- cross-posted to:
- physics@mander.xyz
- cross-posted to:
- physics@mander.xyz
The ability to jump forward and backwards in time has long fascinated science fiction writers and physicists alike. So is it really possible to travel into the past and the future?
I’m no physicist, but this is such massive horseshit:
Imagine, you’ve got a printed photograph. You rip it in half and put each half into identical envelopes. You mix them up and send one of them to Australia.
Now you open the envelope you kept and see that it’s the left half. Boom! Instantaneous knowledge that the envelope in Australia contains the right half. Faster than light!
As far as my understanding goes, this is all there is to quantum entanglement. But because it’s quantum, everyone loses their minds over it.
To my understanding it’s one step more, not only observation but interaction as well, manipulating one side of the entangled particles resulting in an instant (and similar/same) change on the other side as well. In fact even the observation is a form of interaction in this case that changes the state of the entangled system.
AKA ‘Spooky action at a distance.’
That’s just a local “if” statement, where you assume something to be true based on local information.
You wouldn’t actually know if a dingo ate the envelope unless you check it. The information to confirm your assumption is still in Australia.
Yes, in particular, the information about your letter’s contents isn’t available in Australia either. You would now need to use traditional, at-most-light-speed communication methods to actually deliver this information to whomever holds the second letter.
It’s just ‘instant’, if you look at the whole system from the outside, as an omnipotent being.
https://www.forbes.com/sites/chadorzel/2016/05/04/the-real-reasons-quantum-entanglement-doesnt-allow-faster-than-light-communication/
You’re absolutely right. You’re no physicist.
But seriously, for a practical example of “action at a distance”, consider quantum key distribution.