Quantum Jitter and 120 Magnitude Prediction

[rogerl]

Quantum Jitter is supposed to fill space with very dense energy that the cosmological constant should increase by over 120 magnitude. Yet it is not so and the worse prediction ever made by physics as they say. Could the reason this be so is because virtual particles are just figment of the imagination as Arnold Neumaier keeps saying? Do you agree that virtual particles are just multivariate integrals and not real. When pressed that virtual particles can affect the muon geomagnetic ratio by 7 significant digists. Neumaier claims it is the field that do it and not virtual particles. Anyone can expand or refute what he is saying?

But then even if virtual particles not real. The math should in principle still cause the cosmological constant to be 120 magnitude bigger because spacetime is also math... virtual particles are math.. so both math should interact too.. right?

 

[Chalnoth]

Could the reason this be so is because virtual particles are just figment of the imagination as Arnold Neumaier keeps saying?

Obscenely unlikely. These virtual particles govern our understanding of interactions in quantum mechanics, a theory which predicts experiment tremendously accurately (so much so that we have to build monstrous machines like the LHC to try to find any deviations from current theory).

Is it possible that the entire standard model of particle physics is just smoke and mirrors, that it doesn't describe the true behavior of particles, even at an approximate level? I suppose so. It is not completely impossible for there to be some other theory that provides all of the same predictions while having a very different underlying description.

But it is near enough to impossible that it isn't worth worrying about. The standard model of particle physics has been tested up the wazoo. It almost certainly provides an accurate description of the underlying nature of reality, at least at an approximate level.

But then even if virtual particles not real. The math should in principle still cause the cosmological constant to be 120 magnitude bigger because spacetime is also math... virtual particles are math.. so both math should interact too.. right?

The answer, it seems to me, is just that we don't yet understand how physics works at very high energies. Understand that, and we'll probably have no difficulty understanding the cosmological constant.

 

[rogerl]

Obscenely unlikely. These virtual particles govern our understanding of interactions in quantum mechanics, a theory which predicts experiment tremendously accurately (so much so that we have to build monstrous machines like the LHC to try to find any deviations from current theory).

You believe that virtual particles are real? But virtual particles don't have any wave function and don't occur in space and time. How can something be real when they don't occur in space and time?

Is it possible that the entire standard model of particle physics is just smoke and mirrors, that it doesn't describe the true behavior of particles, even at an approximate level? I suppose so. It is not completely impossible for there to be some other theory that provides all of the same predictions while having a very different underlying description.

But it is near enough to impossible that it isn't worth worrying about. The standard model of particle physics has been tested up the wazoo. It almost certainly provides an accurate description of the underlying nature of reality, at least at an approximate level.


The answer, it seems to me, is just that we don't yet understand how physics works at very high energies. Understand that, and we'll probably have no difficulty understanding the cosmological constant.

High energies? But quantum jitter in even a square inch of space in say a football field is enough to blow the entire stadium apart. So it doesn't have to do with high energies but why the one inch square space in the foot ball field doesn't blow up

 

[Chalnoth]

You believe that virtual particles are real? But virtual particles don't have any wave function and don't occur in space and time. How can something be real when they don't occur in space and time?

Quantum mechanics, as we know it today, doesn't provide a clear distinction between virtual particles and real particles: a virtual particle becomes a real particle in the limit of infinite interaction length. But since there are no infinite interaction lengths, we can consider all particles to be virtual particles. The particles we consider to be "real" are just near enough to the limit of infinite interaction length that we can't tell the difference. So virtual particles absolutely occur in space-time according to the standard model.

High energies? But quantum jitter in even a square inch of space in say a football field is enough to blow the entire stadium apart. So it doesn't have to do with high energies but why the one inch square space in the foot ball field doesn't blow up

Actually, it is precisely the high-energy behavior that leads to the large prediction for energy density. Basically, when calculating the expected energy density within a region of space-time, we end up with some integrals that go to infinity in energy. So technically, if we take those integrals seriously, we would end up with an infinite energy density. Instead what we do is say, "Well, that's nonsense. But maybe I can cut off these integrals at some finite number and get a sensible answer?" So a some reasonable number is picked (e.g. the Planck energy), and you get a number. That number isn't infinity, but it is obviously wrong.

If we understood what was going on at high energies in these integrals, we would most likely be able to show that they're actually finite, and arrive at the value we observe.

 

[rogerl]

Quantum mechanics, as we know it today, doesn't provide a clear distinction between virtual particles and real particles: a virtual particle becomes a real particle in the limit of infinite interaction length. But since there are no infinite interaction lengths, we can consider all particles to be virtual particles. The particles we consider to be "real" are just near enough to the limit of infinite interaction length that we can't tell the difference. So virtual particles absolutely occur in space-time according to the standard model.

What do you mean by "infinite interaction length"? It's not a mainstream term. Pls. use mainstream semantics so I can understand what you are saying. Anyway. You are arguing that real particles are virtual particles so virtual particles are real. Well. Let's avoid semantics ambiguity. Let's define real particles are ones where it has wave function and located in space and time. Virtual particles or internal lines in the feynman diagram has never been observed because it doesn't occur in space and time.. so we can treat virtual particles as just side effect of the math and not physical at all? If you'd say it is physical. How can something be physical if it is not located in space and time?

 

[Chalnoth]

What do you mean by "infinite interaction length"? It's not a mainstream term. Pls. use mainstream semantics so I can understand what you are saying.

What I mean is as you take the distance between interacting particles to infinity.

Anyway. You are arguing that real particles are virtual particles so virtual particles are real. Well. Let's avoid semantics ambiguity. Let's define real particles are ones where it has wave function and located in space and time.

That's not the way they're defined, though. Real particles are particles "on the mass shell." That is, they have a mass equal to the rest mass of the particle.

Virtual particles or internal lines in the feynman diagram has never been observed because it doesn't occur in space and time.. so we can treat virtual particles as just side effect of the math and not physical at all? If you'd say it is physical. How can something be physical if it is not located in space and time?

You're not making any sense here. By your definition, the particles on the outside of the Feynman diagrams have also never been observed, because they are assumed to enter from infinity and leave to infinity. The fact remains that the particles on the interior of a Feynman diagram have momentum, and therefore exist in space and time.

The thing you don't seem to be getting is that the only way we know anything at all exists is by its effects on other things. We can be pretty darned sure that virtual particles exist because our calculations using them give the right predictions for interactions.

 

[rogerl]

What I mean is as you take the distance between interacting particles to infinity.


That's not the way they're defined, though. Real particles are particles "on the mass shell." That is, they have a mass equal to the rest mass of the particle.


You're not making any sense here. By your definition, the particles on the outside of the Feynman diagrams have also never been observed, because they are assumed to enter from infinity and leave to infinity. The fact remains that the particles on the interior of a Feynman diagram have momentum, and therefore exist in space and time.

The thing you don't seem to be getting is that the only way we know anything at all exists is by its effects on other things. We can be pretty darned sure that virtual particles exist because our calculations using them give the right predictions for interactions.

Pls. kindly find time today to read the following article by Arnold Neumaier and comment what is the difference between your belief and him because it's confusing already that half of physicists believe they are real and half believe they are not real. Pls. make sense out of it. Thanks.

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

Sample passage:

"Virtual particles must not be considered real since they arise only in a particular approach to high energy physics - perturbation theory before renormalization - that does not even survive the modifications needed to remove the infinities. Moreover, the virtual particle content of a real state depends so much on the details of the computational scheme (canonical or light front quantization, standard or renormalization group enhances perturbation theory, etc.) that
calling virtual particles real would produce a very weird picture of reality."

"However, these virtual particles do not live in space and time, and are not created and annihilated somewhere or sometime. They occur in the interpretation of expressions for scattering amplitudes that have meaning only at infinitely long times, and describe the cumulative long-time transition behavior of _real_ particles (asymptotic states)."

 

[Chalnoth]

"Virtual particles must not be considered real since they arise only in a particular approach to high energy physics - perturbation theory before renormalization - that does not even survive the modifications needed to remove the infinities. Moreover, the virtual particle content of a real state depends so much on the details of the computational scheme (canonical or light front quantization, standard or renormalization group enhances perturbation theory, etc.) that
calling virtual particles real would produce a very weird picture of reality."

Due to the way second quantization works, with the number of particles no longer conserved, it should be no surprise that a different representation will find a different number of particles given the observables are conserved. I don't see this as being any different from talking about a particle as a superposition of momentum states vs. as a superposition of position states.

And by the way, because the virtual particles can be explicitly written down as a superposition of momentum states, it is, in principle, possible to rewrite them as a superposition of position states, explicitly locating the virtual particles in space-time.

"However, these virtual particles do not live in space and time, and are not created and annihilated somewhere or sometime. They occur in the interpretation of expressions for scattering amplitudes that have meaning only at infinitely long times, and describe the cumulative long-time transition behavior of _real_ particles (asymptotic states)."

As he points out, "real" particles are just virtual particles taken to infinity. So I think he defeats his own case here.

 

[rogerl]

Due to the way second quantization works, with the number of particles no longer conserved, it should be no surprise that a different representation will find a different number of particles given the observables are conserved. I don't see this as being any different from talking about a particle as a superposition of momentum states vs. as a superposition of position states.

And by the way, because the virtual particles can be explicitly written down as a superposition of momentum states, it is, in principle, possible to rewrite them as a superposition of position states, explicitly locating the virtual particles in space-time.


As he points out, "real" particles are just virtual particles taken to infinity. So I think he defeats his own case here.

I've been reading the following thread for 3 hours already and 2 more to go :)

https://www.physicsforums.com/showthread.php?t=75307
Thread title: "Are virtual particles really there?"

Here's what I read at the bottom of thread page #6 to give you a main idea of their arguments which is of the line that virtual particles are just mathematical artifact of perturbation theory (Are you a quantum field physicists or astrophysicists or just nonphysicist?):

"
The calculational tool represented by Feynman diagrams suggests an often abused picture according to which “real particles interact by exchanging virtual particles”. Many physicists, especially nonexperts, take this picture literally, as something that really and objectively happens in nature. In fact, I have never seen a popular text on particle physics in which this picture was not presented as something that really happens. Therefore, this picture of quantum interactions as processes in which virtual particles exchange is one of the most abused myths, not only in quantum physics, but in physics in general. Indeed, there is a consensus among experts for foundations of QFT that such a picture should not be taken literally. The fundamental principles of quantum theory do not even contain a notion of a “virtual” state. The notion of a “virtual particle” originates only from a specific mathematical method of calculation, called perturbative expansion. In fact, perturbative expansion represented by Feynman diagrams can be introduced even in classical physics [52, 53], but nobody attempts to verbalize these classical Feynman diagrams in terms of classical “virtual” processes. So why such a verbalization is tolerated in quantum physics? The main reason is the fact that the standard interpretation of quantum theory does not offer a clear “canonical” ontological picture of the actual processes in nature, but only provides the probabilities for the final results of measurement outcomes. In the absence of such a “canonical” picture, physicists take the liberty to introduce various auxiliary intuitive pictures that sometimes help them think about otherwise abstract quantum formalism. Such auxiliary pictures, by themselves, are not a sin. However, a potential problem occurs when one forgets why such a picture has been introduced in the first place and starts to think on it too literally."

-----------------

The essence of it all is that when you write a non-perturbative approach to Quantum Field Theory, the virtual particles disappear.

 

[Chalnoth]

Well, when virtual particles can become real particles through processes like the Unruh effect or Hawking radiation, I have a hard time seeing how there can be any firm distinction between "real" and "virtual" particles. Of course, it is curious that many aspects of virtual particles are representation-dependent, but then so are many properties of real particles, so I see no difficulty there.

 

[jtbell]

If there's going to be yet another argument about whether virtual particles are "real," how about doing it in the Quantum Physics forum?

 

[dm4b]

Quantum mechanics, as we know it today, doesn't provide a clear distinction between virtual particles and real particles: a virtual particle becomes a real particle in the limit of infinite interaction length. But since there are no infinite interaction lengths, we can consider all particles to be virtual particles. The particles we consider to be "real" are just near enough to the limit of infinite interaction length that we can't tell the difference. So virtual particles absolutely occur in space-time according to the standard model.

This is a good point.

I can't help but wonder if this whole debate is like wave/particle duality. At one time we argued whether things were wavelike in their nature, or particle-like in their nature. After blowing much hot air, we realized it's both.

Is the whole virtual particles vs real particles argument destined to go down the same path?

If we can't explain away the virtual particles for the Cosmological Constant problem like was done for the Casmir Effect, I think it's a very important question for Cosmology.

 

[rogerl]

If there's going to be yet another argument about whether virtual particles are "real," how about doing it in the Quantum Physics forum?

Oh, I started one there at at the QM forum entitled:

"Non-Perturbative QFT without Virtual Particles"

https://www.physicsforums.com/showthread.php?t=485597

It's not as much as debate as finding versions of non-perturbative QFT. If these can be found and can replace QFT. Then we can totally do away with virtual particles which may really be just mathematical artifact of perturbation theory, meaning, dependent on the calculation method used hence not real.