We know that light and even gravitational waves propagate at the speed of light.
So if something catastrophic happened to the black hole at the center of our galaxy (about 26,000 lightyears away), would there be any way for us to have advance knowledge of it before we could observe it with telescopes or before we could measure the gravitational changes?
Ludicrous example: say the black hole at the center of the galaxy disappeared 25,999 years ago. Is there a way we would have known about it by now, or do we just have to wait out another year to see if we’re all screwed?
I thought FTL communication is just a fun typical science fiction understanding of quantum entanglement.
I thought we would still have to know what is going on at the probe via another means to know or decode the message sent by the entangled particles to their counterparts on Earth.
Kind of like putting two letters in two envelopes but we don’t know what colour they are, just that they will always be opposite colours. Even the person arranging them doesn’t know which colour they are. We don’t know if a red letter is sent to London or a green one is sent to LA or what colour they’ll be at all. But when we open the letter in London and see that it’s the red one we know the other one in LA is green.
So no matter where or when the person with the red letter is, they’ll always know the other person has the green one once they open the letter. But no information has been mysteriously transported across space and time, just the correlation between the two has been discovered.
This is correct. FTL communication using any form of quantum entanglement is provably mathematically impossible by the no-communication theorem. Most common sci-fi trope though.