Virtual Particles: Fact or Fiction?

[kexue]

What do you think?

I thought a poll, just for the fun of it!

 

[kexue]

Come on! 87 views and only 4 people voted? It is anonymous, in case someone worries.

So do you have an opinion?

A - concept of "virtual particle" is used in physics to organize and visualize perturbative solutions of quantum field theory, they are not "really out there"

B - they are "really out there", they interact with 'real' directly observable particles and have real observable effects, they are a part of reality

C - not a physical question, I do not bother

In which way are you leaning? Why do you don't vote?

Maybe, this poll is just on big waste of time, but so are most of things in life. So just vote, it is fun.

 

[sheaf]

I know it's only for fun, but it would be nice if we could settle questions of physics by means of a poll ! However:

I think the wording of the second option isn't clear and unambiguous:

"They are real in the sense that their contributions affect the amplitudes of particle transitions"

could be interpreted as being compatible with the first option - a "contribution" could be a contribution to a perturbation calculation of an amplitude. Perhaps it would have been better to have added "whether or not a perturbation calculation is being done" or something like that.

 

[A. Neumaier]

What do you think?
I thought a poll, just for the fun of it!

Your way of doing physics has nothing to do with science.

 

[Phrak]

Can I vote for all three with weighted values that sum to one vote?

 

[kexue]

I know it's only for fun, but it would be nice if we could settle questions of physics by means of a poll !

Well, I believe , but I'm not sure, that it is a rather a philosophical question than a physical question. More a matter of taste than a physical question.

But of course, you can take this "very little of boldness", as Wilczek puts it, and say they are part of physical reality or you can stress the things that Tom and A.Neumaier did in other threads and say they don't.

I take this "very little of boldness" as many other distinguished physicists do and say they are part of reality, knowing at the same time that it is more a philosophical question.

But I'm also fine with people saying they are not real in any sense, they are just mathematics. Or with people who say it depends on what you think is real, so I do not bother.

What I have a problem with here at PF is, that it is always claimed with absolute certainty that they are only 'mathematics' and that is clear and simple, which I think is not.

 

[Phrak]

I know it's only for fun, but it would be nice if we could settle questions of physics by means of a poll !

Nice or not, this is how questions of physics are settled--or partially settled. Nothing is ever settled. And it's never one-man-one-vote. That would be silly. If you don't publish, you have no vote. Getting published gets you votes. Getting cited by others obtains additional chits. Get the picture?

 

[nismaratwork]

Great, physics by poll... this is a great way to start on another tangent about your personal theories to do with virtual particles kex. On the bright side, you made in GD so at least this discussion has found its level.

edit:

Come on! 87 views and only 4 people voted? It is anonymous, in case someone worries.

Amazingly enough, the barrier to science isn't "admitting" publicly that you believe something unfounded and contrary to current theory, but claiming that you belief carries any weight in regards to how the universe actually functions.

Oh, I voted, "just artifacts" as I'm not concerned about persecution which requires anonymity in a poll.

 

[kexue]

Ok, because some higher force of this forum has sent this thread without any explanation to the public discussion thread, let me summarize what it's all about.

In quantum physics there is this funny business about measurement, as some of you might have heard of. Especially, what happens between measurements in the quantum world, though well described in the mathematical laws of quantum physics, is very hard to translate in our concepts of reality and imaginations which are trained by the world we see around us, which is, of course, classical.

In the physical branch called quantum field theory, that incorporates quantum mechanics and special realtivity, there are these so-called 'virtual' particles which describe what happens in these intermediate states between measurement.

By their very definition, they are not directly observable but they have many, many observable effects, since they interact with directly observable particles.

Other say they are only lanuage to visuliaze what happens in the calculations of quantum field theory. They say they are not real, only mathematical artefacts of some computations.

I asked many physicsts what they think: real or just mathematical devices? Or is it a philosophical question? I got a wide range of answers. At least, four Nobel prize winner answered very explicitly that they think they are a features of physical reality, not only mathematics. Many others thougth this is more a philosophical question, yet they are leaning towards considering them as part of reality.

Still, it is claimed repeatedly at the quantum forum of PF that it is clear and simple that they are only mathematics. That their can be no other view. That's what I have a problem with. That's why the poll.

 

[nismaratwork]

Ok, because some higher force of this forum has sent this thread without any explanation to the public discussion thread, let me summarize what it's all about.

In quantum physics there is this funny business about measurement, as some of you might have heard of. Especially, what happens between measurements in the quantum world, though well described in the mathematical laws of quantum physics, is very hard to translate in our concepts of reality and imaginations which are trained by the world we see around us, which is, of course, classical.

In the physical branch called quantum field theory, that incorporates quantum mechanics and special realtivity, there are these so-called 'virtual' particles which describe what happens in these intermediate states between measurement.

By their very definition, they are not directly observable but they have many, many observable effects, since they interact with directly observable particles.

Other say they are only lanuage to visuliaze what happens in the calculations of quantum field theory. They say they are not real, only mathematical artefacts of some computations.

I asked many physicsts what they think: real or just mathematical devices? Or is it a philosophical question? I got a wide range of answers. At least, four Nobel prize winner answered very explicitly that they think they are a features of physical reality, not only mathematics. Many others thougth this is more a philosophical question, yet they are leaning towards considering them as part of reality.

Still, it is claimed repeatedly at the quantum forum of PF that it is clear and simple that they are only mathematics. That their can be no other view. That's what I have a problem with. That's why the poll.

"Ok, because some higher force of this forum has sent this thread without any explanation to the public discussion thread, let me summarize what it's all about."

HUH?

For the rest... thanks for the update, here I was just thinking you were wanting to make your case where the most lenience and least evidence are required.

On TEENSY thing... it's not "claimed at the quantum forum of PF..." If you want to show that something utterly invented as a mathematical artifact has a physical reality, again, the burden of proof is on you. Rephrasing the debate as a poll is just sad, especially as it's that "claim" isn't something PF just came up with... it's the mainstream view. Mainstream science education being the mission of PF, again, maybe you need to be somewhere you can find more gulls, and less oversight.

 

[nismaratwork]

I asked many physicsts what they think: real or just mathematical devices? Or is it a philosophical question? I got a wide range of answers. At least, four Nobel prize winner answered very explicitly that they think they are a features of physical reality, not only mathematics. Many others thougth this is more a philosophical question, yet they are leaning towards considering them as part of reality.

Other than your claim, I'm yet to see evidence of these discussions, and if they exist I'd want to read the response to your question, not your interpretation of it. Either present your emails, or stop referring to them: they could be a pure fiction AFAIK... this is the internet after all.

I'd note that even if every word you've said is accurate, so what? Science isn't a matter of opinion polls, especially when you need the math to work a certain way. You could have polled virtually every authority in the world at times, and made the argument that the world is flat: it's called an appeal to authority, and it's a logical fallacy.

 

[peterfreed]

I'd like to add my vote of confidence in Kexue & his noble endeavor. The physicists on this forum who incessantly say "physics is physics, not metaphysics" and "we don't speculate" and "all we do is empiricism" and "just the facts, ma'am" don't know what they are talking about from a philosophical standpoint. The position that there is no metaphysics is metaphysical. Karl Popper - whose falsifiability theory of science still rules in practice if not in all theoretical quarters - also said that a statement that can neither be proven nor disproven by science, but which does not reject the findings of science, is a metaphysical position. Kexue is asking whether virtual particles "exist". The answer yes or no or "unanswerable" has no bearing on the practice of science, as everyone keeps pointing out. But - and this is what everyone seems to be missing - it also cannot be *rejected* by science. It can tag along or not, and it is not "more" scientific to reject the question than to accept it - save by occam's razor, which of course is an aesthetic principle and itself not scientific.

Finally, Kexue - for god's sake, publish a single document with all the physicists' responses to your question. They didn't sign a confidentiality agreement! They are aware they won all their prizes and people are likely to quote them! They could have kept quiet if they didn't want their views expressed. That will certainly make this whole discussion much more content-heavy.

 

[jtbell]

Can I vote for all three with weighted values that sum to one vote?

Better yet, as a quantum superposition with complex coefficients so they interfere with each other.

 

[nismaratwork]

I'd like to add my vote of confidence in Kexue & his noble endeavor. The physicists on this forum who incessantly say "physics is physics, not metaphysics" and "we don't speculate" and "all we do is empiricism" and "just the facts, ma'am" don't know what they are talking about from a philosophical standpoint. The position that there is no metaphysics is metaphysical. Karl Popper - whose falsifiability theory of science still rules in practice if not in all theoretical quarters - also said that a statement that can neither be proven nor disproven by science, but which does not reject the findings of science, is a metaphysical position. Kexue is asking whether virtual particles "exist". The answer yes or no or "unanswerable" has no bearing on the practice of science, as everyone keeps pointing out. But - and this is what everyone seems to be missing - it also cannot be *rejected* by science. It can tag along or not, and it is not "more" scientific to reject the question than to accept it - save by occam's razor, which of course is an aesthetic principle and itself not scientific.

Finally, Kexue - for god's sake, publish a single document with all the physicists' responses to your question. They didn't sign a confidentiality agreement! They are aware they won all their prizes and people are likely to quote them! They could have kept quiet if they didn't want their views expressed. That will certainly make this whole discussion much more content-heavy.

Welcome to Physics Forums; I see this is your first post since joining in November.

Unfortunately you seem have read a lot of threads without offering this critique at the time, so now you're speaking in sweeping generalizations... most of which are part of the rules of the site. You also seem to be preaching and praising... not offering any coherent argument for your position, except insofar as your position is that Kexue is essentially your... Virtual Prophet.

 

[kexue]

Finally, Kexue - for god's sake, publish a single document with all the physicists' responses to your question. They didn't sign a confidentiality agreement! They are aware they won all their prizes and people are likely to quote them! They could have kept quiet if they didn't want their views expressed. That will certainly make this whole discussion much more content-heavy.

I posted many of them in an earlier thread. I was so excited that they answered and gave it not much thought to post private emails on a public forum. Please look there if you are interested. I asked many more, but stopped posting them. As I said the answers varied between the three views, but most of them were leaning more towards the latter two views.

Here is Frank Wilczek reply, which I liked most.

It comes down to what you mean by "really there". When we use a concept with great success and precision to describe empirical observations, I'm inclined to include that concept in my inventory of reality. By that standard, virtual particles qualify. On the other hand, the very meaning of "virtual" is that they (i.e., virtual particles) don't appear *directly* in experimental apparatus. Of course, they do appear when you allow yourself a very little boldness in interpreting observations. It comes down to a matter of taste how you express the objective situation in ordinary language, since ordinary language was not designed to deal with the surprising discoveries of modern physics.

I allow myself this 'very little boldness' and say 'virtual' particles are a part of reality.

 

[Jimmy Snyder]

Warning: I don't really understand QFT and this post may display that deficiency.

A beam of electrons collides with another beam of electrons and there are sensors at various locations to detect the particles that emerge. The best way known to predict what the sensors will detect is to assume that there are virtual particles passing between colliding electrons. It seems reasonable to ask whether these virtual particles really exist. However, it is not sufficient to consider that only a few such particles come into being. Part of the calculation involves assuming that a perfect copy of the Taj Mahal is created out of virtual particles and then rapidly disappears. Then you calculate the effect this would have on the detectors and multiply it by the probability that it will actually occur. The only difference between the creation of a single virtual particle and the creation of a virtual Taj Mahal is the probability. Therefore it seems to me that if you want to call a few virtual particles real, but don't want to call the virtual Taj Mahal real, you would need to provide a probability cutoff. What probability cutoff would you use to distinguish between virtual particles that are real and those that are not?

 

[nismaratwork]

I posted many of them in an earlier thread. I was so excited that they answered and gave it not much thought to post private emails on a public forum. Please look there if you are interested. I asked many more, but stopped posting them. As I said the answers varied between the three views, but most of them were leaning more towards the latter two views.

Here is Frank Wilczek reply, which I liked most.

It comes down to what you mean by "really there". When we use a concept with great success and precision to describe empirical observations, I'm inclined to include that concept in my inventory of reality. By that standard, virtual particles qualify. On the other hand, the very meaning of "virtual" is that they (i.e., virtual particles) don't appear *directly* in experimental apparatus. Of course, they do appear when you allow yourself a very little boldness in interpreting observations. It comes down to a matter of taste how you express the objective situation in ordinary language, since ordinary language was not designed to deal with the surprising discoveries of modern physics.

I allow myself this 'very little boldness' and say 'virtual' particles are a part of reality.

You've already been asked to produce those emails, not just quote them. Have you done so?

 

[Evo]

I know this thread was dumped in GD because it's not suitable for the science forums, but I don't think it's suitable for GD either, unless it's a joke.

 

[A. Neumaier]

I know this thread was dumped in GD because it's not suitable for the science forums, but I don't think it's suitable for GD either, unless it's a joke.

It really is a joke - who does science like that? -, except that kexue, the poster of the joke, defends his thesis over various threads with hundred's of postings trying to convince others that they should think like him.

 

[kexue]

You've already been asked to produce those emails, not just quote them. Have you done so?

You are free to email Wilzcek, t'Hooft, Glashow, Anderson, Polchinsky or who else and see what they say to 'virtual' particles are only mathematical artefacts and not part of physical reality. I just copied and pasted from the email that Wilczek sent me, the others you saw in an earlier thread. So what you want?

 

[peterfreed]

Welcome to Physics Forums; I see this is your first post since joining in November.

Unfortunately you seem have read a lot of threads without offering this critique at the time, so now you're speaking in sweeping generalizations... most of which are part of the rules of the site. You also seem to be preaching and praising... not offering any coherent argument for your position, except insofar as your position is that Kexue is essentially your... Virtual Prophet.

Wait - what's the sweeping generalization. I am giving a very specific definition of metaphysics: a claim that neither refutes nor supports a scientific claim, and which can be neither supported nor refuted by a scientific (testable) hypothesis. I then claim that metaphysical claims can be neither accepted nor rejected, but can be used if the thinker finds them useful. Virtual particles may be real, may not be real, as long as they appear in the maths, people can believe whichever they like. What's sweeping about that?

 

[nismaratwork]

I know this thread was dumped in GD because it's not suitable for the science forums, but I don't think it's suitable for GD either, unless it's a joke.

It's not... Kexue is utterly serious, and as you see, still unwilling to produce evidence of something these 'emails'. As for the science of it... that's a different kind of joke entirely.

peterfreed: :rofl: Nothing I have to say to you can be said here.

 

[kexue]

I know this thread was dumped in GD because it's not suitable for the science forums, but I don't think it's suitable for GD either, unless it's a joke.

Why is it a joke?

I wrote about 30 leading scientists this question, six Nobel prize winner among them. Most liked the question, some felt that this question is touching the depths of the very concept of quantum field theories.

David Politzer, for example, told me, quote: This is precisely the kind of question you should be asking as you're learning about relativistic quantum mechanics. And in trying to find answers, you'll surely learn quite a bit of physics.


Evo, why then do you think this question is not worthy being raised?

As I said earlier that it is more a question of taste what to think of 'virtual' particles, though I'm leading towards saying they are 'real'.

A.Neumaier and others insists it is not a matter of taste, 'virtual' particles are only in the mathematics and their are no others view. I strongly disagree to that.

I want to find out what others think. That's why this thread.

 

[nismaratwork]

Why is it a joke?

I wrote about 30 leading scientists this question, six Nobel prize winner among them. Most liked the question, some felt that this question is touching the depths of the very concept of quantum field theories.

David Politzer, for example, told me, quote: This is precisely the kind of question you should be asking as you're learning about relativistic quantum mechanics.* And in
trying to find answers, you'll surely learn quite a bit of physics.


Evo, why then do you think this question is not worthy being raised?

As I said earlier that it is more a question of taste what to think of 'virtual' particles, though I'm leading towards saying they are 'real'.

A.Neumaier and others insists it is not a matter of taste, 'virtual' particles are only in the mathematics and their are no others view. I strongly disagree to that.

I want to find out what others think. That's why this thread.

Are you giving me blanket permission to PM you with EXACTLY what I think?

 

[berkeman]

Are you giving me blanket permission to PM you with EXACTLY what I think?

Nope, that's not going to happen.

Thread closed.


EDIT -- Tied with Evo!

 

[Evo]

This thread is serving no purpose.

Closed. Permanenly.