Planck level effects of virtual particles

[DGator86]

Knowing that virtual particles appear and disappear at the Planck length, what is the effect of the annihilation on space-time where the particles used to be?

 

[PeterDonis]

Knowing that virtual particles appear and disappear at the Planck length

We don't know this. It's a reasonable speculation, but there is no evidence to support it (because the Planck length is about 20 orders of magnitude smaller than the smallest length scale we can probe experimentally).

what is the effect of the annihilation on space-time where the particles used to be?

I'm not sure what you mean by "spacetime where the particles used to be".

 

[Vanadium 50]

We don't know this. It's a reasonable speculation

I don't think it's reasonable, as virtual particles cannot be counted, and this is a counting experiment.

 

[DGator86]

I guess what I am trying to ask is if virtual particles are popping in and out of existence in any theoretical framework, what happens to the space once occupied by the matter?

Also, do these virtual particles have theoretical mass? If so, does that mass come as a ratio (1/2, 2/2, 4/2, etc.) of the two particles creating the virtual particle?

I understand that they are a result of particle interactions and can in some ways act as true particles. But shouldn't the particles, if they have mass, then therefore effect local space-time on the quantum level?

 

[Vanadium 50]

guess what I am trying to ask is if virtual particles are popping in and out of existence in any theoretical framework

They do not do this. As I said earlier, they cannot be counted.

 

[PeterDonis]

this is a counting experiment

I haven't seen the OP describe any experiment, so I'm not sure if "counting experiment" is a reasonable description of what the OP is thinking.

if virtual particles are popping in and out of existence in any theoretical framework, what happens to the space once occupied by the matter?

Your question is based on a mistaken premise. Virtual particles are not "popping in and out of existence" in the sense you mean.

do these virtual particles have theoretical mass?

This is really a meaningless question, since virtual particles are not on the mass shell, so there is no way of defining what their "mass" would even mean.

I understand that they are a result of particle interactions and can in some ways act as true particles.

Then you understand incorrectly. Where are you getting your understanding from?

 

[kurt101]

I guess what I am trying to ask is if virtual particles are popping in and out of existence in any theoretical framework, what happens to the space once occupied by the matter?

From the book "The Quantum Story: A history in 40 moments" by Jim Baggott:
"The photons created and destroyed in the virtual processes described by the Feynman diagrams carry away some of the mass of the electron but leave its charge unchanged, affecting the electron's magnetic moment."

 

[PeterDonis]

From the book "The Quantum Story: A history in 40 moments" by Jim Baggott

This is not a textbook or peer-reviewed paper, and is not a valid source.

The photons created and destroyed in the virtual processes described by the Feynman diagrams carry away some of the mass of the electron

I don't know where this author is getting this from, but it's not correct. The electron mass is renormalized, and virtual particle processes contribute to that, but this is not properly described as virtual photons "carrying away some of the mass" of the electron. The mass of the electron is what it is; having to renormalize it in the model is an issue with the model, not the actual electron.

 

[weirdoguy]

I guess what I am trying to ask is if virtual particles are popping in and out of existence in any theoretical framework

Nope:
https://www.physicsforums.com/insights/misconceptions-virtual-particles/
https://www.physicsforums.com/insights/physics-virtual-particles/

 

[Vanadium 50]

so I'm not sure if "counting experiment" is a reasonable description of what the OP is thinking.

"Appearing and disappearing" is a counting experiment. When something appears, you count it and get 1. When it disappears, you count it and get 0.

 

[kurt101]

I don't know where this author is getting this from, but it's not correct. The electron mass is renormalized, and virtual particle processes contribute to that, but this is not properly described as virtual photons "carrying away some of the mass" of the electron. The mass of the electron is what it is; having to renormalize it in the model is an issue with the model, not the actual electron.

What about the lamb shift? According to the following Wikipedia article the difference of energies levels that are measured between two energy levels 2S1/2 and 2P1/2 of the hydrogen atom are not accounted for by the Dirac equation and the virtual particle contributions in the path integral approach are needed to account for it. I realize it is still just a model, but the model is describing reality very well. And reality seems to indicate there actually is fluctuations in energy, because of the virtual particle contribution. You say the author is wrong to say mass (energy) is being carried away, but how else would you describe it?
https://en.wikipedia.org/wiki/Lamb_shift

 

[weirdoguy]

Please read the links I gave. Besides, wikipedia is not generally accepted source here...

 

[PeterDonis]

reality seems to indicate there actually is fluctuations in energy

No, reality says that two different state transitions, which in the bare Dirac model have the same energy, actually have different energies. Including the Lamb "shift" in our model makes it more accurate. But each of the transition energies, taken by itself, is exact; they don't "fluctuate" or "shift". The only change is in our model, not in reality.

And even looking at the difference in energy between the two state transitions, it still has nothing whatever to do with any mass of the electron being "carried off" by virtual photons.

 

[George Jones]

... virtual particle contributions ...

From Folland's quantum field theory book:

"The correspondence between the integrals that make up the Dyson series and Feynman diagrams is perfectly precise and well-defined. However, it is customary to go further and think of the Feynman diagrams as schematic pictures of physical processes, and here the interpretation acquires a more imaginative character. ... They are, in short, the infamous virtual particles that are so ubiquitous in physicists' discourse. In the final analysis, the only existence they possesses for certain is as picturesque ways of thinking about the ingredients of the integrals in the Dyson series."

 

[mattt]

From the book "The Quantum Story: A history in 40 moments" by Jim Baggott:
"The photons created and destroyed in the virtual processes described by the Feynman diagrams carry away some of the mass of the electron but leave its charge unchanged, affecting the electron's magnetic moment."

Every time you see a set of precise mathematical statements "transmuted" into an English sentence of that kind...just run!

Seriously, Arnold Neumaier took the pains to write an extremely precise and detailed account of these matters about two years ago (in the form of an Insight article), so please, take a look at them.

 

[bhobba]

What about the lamb shift?

Feynman was too successful - people think, even some professionals, virtual particles exist. His good friend, Dyson, sorted it out - they are simply the pictorial representation of a Dyson series:
https://en.wikipedia.org/wiki/Dyson_series

They do not really exist. It's one of the many misconceptions we have to often deal with here:
https://arxiv.org/abs/quant-ph/0609163

This is a B level thread - we do not of course expect you to know this advanced material, simply be aware what you read in popularization's, beginner texts etc is sometimes/even on occasion often - not correct - especially in Quantum Field Theory. Also strictly speaking they are not valid references here which are well respected textbooks and peer reviewed papers, but of course we are all willing to help a beginner with what is really going on so it's OK to mention in passing that's where you got it from and then we explain what's really happening.

The Lamb Shift can be explained without Virtual Particles - Bethe essentially explained it in a back of the envelope calculation he did while on the train returning from the conference where Lamb presented his results:
https://www.ias.ac.in/article/fulltext/reso/010/10/0033-0048

But Schwinger and Feynman decided to try for a more general framework to explain it - Feynman with Bethe as his Mentor - they were at Cornell together - and Dyson was there as well. Feynman came up with a pictorial way to view it, but its physical basis left something to be desired. However it was computationally very efficient in calculating such results. Schwinger went down a different path that was computationally quite hard - but still got the correct answer. Dyson showed they were the same - but since Feynman's methods were more efficient his ideas won out. They included imagery like virtual particles and positrons as electrons traveling backwards in time. It all helped with the calculations - but as Dyson proved their existence in any kind of usual sense was mistaken - they are simply mathematical 'tricks' to make calculation easier.

Interesting story. Dyson never got a PhD - he actually can't be called doctor. There is something higher than a PhD called a DSc - Doctor of Science that also entitles it's holder to be called Doctor. To get one you present your papers to a committee and if they think they are of the caliber to get the degree then you get it. Dyson made many important contributions to physics so it would be a mere formality for him to get one. But you know what - he never bothered - if fact he doesn't even like the whole system:
http://blogs.sciencemag.org/pipeline/archives/2014/04/01/freeman_dyson_on_the_phd_degree

While Dyson was presenting his results showing the equivalence of the two methods Feynman was in the audience down the back cracking jokes and leaving everyone in stitches. He of course knew of Dysons work so had no need to hear the lecture. At the end he said - your in Doc - a reference to the fact he did not have a PhD, but after work of that caliber it was just a formality. Its likely, secretly, Feynman would have liked to not bother with a PhD either - he would have liked to have said, in his Brooklyn accent (strange since he was borne in Far Rockaway - not Brooklyn - just more of Feynman's mystique), hey buddy - even I know that and I don't have a PhD. On his death bed Heisenberg was asked about physicists he knew. When asked about Feynman he said - Feynman, oh that Feynman - he talks like a gangster. When told of it Feynman laughed his head off.

Thanks
Bill

 

[diPoleMoment]

I haven't seen the OP describe any experiment, so I'm not sure if "counting experiment" is a reasonable description of what the OP is thinking.
Your question is based on a mistaken premise. Virtual particles are not "popping in and out of existence" in the sense you mean.
This is really a meaningless question, since virtual particles are not on the mass shell, so there is no way of defining what their "mass" would even mean.
Then you understand incorrectly. Where are you getting your understanding from?

So I was wondering, if virtual particles are just not seen. Could that be from time not reduced to a small enough division? Don't know theory, but I have had experience with coding. A search algorithm showed as happening in 0 time until it was given smaller time increments. Know this is not that similar, but I was wondering if it is possible.

Also if quantum particles exist, could the void particle be the distancing of component particles and coalescing of component particles?

 

[Nugatory]

So I was wondering, if virtual particles are just not seen. Could that be from time not reduced to a small enough division...

No.
Neither photons nor virtual particles are what you're thinking they are, so these and your subsequent questions make no sense. Please review the links in post #9 of this thread by @weirdoguy post #9 and some of our other threads about virtual particles and what photons are.