4 ms·

I knew that about the speed of light (but thank you for writing it out). My knowledge of entanglement is limited, but haven't we observed entangled particles s

I knew that about the speed of light (but thank you for writing it out). My knowledge of entanglement is limited, but haven't we observed entangled particles seemingly communicate faster than light? While time travel may not be possible, maybe time traveling data is?

dsr_ 4y ago
No, we have not. We have observed that we can generate a pair of particles and separate them, and when we look at the close one, we now know that the far one has the complementary property. You can't use that to send information. You could use it as a shared secret, but you still had to move the particle out where your recipient is for them to use it. You can take a flashlight and shine it at the moon, and if you sweep the beam back and forth, you can make the notional front of illumination move faster than the speed of light -- but you can't modulate the signal faster than the propagation velocity c. Time travel into the future is easy. Time travel into the past doesn't work in this universe.
ynik 4y ago
Entanglement doesn't involve any form of communication. Only the imaginary "wave function collapse" is faster than light. But collapse isn't actually part of quantum mechanics: there's no formula that would tell you when collapse is triggered. The many world interpretation doesn't have any wave function collapse at all; and it's a valid interpretation of the underlying maths. Any "wave function collapse" is merely an interpretation trick to map the quantum world back to the classical world as experienced by humans. You can't build technology out of imaginary physics.
tambourine_man 4y ago
Nope, it’s a common misunderstanding. While the particles are entangled regardless of distance and the action is instantaneous (at least, that’s one way of interpreting it) there’s no way to actually transmit information. You may try to come up with clever encodings for electron spins, but you’ll see that you end up having to know a priory what the other end had. It’s a long topic to discuss on a HN thread but a quick YouTube search will get you interesting videos.
nly 4y ago
If time travel isn't possible how come we're all moving in to the future right now?
- teddyh 4y ago
  “If flying is impossible for me after I have jumped off this tall building, how come I am currently moving through the air towards the ground at high speed?”
  - teddyh 4y ago
    Related: https://www.youtube.com/watch?v=sdUUx5FdySs https://www.youtube.com/watch?v=sdUUx5FdySs
dekhn 4y ago
personally, I think it's easiest to just think of the speed of light actually being the maximum speed of information propagation.
vbezhenar 4y ago
Time travelling data leads to paradoxes. It’s unlikely to be possible. Think of entanglement as pair of boots. You’ve got one boot with you and unwrapped it on the mars. Voila, you know that one left on Earth is left one. This analogy is wrong but good enough to understand why entanglement does not help with communication.

dsr_ 4y ago

No, we have not. We have observed that we can generate a pair of particles and separate them, and when we look at the close one, we now know that the far one has the complementary property. You can't use that to send information. You could use it as a shared secret, but you still had to move the particle out where your recipient is for them to use it. You can take a flashlight and shine it at the moon, and if you sweep the beam back and forth, you can make the notional front of illumination move faster than the speed of light -- but you can't modulate the signal faster than the propagation velocity c. Time travel into the future is easy. Time travel into the past doesn't work in this universe.

ynik 4y ago

Entanglement doesn't involve any form of communication. Only the imaginary "wave function collapse" is faster than light. But collapse isn't actually part of quantum mechanics: there's no formula that would tell you when collapse is triggered. The many world interpretation doesn't have any wave function collapse at all; and it's a valid interpretation of the underlying maths. Any "wave function collapse" is merely an interpretation trick to map the quantum world back to the classical world as experienced by humans. You can't build technology out of imaginary physics.

tambourine_man 4y ago

Nope, it’s a common misunderstanding. While the particles are entangled regardless of distance and the action is instantaneous (at least, that’s one way of interpreting it) there’s no way to actually transmit information. You may try to come up with clever encodings for electron spins, but you’ll see that you end up having to know a priory what the other end had. It’s a long topic to discuss on a HN thread but a quick YouTube search will get you interesting videos.

nly 4y ago

If time travel isn't possible how come we're all moving in to the future right now?

teddyh 4y ago
“If flying is impossible for me after I have jumped off this tall building, how come I am currently moving through the air towards the ground at high speed?”
- teddyh 4y ago
  Related: https://www.youtube.com/watch?v=sdUUx5FdySs https://www.youtube.com/watch?v=sdUUx5FdySs

dekhn 4y ago

personally, I think it's easiest to just think of the speed of light actually being the maximum speed of information propagation.

vbezhenar 4y ago

Time travelling data leads to paradoxes. It’s unlikely to be possible. Think of entanglement as pair of boots. You’ve got one boot with you and unwrapped it on the mars. Voila, you know that one left on Earth is left one. This analogy is wrong but good enough to understand why entanglement does not help with communication.