# Virtual particles and entanglement

wimms
Are virtual particles entangled when they appear? If so then when one of the pair falls into a black hole and other flies off, do they remain entangled? If so, does this mean that by observing black hole radiation we can in principle 'see inside'?

Mentat
Originally posted by wimms
Are virtual particles entangled when they appear?

I should assume so, though I have no reference to substantiate my assumption. If a photon temporarily becomes two particles, then those must be "entangled" - or so it appears logical to me.

If so then when one of the pair falls into a black hole and other flies off, do they remain entangled?

It would appear so, but I thought that virtual particles anhialated (sp?) themselves in an "instant", and thus one would not fall into the BH without the other, would it?

If so, does this mean that by observing black hole radiation we can in principle 'see inside'?

I don't know. Blackhole radiation has always confused me (as you can see from my (above) previous question).

Mentat,

Yes, according to Hawking at least, those pairs that emerge right at the edge of the BH's event horizon are split, one falling into the black hole and the other spiraling out. These extra particles are what make up black hole radiation. I find it interesting that there's actually matter here coming out of nowhere! Seems to me that BH's suck in more than they put out probably though (just a guess).

Here's a tangent thought...

As many know, gravity is the weakest of the fundamental forces. Now, the only thing that gives a black hole that event horizon is that it's escape velocity is greater than c. Seems to me, that if you used MAGNETIC force (a lot stronger than gravity), that you could create conditions where an object would have to be moving at greater than c to get away from the pull. In effect, you'd have a "greater-than-c escape velocity", only based on magnetism instead of gravity.

Now, if you could somehow charge a fluctuating vacuum quick enough to be reactant to your magnets, couldn't you create a force strong enough to rip apart virtual particles at this artificial event horizon? Thus, you'd be creating matter out of nowhere. Of course, my guess is that the mass-energy expended to get x amount of material is more than the mass-energy of the material. But it would still be cool to do (like when they turned lead into gold, even though the cost of doing so was more than the gold was worth).

ok sorry, should have made a new thread for that. But as for still being entangled, I really have no idea. I would imagine that all we would "see" (i.e. calculate backwards) if we could would be a bunch of the other particles smushed into a point.

Tail
To my knowledge, particles are not 'entangled' in any way. They annihilate with each other VERY quickly and are not much apart, that's all.

It's true that one of the particles might fall into a black hole. It's almost always the negatively charged particle (cannot remember why), and the gravitation of the black hole is powerful enough to somehow make it into a 'real' particle.

Nothing really comes out of the black hole. It SEEMS something is coming out because the black hole's mass is a bit smaller (negative energy was brought into it, remember?) and there is a new lone particle in the space, but it isn't that the particle has come out of the black hole, it's just that the negatively charged particle has gone in.

Tiberius, there is no matter coming out of nowhere, because there is also antimatter with it, so the general amount of matter stays the same.

Gold Member
Yes of course they are entangled, the clear example of this is when one falls into a black hole.

Gold Member
Originally posted by Tiberius
Mentat,

Yes, according to Hawking at least, those pairs that emerge right at the edge of the BH's event horizon are split, one falling into the black hole and the other spiraling out. These extra particles are what make up black hole radiation. I find it interesting that there's actually matter here coming out of nowhere! Seems to me that BH's suck in more than they put out probably though (just a guess).

Black holes do have negative energy flowing into them, but this is an absolutely minute quantity for any decent sized black hole compared to the amount of postive energy flowing into them.

Here's a tangent thought...

As many know, gravity is the weakest of the fundamental forces. Now, the only thing that gives a black hole that event horizon is that it's escape velocity is greater than c. Seems to me, that if you used MAGNETIC force (a lot stronger than gravity), that you could create conditions where an object would have to be moving at greater than c to get away from the pull. In effect, you'd have a "greater-than-c escape velocity", only based on magnetism instead of gravity.

Now, if you could somehow charge a fluctuating vacuum quick enough to be reactant to your magnets, couldn't you create a force strong enough to rip apart virtual particles at this artificial event horizon? Thus, you'd be creating matter out of nowhere. Of course, my guess is that the mass-energy expended to get x amount of material is more than the mass-energy of the material. But it would still be cool to do (like when they turned lead into gold, even though the cost of doing so was more than the gold was worth).

ok sorry, should have made a new thread for that. But as for still being entangled, I really have no idea. I would imagine that all we would "see" (i.e. calculate backwards) if we could would be a bunch of the other particles smushed into a point.

No escape velocity is only a function of the gravity of an object not for example the strength of it's charge.

In a balck hole you already have regions were the escape velocity is greater than c but these lie beyond the event horizon.

wimms
well, my main interest was reasoning that if escaped particle has reached us, it has quite large chance of having not interacted with anything, thus it could include sort of information about its entangled partner. no?

Mentat
Originally posted by wimms
well, my main interest was reasoning that if escaped particle has reached us, it has quite large chance of having not interacted with anything, thus it could include sort of information about its entangled partner. no?

Well, this is probably true, but for all practical purposes I don't think it could happen. I say this because it still hasn't been shown to me that a virtual particle actually continues existing, after it's partner has fallen into a BH. Seriously, the virtual particle (according to Feynmann's hypothesis) to all of the possible paths into the BH, and some of those paths lead it right back into the vicinity of it's partner, where they would annihilate each other.

Originally posted by Tail
Tiberius, there is no matter coming out of nowhere, because there is also antimatter with it, so the general amount of matter stays the same.

But whether matter or antimatter, you still have more particles than you had before, even though some are matter and some are anti-particles. The two are not cancelling each other out. In fact, even if they did, then there would be the energy from the particles and antiparticles mingling. Is short, SOMETHING is coming out of nowhere with black hole radiation or else there wouldn't be something to be given that name.

So, as I understand it, in a vacuum you have pairs of particles constantly appearing and cancelling each other out. Then on the edge of an event horizon, where the pair appear and strattle that line, one of the particles is "sucked in" so to speak, and the other then is left behind and NOT canceled out. In some of these pairs, the anti-particle is left behind and the matter particle falls in, and in others the opposite is true. The result is that gozillions of matter AND antimatter particles are radiating away from the black hole, virtually from nowhere. Even antimatter has mass (it doesn't have NEGATIVE mass) so the total mass-energy has increased.

One science correspondent recently reported that he had made serious enquiries as to why Hawking's has never received a Noble Prize. The answer was that none of his (Hawking's) work could be related to reality. One should take purely theorectical work with the same caution shown by the committee.

Originally posted by elas
One science correspondent recently reported that he had made serious enquiries as to why Hawking's has never received a Noble Prize. The answer was that none of his (Hawking's) work could be related to reality. One should take purely theorectical work with the same caution shown by the committee.

I think you're interpreting that response wrong. The comment about not relating to reality is not a snide remark that addresses the reliability of the work in any way. Rather, what they mean is more likely that there are no direct applications of the work at this time. For example, Einstein did not win a Nobel prize for his well known and appreciated Relativity, but rather for the Photoelectric effect. Although, in the larger scheme of things, relativity will be better remembered as an "eye opener", the photoelectric effect had immediate and direct applications in inventions. The Nobel prizes seem to favor work that has immediate and direct practical application, and perhaps that's as it should be. But to take their comments as relating in any way to the reliability or soundness of the theories is misguided I think.

Tail
Originally posted by jcsd
Yes of course they are entangled, the clear example of this is when one falls into a black hole.
?

Gold Member
If one falls into a black hole, the other one will instantly become a real particle.

Tail
Originally posted by wimms
well, my main interest was reasoning that if escaped particle has reached us, it has quite large chance of having not interacted with anything, thus it could include sort of information about its entangled partner. no?
Actually, it's free to interact with whatever it wants once it has escaped. And what information are you hoping to receive?

Tail
Originally posted by jcsd
If one falls into a black hole, the other one will instantly become a real particle.
Actually, both of them will, and that doesn't mean they are entangled. It's the black hole's gravitation that turns them into real particles, not the fact one of them falls into the black hole.

Tail
Originally posted by Tiberius
But whether matter or antimatter, you still have more particles than you had before, even though some are matter and some are anti-particles.
Just like you have more numbers if you have -1 and +1, but it's still 0...
The two are not cancelling each other out.
Yes they are.
In fact, even if they did, then there would be the energy from the particles and antiparticles mingling.
True. But the particles don't REALLY come out of anywhere, their birth is strongly connected to the fiels that are in the space...
Is short, SOMETHING is coming out of nowhere with black hole radiation or else there wouldn't be something to be given that name.
The name just implies the hole radiates - meaning, it becomes smaller and there are particles coming out of its vicinity. Something coming out of nowhere would violate some laws of energy conservation or whatever they are called.

So, as I understand it, in a vacuum you have pairs of particles constantly appearing and cancelling each other out.
That's right, although you were saying the exact opposite of this a few sentences ago...
Then on the edge of an event horizon, where the pair appear and strattle that line, one of the particles is "sucked in" so to speak, and the other then is left behind and NOT canceled out.
Right, but don't forget that the antiparticle that went inside the black hole 'cancelled' out some particle there...
In some of these pairs, the anti-particle is left behind and the matter particle falls in, and in others the opposite is true.
Let me assure you that's far less probable (I can't remember what it is, but I've read several times that particles with negative energy have a far greater chance of getting 'sucked in').
Even antimatter has mass (it doesn't have NEGATIVE mass) so the total mass-energy has increased.
Here's where you're wrong. There is a particle and an antiparticle, and the antiparticle has NEGATIVE energy. That's the whole point. It's like in simple mathematical equations - you can add 1 to anything if you also subtract 1. +1-1=0. The whole point is that one has positive and the other has negative mass/energy.
Questions?

Gold Member
No, Tail they DO NOT both become real, the particle that fulls into the hole represents negative energy flowing into the black hole.

The black hole's grvitation makes one of the pair become a real particle due to the fact that it accretes one of the pair.

wimms
Originally posted by Tail
Actually, it's free to interact with whatever it wants once it has escaped. And what information are you hoping to receive?
Is it free? What happens with escaped particle when fallen antiparticle annihilates with some matter inside BH? Would entangled particle receive all properties of that its pair encountered?
Initially, "there was" 1 particle (in BH), then, pair appears, total 3. One goes off to earth, other falls into BH where it interacts with its destined one. End-result - 1 real particle on way to earth. If conservation laws hold, then it must have all properties of initial particle inside BH?

I don't hope anything practial about that info. Still, some remote estimates about BH-internal environment could be extracted in principle, i guess. Thus some observational evidence.

Also, I recall there was some issue with BH's information loss. I thought those entangled pairs might be related, but haven't heard anything on that.

Originally posted by jcsd
No, Tail they DO NOT both become real, the particle that fulls into the hole represents negative energy flowing into the black hole.
If I think of abstraction where only instant is viewed when anti-energy interacts inside BH, that happens after it has traveled some distance into BH and its matter-pair has traveled away, then picture arises that energy of poor particle inside BH effectively travels at 2c to outside...

Gold Member
Basically a measurement on one of the virtual particles defines the properties of the other so they are entangled.

wimms
Originally posted by jcsd
Basically a measurement on one of the virtual particles defines the properties of the other so they are entangled.
Does annihilation qualify as 'measurement'?

Originally posted by jcsd
Basically a measurement on one of the virtual particles defines the properties of the other so they are entangled.

and so the knowledge and not the particles are entangled...

Note that the Aspect-type experiments cannot even isolate a single "photon" let alone split it and send them on their merry way.

see: http://users.aber.ac.uk/cat/Tangled/tangled.html [Broken]

and see this talk at the Kavli Institute of Theoretical Physics
http://online.kitp.ucsb.edu/online/qo02/milonni/

Last edited by a moderator:
Gold Member
Yeah, I've heard people rubbish the Aspect exp. nuff time but at the end of the day they're the best results and agree with Bell's theorum.

Originally posted by jcsd
Yeah, I've heard people rubbish the Aspect exp. nuff time but at the end of the day they're the best results and agree with Bell's theorum.

If you like that sort of thing...

Staff Emeritus
Gold Member
Originally posted by subtillioN
Note that the Aspect-type experiments cannot even isolate a single "photon" let alone split it and send them on their merry way.
see: http://users.aber.ac.uk/cat/Tangled/tangled.html [Broken]
and see this talk at the Kavli Institute of Theoretical Physics
http://online.kitp.ucsb.edu/online/qo02/milonni/

Aspect's experiments are not the only ones that show entanglement. The effect has also been used for the so-called "teleportation" experiments.

Also, it is strongly present in the measurement of CP violation made in the electron-positron colliders BaBar and Belle. In those experiments, two B mesons are produced in an entangled state. As soon as the "flavor" of one of the particles is determined (say, a B0), the other is projected into the complementary flavor (an anti-B0). It is due to this correlation that the "sin2beta" measurement can be obtained.

The (clear) asymmetry observed between matter and antimatter in these experiments is, therefore, an experimental proof of the correctness of the QM description of the EPR effect.

Last edited by a moderator:
Originally posted by ahrkron
Aspect's experiments are not the only ones that show entanglement. The effect has also been used for the so-called "teleportation" experiments.

Also, it is strongly present in the measurement of CP violation made in the electron-positron colliders BaBar and Belle. In those experiments, two B mesons are produced in an entangled state. As soon as the "flavor" of one of the particles is determined (say, a B0), the other is projected into the complementary flavor (an anti-B0). It is due to this correlation that the "sin2beta" measurement can be obtained.

The (clear) asymmetry observed between matter and antimatter in these experiments is, therefore, an experimental proof of the correctness of the QM description of the EPR effect.

It is still an effect of a change in the state of knowledge of an event. There is no actual superluminal transfer of information from one particle to the other. QM thinks the "flavor" is undetermined until measured and this determination is transferred instantaneously to the other particle once the measurement is made. There are other models that don't include "uncertainty" and the consequent nonsense of the collapse of the wave-function, so the "entanglement" interpretation is superfluous.

If they can ever send an actual message across this change in certainty then I will take quantum entanglement a bit more seriously until then it is a waste of time.

Staff Emeritus
Gold Member
Originally posted by subtillioN
It is still an effect of a change in the state of knowledge of an event.

Not at all. If there was no entanglement, the measurements would be different.

For instance, in Fermilab we are also working towards the measurement of Sin2Beta. Due to the fact that we collide protons vs antiprotons (which, being a quark mess, have a very different physics than that of electron-positron collisions), the
B meson pairs are not quantum-entangled. As a result, the asymmetry behaves in a different way than those in BaBar and Belle.

There is a somewhat simple way to show that the observed properties of spin are incompatible with the idea of a well determined value, hidden from observation. It was published some three years ago by David Mermin (I think). I'll try to find the complete reference.

Another, somewhat older, proof that classical thinking is incompatible with the (experimentally) observed behavior of quantum systems is called the "Kocher-Specker paradox". I'm not sure about the spelling,... I'll check on the net later.

[Edit: I just checked: Kochen-Specker theorem]

Last edited:
Originally posted by ahrkron
Not at all. If there was no entanglement, the measurements would be different.

Not if they stem from the same process. In such a case the corelation can come from the causal interaction in the past.

Staff Emeritus
Gold Member
Originally posted by subtillioN
Not if they stem from the same process. In such a case the corelation can come from the causal interaction in the past.

Can you elaborate?

Also, I surfed for it a little: it was a paper by David N. Mermin. I still don't find the complete reference, but will keep trying.

Originally posted by ahrkron
Can you elaborate?

I can if you give me a good idea of what you know is physically happening in this particular experiment. I am assuming that you are actually working in the lab? I have never done the experiments and seen the results firsthand so your deeper firsthand knowledge-base will be very helpful in fleshing out the causal root.

Staff Emeritus
Gold Member
Originally posted by subtillioN
I can if you give me a good idea of what you know is physically happening in this particular experiment.

Do you mean the CP violation experiment?

The basic idea of the experiment is quite simple: B0 mesons (particles that contain quarks anti-b and d) decay differently (in time) than their counterparts (b and anti-d). When you subtract the two plots (number of decays vs time), you see an oscillation.

(if matter and antimatter behaved the same, you would get zero when doing the subtraction, since both plots would be identical).

When they are created in a e+e- collision, B mesons are entangled, so that the behavior of one of them depends on the measurements you do on the other one. If you decide to measure what flavor one of them was, the other is forced into being the opposite flavor at that moment (this is the "collapse"). From then on, it starts to do its usual stuff.

If such collapse didn't happen, you would not find the asymmetry, or the process would be quite different. I'll try to find a decent webpage about this for you later.

Originally posted by ahrkron
If you decide to measure what flavor one of them was, the other is forced into being the opposite flavor at that moment (this is the "collapse").

What do you mean when you say "forced"? Do you actually see something different happen to the other meson? Or do you mean that its flavor was indeterminate until the moment of the collapse? If the latter then how do we know it wasn't already this flavor before its partner was measured? How does one measure "flavor"?

Can you give me a time breakdown of this experimental procedure?

NEOclassic
Originally posted by elas
One science correspondent recently reported that he had made serious enquiries as to why Hawking's has never received a Noble Prize. The answer was that none of his (Hawking's) work could be related to reality. One should take purely theorectical work with the same caution shown by the committee.

Hi elas,
I couldn't agree with you more. However, the criterion that Nobel Laurelhood is proof of some kind of genius is pretty well strained when you see how many false theories that defy understanding have resulted in fraudulently granted prizes. So-called "thought experiments" since the time of Kepler have been accepted as laws of physics mostly because peer reviews come from theory collabrolators. Too often, Computer-aided science methods have resulted in potential peers, (including so-called think tanks) using borrowed "software".

Notice the contributors of this string have birthdays that are called N/A (meaning that they are possibly pre-teen "trekies") and two who are not N/As are less than twenty years old. You are over seventy and are my junior by seven years. I am normally reluctant to join strings that are concerned with arguable topics. But your clear channel posting deserved some cheering from your peers. Cheers, Jim Osborn

Tail
Originally posted by jcsd
No, Tail they DO NOT both become real, the particle that fulls into the hole represents negative energy flowing into the black hole.
I don't see the contradiction there. It becomes real AND represents the negative energy.

Tail
Originally posted by wimms
Is it free? What happens with escaped particle when fallen antiparticle annihilates with some matter inside BH? Would entangled particle receive all properties of that its pair encountered?
Initially, "there was" 1 particle (in BH), then, pair appears, total 3. One goes off to earth, other falls into BH where it interacts with its destined one. End-result - 1 real particle on way to earth. If conservation laws hold, then it must have all properties of initial particle inside BH?

That's exactly right. The anti-particle that goes into the black hole and annihilates with a particle exactly opposite itself, and not only THAT particle is opposite of the antiparticle, the one that escapes also is. They are very much the same.

I don't hope anything practial about that info. Still, some remote estimates about BH-internal environment could be extracted in principle, i guess. Thus some observational evidence.
No, no, no.
If I think of abstraction where only instant is viewed when anti-energy interacts inside BH, that happens after it has traveled some distance into BH and its matter-pair has traveled away, then picture arises that energy of poor particle inside BH effectively travels at 2c to outside...
It CANNOT travel faster than light. And mass is just concentrated energy.

Tail
Originally posted by jcsd
Basically a measurement on one of the virtual particles defines the properties of the other so they are entangled.
I agree that 'a measurement on one of the virtual particles defines the properties of the other', but they're still not entangled. It's like in basic maths, you can add 1 if you also subtract 1. In this case also they are exactly the opposite of the other, but it has NOTHING to do with entanglement.