Recent content by Erland

Actually, it was Dale, not me, who first mentioned the aether in this thread. And in fact, I can give a reference to back up my "interpretation". I hope that Einstein isn't regarded as completely obsolete today. He writes in his 1905 paper, section 3, where he is deriving the Lorentz...

The 2nd postulate, in "my" interpretation, says that there is at least one intertial frame in which the light speed always is measured to c. If there is an aether, this means that it must be at rest in this frame. Of course, a consequence of the postulates is that we can do better without the...

Well, there is some inertial frame in which some local volume of air happens to be at rest at some time. There is no inertial frame in which all air always must be at rest.

No, the problem doesn't arise for sound. There is no inertial frame in which air cannot move.

Then we would have one intertial frame where there can be no aether drag which can influe the light speed, but other intertial frames with aether drag which influe the light speed. Seems to me that the laws of physics are different in those frames, hence violating the 1st postulate.

Do I understand you correctly: You imagine that in one inertial frame, the one we call "stationary", there is no local aether drag and the light speed is measured to c everywhere, but in another inertial frame, there is local aether drag and the light speed is measured to different values at...

I don't understand. Are you thinking of some kind of "aether drag" hypothesis?

No, I don't assume that "moving" and "stationary" have some absolute meaning. I mean the same as you: "sources that are moving [or not moving] relative to the observer". One could imagine making experiments where several observers moving with various velocities relative to each other all measure...

I meant of course the speed of light in vacuo. I took that for granted and didn't write out.

The way I understand what Einstein wrote is that one picks an inertial frame (in principle arbitrarily, since they cannot be distingushed from each other by any physical means, as many of you point out), but that it is only for this selected frame that the light speed is assumed to be measured...

Einstein's two postulates of special relativity reads, according to Wikipedia: The postulates are most often formulated similarly to this. But in my opnion, the second postulate shouldn't be formulated as above, because then one misses the point. This is particular true for the second...

##\sqrt 3## is here defined as the supremum of the set ##A##. It is not a priori given that the square of this number is 3, nor that it cannot be greater than any number whose square is less than or equal to 3.

Can one really by using such an oscilloscope measure the light speed with a relative accuracy of 0,0003%? This is required if we want to measure the hypothetic difference in light speed caused by the daily rotation of the Earth.

Well, one simple experiment would be to walk and bounce a ball, or something like that, to demonstrate the special relativity principle. But would that suffice? Mustn't one also demonstrate the invariance of light speed? This seems impossible without advanced equipment?

Wouldn't it suffice to just describe some of the most important experiments, without actually carry them out? It seems unlikely that a college should have the equipment to test any of most important experiments to corroborate SR. If it is really required to actually carry out an experiment...