Astrocast

Episode 215 was about the echoing of light. Light can echo in the same way sound can echo, though the angles are more particular. The reason we can hear sound echo is because of sound's slower speed. This is something that seems pretty obvious, but I never really considered it. Like sound, pulses are easier to hear than a constant stream (you'd never hear the echo if the sound was still drowning it out). Supernovas from stars are the best source of light pulses, though it is quite difficult to pin when they started through the pulses themselves. I also listened to episode 213, which was about supermassive black holes. The difference between a supermassive black hole and a regular ol' hole is simply the supermassive black hole is more massive; about a hundred million solar mass objects at least. They form at the center of galaxies, and we're not totally sure how they formed, but since detector technology is getting better, hopefully the newer information will shed more light. What I found most interesting was that from current models, black holes did not exist in the beginning of the universe- the distribution of mass was much too even for anything but microscopic holes to exist. This means that they are something progressive, and just pretty damn cool.