ASTR 5 Lecture Notes - Lecture 2: Ecliptic, Positive Feedback, Photon
Document Summary
The universe is very carefully fine-tuned : inhomogeneities were born, inflation caused them to expand a lot, producing huge structures. These are no longer at quantum level, it"s at a solar system level. Very small differences in reality but the image is enhanced. The denser (red) regions had more gravity so they didn"t expand as fast, more gravity means they slowed down and collapsed! High density= a lot of matter and a lot of gravity. They are born with a wide variety of masses and the biggest ones are always the rarest. Currently, our entire milky way galaxy forms about 1 new star per year, mostly in its gas-rich spiral arms: the sun is 4. 57 billion years old. Water waves need water, but sound waves need air, it"s a wave that travels through a vacuum: brightness (of light) or intensity (light, sounds, etc. ) is power per unit.
