# Thread: Could a Particle have mass if in a Magnetic field?

1. ## Could a Particle have mass if in a Magnetic field?

If a particle is traveling at the speed of light can it have mass if its within a magnetic or electrical field? Like a photon? I mean mass has to be moving right? But what if the photon were moving and the particle was just hitching a ride so to speak? Would that be possible? I know a photon has 0 mass but could it carry another particle or charge in its fields?

2. Order of Kilopi
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Ouch. Ouch ouch ouch.

-- Jeff, in Minneapolis

3. I will come rescue you Jeff...

NO.

We have mass and are in a magnetic field.... Photons are not able to Carry anything... and are massless...

4. Originally Posted by coliver
If a particle is traveling at the speed of light can it have mass if its within a magnetic or electrical field? Like a photon?
No massive particle can travel at the speed of light, it can get close, but it cannot reach it (unless you prove GR wrong). Now being in a magnetic or electric field does not do anything to the particle if it is neutral. If it is charged the magnetic field will let it gyrate (through the Lorentz force) and the electric field will accelerate (decelerate) it through the electric force.

Now a photon does not have mass, never had any, never will have any, it has momentum though. A photon in an magnetic or electric field does not obtain any mass, it does not do much at all in those fields.

Originally Posted by coliver
I mean mass has to be moving right?
no no, mass can be at rest too, no problem, that's why we have couch potatoes.

Originally Posted by coliver
But what if the photon were moving and the particle was just hitching a ride so to speak? Would that be possible? I know a photon has 0 mass but could it carry another particle or charge in its fields?
You are getting at something, but you don't know the details. You have probably heard of particles surfing on an electromagnetic wave. This can happen in a plasma, the details are rather complicated, but if the particle has the correct velocity etc. then it can "surf" on the crests of an electromagnetic wave. However, this only works if you consider the wave properties of "light" and not if you consider it a "particle". (I am not sure if surfing has been described at the photon level.)

So, particles can "hitch a ride" on a plasma wave, however, these waves usually do not travel at the speed of light, so there is no problem for the particle to reach the wave velocity.

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I believe that it may have mass if you are in the same reference frame as the particle (irregardless of the field its in), and you and the particle see a reference point move by at the speed of light. It does not have mass if you see the particle move at velocity c, with respect to yourself. I could be wrong. Its all a question of reference frames.

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Originally Posted by coliver
If a particle is traveling at the speed of light can it have mass if its
within a magnetic or electrical field? Like a photon? I mean mass has
to be moving right? But what if the photon were moving and the
particle was just hitching a ride so to speak? Would that be possible?
I know a photon has 0 mass but could it carry another particle or
charge in its fields?
On re-reading this it occurs to me that there may be a tiny grain of
correct information hidden in there -- it just happens to be exactly
backwards. Massive things don't have to be moving, but massless
things do. Light is always in motion, relative to everyone.

-- Jeff, in Minneapolis

7. You are getting at something, but you don't know the details. You have probably heard of particles surfing on an electromagnetic wave. This can happen in a plasma, the details are rather complicated, but if the particle has the correct velocity etc. then it can "surf" on the crests of an electromagnetic wave. However, this only works if you consider the wave properties of "light" and not if you consider it a "particle". (I am not sure if surfing has been described at the photon level.)

So, particles can "hitch a ride" on a plasma wave, however, these waves usually do not travel at the speed of light, so there is no problem for the particle to reach the wave velocity.
Exactly Tusenfem, thanks for straightening me out, and to Jeff Root as well. I do have it backwards. But thats what I was wondering if it would be possible for a particle to surf the photons wave or whatever

8. There is actually something interesting that emerges from thinking about this question. If it were possible for a zero-mass particle to have a charge (that probably isn't possible, but let's imagine it), then in the presence of a magnetic field, that zero-mass particle would not have to be moving at the speed of light. In fact, it would be impossible to get any motion relative to that magnetic field-- the massless particle would be completely "frozen in" to the field by the Lorentz force. So it does not appear to be true in all hypothetical situations that a massless particle must move at the speed of light. This hypothetical particle, in the "guiding center" picture, would actually act as if it had infinite inertia but no rest mass (by virtue of its connections with the magnetic sources).

9. There is actually something interesting that emerges from thinking about this question. If it were possible for a zero-mass particle to have a charge (that probably isn't possible, but let's imagine it), then in the presence of a magnetic field, that zero-mass particle would not have to be moving at the speed of light. In fact, it would be impossible to get any motion relative to that magnetic field-- the massless particle would be completely "frozen in" to the field by the Lorentz force. So it does not appear to be true in all hypothetical situations that a massless particle must move at the speed of light. This hypothetical particle, in the "guiding center" picture, would actually act as if it had infinite inertia but no rest mass (by virtue of its connections with the magnetic sources).
I'm not sure if I understood everything you posted Ken but in plain English, would that be similar to saying that since the photon is moving at the speed of light and the particle is say riding between the waves that it would have inertia but not necessarily be moving itself?.. Thats basically why I asked the question. My thinking is that if a massless Photon could carry a charge within its frequency somehow, that it may interact with particles on a quark level or something to that effect. Or that possibly the photon could carry a Neutrino with its small mass in the same fashion? If you see my post in ATM about Photons creating Elements you'll see what I'm hypothesizing?
Last edited by coliver; 2008-Jul-13 at 07:40 AM.

10. I was just wondering what would happen if a massless particle had a charge, not if a particle with mass were dragged by a photon (it could not be dragged at c). It is probably impossible for a particle with zero mass to have a charge, but it is normally assumed that any such particle would have to be moving at c, on the grounds that any electric potential that it encountered would convey energy to it, and any energy would require motion at c. I was wondering if a magnetic field could prevent that, but any electric potential along the direction of the magnetic field would still produce that result-- it would have to move at c. Don't ask me what happens if a charge moves at c! That's the part that is probably impossible.

11. I was just wondering what would happen if a massless particle had a charge
Hmmm thats an interesting possibility too? My thinking has been that maybe the magnetic field acts as an insulator? Kind of like a sheathing or insulation on a wire. Once the photon makes contact with a mass the result would be absorption or reflection of the radiation, but on the way down its insulated.

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