Real or Virtual Particles: Chicken or the Egg?

  • Thread starter Thread starter sujiwun
  • Start date Start date
  • Tags Tags
    Egg
Click For Summary
The discussion centers on the relationship between real and virtual particles, questioning whether real particles cause virtual particles or vice versa. It highlights the ambiguity of defining "real" in the context of quantum mechanics, with some arguing that both types of particles are merely mathematical constructs used to describe observable phenomena. The conversation also touches on the nature of mass and whether it arises from interactions mediated by virtual particles. Participants express differing views on the reality of virtual particles, with some asserting their effects can be measured, while others maintain that they are not real in a traditional sense. Ultimately, the debate reflects ongoing uncertainties in quantum field theory and the interpretation of particle existence.
  • #31
QuantumClue said:
Well, aren't we just being a little pedantic however?

The Casimir Force, or more specifically the Lamb shift is caused by virtual particle energies. The Casimir force is in fact nothing more than an increasingly negative energy density between two plates in a vacuum via the interaction of virtual particles.

So I am interested how you can say what you say?
You can derive the Casmir force nonperturbatively, in fact I think it's done in introductory textbooks like "Quantum Field Theory in a nutshell" by A. Zee. In such a derivation there are no "virtual particles".
 
Physics news on Phys.org
  • #32
DarMM said:
You can derive the Casmir force nonperturbatively, in fact I think it's done in introductory textbooks like "Quantum Field Theory in a nutshell" by A. Zee. In such a derivation there are no "virtual particles".
That's true. In fact, I have never seen a derivation of the Casimir effect with virtual particles. The issue is not whether Casimir effect proves the reality of virtual particles (which it certainly doesn't), but whether it proves the reality of the zero-point energy (which is controversial, especially after the Jaffe's paper). Contrary to a frequent misconception, zero-point energy has absolutely nothing to do with virtual particles.
 
  • #33
For the last few posts, especially A. Neumaier's response, this is all down to interpretation.

Quantum mechanics directly predicted the existence of virtual particles long before any other explanations where concocted - and really were only created because certain scientists did not fully appreciate this existence which seems to have been for all practical terms, has been proven experimentally. Inviting new interpretations because people do not like the idea of virtual particles seems superfluous and redundant.
 
  • #34
  • #35
Demystifier said:
Contrary to a frequent misconception, zero-point energy has absolutely nothing to do with virtual particles.

You sure?

I'd agree that zero point energy ISN'T virtual particles and doesn't derive from virtual particles or what they are doing, but I wouldn't say it has nothing to do with them. More like the virtual particles are "anomalies" within the zero point energy field.
 
  • #36
Demystifier said:
The issue is not whether Casimir effect proves the reality of virtual particles (which it certainly doesn't), but whether it proves the reality of the zero-point energy (which is controversial, especially after the Jaffe's paper).

except that this guy has recorded it...

http://www.geo600.org/documents/audio-files

http://arxiv.org/PS_cache/arxiv/pdf/0709/0709.0611v1.pdf

http://en.wikipedia.org/wiki/GEO_600

http://www.fnal.gov/directorate/program_planning/Nov2009PACPublic/holometer-proposal-2009.pdf

http://holometer.fnal.gov/
 
Last edited by a moderator:
  • #37
sujiwun said:
You sure?

I'd agree that zero point energy ISN'T virtual particles and doesn't derive from virtual particles or what they are doing, but I wouldn't say it has nothing to do with them. More like the virtual particles are "anomalies" within the zero point energy field.

This is partially right. Zero point energy actually has a lot to do with our understanding of virtual particles when viewed as a vacuum which spontaneously bubbles energy at very small quantum levels. you try and remove all the energy from a part of space by cooling it down, you will never reach zero temperatures. What is left is an intrinsic energy which may as well be seen in terms of a virtual particle couldron boiling from the vacuum.
 
  • #38
sujiwun said:
how are imaginary virtual particles any different from imaginary electrons?

Do electrons actually exist?

According to the mainstream view, yes. Whereas virtual particles and imaginary electrons don't.
 
  • #39
A. Neumaier said:
According to the mainstream view, yes. Whereas virtual particles and imaginary electrons don't.

consensus reality - have you ever seen an electron, I know I haven't. It seems that scientists are just as capable of believing in their invisible imaginary friends as deists are, lol.

I've found reference to research on 'wet electrons' that claim to have isolated electrons in a sort of limbo state, but still no piccie.

For something to exist - in any meaningful sense - it ought to at least have a shape and definable size.

Now that doesn't dismiss the usefulness and validity of the concept of an electron within physics and its function in the world, but, by the same token, the usefulness and validity of virtual particles would be no less valid. If it works, use it.

Re: size of an electron.
This looked promising until I realizeed who the author was....lol.
http://prola.aps.org/abstract/PR/v14/i1/p20_1
 
  • #40
sujiwun said:
For something to exist - in any meaningful sense - it ought to at least have a shape and definable size.
Which is the size and shape of the wind? And of a collection of sea waves? So they don't exist?
 
  • #41
lightarrow said:
Which is the size and shape of the wind? And of a collection of sea waves? So they don't exist?

Yes, all very Taoist - but this just adds weight to my argument.

Does wind exist, really?

Waves can be defined as the propagation of information and energy, and in that sense be said to have real existence. Of course, you could carry the skepticism further and question whether energy itself exists - I mean seriously, is energy anything other than a mathematical abstraction - a conceptual map to model reality but not a reality in and of itself?

The mind carves experience up into perceived entities which we deem to "exist". Yes, you can say that ultimately, reality isn't a collection of "things" but a succession of processes/events. But still, we use signs and symbols to divide and represent those events as individual entities.

I started this thread with the question of whether virtual particles might be considered more fundamental than elementary particles? This was rejected on the grounds that virtual particles were mathematical constructs having no real existence but useful in modeling reality whereas electrons do have real existence irrespective of mathematical models of their nature.

I challenged that electrons have no more real existence than virtual particles, thus rendering them equivalent abstract constructs that may both be employed according to convenience and utility.

Here, in questioning the existence of wind, we take a Wittgensteinian view that nothing exists, and all is conceptual abstraction. True, possibly, but of little use.

So back to my original question, would it make more sense to consider electrons and quarks as products of the spontaneous emergent stochastic machinations of virtual particles briefly bursting forth from a chaotic quantum flux or to consider electrons and quarks as having fundamental existence that "produces" virtual force carrier particles in order to interact with each other?

Order(matter) as an essential component of chaos(space) rather than order as something other than chaos having "magical" properties that enables it to interact with itself.
 
  • #42
sujiwun said:
Yes, all very Taoist - but this just adds weight to my argument.

Does wind exist, really?

Waves can be defined as the propagation of information and energy, and in that sense be said to have real existence. Of course, you could carry the skepticism further and question whether energy itself exists - I mean seriously, is energy anything other than a mathematical abstraction - a conceptual map to model reality but not a reality in and of itself?

The mind carves experience up into perceived entities which we deem to "exist". Yes, you can say that ultimately, reality isn't a collection of "things" but a succession of processes/events. But still, we use signs and symbols to divide and represent those events as individual entities.

I started this thread with the question of whether virtual particles might be considered more fundamental than elementary particles? This was rejected on the grounds that virtual particles were mathematical constructs having no real existence but useful in modeling reality whereas electrons do have real existence irrespective of mathematical models of their nature.

I challenged that electrons have no more real existence than virtual particles, thus rendering them equivalent abstract constructs that may both be employed according to convenience and utility.

Here, in questioning the existence of wind, we take a Wittgensteinian view that nothing exists, and all is conceptual abstraction. True, possibly, but of little use.

So back to my original question, would it make more sense to consider electrons and quarks as products of the spontaneous emergent stochastic machinations of virtual particles briefly bursting forth from a chaotic quantum flux or to consider electrons and quarks as having fundamental existence that "produces" virtual force carrier particles in order to interact with each other?

Order(matter) as an essential component of chaos(space) rather than order as something other than chaos having "magical" properties that enables it to interact with itself.

With that kind of reasoning you could prove that nothing exist, and all. What if you pay for a house that doesn't actually exists and the seller tells you that it exists "virtually" in the net and so it exists? Would you feel satisfied of that answer?
 
  • #43
sujiwun said:
Then perhaps you can tell me what the radii are for quarks and electrons?

QFT may not predict that electrons and quarks are point particles, but, as far as I am aware it doesn't predict that they are not point particles either, and physics has no size for either of these.
Well for the electron one could always define the radius in a way related to the form factors. QFT says that electrons are not point particles, it explicitly predicts that. Any sensible meaning you can give to the word "point particle" is not obeyed by electrons in QFT. They are quanta of the field or quantum particles, separate notion from point particle.

Anyway, your talk of what is or isn't real (e.g. are biscuits real or just an abstraction of data received through our senses) is beside the point and distracts from the real issue of this thread. There is a difference between virtual particles and real particles. Real particles are eigenstates of the Hamiltonian and are predicted to exist by the theory. Virtual particles are simply labels on the internal lines of Feynman diagrams, which are themselves perturbative artefacts. QFT does not predict the existence of virtual particles, so according to the theory itself they are not real.
 
  • #44
What Are and Are-Not the characteristics of what are commonly referred to as a fundamental particles?

For the Are's, I get: mass, spin, charge, name, symbol, lepton number, quark number (maybe), family. To add to this, it's localizable. However, these are still idealized, on shell attributes. Anything else?

For the Are-Not's, I get: no size, no shape, no definite position, no definite momentum, not identifiable as a 'thing', and not identifiable as a 'particle'--whatever these mean.
 
  • #45
lightarrow said:
With that kind of reasoning you could prove that nothing exist, and all. What if you pay for a house that doesn't actually exists and the seller tells you that it exists "virtually" in the net and so it exists? Would you feel satisfied of that answer?

Exactly! Its all BS anyway, there is no wind, no house, no electron or virtual particles, just projections of abstract conceptions dreamt up by the fallible human mind. So if its all BS anyway, then why not go with the simplest GUT BS and make everything one, energy in physics, god in religion, consciousness in new age theosophy all the same none existent nonsense - so make determinism (matter) and indeterminism (quantum vacuum) one and the same, and build from the bottom up.
 
  • #46
sujiwun said:
Exactly! Its all BS anyway, there is no wind, no house, no electron or virtual particles, just projections of abstract conceptions dreamt up by the fallible human mind. So if its all BS anyway, then why not go with the simplest GUT BS and make everything one, energy in physics, god in religion, consciousness in new age theosophy all the same none existent nonsense - so make determinism (matter) and indeterminism (quantum vacuum) one and the same, and build from the bottom up.
And all this has to do with physics?
 
  • #47
lightarrow said:
And all this has to do with physics?

Do away with the particles and run with the quantum field.
 
  • #48
sujiwun said:
Do away with the particles and run with the quantum field.

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?
 
  • #49
sujiwun said:
consensus reality -

have you ever seen an electron, I know I haven't. It seems that scientists are just as capable of believing in their invisible imaginary friends as deists are, lol.

I've found reference to research on 'wet electrons' that claim to have isolated electrons in a sort of limbo state, but still no piccie.

For something to exist - in any meaningful sense - it ought to at least have a shape and definable size.

Now that doesn't dismiss the usefulness and validity of the concept of an electron within physics and its function in the world, but, by the same token, the usefulness and validity of virtual particles would be no less valid. If it works, use it.


http://prola.aps.org/abstract/PR/v14/i1/p20_1

great! good joke, a deep one ...lol...
consensus, mainstream view... ...lol...

like ants with sugar, running ! run madly
 
  • #50
Last edited by a moderator:
  • #51
A. Neumaier said:
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.
 
Last edited:
  • #52
QuantumClue said:
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
 
  • #53
yuiop said:
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.
yuiop said:
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.
 
  • #54
A. Neumaier said:
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
 
  • #55
sujiwun said:
"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!
 
  • #56
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.
 
  • #57
QuantumClue said:
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.
 
Last edited:
  • #58
sujiwun said:
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.
 
  • #59
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.
 
  • #60
QuantumClue said:
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
 
Last edited by a moderator:

Similar threads

I QED Picture of static EM Fields
  • · Replies 3 ·
Replies
3
Views
2K
I Virtual particle content of the vacuum state....
  • · Replies 10 ·
Replies
10
Views
2K
B Where do virtual particles come from?
  • · Replies 9 ·
Replies
9
Views
2K
I Clarify interaction between real and virtual particles....
  • · Replies 1 ·
Replies
1
Views
1K
I On-shell virtual particles and 'physical' Hilbert spaces....
  • · Replies 7 ·
Replies
7
Views
2K
I 'Real particle and virtual particle interactions' Part 2....
  • · Replies 19 ·
Replies
19
Views
3K
I Loop Quantum Gravity and Virtual Particles....
  • · Replies 5 ·
Replies
5
Views
2K
A In light of new evidence, what might be behind the Casimir Effect?
  • · Replies 46 ·
2
Replies
46
Views
5K
B New hypothesis of continuous wave function collapse
  • · Replies 5 ·
Replies
5
Views
3K
I Are virtual particles real or just math filler
  • · Replies 81 ·
3
Replies
81
Views
13K