Real or Virtual Particles: Chicken or the Egg?

[yuiop]

Only people informed primarily by lay men's literature claim that. See Chapter A7 of my theoretical physics FAQ at http://arnold-neumaier.at/physfaq/physics-faq.html#A7 and the PF thread https://www.physicsforums.com/showthread.php?t=460685

Hi, I read some of your FAQ which I found interesting. This part about what really happens in Hawking radiation caught my interest:

What happens is that the high energy of the gravitational field of the
black hole creates real particle-antiparticle pairs -- that before
that event it could be viewed in terms of Feynman diagrams as virtual
is completely irrelevant to his argument.

One of these real particles is swallowed by the black hole, the other
is radiated away. As a result, the black hole loses radiation, hence
total energy, and its effective mass decreases because of mass-energy
equivalence.

OK, the phrase "the black hole loses energy" is a bit vague. Let's try and define it a bit more clearly. Let us say that the black hole is the region enclosed within r=2M. The gravitational field of said black hole extends all the way to infinity and so by definition cannot lose anything, so let's for the sake of argument define the "high energy" gravitational field of the black hole as an arbitrary region from r>2M to r=3M. Some of this gravitational energy condenses into a real particle-antiparticle pair. Both real particles and real antiparticles have positive energy. Let us say that the gravitational field loses 2 units of energy in the creation of these real particles. One of these real particles has a trajectory that takes it beyond r=3M and represents energy/mass radiated from the gravitational field external to the black hole. There is a 50% probability that this radiated particle is an antiparticle and so I prediction of this explanation is that if Hawking radiation is detected it will consist to 50% real particles and 50% real antiparticles. Is that correct?

Now the remaining particle of the pair falls into the black hole. Whether this infalling particle is a particle or an antiparticle is immaterial, because either way it has positive energy and adds to the total mass/energy of the black hole. Now in the original popular interpretation of Hawking radiation, the infalling particle was a virtual particle with negative energy and the addition of this virtual particle to the black hole diminished the black holes mass, but if we do not accept the "reality" of virtual particles then we do not allow ourselves the luxury of this negative energy explanation.

So what have we ended up with. The gravitational field outside the black hole is losing energy by radiating particles and the black hole itself is gaining mass? Eventually we end up with a black hole with increased mass but no energy in its external gravitational field? A very strange situation. Of course, I am probably missing the point greatly. Could you clarify?

It would seem that while mass and energy cannot escape from a black hole, mass inside the black hole somehow converts to gravitational energy that can seep out of the black hole on the quiet. Then it condense into particles outside the event horizon and is radiated, thereby bypassing the restriction on energy not being able to cross outwards across the event horizon.

 

[sujiwun]

Whilst it is an interpretation of physics, that our understanding is not really made of well-defined matter, where the world is intrinsically made up of probabilities - it's not a well-accepted view. It's very speculative to think nothing exists. It does not let you draw any conclusions on our existence, because existence would not exist! It must be true that what we have done is create and label a tool which is vast in its applications, and call it mathematics, and apply it to the working world. Our equations are not reality, this is true, but they help represent reality. While they are built on proposals based soley on mathematical knowledge, they do describe the physical world for us. There needs to be something out there, or there would be nothing to measure, right?

"There needs to be something out there, or there would be nothing to measure, right?"

Yes, but it is always human beings who are the measure of things and we tend to be a bit repetitive in how we divide things up...

four fundamental forces, four base nucleotide bases, four seasons, four cardinal directions, four archangels, four classical greek elements, four temperaments, lucky four leaved clovers...

http://en.wikipedia.org/wiki/4_(number)#In_religion

 

[A. Neumaier]

OK, the phrase "the black hole loses energy" is a bit vague. Let's try and define it a bit more clearly. Let us say that the black hole is the region enclosed within r=2M. The gravitational field of said black hole extends all the way to infinity and so by definition cannot lose anything, so let's for the sake of argument define the "high energy" gravitational field of the black hole as an arbitrary region from r>2M to r=3M. Some of this gravitational energy condenses into a real particle-antiparticle pair. Both real particles and real antiparticles have positive energy. Let us say that the gravitational field loses 2 units of energy in the creation of these real particles. One of these real particles has a trajectory that takes it beyond r=3M and represents energy/mass radiated from the gravitational field external to the black hole. There is a 50% probability that this radiated particle is an antiparticle and so I prediction of this explanation is that if Hawking radiation is detected it will consist to 50% real particles and 50% real antiparticles. Is that correct?

Seems so.

The gravitational field outside the black hole is losing energy by radiating particles and the black hole itself is gaining mass? Eventually we end up with a black hole with increased mass but no energy in its external gravitational field?

In general relativity, mass and energy are the same thing, apart from the factor c^2. Some of the black hole's mass=energy is in the form of a gravitational field; therefore mass=energy is lost when a particle is radiated.

But I am not an expert on black holes; so what I wrote might be a bit simplistic, and so may be my attempt to answer your question.

 

[sujiwun]

Seems so.

In general relativity, mass and energy are the same thing, apart from the factor c^2. Some of the black hole's mass=energy is in the form of a gravitational field; therefore mass=energy is lost when a particle is radiated.

But I am not an expert on black holes; so what I wrote might be a bit simplistic, and so may be my attempt to answer your question.

If you use Planck Units then E=mc^2 becomes E=m.

http://en.wikipedia.org/wiki/Planck_units

 

[QuantumClue]

"There needs to be something out there, or there would be nothing to measure, right?"

Yes, but it is always human beings who are the measure of things and we tend to be a bit repetitive in how we divide things up...

four fundamental forces, four base nucleotide bases, four seasons, four cardinal directions, four archangels, four classical greek elements, four temperaments, lucky four leaved clovers...

http://en.wikipedia.org/wiki/4_(number)#In_religion

Don't be silly. There needs to be something there... how can you talk about a non-entity? You can only infer on one existence if you are willing to have another. We suit well for frames of reference in this universe... just because QM differs in bad press on the subject of the observer, does not mean one is needed to create the universe!

 

[QuantumClue]

In other words...

You cannot say:Yes, but it is always human beings who are the measure of things

The reason is because we are not the measure of all things. We are a measure of observation nontheless.

 

[sujiwun]

In other words...

You cannot say:Yes, but it is always human beings who are the measure of things

The reason is because we are not the measure of all things. We are a measure of observation nontheless.

Of course we are. To suggest otherwise would be silly. What else defines the lines that divides entities. What is it that identifies that there is a vase standing on a table rather than one single entity? Does the vase know that it is separate or does the table? It is we that say that they are.

Or, to take the Zen argument, if you break the spokes out of a wooden wheel one by one, at which point does it cease to be a wheel and just become a pile of wood?

That is not to say that there is nothing there, just that whatever it is, it is not what we say it is.

 

[QuantumClue]

Of course we are. To suggest otherwise would be silly. What else defines the lines that divides entities. What is it that identifies that there is a vase standing on a table rather than one single entity? Does the vase know that it is separate or does the table? It is we that say that they are.

Or, to take the Zen argument, if you break the spokes out of a wooden wheel one by one, at which point does it cease to be a wheel and just become a pile of wood?

That is not to say that there is nothing there, just that whatever it is, it is not what we say it is.

Particles make perfectly fine observers. They can define a reality quite fine without intelligent recording devices, like ourselves.

 

[QuantumClue]

There is still sound in the forest when no one is around, if there was no sound, there would be nothing for us to listen for.

 

[sujiwun]

Particles make perfectly fine observers. They can define a reality quite fine without intelligent recording devices, like ourselves.

Except they don't exist, we made them up. Show me a quark or an electron. Extraordinary claims require extraordinary evidence.

http://compukol.com/mendel/articles/articles.html

 

[lightarrow]

"There needs to be something out there, or there would be nothing to measure, right?"

Yes, but it is always human beings who are the measure of things and we tend to be a bit repetitive in how we divide things up...

four fundamental forces, four base nucleotide bases, four seasons, four cardinal directions, four archangels, four classical greek elements, four temperaments, lucky four leaved clovers...

...a particle here and another there (instead of no dividing the field at all...)

 

[QuantumClue]

Except they don't exist, we made them up. Show me a quark or an electron. Extraordinary claims require extraordinary evidence.

http://compukol.com/mendel/articles/articles.html

http://www.mizozo.com/tech/09/2009/15/first-picture-of-an-atom.html

I think that artical shows that there is something there. Whether it be a particle, a string or something else, there is still something there, and is a far shot from being nothing at all.

 

[Maui]

http://www.mizozo.com/tech/09/2009/15/first-picture-of-an-atom.html

I think that artical shows that there is something there. Whether it be a particle, a string or something else, there is still something there, and is a far shot from being nothing at all.

So someone did a measurement(atom bombardment) and found that there is an electron cloud? Great, that's revolutionary.

How about you tell us where in the statement - "physical matter is a propensity" there is an inconsistacy? Questions concerning what and how reality is aren't really answerable anyway, all the theroies we built so far are inconsistent with either human logic or with some of the evidence we gathered so far. All you could possibly have is a collection of prejudices that you picked up from other prejudiced individuals looking for answers to diffucult philosophical questions.

 

[yoda jedi]

Whether it be a particle, a string or something else, there is still something there, and is a far shot from being nothing at all.

Right.

"being qua being"

...anything that exists just because of its existence and not because of any special qualities it has.

 

[sujiwun]

http://www.mizozo.com/tech/09/2009/15/first-picture-of-an-atom.html

I think that artical shows that there is something there. Whether it be a particle, a string or something else, there is still something there, and is a far shot from being nothing at all.

I don't think the argument is that there is nothing there, but rather that any description of it as a sum of parts will be incomplete.

Mandel Sachs holistic field ideas suggest to me that the random vacuum quantum flux is the ground of existence - white noise static as an analogy. Within the random noise, there emerge sporadic localised regions that deviate breifly from the overall randomness - literally incidental filaments of order within a global chaos - matter out of empty space, the symmetry of the noise broken.

This order represents the virtual particles popping in and out of existence which in turn give rise to the appearance of interacting electrons, and quark etc by the defining regional field properties by which we know them, because these virtual particle are the regional field properties and seemingly electrons and quarks are nothing without them.

Philosophically, this still wouldn't settle any old scores. There's no account for why there should be order in chaos. One could take a materialist stance that it is just incidental, one could equally take a transcendental stance that a personal God put it there, or one could take a pantheistic stance that the order (being literally meaningful in constrast to chaos being meaningless) is or contains some form of intelligence, not least our own. So belief one way another would still be a matter of personal conviction.

 

[QuantumClue]

Well maybe not. Maybe the special qualities it has is because it has existence...


(forgot to qoute... that was to jedi)

 

[ibysaiyan]

Seems so.

In general relativity, mass and energy are the same thing, apart from the factor c^2. Some of the black hole's mass=energy is in the form of a gravitational field; therefore mass=energy is lost when a particle is radiated.

But I am not an expert on black holes; so what I wrote might be a bit simplistic, and so may be my attempt to answer your question.

Very true,the fluctuation of energy caused near to the event horizon causes the formation of particle-antiparticle of which one is sucked into the BH before the occurrence of annihilation. So to the observer outside the BH would appear to have emitted H-radiation.The outward is the positive energy,this is how entropy is picturized for a BH.

 

[QuantumClue]

So someone did a measurement(atom bombardment) and found that there is an electron cloud? Great, that's revolutionary.

How about you tell us where in the statement - "physical matter is a propensity" there is an inconsistacy? Questions concerning what and how reality is aren't really answerable anyway, all the theroies we built so far are inconsistent with either human logic or with some of the evidence we gathered so far. All you could possibly have is a collection of prejudices that you picked up from other prejudiced individuals looking for answers to diffucult philosophical questions.

On the contrary. You have used a very subjective line of thought, which would be from a quantum viewpoint, a dogma based faith of ideologies.

Very early on as you should know, quantum theory did, and still does rely heavily on the Copenhagen Interpretation. This takes the same conjunction as you do. If it is not really measurable then there is no consensus on how to deal with the problem. This is a inconsistency.

There is no reason not to be able to fill in the gaps to unify physics, just because something is beyond a screen. Questions asking how reality really fits our picture is not irrelevant as you claim, but rather enlightens the theories we have that work only to a certain degree. If we can mathematical formulate a theory without considering other possibilities, then we are in the dark with what to expect out of an otherwise, very complicated theory.

More to the point, if one says unobservable parts of a theory are not worth looking into, does not give us a whole picture on aspects which should be avoidable.

 

[yoda jedi]

Well maybe not. Maybe the special qualities it has is because it has existence...


(forgot to qoute... that was to jedi)

special like distinctive.

as you said:

Whether it be a particle, a string or something else,

there is still something there, and is a far shot from being nothing at all.

Qualities are just attributes, no Existence per se.

 

[_PJ_]

Since 'virtual particles' are essentially "fluctuations in the quantum foam" that just happen to give rise to interactions as if 'real' particles had appeared, neither "virtual particles" or "real particles" necessarily 'cause' one another.

That both types can be considered, (i.e. by Feynam-like trajectory models) to be time-symetric, the answer to your question is, in my opinion, neither.