3 ms·

> He approached understanding of the nature of the speed of light by realizing that a universe where you could travel as fast as (or faster than) a light ray wo

> He approached understanding of the nature of the speed of light by realizing that a universe where you could travel as fast as (or faster than) a light ray would have consequences that we didn't see. A sound wave could be outrun though. I don't see any step in why a such an philosofical approach would apply to light but not sound?

xorbax 2y ago
Because photons behave in a fundamentally different way than sound. See the Michelson-Morley experiment.
shadowgovt 2y ago
The relevant quote from his Autobiographical Notes is "...a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam of light as an electromagnetic field at rest though spatially oscillating. There seems to be no such thing, however, neither on the basis of experience nor according to Maxwell's equations. From the very beginning it appeared to me intuitively clear that, judged from the standpoint of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest. For how should the first observer know or be able to determine, that he is in a state of fast uniform motion? One sees in this paradox the germ of the special relativity theory is already contained." In short, he realized that if things could travel at lightspeed, we should be moving relative to something out there at lightspeed, so we should be experiencing its light as this weird "electromagnetic field at rest though spatially oscillating" (i.e. a field coming from apparently nowhere that changes in intensity as you move around in space but not in time)... but nobody had ever seen that phenomenon. Einstein seems to have put a lot of stock in "If physics allows it, we should be seeing it" as a razor of sorts, so it makes sense that when the math said black holes should exist but they hadn't been seen, his default position was to be skeptical of the math and the intuition. Such skepticism had served well in the past for him. (Worth noting for completeness: The "variable speeds of light predict stationary waves, but we never observe such things" objection is just one objection that comes up in Einstein's thought experiments. A more complete treatment of the subject is given in at https://sites.pitt.edu/~jdnorton/Goodies/Chasing_the_light/ https://sites.pitt.edu/~jdnorton/Goodies/Chasing_the_light/).

xorbax 2y ago

Because photons behave in a fundamentally different way than sound. See the Michelson-Morley experiment.

shadowgovt 2y ago

The relevant quote from his Autobiographical Notes is "...a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam of light as an electromagnetic field at rest though spatially oscillating. There seems to be no such thing, however, neither on the basis of experience nor according to Maxwell's equations. From the very beginning it appeared to me intuitively clear that, judged from the standpoint of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest. For how should the first observer know or be able to determine, that he is in a state of fast uniform motion? One sees in this paradox the germ of the special relativity theory is already contained." In short, he realized that if things could travel at lightspeed, we should be moving relative to something out there at lightspeed, so we should be experiencing its light as this weird "electromagnetic field at rest though spatially oscillating" (i.e. a field coming from apparently nowhere that changes in intensity as you move around in space but not in time)... but nobody had ever seen that phenomenon. Einstein seems to have put a lot of stock in "If physics allows it, we should be seeing it" as a razor of sorts, so it makes sense that when the math said black holes should exist but they hadn't been seen, his default position was to be skeptical of the math and the intuition. Such skepticism had served well in the past for him. (Worth noting for completeness: The "variable speeds of light predict stationary waves, but we never observe such things" objection is just one objection that comes up in Einstein's thought experiments. A more complete treatment of the subject is given in at https://sites.pitt.edu/~jdnorton/Goodies/Chasing_the_light/ https://sites.pitt.edu/~jdnorton/Goodies/Chasing_the_light/).