- #1
Tio Barnabe
Is it true that when we dig deep into the math, we realize that Quantum Fluctuations and virtual particles are just a heuristic way of explaining certain phenomena to lay public?
Tio Barnabe said:Is it true that when we dig deep into the math, we realize that Quantum Fluctuations and virtual particles are just a heuristic way of explaining certain phenomena to lay public?
We may need clarity from this, with a definition. A virtual particle, is a fluctuation of the vacuum.Demystifier said:Quantum fluctuations are fundamental and real. Virtual particles are not.
PhysicsExplorer said:A quantum vacuum is different to a Newtonian vacuum. A quantum vacuum, actually never reaches zero Kelvin, no matter how much energy you pump into the system to try and create a perfect vacuum.
PhysicsExplorer said:He said, ''through Bogoliubov transformations...'' and continued to say, ''I can link you to Hawking paper, he never once mentions virtual particles.''
I replied, ''that's nice. But if that is the case, why do these transformations have creation and annihilation operators?''
Demystifier said:Quantum fluctuations are fundamental and real. Virtual particles are not.
LeandroMdO said:If you construct a field theory at finite temperature via any of the usual formalisms (Matsubara imaginary time formalism, Schwinger-Keldysh, TFD, et al.) temperature is a tunable parameter that can take any positive value. Of course the third law of thermodynamics prevents a physical system from reaching absolute zero in a finite number of steps just as it does in nonrelativistic physics, but nothing stops you from writing down a quantum field theory at zero temperature.
PhysicsExplorer said:But what is the point other than an approximation? The physical interpretation of systems never ceasing to have an intrinsic temperature is very important - sure, most of the vacuum sits on the precipice of zero kelvin, but so what?
Chemists tend to think about systems at zero point, doesn't make it right.
Not normally no, I grant you that. Though... it is an interpretation of the physics which seems to hold water? I mean, it should have been enough that quantum physics predicted Casimir energy, and in finding it, but clearly, this was not the case, not everyone was convinced. Personally, a whole array of quantum subjects do not make sense to me, without fluctuations.LeandroMdO said:I don't think that what people typically mean when they talk about "quantum fluctuations" is about the impossibility of reaching the absolute zero in practice. The words that would be used in such a circumstance are "thermal fluctuations" (another term I usually avoid, for the same reasons). The term seems to refer to some property that is present at any temperature, zero or no.
PhysicsExplorer said:They do actually exist.
Any of the professors here?bhobba said:They do not as any of the many professors that teach QFT and post here, or an actual textbook, not pop sci hand-wavy half-truths, but actual textbooks, will tell you.
If you believe otherwise here is an actual textbook:
https://www.amazon.com/dp/019969933X/?tag=pfamazon01-20
Tell me the page where the existence of virtual particles is derived. Not as lines in a Feynman diagram - as that they of course exist. But a Feynman diagram is just a pictorial representation of a Dyson series. That's not what I mean - I mean as actual particles that pop into and out of existence like the pop-sci books say.
Thanks
Bill
PhysicsExplorer said:I mean, it should have been enough that quantum physics predicted Casimir energy, and in finding it, but clearly, this was not the case, not everyone was convinced.
atyy said:
PhysicsExplorer said:There is even mention, by some physicists we can actually measure the effects of the virtual particle, in a physical way.
bhobba said:Its called heuristics.
Thanks
Bill
PhysicsExplorer said:Here's a good example, scientific american, which testifies to the existence of the virtual particles
https://www.scientificamerican.com/article/are-virtual-particles-rea/
So yeah, while the view of the 'professors' here would be valuable, I make it clear, its not a general consensus that virtual particles are not real.
Talk about downplaying the main point of the article. The point is, that these fluctuations are real. Why are you brushing over the conclusion, like it was a deliberate attempt to smear the physics? It's really not.LeandroMdO said:The examples in that article are of quantum effects in field theory, not of virtual particles themselves.
PhysicsExplorer said:Talk about downplaying the main point of the article. The point is, that these fluctuations are real. Why are you brushing over the conclusion, like it was a deliberate attempt to smear the physics? It's really not.
PhysicsExplorer said:Any of the professors here?
PhysicsExplorer said:What about top professionals, outside the forum who make a living on the subject, who testify to their existence? I have met more scientists who appreciate their existence, than not.
PhysicsExplorer said:That says something to me.
I tried to talk about the Casimir effect as little as possible, due to the disparity of understanding. There seems to be, much more evidence than just the Casimir force. For instance, it should be theoretically possible to provide this evidence. Zero point energy seems to be the best example.LeandroMdO said:I am undoing a conflation that was done illegitimately. I am not saying it was done maliciously, but it is illegitimate.
For example, it is often useful for computations to introduce a "proper-time" parameter so that the dynamics of a field theory in four dimensions reduce to the dynamics of nonrelativistic quantum mechanics in five dimensions. This is how Schwinger derived the Euler--Heisenberg Lagrangian that gives the effective interaction between photons and an external electromagnetic field. Should I take this formal trick to mean that there are really 5 dimensions? Of course not. There are other ways to derive the Euler--Heisenberg Lagrangian, such as by writing the usual perturbative Feynman diagram expansion and carefully resumming it. I shouldn't confuse Nature with the tricks that I invented to study it.
I emphasize that the Casimir effect is not typically computed via the use of Feynman diagrams. There's no need.
You're keen for textbooks. Yes they are good, but very dry and won't always answer your questions. Yes, there really are top scientists who believe in its existence. We can start with the genius Wheeler who predicted fluctuations, called quantum foam. The idea has not died today. Yes, there are many, if not most of physicists believe in the existence of these particles.bhobba said:They do? I mean they actually say they exist 100% for sure and make no mistake about it? If so it should be in the textbooks they write.
Thanks
Bill
But it's not! I have already shown in a link, scientists still seem to believe in their existences. I doubt scientificamerican would be as stupid to get writers into make such drastic errors in lingo.bhobba said:Physicists are just normal people who will often converse in technical lingo and heuristics.
Thanks
Bill
LeandroMdO said:I am undoing a conflation that was done illegitimately. I am not saying it was done maliciously, but it is illegitimate.
PhysicsExplorer said:I tried to talk about the Casimir effect as little as possible, due to the disparity of understanding.
PhysicsExplorer said:The reason why, is as I have explained before: even if you remove all the visible matter and energy from a region of space by making say, a vacuum, there should still be energy left over. In other words, it doesn't matter if you try and make a Newtonian vacuum, its impossible due to virtual particles in system.
bhobba said:There is no need - people that have actually studied this stuff know what you mean. It is just people that may have chatted with some physicists or read pop-sci accounts or even textbooks that are not actual QFT textbooks get the wrong impression.
Thanks
Bill
LeandroMdO said:Let's put it this way. Can you come up with an experiment that can test whether this interpretation is correct?