Science Buddies: "Ask an Expert"

What if you could generate a magnetic field around a particle once it is traveling at the speed of light? Would the magnetic field be bent to follow only behind the particle and not in front of it? If it did reach out in front of the particle then the magnetic field will have traveled faster than the particle itself. If time theoretically equals zero at light speed and the magnetic field were to spread out in front of the particle, then could you assume that a portion of that magnetic energy will have traveled back in time? What would come of an experiment like this? I would like to hear your thoughts, this is something I've not heard of being attempted in a laboratory.

SeaLeg - Interesting question. About half physics, the other half, philosophical. For a moment, lets assume that Albert Einstein was probably smarter than both of us. His immediate response might be that the speed of light (or your particle) was at a maximum velocity. Therefore your question about creating a magnetic field around this particle, inferring that it was a symmetrical space, and had a leading and lagging displacement, or position, would invoke the problem that the leading component would have to have achieved a velocity greater than the speed of light to establish it's position in front of the particle. I think Einstein may have asked "where was the particle when you attempted to introduce the magnetic field, and why do you think the field would be created in front of the position of the particle at that instant"? Perhaps you would answer that half of the field would lag, or be behind the position or the particle, inferring that the other half would by necessity be leading, or ahead of the particle. To which, he may answer that the field would always be behind the particle, and never see the particle as the center of activity. I'm certainly not very sure of this, and invite other 'Experts' to share their theories. As I said, more of a philosophical question than a physical question. Looking forward to the input of others.

Rick Marz

Well, this is a bit of an abstract question. Only massless particles can travel at the speed of light, and as far as I know, they are all chargeless and therefore can't "generate" magnetic fields.

Another issue is that magnetic and electric fields are kind of different views of the same phenomenon... a photon, in one view, *is* an oscillating electromagnetic field. The wavefront of that photon consists of both magnetic and electric fields, and so I don't see why they would propagate at different speeds.