- #31
Sterj
@marlon: I found the first attachement in a pdf file. So, the formula is false? (I hope it is so)
What Are Vacuum Fluctuations and Their Role in Particle Creation?
- Thread starter Sterj
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Vacuum fluctuations, as described by the Heisenberg uncertainty principle, can lead to the temporary creation of particle-antiparticle pairs, which annihilate each other almost instantly. The Casimir effect arises from the difference in energy density between virtual particles inside and outside two closely spaced plates, resulting in a net attractive force. Virtual photons that do not fit between the plates do not manifest, as only certain wavelengths can exist in that confined space. The energy density of vacuum fluctuations is crucial in understanding these phenomena, as it varies with boundary conditions imposed by the plates. Overall, the discussions emphasize the complex interplay between quantum field theory and the behavior of virtual particles in vacuum states.
- #32
marlon
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Well, in the first formula that you gave there were no creation and annihilation operators and yet, there was a summation over lambda. I mean, YOU corrected it yourself
marlon
marlon
- #33
Lucretius
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- 0
If someone doesn't mind answering me, I am only 16 years old, but I want to learn about this stuff because it is very interesting…
What exactly is a photon? Someone said it was a quantum of energy, but what exactly is that? It's massless, so it isn't matter.
How does something get mass?
What exactly is a photon? Someone said it was a quantum of energy, but what exactly is that? It's massless, so it isn't matter.
How does something get mass?
- #34
marlon
- 3,779
- 11
Lucretius said:
A photon is indeed a quantum of energy. You know light is basically electromagnetic radiation. Physics has proven that a wave can also be looked at as a ray of particles. The particles associated with an EM-wave are the photons.
How elementary particles acquire mass is not easy to explain to someone who is not well trained in both QM and SR. this is a quantum field theory related subject
regards
marlon
- #35
Lucretius
- 151
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marlon said:
Ah, so photons just touch one another in a big line, and are able to transfer electromagnetic radiation through one another that way? Is this what is called "wave-particle duality"?
- #36
EL
Science Advisor
- 557
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Sterj said:
Since lambda takes on two values (polarizations)...?
- #37
Sterj
Another question:
We describe the ground state energy of the em-field with harmonic oscillators beeing at lowest energy level.
Now, someone told that the ground state vibration of the em-field are the photons, sounds logically (marlon) if we are in QFT.
If we are in vacuum and "watch" at the vacuum fluctuation there must always be a particle and its antiparticle exist. In the case of the photon it has to be two photons (because the photon is its own antiparticle).
1. Can the annihilation and creation of this pairs be explained with QFT where photons are vibrations? I mean you can't really add a photon to the zero point oscillation of the em field because then the em field isn't really in ground state. What I think is that these zero point energy of the em field is just the average energy of the field (marlon's posted formula).
2. If we work in QM the particle are wave (packets). So if I wonna explain this creation and annihilation of the two photons I have to do it as follows:
"Creation: HUP allows to create a particle and an antiparticle.
Lifetime: Both wave packets are flying around, simply said.
Annihilation: These wave packets interfer and thus energy is given back to vacuum"
We describe the ground state energy of the em-field with harmonic oscillators beeing at lowest energy level.
Now, someone told that the ground state vibration of the em-field are the photons, sounds logically (marlon) if we are in QFT.
If we are in vacuum and "watch" at the vacuum fluctuation there must always be a particle and its antiparticle exist. In the case of the photon it has to be two photons (because the photon is its own antiparticle).
1. Can the annihilation and creation of this pairs be explained with QFT where photons are vibrations? I mean you can't really add a photon to the zero point oscillation of the em field because then the em field isn't really in ground state. What I think is that these zero point energy of the em field is just the average energy of the field (marlon's posted formula).
2. If we work in QM the particle are wave (packets). So if I wonna explain this creation and annihilation of the two photons I have to do it as follows:
"Creation: HUP allows to create a particle and an antiparticle.
Lifetime: Both wave packets are flying around, simply said.
Annihilation: These wave packets interfer and thus energy is given back to vacuum"
- #38
Creator
- 566
- 6
selfAdjoint said:
Excellent question, selfAdjoint. The answer is yes. I have seen reports confirming that standing wave patterns can be created with oscillating walls which can locally lower (or raise) the energy density in certain regions in the cavity.
O. Meplan has shown that, due to oscillating walls, in principle the vacuum fluctuations inside the cavity can be made to increase exponentially, and gives the experimental possibility & feasability to be able to observe photon creation from the vacuum!
See:
"Exponential Growth of the the energy of a Wave in a 1D Vibrating Cavity...",O. Meplan & C. Gignoux, Physical Review Lett, Vol.76, #3, pg.408, 1996.
Creator
--He who laughs last thinks slowest.--
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