Am I misunderstanding something...

The particle doesnt travel faster than light, it doesn't travel at any speed. Its position is spread out over a large distance, and when it is observed, the amplitude of its wave function determines the probability of its position being in or outside the barrier.
So when you observe the particle outside the barrier, it didn't "go through", it just happened to appear outside.

And, yes, certain quantum systems can appear to transmit information faster than light, but no information is actually being transmitted, so causality is preserved.

>but holy fuck this thread is awful

When two photons are produced at the same time and one resolves at the detector before the other one, how is that not transmitting information faster than light?

>two photons
this is not about photons, Heisenberg

best answer

That probably means that one detector is closer to the source

Information is a pretty vague term in QM, but image you created a pair of entangled photons, both of which are in a superposition of spins. Because they are entangled, the observation of one will *immediately* determine the state of the other (even across cosmic distances).
If an astronaut took one photon to the opposite end of the galaxy, you would think that observing one photon, thereby affecting the state of the other, would allow FTL communication. But because the state of your photon is outwith your control, you couldn't send them a coherent message. All the astronaut would get is noise, and they wouldn't even be able to tell who broke the superposition by observing the photons.

*imagine

This isn't about entanglement though, it's about photons having a small chance of being "anywhere". The idea that a particle governed by quantum physics could sometimes beat a particle governed purely by classical physics in a race, because the quantum particle has a small chance of resolving slightly ahead of the classical particle when they reach the detector, even though they started from the same point. If something can even potentially move faster than c, it means potential causality violation, which means it's possible to demonstrate the Novikov self-consistency principle, which means it's possible to create temporal computers that can solve NP problems in polynomial time.

I'm a brainlet, but here's that:
Take to another galaxy n entangled photons, let n be let's say a few thousand. When you need to send a massage: observe each particle one by one with certain time interval. Each time interval corresponds to a particular letter. You now can send a message faster than light. The downside is that you have limited amount of particles.

Yes. Schrodinger's equations appear to possibly violate FTL because they're not Lorentz invariant.

This is resolved by using the Lorentz invariant form - the Dirac equation. The Dirac equation is one of the relativistic form of QM and describes quantum field theory, which does not have any FTL violations.

i love your idioism to think so hard and be so stupid that shit does not exist go to bed dummy

That won't send a message because when you observe one half of an entangled pair the other one doesn't visibly do anything, it just collapses into some state that you'll only find out once you measure it.

It's the OP LARPing

You were never aware of the position in the first place though. Your starting line has just as much uncertainty as the detector.

With this in mind, shouldn't teleportation be possible, at least at the particle-level? Like, actual, controlled teleportation.