# Is the study of black holes using entanglement practical?

1. Jun 9, 2007

### pinkumbra

That is, entangling two particles and sending one off in a controlled manner (i'm not sure if we're sophisticated enough to even contain a particle in a quantum state without interference so please fill me in) to a black hole and then observing the entangled particle that we kept in some lab on Earth.

2. Jun 9, 2007

### cesiumfrog

The thing with entanglement, is that it still doesn't transmit information.

3. Jun 10, 2007

### pinkumbra

So what would happen to the particle on Earth when its entangled partner dives in a black hole?

4. Jun 10, 2007

### cesiumfrog

Why would you expect something to happen?

5. Jun 10, 2007

### pinkumbra

If the particles are entangled, isn't there "spooky action at a distance" in that if you act on one, the other instantaneously is affected before they lose their quantum state?

6. Jun 10, 2007

### cesiumfrog

The affection is spooky in the sense that you need to compare measurement results from *both* particles to see it.

Last edited: Jun 10, 2007
7. Jun 18, 2007

Will the entangled particle falling into the black hole ever pass completely through the event horizon relative to the observer's frame of reference?

8. Jun 18, 2007

### cesiumfrog

At first you'd think not, but then "event horizon" is a funny concept: no reason the particle can't be placed at the centre of a star before it collapses (or else just send significantly more mass after the particle so that, in the distant observer's frame, the event horizon moves further out and encompasses the particle). So that isn't the problem.

9. Jun 21, 2007

### michael879

spooky action at a distance doesnt mean if you move one particle it will move the other. It just means that if you measure both particle's independently they will have some guaranteed relation. For example, if you take two electrons in the ground state of an atom. They are both in the superposition state that is 50% spin up and 50% spin down. If you measure one electron to be spin up, the other one instantly becomes spin down. However, you can not transmit information this way.