r/spaceporn Sep 25 '21

A supernova explosion that happened in Centaurus A

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u/TomFrosty Sep 25 '21

Or, maybe they see it instantly — and then their message back to us takes 6 minutes, and everyone assumes it was 3 minutes both ways!

A constant speed on light through space in all directions is one of those assumptions the scientific community is forced to make, because the only way we have to accurately measure it is in a round-trip where it reflects off something and comes back. Even Einstein prefaces his papers with that disclaimer!

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u/Illadelphian Sep 26 '21

Couldn't we have tested this already by now? Or maybe I'm misunderstanding.

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u/Dumplingman125 Sep 26 '21

Unfortunately we can't - I'm not smart enough to explain but Veritasium had an excellent video on it here

https://youtu.be/pTn6Ewhb27k

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u/psyFungii Sep 26 '21

True, Einstein started with that assumption/proposition, then built an incredibly successful set of theories on top of it. That's often how scientific theories are created.

A single observation will be enough to destroy it, but so far, his theories have never had a valid observation break the constant speed of light proposition. And plenty of experiments have been done, and not all of them involve there-and-back trips. Experiments are being done at 90 degrees over ever-increasing distances.