Insights Misconceptions about Virtual Particles - Comments

  • #251
RockyMarciano said:
to give them some ontological meaning
requires to be able to assign to them a state, since only that gives the conceptual basis for assigning probabilities to events in space and time. It is impossible to assign states to virtual particles (internal lines), while states are always assigned to real particles (external lines).
This is the physics. It has nothing to do with physical intuition or subjective or context-dependent side issues that you try to bring to bear on the problem.
 
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  • #252
A. Neumaier said:
requires to be able to assign to them a state, since only that gives the conceptual basis for assigning probabilities to events in space and time. It is impossible to assign states to virtual particles (internal lines), while states are always assigned to real particles (external lines).
You are again relying on the superficial appearance of a graphic diagram. The key here is that to obtain any kind of precise prediction of what is to be measured, and that is what we do with those diagrams in physics, you are using renormalization that allows you to keep assigning probabilities to the different interactions and this uses the math as much of what is represented as internal lines(the perturbation in the perturbative process), as the math that represents the external lines(the perturbed part). You shouldn't go back to the states assigning of nrqm because as you said in a previous state you no longer have a Fock space as in the free theory. So the events in spacetime are mathematically relegated to fixed-points describing the interaction at some order.
It has nothing to do with physical intuition or subjective or context-dependent side issues that you try to bring to bear on the problem.
Certainly, when you are ready to let go of a false virtual/real dilemma.
 
  • #253
A. Neumaier said:
After the collision products separated well enough, the semiclassical description becomes feasible again, and one can talk again about particles traveling along beams.
What is "well enough"? That is exactly the arbitrary cutoff discussed.

Also, "can" is exactly the right word: We can use the description. We don't have to.
 
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  • #254
mfb said:
What is "well enough"? That is exactly the arbitrary cutoff discussed.
It depends on the accuracy with which you want to rely on the semiclassical description.

Mathematically speaking, it means close enough to infinity, so that the error in working with the S-matrix is less than the error in the semiclassical approximation. In a reaction rate calculation, the intermediate states can be treated as real when the total reaction rate factors to the intended accuracy into an integral over the product of the reaction rates for the partial processes to and from the intermediate states. Sometimes one can make both calculations and then sees whether or not the intermediate particles can be treated as real.

But there remain always these qualitative and somewhat ambiguous statements when it comes to deciding when to use which approximation. That's why we have these terms in the language to express fuzzy concepts.
 
  • #255
Well, that was my point earlier, and I think also what Collin and nikkkom mentioned. There is no sharp line between things we call virtual particles and things we call real particles.
Technically you can treat a muon produced in cosmic rays or a proton produced in an LHC collision as virtual particle (which means: not treating it as particle). It doesn't make sense, but you can, and it leads to the same predictions if you do it correctly.
 
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  • #256
A. Neumaier said:
But when they come close, the semiclassical description breaks down and one needs full quantum field theory to describe what happens.

Define "close".
Two electrons repelling each other (in term of Feynman diagrams, "by exchanging virtual photons") over a separation of, say, one kilometer, still involves virtual photons.

There is no cutoff. It would be illogical to declare that unstable particles up to particular short lifetime are virtual, but above it they can be either real or virtual.

Maybe "virtualness" should not be seen as a boolean quantity, "yes or no". It can be more useful to explain it this way: with increasingly smaller scales and higher energies, the notion of a "particle" with definite energy, position, momentum, etc is increasingly inaccurate. The short-lived particles are "increasingly virtual".
 
  • #257
nikkkom said:
the notion of a "particle" with definite energy, position, momentum, etc

What do you mean by "definite"? Obviously a particle's position and momentum are fuzzy just by dint of being wave operators (by the wave interpretation of the HUP). Do you mean this as opposed to also having another kind of fuzz?
 
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  • #258
nikkkom said:
Two electrons repelling each other (in term of Feynman diagrams, "by exchanging virtual photons") over a separation of, say, one kilometer, still involves virtual photons.
This doesn't change the status of the electrons from real to virtual.
 
  • #259
nikkkom said:
"virtualness" should not be seen as a boolean quantity, "yes or no". It can be more useful to explain it this way: with increasingly smaller scales and higher energies, the notion of a "particle" with definite energy, position, momentum, etc is increasingly inaccurate. The short-lived particles are "increasingly virtual".
No, definitely not. Virtualness is a matter of where something appears in a Feynman diagram, hence none-or-all. It is meaningless to say that a particle is described to 90% by an external line and to 10% by an internal line. Virtual particles are by definition (in any textbook where they are defined) terminology for internal lines of a diagram.
 
  • #260
mfb said:
as virtual particle (which means: not treating it as particle). It doesn't make sense, but you can, and it leads to the same predictions if you do it correctly.
You can as well treat any physical system as a black box, even classically. This doesn't make the content of the black box less real. It just means that one is modeling at a lower resolution.

Thus, making my account precise, whenever the factorization is possible, the particle is real, even when you choose to take the black box road.

However, one cannot go the other way with virtual particles - you cannot make them real by going to a higher resolution, since the calculations then lead to different predictions.
 
  • #261
So on the one hand you claim that the theory doesn't work unless you define virtual particles this way. But on the other hand you claim that most of the community that studies the theory and performs the experiments that confirm it has been led astray from this definition. You can't have it both ways.
 
  • #262
Collin237 said:
So on the one hand you claim that the theory doesn't work unless you define virtual particles this way. But on the other hand you claim that most of the community that studies the theory and performs the experiments that confirm it has been led astray from this definition. You can't have it both ways.
No. I only claim that the community is sloppy in their use of the terminology, and that there is a higher standard (defined in the textbooks) worth paying attention to, since it reduces ambiguity and hence improves the communication quality. Sloppy usage of terms is very common in many branches of science; so this is not a criticism specific to experimental particle physics.
 
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  • #263
A. Neumaier said:
Sloppy usage of terms is very common in many branches of science
So are books that resolve the ambiguities. But those books are not meta-studies of textbook usage; they are the textbooks themselves.

The higher standard is commitment to honestly understanding the theory as established by experimental verification. The textbooks don't define the standard. They follow it, or else get roundfiled.
 
  • #264
It's not that difficult. Any textbook about QFT starts with analyzing free fields, and for these free fields everything can be solved analytically. It turns out that for free fields there is a particle interpretation in the sense of a complete set of states with definite particle number, where the particle number can take any integer (including 0) value. Given a one-particle basis (for massive particles usually defined by the Lorentz boosts of a particle at rest with definite spin-##z## component or for massless particles by the Lorentz boosts of the quantum with momentum in ##z## direction and definite helicity ##\pm s##), the complete Hilbert space is spanned by the occupation number eigenstates for these single-particle states, and depending on the integer or half-integer spin you necessarily must quantize the fields as bosons or fermions, respectively (spin-statistics theorem following from microcausality and boundedness of the Hamiltonian). In this way you get a definite particle (or massless quantum) interpretation of QFT. This is all pretty straight forward and just a bit of more or less complicated math of the representation theory of the proper orthochronous Lorentz group and some thought about the discrete factors of the rest of the Lorentz group (parity, time reversal, and charge conjugation).

Now the trouble starts when you switch on interactions. Here, the particle interpretation breaks generally down, and (except in some academic toy cases in low space-time dimensions) you can't solve the problem to construct the Hilbert space out of the Lagrangian/Hamiltonian and symmetries as in the free case. Usually, what's done is to restrict oneself to the socalled S-matrix that describes the transition probabilities from an asymptotically free initial to another asymptotically free final state, i.e., you start usually with two free particles and ask what's the probability (per unit time and unit volume) that these particles scatter to some final state with again asymptotic free particles, and you use perturbation theory to evaluate these transition probabilities. This evaluation is tremendously simplified by introducing the ingenious notation in terms of Feynman diagrams, which even suggest to interpret them as the "microscopic mechanism" of this scattering process. The important point is that one cannot take this intuition too far. The internal lines of Feynman diagrams, which are just a clever notation for the expressions of perturbation theory to get the S-matrix elements, are called "virtual particles", but that's a misnomer since even in the sense of perturbation theory, there's no way to interpret these mathematical expressions, the socalled free time-ordered propagator (which in vacuum QFT is identical with the Feynman propgator), as particles in any way. A more close to physics interpretation is indeed as in classical field theory (i.e., electrodynamics) to see it as a solution of the field equations describing the interactions leading to the scattering process whose S-matrix element you want to calculate. A proper physical interpretation in terms of particles are only given by the asymptotic free Fock states of the free theory, and these are represented exclusively by the external legs of S-matrix Feynman diagrams, and stand mathematically for certain coefficients in the plane-wave solutions of the corresponding free field equations.

Another complication is that as soon as you have massless quanta in the theory (e.g., photons in QED), the above given picture of asymptotic free particles is too naive, and one usually has to resum an infinite number of Feynman diagrams to get useful results (e.g., for bremsstrahlung in QED even at the tree level), i.e., you have to dress the "naive" plane-wave solutions of the free particles to describe the long-range interactions described by the massless fields/quanta. In other words the true "asymptotic free electron" in QED with it's own electromagnetic field around it is not fully described by the free solutions of the Dirac field, but in this picture is always surrounded by a "cloud of soft photons" or better said "coherent em. fields".

In short: The "particle interpretation" of relativistic QFT is much more involved than in non-relativistic QT or even suggested by the apparently "intuitive pictures" of Feynman diagrams.
 
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  • #265
vanhees71 said:
these mathematical expressions, the socalled free time-ordered propagator

Ah, now we're finally getting somewhere! Would you be willing to write a series of Insights about these expressions?
 
  • #267
Collin237 said:
So are books that resolve the ambiguities. But those books are not meta-studies of textbook usage; they are the textbooks themselves.
All textbooks on QFT define virtual particles via internal lines of Feynman diagram. There is no other definition. Sticking to this definition there is no ambiguity at all. Thus nothing is resolved. The sloppy usage happens outside of any sensible definitional framework!
 
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  • #268
Why do you have what you call a "Thermodynamic Interpretation"? If there's no ambiguity, why don't you have a textbook like the one vanhees71 wrote, and gave me in a pdf just for the asking?
 
  • #269
Collin237 said:
If there's no ambiguity, why don't you have a textbook like the one vanhees71 wrote, and gave me in a pdf just for the asking?
There are enough textbooks on quantum field theory, so I don't need to write my own. They all agree on the meaning of the notion of a virtual particle.
Collin237 said:
Why do you have what you call a "Thermodynamic Interpretation"?
My ''thermal interpretation'' is an interpretation of quantum mechanics in general, and the measurement problem in particular. I developed this since none of the present interpretations gives an interpretation fully compatible with the actual practice of using quantum mechanics - where many things - such as spectral lines, Z-boson masses, or electric fields) are measured that are impossible to capture with the Born interpretation underlying all previous interpretations.

But the thermal interpretation is completely independent of virtual particles. Most of quantum mechanics does not use the notion of virtual particles at all. Even in quantum field theory, this notion can be completely avoided - see the book Diagrammatica by Veltman (and my partial review of it in my insight article “Misconceptions about Virtual Particles“)
 
  • #270
A. Neumaier said:
Even in quantum field theory, this notion can be completely avoided
Lots of things can be avoided. I've read that the Beatles didn't use sheet music drafts to develop their songs.

But having found a way to get by without a formal technique doesn't justify calling it misconception that others who do use it are being sloppy about!
 
  • #271
Well, all these quantities are measured with the corresponding measurement devices like spectrometers, particle detectors (for the Z-boson mass and width you measure dilepton spectra in various ways), etc. you find in the physics labs around the world. In physics in fact quantities are defined by giving appropriate (equivalence classes of) measurement protocols to quantitatively observe them. That's why they are called observables after all. Also there is nothing more needed concerning the application of the quantum-theoretical formalism (e.g., formulated as the representation of an observable algebra on Hilbert space, based on various symmetry principles which themselves are discovered by observation of conservation laws) than Born's rule, i.e., the minimal interpretation.

Where you need something like a "thermal interpretation" is when it comes to understand the overwhelming success of classical physics (including classical relativistic and non-relativistic mechanics, electrodynamics, and thermodynamics) to describe macroscopic systems. Here you need some coarse graining to describe macroscopic effective (relevant) degrees of freedom as (spatio-temporal) averages over many microscopic degrees of freedom.
 
  • #272
vanhees71 said:
Well, all these quantities are measured [...] as (spatio-temporal) averages over many microscopic degrees of freedom.
To avoid that this thread (about virtual particles) is polluted by a discussion of measurement issues I created a new thread answering this.
 
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  • #273
A. Neumaier said:
However, one cannot go the other way with virtual particles - you cannot make them real by going to a higher resolution, since the calculations then lead to different predictions.

So? External lines become internal if the diagram is extended to show more interactions "surrounding" the scattering, but internal lines don't become external unless the diagram is changed by breaking a line. That's just basic topology. What does it have to do with "existence" vs "myth" or anything?
 
  • #274
Collin237 said:
External lines become internal if the diagram is extended to show more interactions "surrounding" the scattering, but internal lines don't become external unless the diagram is changed by breaking a line.
In both case you get diagrams describing different situations, corresponding to calculations of different collision processes, compared to the original diagram.
 
  • #275
A. Neumaier said:
In both case you get diagrams describing different situations, corresponding to calculations of different collision processes, compared to the original diagram.

There are collision processes happening everywhere all the time. The vast majority of them occur without anyone situating or calculating them.
 
  • #276
Collin237 said:
There are collision processes happening everywhere all the time. The vast majority of them occur without anyone situating or calculating them.
This doesn't change what I said. One can always ignore or coarse-grain things (unobserved things being very coarse-grained) without changing what happens. It is a big conceptual mistake to think of a sequence of collisions with particle worldlines in between as being a particular Feynman diagram, so that the worldlines would become internal lines of a diagram. Most paths in a complex Feynman diagram have a very different topology from those you'd get by a sequence of collisions, and their mathematics is completely different!
 
  • #277
What? The theory is non-extensible? Can someone corroborate this?
 
  • #278
Collin237 said:
What? The theory is non-extensible? Can someone corroborate this?
My assertion was that the theory of properties of virtual particles (aka internal lines of Feynman diagrams aka integration variables of multivariate integrals) has very different properties from the theory of properties of systems of multiply colliding particles (aka systems with states changing upon collisions according to computable scattering statistics). Thus there is no way to mix them up.
 
  • #279
A. Neumaier said:
(aka systems with states changing upon collisions according to computable scattering statistics).
But wouldn't that be a collapse, i.e., an interpretational issue? Which, as I've seen oft repeated here, doesn't change the basic math?

I'm still waiting for someone else to corroborate.
 
  • #280
Collin237 said:
But wouldn't that be a collapse, i.e., an interpretational issue? Which, as I've seen oft repeated here, doesn't change the basic math?
No. The Boltzmann equation is based on such a collision picture, and nothing ever collapses there. Collapse is related to the change of state of a few-particle system upon acknowledging a measurement as definite. But as you correctly observed, most collisions in nature are never observed. But they still happen, or the Boltzmann equation would not work.

Better learn the math rather than complaining about formal issues without understanding them!
 
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  • #281
A. Neumaier said:
No, definitely not. Virtualness is a matter of where something appears in a Feynman diagram, hence none-or-all. It is meaningless to say that a particle is described to 90% by an external line and to 10% by an internal line. Virtual particles are by definition (in any textbook where they are defined) terminology for internal lines of a diagram.

I think everyone agrees with the above.

The thing is, you don't just state the above statement, you proceed with other statements such as:

"The word virtual is an antonym to real – unlike the general readership of popular literature on particle physics, the creators of the terminology were well aware that virtual particles are not real in any observable sense".
and
"They cannot cause anything or interact with anything".

Since we established that all unstable particles can be seen as virtual, this means that muons from cosmic ray showers are virtual too.

It's hard to agree that these muons "are not real in any observable sense" and "cannot cause anything or interact with anything", when physicists have to hide under several kilometers of rock (!) to decrease muon-induced background in their DM detection experiments. Clearly, muons do "interact", "cause" events to happen and thus are "real" and "observable".
 
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  • #282
A. Neumaier said:
>> But when they come close, the semiclassical description breaks down and one needs full quantum field theory to describe what happens.

> Define "close".
> Two electrons repelling each other (in term of Feynman diagrams, "by exchanging virtual photons") over a separation of, say, one kilometer, still involves virtual photons.

This doesn't change the status of the electrons from real to virtual.

My point is that virtual *photons* do not need electrons to be close. Virtual photons work across any distances, even quite macroscopic. There is no cutoff when QFT should be abandoned and semiclassical description should be used.
 
  • #283
nikkkom said:
Since we established that all unstable particles can be seen as virtual, this means that muons from cosmic ray showers are virtual too.
I didn't establish this. There is a difference between ''particle'' and ''particle'' dependent on the context; you are mixing context to ''establish'' this.

A particle is virtual in the context of a Feynman diagram with internal lines, and real in the context of something requiring a state. This makes the difference. A given occurrence of the word particle must be interpreted in its context according to this rule. Then things are unambiguous.
 
  • #284
nikkkom said:
Since we established that all unstable particles can be seen as virtual, this means that muons from cosmic ray showers are virtual too.
Muons from cosmic rays are not virtual at all since they are located in space and time, which is only possible if one can assign states to them. A virtual muon cannot ''arrive'' since that notion is meaningless for an internal line in a Feynman diagram.

nikkkom said:
It's hard to agree that these muons "are not real in any observable sense" and "cannot cause anything or interact with anything", when physicists have to hide under several kilometers of rock (!) to decrease muon-induced background in their DM detection experiments. Clearly, muons do "interact", "cause" events to happen and thus are "real" and "observable".
All these muons are real since to talk about interaction, cause, real, and observable all requires that they have a state.
 
  • #285
The assigning of states you keep bringing up is again referring back to free states of the free quantum field theories that are known not to be valid in the interacting qft's in the presence of observable interactions, so why do you use it as an argument?
 
  • #286
RockyMarciano said:
The assigning of states you keep bringing up is again referring back to free states of the free quantum field theories that are known not to be valid in the interacting qft's in the presence of observable interactions, so why do you use it as an argument?
Particles on external lines in Feynman diagrams always belong to asymptotic states, and these are free and have well-defined states. The particle picture is valid anyway only when this asymptotic description is sufficiently accurate.
 
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  • #287
A. Neumaier said:
Particles on external lines in Feynman diagrams always belong to asymptotic states, and these are free and have well-defined states. The particle picture is valid anyway only when this asymptotic description is sufficiently accurate.
Ok but then you seem to be mixing back and forth the Feynman diagrams, which are limited to a graphical description of terms in the Dyson-Wick expansion, with a clear enough distinction between external and internal lines meanings within this graphic representation that shouldn't be confused with the actual physics in renormalized interacting qft's, with your own ontological views about quantum field theory.
 
  • #288
RockyMarciano said:
Ok but then you seem to be mixing back and forth the Feynman diagrams, which are limited to a graphical description of terms in the Dyson-Wick expansion, with a clear enough distinction between external and internal lines meanings within this graphic representation that shouldn't be confused with the actual physics in renormalized interacting qft's, with your own ontological views about quantum field theory.
In doing real physics it is often unavoidable to switch between representations featuring different levels of detail. If one uses the particle picture at all (and in particular always when one has to interpret what people using the particle language say), one acknowledges that one works in a semiclassical picture where a particle description makes approximate sense except during collisions.

Thus between collisions the particles are described by asymptotic states, hence we have real particles, while during collisions, a black box view featuring the S-matrix is used. To calculate the S-matrix one may work in renormalized perturbation theory using quantum field theory. In this case one utilizes for the computation integrals represented by Feynman diagrams, which are then described pictorially. here the same, free real particles show as external lines, while the interaction is represented in terms of internal lines, figuratively called virtual particles. This is the only mixing that is actually used, and there is nothing ambiguous about it.
 
  • #289
A. Neumaier said:
In doing real physics it is often unavoidable to switch between representations featuring different levels of detail. If one uses the particle picture at all (and in particular always when one has to interpret what people using the particle language say), one acknowledges that one works in a semiclassical picture where a particle description makes approximate sense except during collisions.

Thus between collisions the particles are described by asymptotic states, hence we have real particles, while during collisions, a black box view featuring the S-matrix is used. To calculate the S-matrix one may work in renormalized perturbation theory using quantum field theory. In this case one utilizes for the computation integrals represented by Feynman diagrams, which are then described pictorially. here the same, free real particles show as external lines, while the interaction is represented in terms of internal lines, figuratively called virtual particles. This is the only mixing that is actually used, and there is nothing ambiguous about it.
Well, here you have taken the work of spelling out the mixing, if you don't spell it out this clearly it might be confusing for many. I would then ask you, because this is the impression I get(correct me otherwise) why you consider the asymptotic states that nobody can actually observe to have existence in detriment of the actual interactions that can be observed.
 
  • #290
A. Neumaier said:
The former is what quantum field theory says (and hence what I say): The vacuum is the state containing exactly zero particles anywhere in space and at all times. Since it is an eigenstate of the number operator, there is no uncertainty at all about this.

So, Arnold, vacuum is absolutely nothing according to you? If I imagine a universe with a lone object, for example a lone quark, is there any external influence outside this lone quark?
 
  • #291
Mohd Abdullah said:
So, Arnold, vacuum is absolutely nothing according to you?
No, he is saying (and this is not a "according to you" thing) that the the vacuum is an eigenstate of the number operator.
If I imagine a universe with a lone object, for example a lone quark, is there any external influence outside this lone quark?
That question doesn't make any sense in the context of this discussion.
 
  • #292
Mohd Abdullah said:
So, Arnold, vacuum is absolutely nothing according to you?
Already in the noninteracting case, a system in the vacuum state contains exactly zero particles (since we have an eigenstate of the number operator) without any fluctuation. You can easily check this yourself. States in the interacting case are less well understood, but still the vacuum state has zero 4-momentum since it belongs to a trivial representation of the Poincare group. Hence it has zero energy, again exactly without any fluctuation. But the creation of a particle pair requires a positive energy since states containing particles have positive energy. Thus no particles can ever be created.

Mohd Abdullah said:
If I imagine a universe with a lone object, for example a lone quark, is there any external influence outside this lone quark?
A lone quark is impossible, since physical systems cannot be colored in the sense of quark colors. But already a lone photon in an otherwise empty universe would no longer be a vacuum. On the other hand, there is nothing outside the universe, and by assumption nothing in it except the photon - so a lone photon would not interact with anything and behave freely.
 
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  • #293
A. Neumaier said:
Already in the noninteracting case, a system in the vacuum state contains exactly zero particles (since we have an eigenstate of the number operator) without any fluctuation. You can easily check this yourself. States in the interacting case are less well understood, but still the vacuum state has zero 4-momentum since it belongs to a trivial representation of the Poincare group, and hence zero energy, again exactly without any fluctuation, while the creation of a particle pair requires a positive energy. Thus no particles are ever created.A lone quark is impossible, since physical systems cannot be colored in the sense of quark colors. But already a lone photon in an otherwise empty universe would no longer be a vacuum. On the other hand, there is nothing outside the universe, and by assumption nothing in it except the photon - so a lone photon would not interact with anything and behave freely.

Thank you for the response, Arnold.

Btw, if someone imagine the photon as a tiny ball, then there is space that gives the photon its shape. But in the context of quantum physics, a photon has no shape (I'm sorry if this is a mistake) as it is massless. So, in an imaginary scenario where there is a lone photon with no other existing objects, the lone photon is actually the whole Universe itself as it has no shape. Thoughts?
 
  • #294
Mohd Abdullah said:
if someone imagine the photon as a tiny ball

You can't imagine photons as tiny balls.
 
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  • #295
Mohd Abdullah said:
in the context of quantum physics, a photon has no shape (I'm sorry if this is a mistake) as it is massless. So, in an imaginary scenario where there is a lone photon with no other existing objects, the lone photon is actually the whole Universe itself as it has no shape.
Yes, but this is not our universe, so I don't care.
 
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  • #296
Mohd Abdullah said:
in the context of quantum physics, a photon has no shape (I'm sorry if this is a mistake) as it is massless

What do you mean by "shape"? What in the math does this correspond to?

Mohd Abdullah said:
in an imaginary scenario where there is a lone photon with no other existing objects, the lone photon is actually the whole Universe itself

No, it isn't. In this imaginary situation, at least if you are imagining it according to the laws of quantum field theory (if you're not then you're imagining something that is out of bounds for discussion here), you have a quantum field in a particular state in a background spacetime. You don't have just the field, which is what "the lone photon is the whole universe" would mean.
 
  • #297
I am very interested in the virtual particles.
For what I understand their existence follows from the principle of indeterminacy in the form

##\Delta E \Delta T \geq \hbar##

When ## \Delta T \rightarrow 0## , ##\Delta E \rightarrow \infty##

For instants of very small time then the energy fluctuation can become so great as to be compatible with the existence of masses. These particles are called "virtual" because their existence times tend to virtually 0 and therefore are not directly observable.
The first point is that I do not see where and how the gravity enters into the matter.
The second point is, if I understand it, that the virtual particles are only the lines that result in calculations of processes but who have no physical reality.
I do not understand how do you reconcile these versions, adding that the fluctuations of the vacuum and all the virtual processes are widely accepted by physics, just think Casimir effect or the Hawking radiation
 
  • #298
Karolus said:
For what I understand their existence follows from
I think you should read the article. Your reasoning is flawed, and the article explains why.

There is no proper energy/time uncertainty principle. Time is not even an operator.

The Casimir effect can be described without virtual particles, and the derivation of Hawking radiation only works without virtual particles. You'll only see virtual particles in pop-science descriptions.
 
  • #299
mfb said:
I think you should read the article. Your reasoning is flawed, and the article explains why.

There is no proper energy/time uncertainty principle. Time is not even an operator.

The Casimir effect can be described without virtual particles, and the derivation of Hawking radiation only works without virtual particles. You'll only see virtual particles in pop-science descriptions.

Then the particles "virtual" does not exist?
 
  • #300
Karolus said:
Then the particles "virtual" does not exist?
They certainly do not exist as objects that exist and move around. Every "existence" lower than that is up to interpretation.
Karolus said:
and the quantum fluctuations of the vacuum is all a hoax invented by Feynman Hawking, taught in universities, in the more advanced courses in theoretical physics, and so much of pop-science?
Nothing is a hoax. It is a different way to describe things. You can use virtual particles - just keep in mind that they are mainly a mathematical tool in perturbation theory. Their existence is about as real as the existence of an integral sign, another mathematical tool used in perturbation theory.
 

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