Stephen A. Lawrence
Mon, 09 Jun 2008 18:38:03 -0700
Robin van Spaandonk wrote:
In reply to Stephen A. Lawrence's message of Mon, 09 Jun 2008 16:51:17 -0400: Hi, [snip]Aether theory is predicated on the notion that there is some kind of aether which carries some kind of vibrations; as such that's a sort of fuzzy explanation (though the details are pretty wild if you stop and think about what sort of material aether must be, keeping in mind the obvious fact that planets and stars plow through the aether with no impediment to their motion, along with the fact that vibrations traveling in any known medium go faster as the medium becomes stiffer and slower as the medium becomes floppier -- and vibrations in the aether travel really wicked fast, so it must be really wicked stiff, which makes those planets cruising through the middle of it all the harder to understand).Perhaps it becomes easier to accept, if it is not a matter of ploughing *through* the medium. Consider how a wave passes through water. The energy of the wave is passed from molecule to molecule, but the molecules themselves don't actually go very far. Maybe the aether works the same way. Particles (e.g. electrons) are then *patterns* in the aether. The pattern can move, simply through the transfer of energy, without the aether itself moving.
But then it seems like this would lead to an issue with "aether dragging", doesn't it? Classical aether theories can't be reconciled with the results of the Fizeau, Michelson-Morley, and Sagnac experiments unless there is partial or complete "dragging" of the aether along with the Earth. If the Earth itself is just a pattern traveling through the aether that doesn't seem like a very obvious thing to have happen.
Alternatively one could assume the Earth is a traveling pattern in a Lorentz aether, which avoids the need for dragging, but the Lorentz ether theory loses a lot of the pleasingly "sensible" feel of classical aether. It leads to the same mathematical model as special relativity, which implies, in particular, that, while there is a distinguished "aether rest frame" in Lorentz ether theory, it cannot be detected in any way. There is no way at all to tell how fast you're moving relative to the aether, because all experiments produce the same results regardless of your absolute velocity; consequently you can't tell if you're stationary with respect to the aether or not. In fact, in so-called LET, the aether cannot be detected in any way; the theory is, in a word, indistinguishable from special relativity. This leaves one in a somewhat uncomfortable position, which is that of taking the existence of the central object in the theory entirely on faith.
*If* the aether itself is incompressible, then compression waves travel at infinite velocity, however transverse waves are probably limited to the velocity of light. Regards, Robin van Spaandonk The shrub is a plant.