## Entanglement and Information

How does science work? And what's all this about quantum mechanics?

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philosopher
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### Entanglement and Information

Entanglement says that two particles can have their spin properties shared, so when one measures the other, it changes the other in an instant (faster than light).

Though according to Bell's No-go-theorem you cannot send information faster than the speed of light.

But itsn't the spin-property or an entangled particle an information in itself?

I'm not sure I understand how they measure entanglement. As far as from what I've read about the subject, scientists are able to measure the spin of a particle that is entangled. The thing is, the entanglement is 50-50 whether the spin is up or down. And as soon as you measure one particle, the entanglement collapse (no entanglement anymore). They should be able to detect this collapse as well.

I've made a terrible thought-experiment, but I fail to realise why it's terrible, so would you please help me out?

If you have a space ship about to fly to the Andromeda Galaxy and a command center on earth, before you send the spaceship off into space, you give the astronaut Alice a box containing non-measured entangled particles, entangled with a box of particles in the command center in the hands of Bob. Let's say you have 10 or 20 or whatever given number of particles in this box.

You might say that it's impossible to send information using this, because the collapse is always going to turn out in a 50-50 % chance.
No way of telling whether the particle was supposed to mean spin "up" or "down".

But we don't need that information at all. All we need is to detect IF/WHEN a collapse (measurement) has happened. As both boxes in the spaceship and command center respectively, are sealed and there's no way they should collapse from external forces or anything else, all we need is a DETECTOR in the spaceship and command center.

The instructions is as follows: 1 entanglement-pair collapse followed by at least 2 sec. delay or more means "Hello".
2 collapses with 1 sec. delay between each, means "Bye".

When Alice measures one of her particles, which is entangled with a particle on Earth, Bob (on Earth) will see his detector signaling (in some way or another, making a noise or displaying something on a monitor) once as one of his particle's entanglements have collapsed.

He instantly knows it means "Hello". He measures two of his particles, wait 1 sec. and measures another. Then Alice's detector should display on some monitor when two of her particles collapsed.

She then knows it means "Bye".

Why is this type of entanglement-information impossible?

Of course given the limited amount of particles, there's only a limited amount of information they can send. But increase the number of entangled particles, and you increase the amount of messages you can send each way.
Atla
Posts: 2979
Joined: Fri Dec 15, 2017 8:27 am

### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 6:16 pm Entanglement says that two particles can have their spin properties shared, so when one measures the other, it changes the other in an instant (faster than light).

Though according to Bell's No-go-theorem you cannot send information faster than the speed of light.

But itsn't the spin-property or an entangled particle an information in itself?

I'm not sure I understand how they measure entanglement. As far as from what I've read about the subject, scientists are able to measure the spin of a particle that is entangled. The thing is, the entanglement is 50-50 whether the spin is up or down. And as soon as you measure one particle, the entanglement collapse (no entanglement anymore). They should be able to detect this collapse as well.

I've made a terrible thought-experiment, but I fail to realise why it's terrible, so would you please help me out?

If you have a space ship about to fly to the Andromeda Galaxy and a command center on earth, before you send the spaceship off into space, you give the astronaut Alice a box containing non-measured entangled particles, entangled with a box of particles in the command center in the hands of Bob. Let's say you have 10 or 20 or whatever given number of particles in this box.

You might say that it's impossible to send information using this, because the collapse is always going to turn out in a 50-50 % chance.
No way of telling whether the particle was supposed to mean spin "up" or "down".

But we don't need that information at all. All we need is to detect IF/WHEN a collapse (measurement) has happened. As both boxes in the spaceship and command center respectively, are sealed and there's no way they should collapse from external forces or anything else, all we need is a DETECTOR in the spaceship and command center.

The instructions is as follows: 1 entanglement-pair collapse followed by at least 2 sec. delay or more means "Hello".
2 collapses with 1 sec. delay between each, means "Bye".

When Alice measures one of her particles, which is entangled with a particle on Earth, Bob (on Earth) will see his detector signaling (in some way or another, making a noise or displaying something on a monitor) once as one of his particle's entanglements have collapsed.

He instantly knows it means "Hello". He measures two of his particles, wait 1 sec. and measures another. Then Alice's detector should display on some monitor when two of her particles collapsed.

She then knows it means "Bye".

Why is this type of entanglement-information impossible?

Of course given the limited amount of particles, there's only a limited amount of information they can send. But increase the number of entangled particles, and you increase the amount of messages you can send each way.
Ha, good one. This time my answer may be wrong.

I think it's because you would need to monitor the particle at the receiver end, in order to be able to determine the time of the collapse. However, monitoring it would also collapse it.
Skepdick
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### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 6:16 pm But itsn't the spin-property or an entangled particle an information in itself?
No. "Information in itself" is essence/identity/form.

From the nomenclature defined here the spin-property is a piece of information. It's still subject to the uncertainty principle.

A piece of information is a particular fact about a thing's identity or properties, i.e., a portion of its instance.
philosopher
Posts: 395
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### Re: Entanglement and Information

Atla wrote: Sat Aug 31, 2019 7:11 pm I think it's because you would need to monitor the particle at the receiver end, in order to be able to determine the time of the collapse. However, monitoring it would also collapse it.
Makes sense, as my question regarding the entanglement-information can really be boiled down to this:

"Is measurement/observation and the resulting collapse crucial to have obtained information about a particle's state of entanglement? Or can a particle's uncertainty somehow be measured without collapse?"

In other words: Can we determine if a particle is entangled or not by not observing it, and let the collapse itself tell us when we're "allowed" to observe it?

Or to phrase the question in Einstein-terms: Can we let the moon tell us when it has become real before we look at it?
Skepdick
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Joined: Fri Jun 14, 2019 11:16 am

### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 7:44 pm
"Is measurement/observation and the resulting collapse crucial to have obtained information about a particle's state of entanglement? Or can a particle's uncertainty somehow be measured without collapse?"
Start here: https://en.wikipedia.org/wiki/Entanglement_witness

You are going to have to build a mental picture of distinguishing between entangled and separable states, and probably get some rudimentary understanding of the maths behind it.

I haven't figured out how to translate this into an English intuition yet (which probably means I don't understand it well enough either).
Atla
Posts: 2979
Joined: Fri Dec 15, 2017 8:27 am

### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 7:44 pm
Atla wrote: Sat Aug 31, 2019 7:11 pm I think it's because you would need to monitor the particle at the receiver end, in order to be able to determine the time of the collapse. However, monitoring it would also collapse it.
Makes sense, as my question regarding the entanglement-information can really be boiled down to this:

"Is measurement/observation and the resulting collapse crucial to have obtained information about a particle's state of entanglement? Or can a particle's uncertainty somehow be measured without collapse?"

In other words: Can we determine if a particle is entangled or not by not observing it, and let the collapse itself tell us when we're "allowed" to observe it?

Or to phrase the question in Einstein-terms: Can we let the moon tell us when it has become real before we look at it?
Not sure I follow, we already know that the particles are entangled, that's how they were created. Their spins are in superposition, but linked ignoring spacetime.
philosopher
Posts: 395
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### Re: Entanglement and Information

Atla wrote: Sat Aug 31, 2019 8:07 pm
philosopher wrote: Sat Aug 31, 2019 7:44 pm
Atla wrote: Sat Aug 31, 2019 7:11 pm I think it's because you would need to monitor the particle at the receiver end, in order to be able to determine the time of the collapse. However, monitoring it would also collapse it.
Makes sense, as my question regarding the entanglement-information can really be boiled down to this:

"Is measurement/observation and the resulting collapse crucial to have obtained information about a particle's state of entanglement? Or can a particle's uncertainty somehow be measured without collapse?"

In other words: Can we determine if a particle is entangled or not by not observing it, and let the collapse itself tell us when we're "allowed" to observe it?

Or to phrase the question in Einstein-terms: Can we let the moon tell us when it has become real before we look at it?
Not sure I follow, we already know that the particles are entangled, that's how they were created. Their spins are in superposition, but linked ignoring spacetime.
We only know they're entangled because we made them so they were entangled, on purpose.
The thing is, when you measure one or the other, both particles seperated by spacetime will lose their entanglement, and become local.

If Alice measures her particle, is there any way for Bob to know if his particle originally entangled with Alice's particle, has collapsed/no longer entangled without looking/observing, and only know if they were entangled by observing the moment of collapse rather than observing the particle?

(remember: observation causes the entanglement to disappear/collapse, all you know is that they WERE entangled, not anymore).

You'll have to know if they're entangled NOW, without collapsing them. Not if they "were" entangled in the past, even knowing if they were entangled a tiny fraction of a second into the past makes it useless, and communication faster than light impossible.
Last edited by philosopher on Sat Aug 31, 2019 9:08 pm, edited 1 time in total.
philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

### Re: Entanglement and Information

Skepdick wrote: Sat Aug 31, 2019 7:54 pm
philosopher wrote: Sat Aug 31, 2019 7:44 pm
"Is measurement/observation and the resulting collapse crucial to have obtained information about a particle's state of entanglement? Or can a particle's uncertainty somehow be measured without collapse?"
Start here: https://en.wikipedia.org/wiki/Entanglement_witness

You are going to have to build a mental picture of distinguishing between entangled and separable states, and probably get some rudimentary understanding of the maths behind it.

I haven't figured out how to translate this into an English intuition yet (which probably means I don't understand it well enough either).
I have no way of learning about tensors or matrix mechanics.
Noax
Posts: 670
Joined: Wed Aug 10, 2016 3:25 am

### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 6:16 pm Entanglement says that two particles can have their spin properties shared, so when one measures the other, it changes the other in an instant (faster than light).
This is a misrepresentation. If both are measured, the measurements will be correlated. So if the spin of both is measured in exactly the same way, one will be measured one way and the other the opposite.
There is nothing in QM that asserts that entangled that asserts that the other is changed in any way in an instant. There is nothing that says it isn't either.
Though according to Bell's No-go-theorem you cannot send information faster than the speed of light.
This is the principle of locality (PoL, or just locality), not Bell's theorem that asserts this. Locality has never been proven, nor has the principle of counterfactual definiteness (PoCD, which would assert that the remote entangled particle has a defined state unmeasured). Bell's theorem simply shows that these two principles are not both true.

So under say an interpretation that holds to locality, the measurement of one entangled particle has zero effect on the other.
Under a different interpretation that holds to PoCD, effects can propagate faster than light and thus occur before the cause, even years into the past.

There is no absolute time, so the is no 'instantly' defined, but again, some interpretations of time assert otherwise.
Last edited by Noax on Sat Aug 31, 2019 9:43 pm, edited 1 time in total.
Atla
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Joined: Fri Dec 15, 2017 8:27 am

### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 9:03 pm We only know they're entangled because we made them so they were entangled, on purpose.
The thing is, when you measure one or the other, both particles seperated by spacetime will lose their entanglement, and become local.

If Alice measures her particle, is there any way for Bob to know if his particle originally entangled with Alice's particle, has collapsed/no longer entangled without looking/observing, and only know if they were entangled by observing the moment of collapse rather than observing the particle?

(remember: observation causes the entanglement to disappear/collapse, all you know is that they WERE entangled, not anymore).

You'll have to know if they're entangled NOW, without collapsing them. Not if they "were" entangled in the past, even knowing if they were entangled a tiny fraction of a second into the past makes it useless, and communication faster than light impossible.
Umm.. aren't you somehow confusing the loss of entanglement with wavefunction collapse?

The particles are entangled theorethically indefinitely, unless the entanglement is broken* by something, like a wavefunction collapse. The thing here is that after the entanglement is broken, even if the spins don't change after that until we look at them, it's still impossible to send information over (or so it's believed).

(*or more like in some form it "leaks out" into the surroundings, and we can't track it anymore, but that's beside the point)
Atla
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Joined: Fri Dec 15, 2017 8:27 am

### Re: Entanglement and Information

Atla wrote: Sat Aug 31, 2019 9:42 pm (*or more like in some form it "leaks out" into the surroundings, and we can't track it anymore, but that's beside the point)
Ok, maybe it's not so beside the point. If (big if) there is something to things like twins feeling each other's emotions, or people sensing a loved one's death, then I think it probably works via all this "leaking out", degrees or remnants of entanglement even after "wavefunction collapse", reaching a threshold where the body can make sense of it.

They would be able to roughly infer what's happening with the other person (even if separated by a billion lightyears). I rather tend to think that this is real and happens all the time..

So maybe if we could find a way to preserve entanglement on a macro scale even after collapses..
HexHammer
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Location: Denmark

### Re: Entanglement and Information

philosopher wrote: Sat Aug 31, 2019 6:16 pmThough according to Bell's No-go-theorem you cannot send information faster than the speed of light.
TL;DR big objects slows time, so time on earth is slowed, if time is measured far away from sol in hyper space, then time is much faster.

If time dilation is greater C is preserved.
philosopher
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Joined: Fri Jun 08, 2018 3:37 pm

### Re: Entanglement and Information

Atla wrote: Sat Aug 31, 2019 10:29 pm
Atla wrote: Sat Aug 31, 2019 9:42 pm (*or more like in some form it "leaks out" into the surroundings, and we can't track it anymore, but that's beside the point)
Ok, maybe it's not so beside the point. If (big if) there is something to things like twins feeling each other's emotions, or people sensing a loved one's death, then I think it probably works via all this "leaking out", degrees or remnants of entanglement even after "wavefunction collapse", reaching a threshold where the body can make sense of it.

They would be able to roughly infer what's happening with the other person (even if separated by a billion lightyears). I rather tend to think that this is real and happens all the time..

So maybe if we could find a way to preserve entanglement on a macro scale even after collapses..
Sorry, I respected you for your previous posts. But this, this is just bullship crap pseudo-"science" (not science at all).
Neither is is philosophy.

Of course you can't share emotions without communicating a message traveling at a max. speed of light using conventional mechanics and classical physics.

The brain is too hot to do any meaningful quantum computations.
Atla
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Joined: Fri Dec 15, 2017 8:27 am

### Re: Entanglement and Information

philosopher wrote: Sun Sep 01, 2019 9:06 pm
Atla wrote: Sat Aug 31, 2019 10:29 pm
Atla wrote: Sat Aug 31, 2019 9:42 pm (*or more like in some form it "leaks out" into the surroundings, and we can't track it anymore, but that's beside the point)
Ok, maybe it's not so beside the point. If (big if) there is something to things like twins feeling each other's emotions, or people sensing a loved one's death, then I think it probably works via all this "leaking out", degrees or remnants of entanglement even after "wavefunction collapse", reaching a threshold where the body can make sense of it.

They would be able to roughly infer what's happening with the other person (even if separated by a billion lightyears). I rather tend to think that this is real and happens all the time..

So maybe if we could find a way to preserve entanglement on a macro scale even after collapses..
Sorry, I respected you for your previous posts. But this, this is just bullship crap pseudo-"science" (not science at all).
Neither is is philosophy.

Of course you can't share emotions without communicating a message traveling at a max. speed of light using conventional mechanics and classical physics.

The brain is too hot to do any meaningful quantum computations.
Thanks, but your last sentence is a word salad (and also ignores quantum biology, which happens at room temperature).
philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

### Re: Entanglement and Information

Atla wrote: Sun Sep 01, 2019 9:23 pm
philosopher wrote: Sun Sep 01, 2019 9:06 pm
Atla wrote: Sat Aug 31, 2019 10:29 pm
Ok, maybe it's not so beside the point. If (big if) there is something to things like twins feeling each other's emotions, or people sensing a loved one's death, then I think it probably works via all this "leaking out", degrees or remnants of entanglement even after "wavefunction collapse", reaching a threshold where the body can make sense of it.

They would be able to roughly infer what's happening with the other person (even if separated by a billion lightyears). I rather tend to think that this is real and happens all the time..

So maybe if we could find a way to preserve entanglement on a macro scale even after collapses..
Sorry, I respected you for your previous posts. But this, this is just bullship crap pseudo-"science" (not science at all).
Neither is is philosophy.

Of course you can't share emotions without communicating a message traveling at a max. speed of light using conventional mechanics and classical physics.

The brain is too hot to do any meaningful quantum computations.
Thanks, but your last sentence is a word salad (and also ignores quantum biology, which happens at room temperature).
Quantum Biology deals with how evolution works through quantum processes. Stuff that speeds up the evolution.

It has nothing to do with how the brain works.
https://en.wikipedia.org/wiki/Quantum_mind
The main theoretical argument against the quantum mind hypothesis is the assertion that quantum states in the brain would lose coherency before they reached a scale where they could be useful for neural processing. This supposition was elaborated by Tegmark. His calculations indicate that quantum systems in the brain decohere at sub-picosecond timescales.[71][72] No response by a brain has shown computational results or reactions on this fast of a timescale. Typical reactions are on the order of milliseconds, trillions of times longer than sub-picosecond timescales.[73]