Recent content by kcdodd

His point is that if there were such a thing as a maximum acceleration, then it would have to be a new fundamental constant, and thus be independent of the observation frame due to the principle of relativity. However, we know how accelerations transform between frames based in SR. Just work it...

Yes that is what I meant. I disagree with his statement at the beginning that it must be a constant. It should of course depend on the boundary conditions of the "vacuum" if it is going to be a result of quantum mechanics. Now, something I find strange. It seems to me that if one had a volume...

Actually it is more simple then acceleration. Imagine two planets A and B separated by 1ly who have Einstein synchronized clocks. A spaceship traveling at a constant 0.99c in a straight line from planet A to planet B, passes planet A when the clock on the planet reads zero in both frames, and...

I have just a very general question regarding the idea of vacuum energy. It seems that it exists it would have to occur such that it would be the same in every reference frame to satisfy the principle of relativity, yes? Would that suggest it would be part of a stress-energy tensor which is...

It's in effect both an inner product and a "cross-product" (actually the outer product). When you take the geometric product of two vectors, what you get is a combination of the two products. For vectors a and b: ab = a\cdot b + a\wedge b Now, this results in an object which is not...

I think knowledge of feedback control is probably more important than EM theory. One can have all the theory and it still just comes down to a feedback loop. The control circuit/code will probably not use any theory at all. All you have to know is bigger current = bigger force. Then tweak the...

Centrifugal force only appears in a non-inertial reference frame. Assuming you're describing this in an inertial frame there is no centrifugal force. The force pair is the centripetal force of the bucket acting inward on the water, which causes the water to follow a circular path, and the force...

Does he mean it is not a vector because it is a pseudo-vector?

I am not quite sure if one can distinguish fields like that. Anywhere there is no source then the field automatically obeys the source-free maxwell equation, whether or not one considers the field to be "sourced" somewhere else. Classically one might suppose that a constant field must be due to...

I have also asked myself if sources can exist without any fields. It seems clearly they cannot. One cannot have an electron without any electric or magnetic field. It is intrinsic to what an electron is. However, one can have EM fields without electrons. A charged particles does not seem...

E&M radiation through conservation of energy.

The question is even actually slightly more interesting then that. There is what is called a duality transformation for Maxwells equations which can transform E and B into E' and B', and electric charge and current into a mixture of electric charge, current, and also magnetic charges and...

So by moving magnetic field you mean a field changing strength and/or direction in time?

How do you define a moving magnetic field? A moving current?

his remark probably comes from Maxwells equations, which has solutions when charge and current density is zero.