever do, and it must do it only in the 'same direction'.

finally, in my view it is space which enables backwards and forwards motion.

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PrimeMcFly 920 days ago
> time is asymmetric BY definition. if time weren't asymmetric I would have to call it space instead.

I don't follow you here. If time were not asymmetric it wouldn't suddenly just be space. What are you actually claiming here?

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