Do Virtual Particles Become Real Under the Weisenberg Uncertainty Principle?

[Kyoma]

Virtual Particles appear due to the Weisenberg Uncertainty Principle.

So if \Deltat is prolonged or something like that, virtual particles become real. Am I right?

 

[tiny-tim]

Hi Kyoma!

Virtual Particles appear due to the Weisenberg Uncertainty Principle.

(it's Heisenberg! … though I suppose you're allowed some uncertainty in the name! )

No, virtual particles are a mathematical device in the Dyson expansion in perturbation theory in quantum field theory, they have nothing to do with the uncertainty principle.

(Even the mathematics does not give them any location or duration.)

 

[Kyoma]

Then how do virtual particles become real?

 

[xepma]

They don't.

 

[HallsofIvy]

Tiny Tim said: "virtual particles are a mathematical device". Do you understand what that means?

 

[nismaratwork]

Tiny Tim: Who has time for "Werner Heisenberg", when you can rock the "Weisenberg". From now on I subscribe to the WUT (anyway **** that nazi Heisenberg...).

Kyoma: At no time are virtual particle intended in math from the outset to be real or "BECOME" real, and if they did they wouldn't BE virtual particles! "What if a horse had black and white stripes and lived in Africa?..." It'd be a Zebra, not a horse, that's what.

In the struggle to 'get' from point A to B in QFT, these little mathematical devices called "virtual particles" are useful in the endeavor, but have no more physical reality than the FOIL method becoming a fencing implement. The only time you could conceivably move in the "striped horse in africa" direction would be Hawking Radiation, but that's not a virtual particle except for meaningless period in the math.

 

[pallidin]

I would not be too quick to dismiss the concept of "virtual" particles/photons.
For example, can the extension of magnetism in free-space make any sense whatsoever without the notion of virtual photons? No.
That is just one example.

Sure, with virtual particles/photons it's all mathematical, but maybe something IS there, transitory as it may be.

 

[tiny-tim]

For example, can the extension of magnetism in free-space make any sense whatsoever without the notion of virtual photons? No.

what's the extension of magnetism?

 

[nismaratwork]

what's the extension of magnetism?

I think the field lines use this:

This to me, is the clear solution to problems in QFT... plus what if I drop the remote, am I supposed to haul *** to pick it up?! I NEED those calories... really I do.

 

[lugita15]

I think that Kyoma is confusing virtual particles with things like W and Z bosons, which have more energy than conservation of energy would allow, but exist for a very short period of time. That is OK because of Heisenberg's uncertainty principle.

 

[jtbell]

There are virtual W and Z bosons, which mediate low-energy weak interactions like nuclear beta decay, and real W and Z bosons, which can be produced in accelerators with enough energy. The difference is exactly like between virtual and real photons.

 

[Kyoma]

I think that Kyoma is confusing virtual particles with things like W and Z bosons, which have more energy than conservation of energy would allow, but exist for a very short period of time. That is OK because of Heisenberg's uncertainty principle.

Not really...

In wikipedia, it states that if a single virtual particle is detected, then the consequences of its existence are prolonged to such a degree that it cannot be virtual... I don't understand this. And then there's the Hawking Radiation... which apparently allows virtual particles to become real...

 

[tiny-tim]

In wikipedia, it states that if a single virtual particle is detected, then the consequences of its existence are prolonged to such a degree that it cannot be virtual... I don't understand this.

That's the second sentence of the second paragraph of the introduction to http://en.wikipedia.org/wiki/Virtual_particle" , and I think most PF members would completely disagree with that introduction …

In physics, a virtual particle is a particle that exists for a limited time and space, introducing uncertainty in their energy and momentum due to the uncertainty principle. Because energy and momentum in quantum mechanics are time and space derivative operators, then due to Fourier transforms their spans are inversely proportional to time duration and position spans, respectively.…​

https://www.physicsforums.com/library.php?do=view_item&itemid=287" exist only in the maths (and even in the maths they have no creation event, annihilation event, or duration, whether limited or otherwise).

A "particle that exists for a limited time and space" is a real particle … that's what "real" means!

If it exists because it has "borrowed enough energy", then the amount of energy it has borrowed is exactly the amount for a real particle (eg, if it's a "borrowed-energy" electron, it has the correct wikipedia rest-mass of an electron), and therefore cannot be a virtual particle (which can have any rest-mass, even according to wikipedia, see below ) … it can only be a real particle!

(Actually, that's not completely correct … there are two types of virtual particle in the maths, those in the position representation, and those in the momentum representation … the first type do have the correct rest-mass, but they only obey conservation of 3-momentum, not of 4-momentum.

Since wikipedia http://en.wikipedia.org/wiki/Virtual_particle#Properties" "A virtual particle is one that does not precisely obey the m²c⁴ = E² − p²c2 relationship for a short time.", ie it defines it as not having the correct rest-mass, that means that wikipedia does not define that first type as a virtual particle! )​

 

[JoaoPais]

No, virtual particles are a mathematical device in the Dyson expansion in perturbation theory in quantum field theory,
(Even the mathematics does not give them any location or duration.)

Tiny Tim said: "virtual particles are a mathematical device". Do you understand what that means?

I’m sorry, correct me if I’m wrong, but virtual particles aren’t only a mathematical device, once, as far as I know, are used to explain the Casimir effect. The virtual particles “come to existence” only to be annihilated again in an infinitesimal variation of time and space, with is associated with the mass of the particle. Either way, they need some space for the appearing and annihilation to occur, and bitten two very close plates (10 nm) there are less virtual particles than outside the plates and this explains the force that appears to attract the plates (Casimir effect).
Also I’m not familiar with Dyson expansion, so I hope this doesn’t become some stupid question =P

 

[nismaratwork]

I’m sorry, correct me if I’m wrong, but virtual particles aren’t only a mathematical device, once, as far as I know, are used to explain the Casimir effect. The virtual particles “come to existence” only to be annihilated again in an infinitesimal variation of time and space, with is associated with the mass of the particle. Either way, they need some space for the appearing and annihilation to occur, and bitten two very close plates (10 nm) there are less virtual particles than outside the plates and this explains the force that appears to attract the plates (Casimir effect).
Also I’m not familiar with Dyson expansion, so I hope this doesn’t become some stupid question =P

That's an extension of a mathematical model, but it doesn't mean whatever is happening between those plates involved (it kills me to say this) "real" virtual photons... that's just how we describe the interaction. Remember, the action of virtual particles are used to explain REAL physical effects, but they're the mathematical intermediary between two states that ARE real.

In other words, I might talk about the tires of my car "biting" the surface of the road as a means of describing what happens vis a vis friction and the road, but the tires don't bite. You can talk about virtual photons between casimir plates or virtual pair creation at the event horizon of a BH, but it's just a MATHEMATICAL artifact used to describe an "in-between" interaction current physics has no physical explanation for.

 

[JoaoPais]

I’m sorry but, for me, the virtual particles seem as real as Higgs Boson, gluons or strings. A physical materialization of mathematic postulates that embody the best hypothesis to explain a certain observed physical phenomenon.
I understand what you mean, but it seems to me the real difference is what we account as real, being your real only the observed, described and experimentally documented.
Maybe I’m extending incorrectly my notion of “real”, that is true =)

 

[nismaratwork]

I’m sorry but, for me, the virtual particles seem as real as Higgs Boson, gluons or strings. A physical materialization of mathematic postulates that embody the best hypothesis to explain a certain observed physical phenomenon.
I understand what you mean, but it seems to me the real difference is what we account as real, being your real only the observed, described and experimentally documented.
Maybe I’m extending incorrectly my notion of “real”, that is true =)

I understand what you're saying, but the issue isn't that these are unobservable by direct means as is the case with a gluon... the gluon being to the the strong force as the photon is to EM. When the word "virtual" is said, in regards to a boson of any type we're talking about something that has no physical reality as you do when you omit the word "virtual".

In fact, here's the feynman diagram:
[PLAIN]http://wpcontent.answcdn.com/wikipedia/commons/thumb/1/1f/Feynmann_Diagram_Gluon_Radiation.svg/287px-Feynmann_Diagram_Gluon_Radiation.svg.png[/img0

SOMETHING happens between the annihilation of the real particles and the emission of the quarks and gluon, but what is only described by a mathematical formalism that has NOTHING to do with physical reality. Something with a physical reality (a force, the exchange of energy, etc) is described down to the point where we have to use "tricks" to fudge a bit to the next step.

I recommend reading this: http://en.wikipedia.org/wiki/Static_forces_and_virtual-particle_exchange

Especially portions dealing with the Coulomb Force, and have this up while you do: http://en.wikipedia.org/wiki/Virtual_particles

This isn't an issue of observed vs. unobserved, this is an issue of a bit of "filler" to do the job of something taking place according to the HUP which can't be described any other way, yet. SOMETHING is going on, yes, but there's no virtual photon there at least.

 

[TrickyDicky]

There are virtual W and Z bosons, which mediate low-energy weak interactions like nuclear beta decay, and real W and Z bosons, which can be produced in accelerators with enough energy. The difference is exactly like between virtual and real photons.

This could be confusing for newcomers, the fact that the gauge bosons come in real and virtual versions, for instance the W boson is defined in the wikipedia as the particle that as well as the Z boson mediaes the weak force, so the doubt arises as to wether is referring to the virtual W or the real boson W and when it describes its basic properties it states that "in practice it can be considered to be a virtual particle". So I would like to ask the experts which are the force mediators the virtual gauge bosons or the "real" ones because often it's not very clearly defined. In case the mediators are virtual bosons, what is the role of the real particles? In the case of the photons it's obvious they are the EM radiation , but what about the W and Z particles? ( I believe the gluon hasn't been found yet)
Also I read the mean-life of the W and Z bosons it's around 10E-25 seconds so I guess they can't be directly detected , and were discovered by indirect means, can someone explain in lay terms how? Thanks

 

[tiny-tim]

Hi TrickyDicky!

This could be confusing for newcomers, the fact that the gauge bosons come in real and virtual versions, for instance the W boson is defined in the wikipedia as the particle that as well as the Z boson mediaes the weak force, so the doubt arises as to wether is referring to the virtual W or the real boson W …

Wikipedia is not reliable on this topic (see post 13 above). Stop reading it!

and when it describes its basic properties it states that "in practice it can be considered to be a virtual particle".

I think wikipedia means that in practice we can't produce real W and Z … hmm … that's not really true either.

So I would like to ask the experts which are the force mediators the virtual gauge bosons or the "real" ones because often it's not very clearly defined.

Always virtual.

In case the mediators are virtual bosons, what is the role of the real particles? In the case of the photons it's obvious they are the EM radiation , but what about the W and Z particles? ( I believe the gluon hasn't been found yet)

Real W and Z buzz around colliding with things just as real photons do … this has nothing to do with the maths of virtual particles "mediating" an interaction.

 

[TrickyDicky]

Thanks, that was my idea but I wanted to check.

 

[jtbell]

the gauge bosons come in real and virtual versions,

So do other particles, e.g. electrons and positrons. See for example the first-order Feynman diagram for Delbrück scattering.

 

[Huttate]

I chuckle at the "Wikipedia is not reliable" post followed immediately by a post referencing Wikipedia as a proof.

Why do not those of you criticising Wikipedia get on there and correct it so that us who rely [too heavily?] on it do not come away misinformed?

 

[oraclelive]

Since there's a discussion going on real and virtual particle. What then is a real particle having understood that a virtual particle prompts the uncertainty of its energy and momentum in Heisenberg uncertainty principle?

 

[ExecNight]

I pose the question;

What's the difference between the operating system installed on your notebook and installed on a virtual machine =)

I guess the point is, the virtual system acts like its on a separate physical system, but its actually not. Just using the resources of another physical system, its not becoming a real notebook all of a sudden.

Hehe analogies :P

 

[3m0k177y]

virtual particles can materialize, its even been observed and tested. but not all virtual particles do so.
what I am saying is this; a virtual particle is what has a probability of being there, meaning that it is possible for it to be there. since everything in the universe is in a way random, we can't assume that a true vacuum without any particles whatsoever is possible, there is a possibility that particles are in the vacuum.
there is also the possibility that ALL particles got out of the vacuum in the first place, but unless we have a head count on all particles all throughout the experiment, there can't be any certainty of a true vacuum.
since we can't have a head count on all the particles, we can't truly observe their positions, their probability of being in any finite place is 0, they are still in superposition. even though they were just taken out of the vacuum, some of the particles that have superposition in the vacuum are observed in there, they have materialized in the vacuum.
but, before they materialized in the vacuum, they were virtual because they weren't observed. using this reasoning, one can theorize that virtual particles can materialize where they stand and become real.
if you think the example i gave has no scientific evidence to back it up, it does, it was tested, it was proven.
you can't say that virtual particles are JUST a tool for calculating.

 

[StevieTNZ]

I chuckle at the "Wikipedia is not reliable" post followed immediately by a post referencing Wikipedia as a proof.

Why do not those of you criticising Wikipedia get on there and correct it so that us who rely [too heavily?] on it do not come away misinformed?

Just simply don't rely on it. People can change the errors, but others can change those changes, so it could end up in a cycle.

 

[StevieTNZ]

Reading this: http://www.scientificamerican.com/article.cfm?id=are-virtual-particles-rea
and looking at the responses to the OP.

Different.

 

[lugita15]

Reading this: http://www.scientificamerican.com/article.cfm?id=are-virtual-particles-rea
and looking at the responses to the OP.

Different.

This is an interpretational question. Perturbation series in quantum field theory consist of terms which can very conveniently be represented as Feynman diagrams, and these Feynman diagrams can very naturally be interpreted as depicting the exchange of virtual particles. It's a matter of philosophical preference whether there terms in the perturbation series are actually discussing the exchange of real objects, or whether the fact that perturbation series can be interpreted using virtual particles is a mathematical coincidences. People who believe in virtual particles point out how intuitive they make phenomena in QFT. Others, however, believe that virtual particles are not real because they only seem to show up when you're doing perturbative calculations, not other kinds of calculations. They also say that virtual particles shouldn't be believed in because they're undetectible, since they just go from one particle to another particle; however, in that sense you could say that ALL particles are undetectable in transit, not just "virtual ones".

 

[salvestrom]

This is an interpretational question.

You're the first person to actually state this that I've come across. All other responses are very much "it's just maths".

A seemingly midway view that I've come across explained that virtual particles are general disturbances in a field that have properties similar to known particles and are treated as such to do the calculation, but at no point should they be thought of as the actual corresponding particle.

It does seem strange that the standard model parades around the 'real' bosons when they apparently only ever exist in collidors and have nothing to do with force mediation.

 

[juanrga]

Virtual Particles appear due to the Weisenberg Uncertainty Principle.

So if \Deltat is prolonged or something like that, virtual particles become real. Am I right?

No virtual particles are not real particles. Moreover, there is a school of thought believing that some 'real' particles as photons are in reality fictitious.