Gabriel Genellina wrote: > Before the famous Michelson-Morley experiment (end of s. XIX), some > physicists would have said "light propagates over ether, some kind of > matter that fills the whole space but has no measurable mass", but the > experiment failed to show any evidence of it existence.
Not just that, but it showed there was something seriously weird about space and time -- how can light travel at the same speed relative to *everyone*? Einstein eventually figured it out. In hindsight, Maxwell's equations had been shouting "Relativity!" at them all along, but nobody had seen it. > previous experiments showed > that light was not made of particles either. Except that the photoelectric effect showed that it *is* made of particles. Isn't the universe fun? > Until DeBroglie formulated > its hypothesis of dual nature of matter (and light): wave and particle > at the same time. Really it's neither waves nor particles, but something else for which there isn't a good word in everyday English. Physicists seem to have got around that by redefining the word "particle" to mean that new thing. So to get back to the original topic, it doesn't really matter whether you talk about light travelling or propagating. Take your pick. -- Greg -- http://mail.python.org/mailman/listinfo/python-list
