re: #7 Bob Levin

Intuition is a tough one… mine, as far as the physical universe goes, isn’t so great - in school I was better at mathematics than physics partly because the universe doesn’t act like the way I think it should.

As far as SR is concerned, even though Einstein claims the Michaelson-Morley experiment result was not the inspiration for his “Electrodynamics” paper, for me as a young student learning of the M-M experiment, and then learning that light changes in frequency when the light source moves relative to me (the observer), helped me get used to the notion that the Galilean type of transformation is not quite right and only works as an approximation for us.

Accepting that the old way of thinking really does fail, I suppose it becomes easier to reprogram oneself… to change the “intuition”.

Here’s how I think of it: if I wanted to generate a magnetic field I would need to have a source of electric charge, say an electron, and make it move relative to me. This can readily be demonstrated with simple equipment (and is done all the time in physics labs.) Yet if I only get the magnetic field when I and the electron are moving relative to each other, if I accelerate myself to move at the same velocity as the electron then the magnetic field I had measured from the electron’s motion earlier disappears. Thus this phenomenon called the “magnetic field” really is a phenomenon dependent upon relative motion, in this case between an electron with the electric field it generates, and another reference frame (the one in which I happen to exist.)

That, anyway, is how I intuitively come to accept that magnetic fields are due to (relativistic) transformations of electric fields. Others probably have more eloquent and insightful ways of viewing these things.

Historically since magnetism was a phenomenon discovered on its own, and thought a property of rocks, it came as a surprise to many later that magnetism really is another manifestation of the phenomenon we call “electricity.”