I just don’t get it.
According to the theory of special relativity, nothing can ever move faster than light speed.
But due to the expansion of the universe, sufficiently distant stars move away from us faster than the speed of light.
And the explanation is…that this universal speed limit doesn’t apply to things that are really far away?
Please make it make sense!
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nothing can move faster than the speed of light in a vaccum
That is not what the theory of special relativity says. It says that nothing with mass can accelerate to the speed of light. This may sound pedantic, but it is quite a different statement.
Aso, the expansion of spacetime isn’t much more than a “best guess” as to why we see the redshift of distant galaxies, but the truth of the matter is that we don’t really understand much yet about this universe. Not really.
Speed is distance/time. But time is relative, how time progresses is not some universal constant. And it gets WAY weirder than that. Here are some links, one of Richard Freymann explaining light much better than I can.
https://www.youtube.com/watch?v=kWCl7diBGos
And another about the mystery of information and time.
nothing can ever move faster than light speed
…pr space-time ‘unit’ ? If max speed is defined inside spacetime, then what if space it self expands everywhere ? So the speed is a limitation of the rules governing a ‘medium’, but the medium it self might not have such limitations.
[contrived analogy] If you start to swim in a large and 20m tall swimming pool, you have a max speed. Imagine everything in the pool have that max speed. Now imagine that the poolwalls suddenly disappears and the water column drops. At the ground, water would make a pan-cake shape, where water moves faster on the edge than in the center. Objects would flow with the water, and still have the same max speed as before. Objects at the edges now moves at the water expansion speed + max speed. Objects relative to other objects in the pool can move away ‘globally’ from each other at many times the max swimming speed, while maintaining the ‘local’ max speed in the water.
This is horrible cosmology/physics on many levels, and I probably made someone go to, or roll over in their grave, but it was the only ‘medium expanding’ analogy I could come up with on the spot. Apologies for the inflicted cognitive dissonance…
Absolutely-excellent analogizing, Hoomin: communicating the essence when many just left the wall of incomprehension!
Thanks for helping lots of people.
& let the graverollers do their thing.
d :
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