Farklurth t1_j9ox052 wrote on February 23, 2023 at 3:13 PM

Reply to comment by Baron_Ultimax in Physicists Use Quantum Mechanics to Pull Energy out of Nothing by Vailhem

Does the distance matter? Can we still measure the properties of the entangled particles that are 1 light year away?

subjectwonder8 t1_j9oynth wrote on February 23, 2023 at 3:24 PM

Yes. In current understanding distance doesn't matter. It could be few atom widths apart or light years. The fact that distance doesn't matter is one of the very interesting things about it and why there was some resistance to it (notably from Einstein) when the idea was first introduced.

Farklurth t1_j9p1n1n wrote on February 23, 2023 at 3:44 PM

That's absolutely amazing. So in theory when we have FTL spacecrafts we can communicate over vast distances without any problems.

videopro10 t1_j9pblra wrote on February 23, 2023 at 4:47 PM

Actually no, you would have to know the state of the particle at your departure point, which you can't know without that info being transmitted at the speed of light.

zabuu t1_j9piwn2 wrote on February 23, 2023 at 5:32 PM

Not quite... once you observe (read: measure) an entangled particle, it is no longer entangled.

Imagine 2 people face to face on a perfectly slippery frozen lake. If they push apart from each other, they would slide away. If you know the mass of each person, and you catch person A (this is like measuring the speed), then you'll know how fast person B is going. But measuring A changed the system and you'll get no additional info about B.

I'm no pro though, this is just how I understand it.