Could High Energy Virtual Particles Destroy a Starship?

[Polyrhythmic]

Wave functions are an odd example though, because their ontological status is highly in doubt anyway. Let's take something more mundane: magnetic fields. In any number of science classes, magnetic fields will be treated as real. Yet can I not argue that the iron filings line up as they do simply because of the way they interact with currents? Yes it's nice to get rid of the action-at-a-distance, but if we don't object to that, we really don't need fields to understand how particles and filings behave, I'll just replace B by the Biot-Savart law and poof, bye-bye reality of magnetic fields. Or I'll take Maxwell's equations, and write them in coordinate-free relativistic form, referring only to invariant entities that never refer directly to a "magnetic field." Does this mean all those classrooms where children are told "here is a magnetic field" are spreading misconceptions that mistake coordinate choices for statements about what is really there? Analogies are never perfect, but I see a similar character in your objections-- the concept of virtual particles is quite useful in so many places, as force-carriers, as perturbing agents that cause spontaneous decay, as descriptions of why the vacuum can be something rather than nothing. I'm sure all the points you are making are very true, and anyone who would use the virtual particle concept should be forewarned of them all, but does it really add up to saying that virtual particles are not even virtually real? That might depend on the "classroom" involved, just like with magnetic fields.

The magnetic field is a mathematically and experimentally well established physical entity. Even if you argue it away like you did, the mechanism definitely is there, in one way or another. That is not the same with virtual particles: their existence is of no significance, they don't represent any physical mechanism. The only thing they represent is, as has been said thousands of times, a mathematical trick.

No analogies are perfect, but that one might be a little less perfect than most!

Think about it, it really hits the core of the problem.

 

[Polyrhythmic]

Yes, "virtual" is probably a poor name for what virtual particles are. There are only two differences between real particles and what a virtual particle is in particle physics. A virtual particle is the same as a real particle except that it is off mass shell and therefore not detectable. Because once you have detected it it becomes a real particle. Alll other properties are the same. I would like to see anyone convince Gordon Kane or Dr. Andy Inopin, a respected hadronic particle physicist, that virtual particles don't really exist.

Well, it's not detectable by definition, that makes it quite unscientific to consider them real. I agree that the virtual particle concept is a nice one, and if it had any truth to it, would give particle physics a more convenient look. But as a physicist (or somebody studying to be one eventually), I have to refuse such an unscientific view. The only thing that is ever measured are particles on mass shell. The consequence is that we can only assume on-shell particles to exist.
If you refer to authority, you should also give some source for your statements. I'd rather hear anything said regarding such issues from those people themselfes, since apparently there is much that can be misunderstood.

 

[Polyrhythmic]

You certainly have a point that the OP took the "virtual particle" concept and ran out of bounds with it. But I'm not sure we have a principle of physics that says "reject all ontrological placeholders that tend to get used incorrectly." A classic example of this is inertial forces. Almost all new students are taught to shun the centrifugal force, because it leads to so much confusion. But eventually, they learn to use the centrifugal force as a potent friend. And the coriolis force is accepted from the outset with open arms, you can't swing a Foucault pendulum without seeing the term appear, it is so difficult to do without. This "convenience of handling" is quite typically elevated to the status of an ontological placeholder-- how many times will we see words to the effect of "Foucault pendulum motion is caused by the coriolis force", or "hurricanes are caused by the coriolis force." It is more careful to call it the "coriolis effect", to avoid the ontological headache, but all the same, I'd say most meteorologists are pretty content to imagine that there really is such a thing as a coriolis force that bends air streams, simply because the calculations are a pain to express in inertial frames.

I agree that "loose usage" of any of these terms is to be avoided, but I think the objections in this thread were more of the flavor "don't use the concept at all, unless you are clear that there is actually no such thing as virtual particles." I'd say that's pretty much what is intended in the word "virtual," in analogy with the word "fictitious" as applied to the coriolis force. Yet all the same, in situations of extreme convenience, these ontological placeholders do have a value, and the purist might well argue that every ontological notion in physics is merely a convenient placeholder for some underlying truth we do not know. I don't have any objection to the way you are putting it here, I just don't think that's how it has been put above. When we encounter a troublesome concept, we just explain it better, we say what the "virtual" is intended to mean-- we don't say "it's nonsense." Isn't the coriolis force just as much nonsense?

The Coriolis effect is something that has measurable consequences, whether it is a force or not. Again, this is not true for virtual particles. They have no consequence, an interpretation as real particles is just nonsensical.

 

[FrediFizzx]

Well, it's not detectable by definition, that makes it quite unscientific to consider them real. I agree that the virtual particle concept is a nice one, and if it had any truth to it, would give particle physics a more convenient look. But as a physicist (or somebody studying to be one eventually), I have to refuse such an unscientific view. The only thing that is ever measured are particles on mass shell. The consequence is that we can only assume on-shell particles to exist.
If you refer to authority, you should also give some source for your statements. I'd rather hear anything said regarding such issues from those people themselfes, since apparently there is much that can be misunderstood.

For Gordon Kane,
http://www.scientificamerican.com/article.cfm?id=are-virtual-particles-rea

Dr. Inopin was my particle physics instructor; that source was by private email but trust me... he definitely agrees with Kane.
http://inspirebeta.net/search?p=author:A.E.Inopin.1+

As you can see from what Kane says, even though virtual particles are not directly detectable, they are indirectly detectable. Besides, muon decay cannot be properly explained without a *real* "off mass shell" W boson involved. No one here has yet shown that muon decay can be explained any other way. I rest my case.

Fred

 

[Vanadium 50]

Sneers and scorn? I don't see that. There is some frustration.

How would you feel if every time you mentioned The Luncheon On The Grass by Manet, someone would pipe in "no - that was by Claude Monet"? After explaining, no, there are two different paintings, and you're talking about the one by Manet, they come back with "but I read that it was by Monet in a book!". After explaining again, you get into a a long argument (possibly involving whether or not there is a nude woman in the painting) where he eventually gets as far "it doesn't really matter. After all, they were both Frenchmen."

And, if through some miracle, you're just about to get through to him, someone else then chimes in "No, no - you're wrong! Manet didn't paint Dejuner - it was Monet!"

What would you do then?

 

[chaszz]

Sneers and scorn? I don't see that. There is some frustration.

How would you feel if every time you mentioned The Luncheon On The Grass by Manet, someone would pipe in "no - that was by Claude Monet"? After explaining, no, there are two different paintings, and you're talking about the one by Manet, they come back with "but I read that it was by Monet in a book!". After explaining again, you get into a a long argument (possibly involving whether or not there is a nude woman in the painting) where he eventually gets as far "it doesn't really matter. After all, they were both Frenchmen."

And, if through some miracle, you're just about to get through to him, someone else then chimes in "No, no - you're wrong! Manet didn't paint Dejuner - it was Monet!"

What would you do then?

I understand what you mean in your analogy, but in itself it misses the point. I think what's mostly being debated on these forums is the meat and meaning of theories, models, reality, what the mathematics means or doesn't mean, not the issues of who created the theories. Your analogy would hit the mark if someone were to say "Maxwell didn't write those equations, it was Planck." But I understand what you mean.

Perhaps the problem here is that both experts and amateurs are mingling on the same board. I have to admit selfishly that as an amateur (not in the sense of any accomplishment at all, but in the original meaning of the word, a lover) I learn a lot here and do not want to leave. Without mathematical ability beyond algebra and geometry, I have spent my life fascinated by physics, cosmology, and especially quantum mechanics and relativity and have tried to soak up as much as I can through popularizations by scientists and science writers. I try to keep the sci-fi separated out and even think I am a lot more skeptical than, for example, many professional string theorists, who seem to me to really be into fiction. These forums are invaluable to someone like me who can actually approach someone with some real knowledge with a question or two. And I form a part of a public needed to support science (for example, in addition to willingly paying my taxes part of which support science, I complain to my senators about the lack of funding for fusion development and other science and technology). Perhaps the experts here would really rather the amateurs left. In the Relativity forum, I opened a topic on what really gets compressed near light speed, the atoms or not, and encountered a good deal of condescension from the experts and/or self-supposed experts, about the nature of the difference between relativity and actual physical reality, etc. etc., until today someone cited a result at Brookhaven that showed that atoms actually do get flattened at relativistic speeds in a collider, a least as perceived from our reference frame. So was I showing bad form to start the topic, as a number of the condescenders hinted broadly?

No conclusions, just some thoughts...

(And by the way, I can't resist taking the coincidental opportunity to recommend "Concert Champetre" (by Giorgione or Titian, or both, no one really knows) which was the inspiration for Manet's "Luncheon" and IMO is one of the two or three greatest paintings in Western art because of its structure.)

 

[Ken G]

The magnetic field is a mathematically and experimentally well established physical entity. Even if you argue it away like you did, the mechanism definitely is there, in one way or another. That is not the same with virtual particles: their existence is of no significance, they don't represent any physical mechanism. The only thing they represent is, as has been said thousands of times, a mathematical trick.

What is the difference between a mathematical trick and a mechanism? Is the principle of least action a mathematical trick or a mechanism? I can't see the distinction you are making as being so clear cut.

 

[Mordred]

Correct me if I'm wrong here but all mathematics and indeed all of physics is merely a definition of the observed and observed effects. Its accuracy is merely its ability to predict or define those two aspects. However that does not make it real. One poster here on this discussion argued that because you cannot describe something by any other means, therefore it must exist is forgetting that mathematics is merely a description. If someone were to develop another mathematical model that could explain that effect with the same degree of accuracy then both theories are correct.
After all it could be equally argued that there is no particles, That what we define as particles are merely a condensed energy state with specific properties.
or another analogy we could descibe human life as a cooperative collection of living cells that coexist and govern each other according to the dictates of our DNA sequence and our ability to think as merely an effect of that cooperation to maintain the society of the whole structure.
Whether the virtual particle is merely a trick to explain an observed effect is a mute point as 1+1=2 can easily be described as a trick/mecanism to understand quantity. So quite frankly does it really matter? Its all just a representation of what we observe. The standard model has two particles that have never been found or observed, they are merely mathetical explanations of effects and until a better and more accurate description comes into play they will probably stay in the standard model. The higgs boson and the gravition.
Quite frankly if they help accurately predict what we observe then its valid science\math.

 

[Ken G]

The graviton is a good example (the Higgs is pretty much in its own class, and might be better to talk about in another couple years!). Is that a real particle, at this point in our physics understanding? As I understand it, the only "real" graviton would be a quantum of a gravity wave, and although we have ample reason to think gravity waves exist, we certainly have never detected one, let alone found it to be quantized. So most of the time when people talk about "gravitons" they are talking about the particles that mediate the gravitational force, but that's a virtual particle. And what about gluons, the virtual particles that mediate the strong force? Do we ever detect "real" gluons? Is the gluon a "real" particle or not, and isn't it part of the standard model?

 

[Polyrhythmic]

For Gordon Kane,
http://www.scientificamerican.com/article.cfm?id=are-virtual-particles-rea

Dr. Inopin was my particle physics instructor; that source was by private email but trust me... he definitely agrees with Kane.
http://inspirebeta.net/search?p=author:A.E.Inopin.1+

Even people who should know better can be mistaken about some things. There is no evidence that virtual particles are real in any way, that's an empirical fact.

As you can see from what Kane says, even though virtual particles are not directly detectable, they are indirectly detectable. Besides, muon decay cannot be properly explained without a *real* "off mass shell" W boson involved. No one here has yet shown that muon decay can be explained any other way. I rest my case.

What do you mean by explained? Muon decay rates can be calculated without the need to invoke the reality of any virtual particles. It's a standard textbook exercise, see for example "Quantum Field Theory" by Srednicki.

 

[Polyrhythmic]

What is the difference between a mathematical trick and a mechanism? Is the principle of least action a mathematical trick or a mechanism? I can't see the distinction you are making as being so clear cut.

Well, the magnetic field actually represents something physical. Even if you doubt its reality, it actually leads to physical results which agree with experiment. That is, as I have said, not the case for virtual particles. They have no significance beyond the visualization of a mathematical quantity, rethink my monkey/banana analogy.

 

[Polyrhythmic]

Do we ever detect "real" gluons?

Yes, we do.

 

[Ken G]

Well, the magnetic field actually represents something physical. Even if you doubt its reality, it actually leads to physical results which agree with experiment. That is, as I have said, not the case for virtual particles. They have no significance beyond the visualization of a mathematical quantity, rethink my monkey/banana analogy.

I certainly doubt the reality of magnetic fields, but I tend toward empirical thinking. I would say that B is a letter that appears in a calculation, which we whimsically associate with a make-believe entity we call a "magnetic field" because we think in terms of mechanistic analogies and we don't like action at a distance, even with a propagation delay. How does that actually represent something physical when other concepts are just mathematical tricks? No, I don't see that as a real distinction, though I will agree that there are "levels of abstraction" that we can meaningfully talk about, and something that is "virtually real but not actually real" is pretty far down on the "degree of abstraction" scale.

 

[Ken G]

Yes, we do.

Can you describe for me an experiment that detects a real gluon? That would make the discussion more concrete. Also, what is a quantized description of the interaction between two stationary charges that admits to no reasonable interpretation involving virtual photons?

 

[Polyrhythmic]

Can you describe for me an experiment that detects a real gluon? That would make the discussion more concrete.

Well, I'm I must admit that my knowledge on experimental physics is limited, but I think that the first experimental evidence of gluons was discovered through so-called three-jet events: http://en.wikipedia.org/wiki/Three_jet_event

Also, what is a quantized description of the interaction between two stationary charges that admits to no reasonable interpretation involving virtual photons?

Well, quantum field theory describes interaction in terms of scattering matrix elements which can be calculated by means of a path integral that depends on the action, which again contains the coupling of the theory. I'm not quite sure what kind of description you are looking for?

 

[Ken G]

OK, the triple jets are well described by gluons that ferry energy around, but it doesn't seem like the gluons end up as gluons, so their "reality" is not quite as clear as if we ever actually "detect a gluon." In the scale of "levels of abstraction", it's not obvious where the gluon resides, but they do seem to carry real energy so in principle they should be detectable directly during one of those interactions. I'm wondering if that's ever been done.

As for the interaction between charged particles, I'm not talking about a scattering calculation. This is the point I made originally-- a scattering calculation is set up to talk about an incoming and an outgoing state, where what happens in between is something of a black box. Of course virtual particles don't show up directly in a setup like that, they aren't allowed to exist in either the incoming or outgoing states. That's why I asked for a description of two stationary charges that are experiencing a force, framed classically. Framed quantum mechanically, I'm asking for a description of "what happens next" to the charges-- on timescales during which virtual particles can still survive (in the limited sense that they ever survive, and within the picture that they do anything in the first place). It seems to me that it is on these timescales where virtual particles would reveal their "true claim to reality", where we must recognize that the very concept of "what is real" on such short times becomes rather nebulous-- which is very much the point.

 

[FrediFizzx]

Even people who should know better can be mistaken about some things. There is no evidence that virtual particles are real in any way, that's an empirical fact.

What do you mean by explained? Muon decay rates can be calculated without the need to invoke the reality of any virtual particles. It's a standard textbook exercise, see for example "Quantum Field Theory" by Srednicki.

Did you even read the article by Kane? There is *empirical* evidence that virtual particles are real. I think I will take what Gordon Kane has to say over you. Sorry.

How does a muon decay to a muon neutrino, electron and electron anti-neutrino without the involvement of a real "off mass shell" W boson? Does the muon decay directly to those three outgoing particles? I don't think that is hardly possible.

I don't have that reference you quote; perhaps you could point it out in one of the following that I do have since I can't find an example that doesn't use a real "off mass shell" W boson. Or perhaps you could quote something from your reference that would indicate what you are describing?

"Quantum Theory of Fields" all three volumes - Weinberg
"Quantum Field Theory in a Nutshell" - Zee
"Leptons and Quarks" - Halzen & Martin
"Modern Elementary Particle Physics" - Kane
"Into. to Elementary Particles" - Griffiths

Fred

 

[Vanadium 50]

It's very difficult to have a discussion about virtual particles. There are 100x as many people whose understanding of virtual particles comes only from popularizations as those who have actually studied them. Unfortunately, when someone from the second group says something in conflict with the popularizations, people from the first group inevitably jump all over them telling them they are wrong.

And once again the people who haven't studied QFT in detail have managed to overwhelm those who have by sheer force of numbers. Heck of a way to win a scientific argument.

 

[FrediFizzx]

Standard Model description of muon^- decay; muon^- decays to a muon neutrino and a real "off mass shell" W^- boson. The W boson then decays to an electron and an electron anti-neutrino. Of course it is difficult to have discussion about that since there is no other way to describe the decay than by a virtual W boson.

I can repeat myself also. Yes, "virtual" is probably a poor name for what virtual particles are. There are only two differences between real particles and what a virtual particle is in particle physics. A virtual particle is the same as a real particle except that it is *off mass shell* and therefore not detectable. Because once you have detected it it becomes a real particle. *All other properties are the same.*

 

[Ken G]

And once again the people who haven't studied QFT in detail have managed to overwhelm those who have by sheer force of numbers. Heck of a way to win a scientific argument.

It isn't a democracy, no one thinks numbers of people means anything. All I would personally like to know is whether there is a way to understand electrostatic interaction (not scattering) at the quantum level without the virtual photon concept being useful. If the claim is made they are not, that calls for some justification, and that is how scientific argumentation should go.

 

[Lapidus]

It isn't a democracy, no one thinks numbers of people means anything. All I would personally like to know is whether there is a way to understand electrostatic interaction (not scattering) at the quantum level without the virtual photon concept being useful. If the claim is made they are not, that calls for some justification, and that is how scientific argumentation should go.

Ken G, I was curious about that, too! How can electrostatic interaction at the quantum level be explained without the virtual photon concept?

I asked that many, many times here at this forum before, but sadly never got an answer to this.

 

[dm4b]

It isn't a democracy, no one thinks numbers of people means anything. All I would personally like to know is whether there is a way to understand electrostatic interaction (not scattering) at the quantum level without the virtual photon concept being useful. If the claim is made they are not, that calls for some justification, and that is how scientific argumentation should go.

KenG,

Just want to say you have made some good points in your posts here. The same points I have been trying to make for some time, but you did so rather eloquently.

Your post above is something I have been asking for some time. All you get in return is abstract mathematics (which I have studied some). This is not a physical description. I think you are probably right that there may not be a better physical description for a "force" than the virtual particle depiction, at this point in time anyhow. If there is one, I would love to hear it too.

 

[jtbell]

All I would personally like to know is whether there is a way to understand electrostatic interaction (not scattering) at the quantum level without the virtual photon concept being useful.

Ken G (and others): See tom.stoer's posts in this thread:

https://www.physicsforums.com/showthread.php?t=445730

where he refers to a paper that he further describes here:

https://www.physicsforums.com/showthread.php?p=3017397#post3017397

with some further comments in this post:

https://www.physicsforums.com/showthread.php?p=3020424#post3020424

 

[Lapidus]

Ken G (and others): See tom.stoer's posts in this thread:

https://www.physicsforums.com/showthread.php?t=445730

where he refers to a paper that he further describes here:

https://www.physicsforums.com/showthread.php?p=3017397#post3017397

with some further comments in this post:

https://www.physicsforums.com/showthread.php?p=3020424#post3020424

Sorry, but I can't follow it. Maybe Tom Stoer could exlain it a bit further...

Jtbell, in the meantime, we ask for a quantum physical explanation of static fields between two charges without virtual exchanges between the charges. Do you have one? It's been said everything that 'virtual' particles explain, can be explained some other way. Then I liked to have answered:

1. Two electron heading at each other, then they repel. The have changed both direction, thus momentum. But energy for both is still the same. What transmitted that momentum change?

2. How do we explain attractive forces?

3. And last but not least, what are all these particle experimenters in CERN doing?

They are searching for particles, very heavy particles, particles they believe exist 'virtually' and if they supply enough energy they will make them become real, i.e. directly measurable. At least, that is the standard story, which every particle physics book and QFT book tells us. No dumbed down popularizations, but the way how the majority of working high energy physicists thinks.

'Virtual' particles have nothing to do with some calculation scheme, it is only time-energy uncertainty and Einstein relation together combined from which they follow, which makes them necessary to exist. They physically explain how in a local quantum relativistic theory interactions are transmitted.

And that's all.

 

[Polyrhythmic]

You should also read this:

http://arnold-neumaier.at/physfaq/topics/virtual3

 

[dm4b]

You should also read this:

http://arnold-neumaier.at/physfaq/topics/virtual3

In his other virtual particle FAQ (http://arnold-neumaier.at/physfaq/topics/virtual) I found this interesting:

-----

" ... it allows one in the simplest (H-like) exchange
diagram between two real particles to relate the possible momenta
of the virtual particle to the measurable ingoing and outgoing momenta.
If the ingoing momenta are p and p' then the outgoing momenta are
p+q and p'-q, where q is the momentum exchanged, i..e, the momentum
transported by the virtual particle. In particular, one can determine
q from measurements.

That's all; this makes up virtual particles and their alleged influence
on real (observable) particles. Everything else is superstition."

-----

How can something that "carries" an experimentally determined momentum not be physically real? In addition, once you allow the virtual particles enough of an existence to do even that, it sort of let's the cat out of the bag, so to speak, and all the "superstitions" come along for the ride, whether we like it or not.

So, as related to the above questions asked by multiple people, how can one describe the above particle interaction w/o the use of virtual particles? What is the "mechanism" behind the force between the two particles? How is the momentum exchanged?

 

[Polyrhythmic]

How can something that "carries" an experimentally determined momentum not be physically real? In addition, once you allow the virtual particles enough of an existence to do even that, it sort of let's the cat out of the bag, so to speak, and all the "superstitions" come along for the ride, whether we like it or not.

If you read the other paragraphs as well, you will see that he doesn't want to say that this is actually happening.

So, as related to the above questions asked by multiple people, how can one describe the above particle interaction w/o the use of virtual particles? What is the "mechanism" behind the force between the two particles? How is the momentum exchanged?

Well, the best description is in the reference to tom.stoer's post. Simply speaking, quantum field theory doesn't change the fact that there is still an electrostatic potential that the field excitations (particles) react to. In this sense, they still feel the presence of an electromagnetic field, which they react to.

 

[dm4b]

If you read the other paragraphs as well, you will see that he doesn't want to say that this is actually happening.

I did read the rest. Whether he wanted to say it, or not, virtual particles are the only, as KenG put it, "useful" way to describe this process, as I believe Numier is saying. But, if at the same time, you ascribe any "reality" to them for that purpose, what I am saying is all the "superstitions" he notes come along for the ride.

As far as I know, there are no other "useful" ways to describe the momentum exchange that takes place. Would love to hear one, though.

Well, the best description is in the reference to tom.stoer's post. Simply speaking, quantum field theory doesn't change the fact that there is still an electrostatic potential that the field excitations (particles) react to. In this sense, they still feel the presence of an electromagnetic field, which they react to.

Yeah, of course they feel a presence. How? How is that "presence" transmitted to the particle? What is the clear-cut physical mechanism? Why do they react?

 

[Polyrhythmic]

I did read the rest. Whether he wanted to say it, or not, virtual particles are the only, as KenG put it, "useful" way to describe this process, as I believe Numier is saying. But, if at the same time, you ascribe any "reality" to them for that purpose, what I am saying is all the "superstitions" he notes come along for the ride.

Then you clearly don't understand it. It has been explained over and over in clear english language in this thread as well.

Yeah, of course they feel a presence. How? How is that "presence" transmitted to the particle? What is the clear-cut physical mechanism? Why do they react?

Well, that question is trickier, but it applies to field theory in general: why does a particle react to the presence of a field? I think it goes more into philosophy than science. Quantum field theory does not provide an answer to this question, it just does what a physical theory is supposed to do: it provides a theoretical framework within which experimental results can be predicted. Virtual particles are certainly not the answer to this question, for the many reasons that have already been discussed.

 

[dm4b]

Really, when you think about it even the virtual particle description is not a very "useful" description, or heruistic, for describing and explaining how forces work. It also seems rather magical. In addition, when you realize the perturbation series is an infinite serires and therefore any process involves an infinite number of virtual paritcles, it gets even more magical.

I personally think all this shows we still have a lot to learn, regardless of how much we think we know.

Lots of folks feel that all the divergences and infinities within QFT indicate an underlying problem with the theory. I can't help but wonder if somehow that was fixed, would we get a new view of how forces "work", which does not include virtual particles.

 

[dm4b]

Then you clearly don't understand it. It has been explained over and over in clear english language in this thread as well.

I'm sorry, what has? I don't think YOU understood what I said. Either that, you are reading too much into it.

Quantum field theory does not provide an answer to this question.

BINGO!

 

[Polyrhythmic]

Really, when you think about it even the virtual particle description is not a very "useful" description, or heruistic, for describing and explianing how forces work. It also seems rather magical. In addition, when you realize the perturbation series is an infinite serires and therefore any process involves an infinite number of virtual paritcles, it gets even more magical.

I personally think all this shows we still have a lot to learn, regardless of how much we think we know.

Lots of folks feel that all the divergences and infinities within QFT indicate an underlying problem with the theory. I can't help but wonder if somehow that was fixed, would we get a new view of how forces "work", which does not include virtual particles.

I agree. Even though perturbative quantum field theory has proven to be extremely successful, the lack of a proper non-perturbative theory is kind of unsatisfying.

 

[dm4b]

it just does what a physical theory is supposed to do: it provides a theoretical framework within which experimental results can be predicted.

When did our physical theories stop having the requirement of actually describing physical processes, and just become a calculational tool.

And, more importantly, why?

 

[Polyrhythmic]

I'm sorry, what has? I don't think YOU understood what I said. Either that, you are reading too much into it.

Sorry, maybe I was misinterpreting you! I thought that you interpreted the text in such a way that virtual particles actually were physical objects, sorry!

BINGO!

Then why are so many people here claiming that virtual particles are the answer?

 

[Polyrhythmic]

When did our physical theories stop having the requirement of actually describing physical processes, and just become a calculational tool.

And, more importantly, why?

I never said that they did. My point is that a physical theory can only answer "why"-questions to a certain degree. At some point, you have to assume fundamental entities within such a theory. In our case the fundamental aspect would be the influence of fields on charges. One could always ask further "why"-questions which the theory can't answer.