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24
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4answers
5k views

Are W & Z bosons virtual or not?

W and Z bosons are observed/discovered. But as force carrying bosons they should be virtual particles, unobservable? And also they require to have mass, but if they are virtual they may be off-shell, ...
13
votes
3answers
4k views

The exchange of photons gives rise to the electromagnetic force

Pardon me for my stubborn classical/semiclassical brain. But I bet I am not the only one finding such description confusing. If EM force is caused by the exchange of photons, does that mean only when ...
13
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2answers
2k views

Virtual photon description of B and E fields

I continue to find it amazing that something as “bulky” and macroscopic as a static magnetic or electric field is actually a manifestation of virtual photons. So putting on your QFT spectacles, look ...
9
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2answers
1k views

Virtual particles and physical laws

Recently, I was reading about Hawking Radiation in A Brief History of Time. It says that at no point can all the fields be zero and so there's nothing like empty space(quantum fluctuation etc.). Now, ...
1
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2answers
1k views

Is all matter made of virtual particles?

This article in New Scientist says that all matter is actually virtual particles popping in and out of existence and nothing more. is this correct?
7
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2answers
2k views

Virtual photons, what makes them virtual?

The wikipedia page "Force Carrier" says: The electromagnetic force can be described by the exchange of virtual photons. The virtual photon thing baffles me a little. I get that virtual particles ...
3
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2answers
323 views

Deriving the Coulomb force equation from the idea of photon exchange?

Since Newton's law of gravitation can be gotten out of Einstein's field equatons as an approximation, I was wondering whether the same applies for the electromagnetic force being the exchange of ...
6
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3answers
1k views

Why aren't all photons virtual particles even in the “vacuum” of empty space? [duplicate]

I'm thoroughly confused about the nature of electromagnetic radiation. Light is supposed to exhibit both wave and particle characteristics. But does that mean that it is both a wave and a particle or ...
5
votes
2answers
12k views

What exists in the Space between atoms

Apologies to all if this has been asked before, I searched but was unable to find one similar. This is a question that has been bugging me for a while that i haven't really been able to find a ...
7
votes
3answers
754 views

What makes a Feynman diagram real or virtual?

Simple question: as the title says, what makes a real Feynman diagram real, and what makes a virtual diagram virtual? Or in other words, how do I tell whether any given diagram is real or virtual? ...
7
votes
3answers
764 views

What really goes on in a vacuum?

I've been told that a vacuum isn't actually empty space, rather that it consists of antiparticle pairs spontaneously materialising then quickly annihilating, which leads me to a few questions. ...
11
votes
3answers
422 views

Does radio use virtual photons?

In radio communication each accelerated electron in the transmitter antenna interacts with an electron in the receiver antenna by exchanging a photon. Is that photon always a virtual photon as ...
8
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2answers
1k views

Is there a “difference” between photons that act as virtual particles and photons that act as the quanta of EM radiation?

I) I know that virtual-photons are known to be the force-carriers for the Electromagnetic force, and that they are called "virtual" because the Energy-Time-inequality version of the Heisenberg ...
2
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1answer
119 views

Virtual Photon transmission speed of a Static Electric Field?

In the case of a non-accelerating point charge "A" of stable velocity, its static field is treated as though it is instantaneously present at a distance, i.e. a second point charge "B" will react to ...
5
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4answers
4k views

What are electromagnetic fields made of?

I am trying to understand electromagnetic fields so I have two question related to them. What is a electromagnetic field made of? Is it made of photons / virtual photons? How about a static electric ...
3
votes
0answers
107 views

At what expansion rate (H) would virtual particles be ripped apart into real particles, and what might be the density (temperature) of such an event?

Is it even possible for a virtual particle-antiparticle pair to be torn apart by cosmological expansion? Virtual particle-antiparticle pairs are ripped apart near black hole event horizons, creating ...
3
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2answers
937 views

Photon as the carrier of the electromagnetic force

My physics background goes as "far" as reading popsci books on QM, Particle Physics, and Cosmology so pardon my ignorance in the below questions. I've read that the photon is the particle (quanta in ...
2
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2answers
1k views

Are there any other mechanisms that can make virtual particles 'real' other than Hawking Radiation and Universe Births?

As I understand it, if virtual particles do not recombine within the plank time they become 'real'. This is proposed to happen in Hawking Radiation, where one virtual particle crosses the black ...
1
vote
1answer
1k views

Is it possible that the Big Bang was caused by virtual particle creation?

As far as I understand, it is understood that throughout the universe there exists, what is known as, a quantum field from which, due to its fluctuations, temporary (pairs of) virtual particles ...
4
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1answer
360 views

Coulomb interaction as virtual particles exchange?

I've been reading about virtual particle exchanges in physics books and in Physics SA posts, where a particle interpretation of gravity and Coulomb interaction is established. The Feynman Diagram ...
2
votes
1answer
111 views

Time taken for gravity of a distant object to interact with a newly created particle? [duplicate]

Possible Duplicate: The speed of gravity Does gravity travel at the speed of light? Imagine there is a large mass $m_1$ (e.g. a star) 1 light-year away from us. It is stable, stationary ...
7
votes
2answers
2k views

What's the relation between virtual photons and electromagnetic potentials?

Given that: 1) virtual photons mediate the electric and magnetic force fields 2) the magnetic field is the curl of the magnetic vector potential 3) the electric field is the negative gradient of ...
4
votes
2answers
677 views

Some questions about virtual particles

When reading about quantum mechanics, I've stumbled upon a description of the force between two electrons as a result of virtual particles being "exchanged" by the two electrons. So far I've ...
7
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4answers
1k views

Hawking Radiation - Why it causes black holes to die? [duplicate]

If a particle is being expelled from the Black Hole and an antiparticle is being driven into it, shouldn't the opposite occur as well and in the same frequencies? I mean Black holes should emit ...
5
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3answers
3k views

How many photons can an electron absorb and why?

How many photons can an electron absorb and why? Can all fundamental particles that can absorb photons absorb the same amount of photons and why? If we increase the velocity of a fundamental ...
6
votes
2answers
457 views

Virtual photon counting

How to calculate number of exchanged virtual photons per unit of time between two electromagnetically interacting objects?
5
votes
1answer
324 views

Energy conservation of Virtual Particles - Quantum Fluctuation?

I (as a middle-school student) was wondering how virtual particles even conserve energy of the entire system? I don't mean just the particle's energy, but conservation with respect to the ...
4
votes
2answers
916 views

What is the physical process (if any) behind magnetic attraction?

I understand that the electromagnetic force can be described as the exchange of virtual photons. I also understand that it's possible for virtual photons, unlike their real counterparts, to have mass ...
3
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4answers
180 views

Virtual particles/quantum tunneling - conservation of energy?

I'm confused as to how the above phenomena can take place since arent they breaking the law of conservation of energy (even, if temporarily)?
2
votes
2answers
196 views

Hawking Radiation and virtual particles

Why is energy/ mass taken away from a black hole? Doesn't the energy coming from the virtual particle come from the vacuum energy? ...if this is so, why does the black hole have to pay the energy ...
1
vote
2answers
462 views

The virtual particles are only a fictive tool in equations? DO they exist or DON'T? And if they exist, why do we call them VIRTUAL?

There is no "action at a distance" in nature. Attraction of a piece of iron by a magnet, attraction between distant electric charges of opposite sign, have to be mediated by something. The virtual ...
7
votes
2answers
252 views

Do virtual photons have a frequency?

Real photons do have frequencies, which is directly related to its energy. So, can virtual photons that take part in EM interactions have frequencies too? When my hand is pressed up against a glass ...
3
votes
2answers
601 views

Spacelike and timelike photons

I know the definition of space-like and time-like intervals. How do you show that in some reaction the virtual photon(s) is spacelike/timelike? On page 191 Peskin and Schroeder, it says "since ...
2
votes
2answers
332 views

Does path integral and loop integral in a Feynman diagram violate special relativity?

Consider a correlation function between two points $A(x_1,t_1)$ and $B(x_2,t_2)$, we need to integrate over paths which could be infinite long. But the time length $(t_1-t_2)$ is finite, so if $A$ ...
1
vote
2answers
355 views

Electron recoil after emitting virtual photon

Assume that a stationary electron $A$ emits a virtual photon with $4$-momentum $k$ and a stationary electron $B$ absorbs it. Let us assume a description in which time is moving forwards. At the ...
1
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1answer
408 views

Conservation of Energy and Quantum Fluctuations

Regarding conservation of mass-energy Wikipedia says: "this is an exact law, or more precisely, has never been shown to be violated." However, regarding quantum fluctuations, Wikipedia says here: ...
2
votes
1answer
145 views

Why don't virtual particles violate conservation of mass/energy?

If virtual particles sometimes add more mass/energy to a system then was inputed or comes out in the output, how do they not violate conservation of mass/energy.
1
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0answers
44 views

Hawking Radiation: Couldn't virtual particles make black holes more massive? [duplicate]

From what I understand about Hawking radiation, a virtual particle comes into existence very near the event horizon of a black hole. This causes one part of the particle to fall into the black hole, ...
0
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1answer
71 views

How do photons mediate (or create) a force?

Is there a somewhat intuitive explanation as to why the exchange of a photon between two particles causes a force between those particles? Is there a difference in the way massless and massive ...
0
votes
1answer
123 views

Why doesn't a changed particle ever lose energy by interacting with others by radiation of virtual photons? Are all virtual photons exchanged?

I've had it explained to me in a separate post that charged particles are constantly exchanging virtual particles with other charged particles and their energy is a steady state. How it is a surety ...
0
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0answers
30 views

Virtual Particles and Causation [duplicate]

Sometimes when people debate what type of cause a universe with a beginning may have Virtual Particles has been used as an example of a thing that can arise without a cause. So my question would be ...
0
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1answer
152 views

How are magnetic and electric fields transmitted?

This may be a duplicate, but how are (ideally) constant E- and B-/H-fields transmitted thru space? In this situation I like think of EM radiation as a note from a particle informing the universe of a ...