Notes by
Ben Borgers
Fâ22
Iâd heard people mention in passing that the universe is expanding, and that the rate of expansion is increasing, but Iâd never understood what that really meant (or how we know this to be true).
Thatâs why I really enjoyed the quick example with California, and how that shows that distances to further-away objects increasing more means the universe is expanding uniformly. It wouldâve normally been something that I wouldâve glossed over a bit, thinking âyeah I guess that makes sense,â without actually understanding it. But the California example really drove it home.
In general, a lot of the things weâve covered so far (like âWhy is the moon red near the horizon?â or âWhy do people think dark matter exists?â) are things that Iâve heard people talk about before, but I didnât actually understand them. I really enjoy filling knowledge gaps like that, so Iâve appreciated this class.