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Author Topic: What are gravitons?  (Read 12732 times)

Offline Soul Surfer

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Re: What are gravitons?
« Reply #25 on: 20/11/2007 23:40:07 »
I am not quite certain what you mean when you use the term SHO but it looks likely that you mean simple harmonic oscillator.  This is a simplification of what is going on because photons do start and stop and for a quantum to be a wave packet it must contain a range of frequencies  it is possible for some quanta of electromagnetic radiation to be extremely broad band like impulses.
 

Offline JP

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Re: What are gravitons?
« Reply #26 on: 21/11/2007 03:54:24 »
Except that photons are the packets of oscillatory energy that a harmonic oscillator has.  Photons are not objects but are like Joules: they are units of energy (the conversion factor is hν J = 1 photon).  Saying that electric fields are made of photons is like saying it is made of cubits or seconds...preposterous.  Of course, I understand that I am the last person to claim he understands QED but if this is the conclusion of the theory, it can't be valid.  Maybe someone can explain the theory better...it is an experimentally proven theory (accurate to 10-12 according to Wikipedia).  I still think that anything that is quantized has to have something to do with a SHO just as every SHO's energy is quantized.

One way of quantizing the free electromagnetic field is by defining the same creation and annihilation operators that is used in the quantum SHO (I also think this same technique works for quantum fields in general, but I've learned it with respect to E&M).  Using a "creation" operator on a state give you an extra hbar*ω or energy (which corresponds to one 'photon').  Using an "annihilation" operator on a state takes away this same amount.  In that way, you can make units of energy, which are associated with photons. 

Why are these "particles"?  I think it's because if you go to measure a photon, you're actually measuring a packet of energy from the field.  The way a detector acts on the field is to usually annihilate some energy from the field (destroy a photon).  In this way, single photons can be "absorbed" by the detector, and they're kind of like particles. 

It's wrong to say that these photons are like "Joules."  A Joule is a unit of measurement.  These SHO states are wave functions, and physicists are used to describing particles by wave functions, so what's the problem with interpreting photons the same way?
 

Offline Alan McDougall

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What are gravitons?
« Reply #27 on: 12/11/2008 11:26:02 »
No one tried to answer What is a graviton, so I will give it a bash

Graviton is a postulated quantum, or carrier of the gravitational field, analogous to the well-established photon of the electromagnetic field. Gravitons, like photons, would be travelling at the speed of light and would be emitted only by highly accelerating, extremely massive objects such as stars. Graviton is postulated to be its own antiparticle, to have zero charge and rest mass, and a spin of 2. Since gravitons are apparently identical to their antiparticles, the notion of antigravity is questionable
 

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What are gravitons?
« Reply #27 on: 12/11/2008 11:26:02 »

 

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