B Number of entangled particles in nature

[entropy1]

I understand that we can create entangled particles in the lab. But how many (non-locally) entangled particles (such as photons/polarisation or electrons/spin) exist in free nature?

 

[Vanadium 50]

All of them.

 

[mfb]

That depends on your favorite interpretation of quantum mechanics.
In many worlds: as many as there are particles.
In collapse interpretations: depends on where exactly you put the collapse and what you count as entangled.
In other interpretations: depends on details of the interpretations.

 

[Mentz114]

I understand that we can create entangled particles in the lab. But how many (non-locally) entangled particles (such as photons/polarisation or electrons/spin) exist in free nature?

Have a look at this. Someone obviously thinks entanglement is ubiquitous.

http://www.nature.com/news/the-quantum-source-of-space-time-1.18797

 

[entropy1]

Have a look at this. Someone obviously thinks entanglement is ubiquitous.

http://www.nature.com/news/the-quantum-source-of-space-time-1.18797

Very nice research. Coincidentally I was working on practically the similar thing today. However, as layman as layman can get. But I find this very nice. Thanks!

 

[DirkMan]

So if space is made of entanglement...what does that mean ? Does it mean that a particle in the universe is entangled with all of the other particles in the universe ?

 

[AlexCaledin]

Perhaps we could say, any particle is lost in the universal entanglement until a physicist get it out of there - in order to observe it entangling back...

 

[bhobba]

Someone obviously thinks entanglement is ubiquitous.

It is.

Everything is excitations in an underlying quantum field so are entangled.

This isn't just speculation either. That electrons are 'entangled' with the EM field is responsible for spontaneous emission.

Strictly speaking pure states don't really exist, but of course are absolutely necessary for theory like points don't really exist but are absolutely necessary for geometry.

Thanks
Bill

 

[anorlunda]

A very tentative speculation : might ever increasing entanglement be related to the 2nd law of thermodynamics?

 

[entropy1]

If all or very many particles in the universe are entangled, does that mean that by measuring, say, a property of a particular particle, the properties of its entangled co-particles collapse into a different value (non-locally)?

 

[bhobba]

If all or very many particles in the universe are entangled, does that mean that by measuring, say, a property of a particular particle, the properties of its entangled co-particles collapse into a different value (non-locally)?

Entangled systems are not separate. QM is not non-local - you have been reading too many pop-sci accounts.

Systems are becoming entangled and un-entangled all the time.

Thanks
Bill

 

[entropy1]

Do I really have to become a physisist to be able to understand some basic aspects of quantum mechanics?

 

[bhobba]

Do I really have to become a physisist to be able to understand some basic aspects of quantum mechanics?

No:
https://www.amazon.com/dp/0465062903/?tag=pfamazon01-20

Thanks
Bill

 

[Nugatory]

Do I really have to become a physicist to be able to understand some basic aspects of quantum mechanics?

No, but QM does require thinking about physical systems in an unfamiliar and more mathematically abstract way. You do have to form at least a qualitative understanding of what we're talking about when we say "operator" and "vector in Hilbert space" and how these concepts relate to the observable properties of stuff around us.

 

[AlexCaledin]

... and how these concepts relate to the observable properties of stuff around us.

- as Dr Henry P. Stapp said in "Mind, Matter and QM" : "How is quantum theory related to reality?" - according to him, it's the second of the "four basic questions concerning the nature of nature".

(The first question is "How is mind related to matter?" and the other two are about relativity.)

 

[Nugatory]

"How is quantum theory related to reality?"

When I said "... relate to the observable properties of stuff" I was deliberately using the wording I did to avoid bringing up this question about "reality". Many people (myself included) find that question interesting and important, but there is little point in taking it on until you understand how quantum theory works as a mathematical tool for predicting the results of observations.

It's fair to say that much of OP's confusion in this thread and some others is the result of trying to relate what quantum theory says to reality before he knows what quantum theory says.

 

[bhobba]

"How is quantum theory related to reality?"

QM is a theory about observations that appear in an assumed common sense classical world. That's how its related to reality. Now the question is how such a world is explained by a theory that assumes it from the start. That is the central mystery of QM - not this mind stuff.

QM is weird - but not as weird as some try to make out.

Thanks
Bill