Virtual particles

[steevey]

Virtual particles are scientific law right? The process in pairs generates gamma rays and this is happening all over the place, so why am I not dead of radiation poisoning? Why aren't there many radioactive atoms in every substance on Earth and in the entire universe?

Couldn't this also account for some of the randomness generated by electrons? Classically, its like an electron gets a little boost of energy once in a while at a random time, which seems like it could be explained by the gamma-rays from virtual particle pairs.

Edited March 3, 2011 by steevey

[ajb]

Virtual particles are scientific law right?

 

They are accepted as part of scientific knowledge, if that is what you mean?

[swansont]

The process in pairs generates gamma rays and this is happening all over the place

 

They generate gamma rays? What reaction are you thinking of?

[steevey]

They generate gamma rays? What reaction are you thinking of?

 

Like a particle and its anti-particle appearing out of nothing then eliminating each other. Or is there some other way random unbound virtual particles disappear more often? I'm actually thinking of a post you made in another thread and a wiki article stating the process of a virtual particle pair anihilating each other once they appeared in space generates 2-3 gamma rays. There's also a bunch of stuff Stephen Hawking said about this, and how radiation might seen to be coming from a black hole because virtual particle pairs didn't always annihilate if one of the particle got sucked in.

Edited March 3, 2011 by steevey

[swansont]

Like a particle and its anti-particle appearing out of nothing then eliminating each other. Or is there some other way random unbound virtual particles disappear more often? I'm actually thinking of a post you made in another thread and a wiki article stating the process of a virtual particle pair anihilating each other once they appeared in space generates 2-3 gamma rays. There's also a bunch of stuff Stephen Hawking said about this, and how radiation might seen to be coming from a black hole because virtual particle pairs didn't always annihilate if one of the particle got sucked in.

 

No, that was after I said for the umpteenth time that electrons you find in an atom are not virtual particles. Annihilation of real electrons with real positrons produces 2 or 3 gammas. Virtual particles are a completely different topic. They involve either force carriers or the energy uncertainty of the vacuum, and (by themselves) do not produce real particles at all.

[steevey]

No, that was after I said for the umpteenth time that electrons you find in an atom are not virtual particles. Annihilation of real electrons with real positrons produces 2 or 3 gammas. Virtual particles are a completely different topic. They involve either force carriers or the energy uncertainty of the vacuum, and (by themselves) do not produce real particles at all.

 

I didn't say virtual particles in an atom, I said a pair, because as I've heard it, pairs of virtual particles seem to come into existence in a vcuum, or otherwise everywhere, then annihilate each other. I know that they are also associated with Gauge Bosons, but that's not what I'm talking about.

Edited March 4, 2011 by steevey

[swansont]

I didn't say virtual particles in an atom, I said a pair, because as I've heard it, pairs of virtual particles seem to come into existence in a vcuum, or otherwise everywhere, then annihilate each other. I know that they are also associated with Gauge Bosons, but that's not what I'm talking about.

 

And there is no gamma involved in that process.

[steevey]

And there is no gamma involved in that process.

 

How can scientists detect them then and know they exist?

[swansont]

How can scientists detect them then and know they exist?

 

Because there are real effects that result from it, such as the Casimir force.

[steevey]

Because there are real effects that result from it, such as the Casimir force.

 

Isn't that just one explanation for it? There doesn't seam to be actual proof of virtual particles, but rather just evidence that would make sense in describing certain things, and wouldn't that also violate the statement that matter and energy can't be created or destroyed? Or is there some quantum mechanical thing about their determination and indetermination too?

Edited March 5, 2011 by steevey

[swansont]

Isn't that just one explanation for it? There doesn't seam to be actual proof of virtual particles, but rather just evidence that would make sense in describing certain things, and wouldn't that also violate the statement that matter and energy can't be created or destroyed? Or is there some quantum mechanical thing about their determination and indetermination too?

 

If you require more evidence, I'm sure you're capable of using Google to look for it.

 

The HUP says that [math]\Delta{E}\Delta{t} > \hbar/2[/math] You can't tell what the energy is if you are looking at a short interval.

[Zarnaxus]

Is the amount of matter and antimatter that "randomly" appears always equal? In other words, would it be possible that over astrinomical amounts of time, matter can start to build up just by the imbalance of virtual particles? That would be important.

[IM Egdall]

Is the amount of matter and antimatter that "randomly" appears always equal? In other words, would it be possible that over astrinomical amounts of time, matter can start to build up just by the imbalance of virtual particles? That would be important.

 

As I understand it, virtual particles come in pairs - particle and antiparticle. They exist for a very brief amount of time then annihilate each other and dissapear. So there is no build up; no resultant imbalance of particles.

Edited March 8, 2011 by I ME

[Zarnaxus]

As I understand it, virtual particles come in pairs - particle and antiparticle. They exist for a very brief amount of time then annihilate each other and dissapear. So there is no build up; no resultant imbalance of particles.

 

 

If they appeared next to a black hole, and for some reason one got pulled in and the other did not, we can get the build up of matter right? If virtual particles appear everywhere, then this occurence should happen often near singularities, correct?

[steevey]

If they appeared next to a black hole, and for some reason one got pulled in and the other did not, we can get the build up of matter right? If virtual particles appear everywhere, then this occurence should happen often near singularities, correct?

 

That's been predicted be Stephen Hawking as an explanation for any radiation that would appear to be coming from a black hole itself aside from obvious jets which don't come from a black hole itself.

Edited March 10, 2011 by steevey

[Mike Smith Cosmos]

Isn't that just one explanation for it? There doesn't seam to be actual proof of virtual particles, but rather just evidence that would make sense in describing certain things, and wouldn't that also violate the statement that matter and energy can't be created or destroyed? Or is there some quantum mechanical thing about their determination and indetermination too?

 

I have just read in Wiiipedia today ( Electron subsection virtual particles ) that :-

 

 

" In classical physics, the angular momentum and magnetic moment of an object depend upon its physical dimensions. hence the concept of a dimensionless electron possessing these properties might seem inconsistent. The apparent paradox can be explained by the formation of virtual photons in the electric field generated by the electron. These photons cause the electron to shift about in a jittery fashion ( known as zitterbewegung) . Which results in a net circular motion with precession. This motion produces both the spin and the magnetic moment of the electron. In atoms this creation of virtual photons explain the Lamb shift observed in spectral lines "

[Widdekind]

Please ponder an electron interacting with a proton. The two particles inter-communicate electromagnetic forces, via 'virtual photons'. Now, by virtue of being 'virtual', those photons are 'off mass shell' -- they do not abide by the Einstein equation E² = m² + p², with m = 0. And, offsetting the particles' gains, in Kinetic Energy, by their losses, in Potential Energy, seemingly implies, that, despite experiences forces, neither particle's overall energy is affected. Does that mean, that the inter-communicating 'virtual' photons, carry momentum (p > 0), but no energy (E = 0), so that they can impart momentum & force, without affecting energy ?? When an electron binds to a proton, a force-carrying virtual photon is "promoted", into an actualized photon, which carries off the appropriate amount of binding energy (Dancing Wu-Li Masters). It seems as if, a virtual photon is 'charged' or 'burdened' with the appropriate amount of energy, like some sort of spring 'compressed' in between the impinging particles, and then 'let loose', in actualized, physical, form.

[Widdekind]

Virtual particles... involve either force carriers or the energy uncertainty of the vacuum, and (by themselves) do not produce real particles at all.

... there are real effects that result from it, such as the Casimir force.

 

So, quantum reality is 'bi-cameral', composed of (1) real particles, mathematically modeled with wave-functions; and (2a) (swarms of) virtual particles, associated to real particles, and (collectively) accounting for real particles' interactions; and (2b) a 'background ethereal sea' of virtual particles (perpetually [re-]appearing & disappearing) ?

 

[math]\hat{E} \Psi= \hat{H} \Psi[/math]

 

[math]i \hbar \partial_t \Psi(\vec{x}) = - \frac{\hbar^2 \, \nabla^2}{2 m} \Psi(\vec{x}) + V(\vec{x}) \Psi(\vec{x})[/math]

 

[math]\nearrow \; \; \; \; \; \; \; \; \; \; \; \; \nwarrow[/math]

virtual

particles

.......

real

particles

By definition, virtual particles are unobserved, & unobservable, directly (except, e.g., by 'promotion', of virtual photons, into real photons, during bindings, of oppositely charged particles*) ? Instead, their presence is only inferred, from influences affecting (the wave functions of) real particles ?

 

*

Perhaps it is possible to build a

virtual

particle 'ghost detector' -- the "goes-into" is a

virtual

photon; the "comes-out-of" is a promoted,

real

photon ? If so, then every time a (presumably promoted)

real

photon was emitted by the device, the (previous) presence, of a

virtual

photon, could be correctly inferred.

 

Electrons are always surrounded by a swarm of virtual photons. (There are other virtual particles in the cloud of virtual particles surrounding an electron, but photons are the most common among them.)

 

If two electrons come close enough to each other, close enough so that their virtual-photon clouds overlap, it is possible that a virtual photon that is emitted from one electron, will be absorbed by the other electron... The close the electrons come to each other, the more this phenomenon occurs. Of course, the process is two-way, with both electrons absorbing virtual photons that were emitted by the other.

 

This is how electrons repel each other. The closer two electrons come, the more virtual photons they exchange. The more virtual photons they exchange, the more sharply their paths are deflected. The "repulsive force" between them is simply the cumulative effect of these exchanges of virtual photons, the number of which increases at close range, and decreases at a distance. According to this theory, there is no such thing as action-at-a-distance -- only more & fewer exchanges of virtual photons. These interactions (absorptions and emissions) happen on location, so to speak, right there, where the particles involved are located.

 

The mutual repulsion of two particles, of the same charge, like two electrons, is an example of an electromagnetic force. In fact, according to QFT, an electromagnetic force is the mutual exchange of virtual photons. (Physicists like to say, that the electromagnetic force is "mediated" by photons). Every electrically charged particle continually emits & re-absorbs virtual photons, and/or exchanges them with other charged particles. When two electrons (two negatively charges) exchange virtual photons, they repulse each other. The same thing happens when two protons (two positive charges) exchange virtual photons. When a proton and an electron (a positive charge & a negative charge) exchange virtual photons, they attract each other.

 

Therefore, since the development of QFT, physicists generally have substituted the word "interaction" for the word "force". (An interaction is when anything influences anything else.) (Gary Zukav. The Dancing Wu Li Masters, pp. 224-226).

Edited April 12, 2011 by Widdekind

[swansont]

I really have no idea how the Schrödinger equation treats virtual particles, if at all.

[ajb]

I really have no idea how the Schrödinger equation treats virtual particles, if at all.

 

I think you can consider the Green's functions for the Schrödinger equation using perturbation theory. You should then be able to use Feynman diagrams and the language of virtual particles.

 

The path integral formulation is however much clearer when it comes to virtual particles.

[swansont]

I think you can consider the Green's functions for the Schrödinger equation using perturbation theory. You should then be able to use Feynman diagrams and the language of virtual particles.

 

The path integral formulation is however much clearer when it comes to virtual particles.

 

Ah, right. I haven't done anything with Green's functions since grad school. Don't have fond memories of that part of the QM class.