Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 06/06/2017 00:15:54

Title: Can quantum spin of laser light be used to get data out of a black hole?
Post by: chris on 06/06/2017 00:15:54
Dean asks:

Has anyone ever thought about using the quantum spin properties of laser light to get data out from beyond the event horizon of a black hole? (If you know the spin of one side of the split beam, then you know the other, instantaneously, no matter the distance between the beams, right?

And if the "spooky physics" holds true in the previous paragraph, couldn't we use a split beam laser, (our distant descendency anyway; once we built it, it would haveto be running for many years/ thousands of years to be of any vast distance communicative use to anybody), to communicate, -instantaneously-, across the Universe?
Title: Re: Can quantum spin of laser light be used to get data out of a black hole?
Post by: chiralSPO on 06/06/2017 00:23:31
Could be an interesting experiment, but I'm not so sure it let's any information out. If I show you a jar that has only one red marble and one blue marble in it, then remove one of the marbles without showing you, and then throw the jar into a black hole. You will be able to know which marble is beyond the event horizon by observing the marble I have in my pocket. No info from beyond the event horizon is necessary.
Title: Re: Can quantum spin of laser light be used to get data out of a black hole?
Post by: evan_au on 06/06/2017 11:31:15
There are various paradoxes about the event horizon of a black hole.

One theory says that, from the viewpoint of an observer outside the black hole, information about objects that have fallen into the black hole still exists in a thin skin an infinitesimal distance outside the event horizon.

This information (severely red-shifted and distorted) will leak out of the black hole over millennia, so you may not need tricky quantum effects - you may just need a lot of patience.
Title: Re: Can quantum spin of laser light be used to get data out of a black hole?
Post by: PmbPhy on 07/06/2017 19:46:09
Dean asks:

Has anyone ever thought about using the quantum spin properties of laser light to get data out from beyond the event horizon of a black hole? (If you know the spin of one side of the split beam, then you know the other, instantaneously, no matter the distance between the beams, right?

And if the "spooky physics" holds true in the previous paragraph, couldn't we use a split beam laser, (our distant descendency anyway; once we built it, it would haveto be running for many years/ thousands of years to be of any vast distance communicative use to anybody), to communicate, -instantaneously-, across the Universe?

You're referring to the question of whether information can be transmitted FTL using two particles which are entangled. The answer is no. Information cannot be transmitted that way.
Title: Re: Can quantum spin of laser light be used to get data out of a black hole?
Post by: dutch on 13/06/2017 03:16:21
Quote
Has anyone ever thought about using the quantum spin properties of laser light to get data out from beyond the event horizon of a black hole? (If you know the spin of one side of the split beam, then you know the other, instantaneously, no matter the distance between the beams, right?

And if the "spooky physics" holds true in the previous paragraph, couldn't we use a split beam laser, (our distant descendency anyway; once we built it, it would haveto be running for many years/ thousands of years to be of any vast distance communicative use to anybody), to communicate, -instantaneously-, across the Universe?

Quantum Entanglement does not send information.

Quantum Entanglement is a correlation and not a causation. Say I have two particles that were created from an event (electron positron pair creation. I may know the total spin is 0 and the two particles are spin 1/2 particles. I also may know I have a 50% chance of measuring one of the particles and getting spin up and 50% chance of getting spin down. Now the particles are in a weird quantum super position before they interact with the environment (such as getting measured). However, when I measure one of the particles it does NOT alter the other particle in ANY way. I simply know if the particle I measured was spin up, the other is spin down. In order for me to convey the result I have to send a signal light-speed or less.

If I measured one of the particles outside of the blackhole it would have a 50% chance of spin up just like it would in my university's physics lab. If the other particle fell into the hole I may know it's spin down but this isn't useful information. If I have a pair of gloves and I give one to a friend then I look down and my glove is left handed I know his glove is right handed. While entanglement does have a weird superposition where each of the gloves is spin up and down before getting measured the amount of information gained is exactly the same as the gloves example (nothing). There is no information sent.


Title: Re: Can quantum spin of laser light be used to get data out of a black hole?
Post by: jeffreyH on 13/06/2017 21:04:20
If it were possible to send information faster than light then the information would be arriving from outside the light cone of the observer. This would appear to come from the future light cone. You may well be able to tell the next weeks lottery numbers somewhere on another planet in another galaxy without the ability to capitalise on it. Saying this is actually from the future is relative and has little meaning.