The show notes are located here and here. As usual, any additional links came from these sources.
1.) It all started with a Big Bang-Hey!: but-why? The universe, as Edwin Hubble knew, is moving away from itself and this expansion originated from a single point. The Big Bang Theory perfectly explains the universe that we observe today but it doesn't explain how it got here. This has been complicated by the results of WMAP (Wilkinson Microwave Anisotropy Probe) which studied the after-image of the Big Bang, the Cosmic Microwave Background which showed that the universe was too homogeneous. There are different theories for the cause: a quantum bounce, something about cosmic foam and the multiverse. But because the Big Bang occurred before time, we don't know and don't know (for now) how to know.
2.) Inflation: on a related note, what exactly "banged" and started the expansion? This deals with a very specific and minute period of time in the first second following the Bang event-well, maybe after the Bang event or, maybe before-when objects when matter was moving away from each other at faster than light speeds. Now, this is confusing and seems to contradict Einstein so Pamela qualifies this by saying, "Now, it wasn’t that they were moving through space faster than the speed of light. It was that the whole universe was expanding such that two points seemed to be moving apart faster than the speed of light, which is completely legal according to relativity." Inflationary theory says the cause is a form of repulsive gravity. Again, the reason this theory of inflation is so appealing is the homogeneous appearance of the universe. There are some good graphics on this here and more than you'll ever want to know here.
We don't know what triggered this high-energy even or what stopped it, partially because it's hidden behind the CMB. Which brings us to...
3.) Will we ever be able to see past the Cosmic Microwave Background: Here's (one of) the important things to remember about the CMB--it's not the glowing remnants of the Bang. It's 300-400 thousand years afterwards when the universe had cooled enough that it was no longer opaque (the opacity was caused by the constant absorption and re-absorption of photons.) One way we might be able to peer past it in the future is with gravitational wave detectors instead of using the spectrum of light. In fact, it might be the only way. But we have to get much better at detecting gravitational waves. The big advantage of gravitational waves is that, while they weaken by distance traveled, they are unchanged by anything they come in contact with, unlike electromagnetic radiation.
4.) What the hell is dark energy: Oh, this thing again. Our understanding of dark energy dates back to 1998 when two competing scientific teams were trying to measure the rate at which the universe's expansion was slowing down (which was as we understood it at the time, because of the gravitational drag caused by all the large masses out there) by studying supernovae. Instead, they found it was expanding. They thought they had made an error and squandered their Hubble time. Much math ensued. But, no. It's not slowing down, it's expanding faster and faster.
5.) Do galaxies top off or bottom out: Amazingly, we don't really understand galaxy formation, which began forming around 13 billion years ago. There are two theories.
"Top-down" says you have a large swirling cloud of gas and dust. The cloud begins collapsing due to internal gravity (so, the galaxy that is formed is smaller than the original cloud.) The speed of the original rotating cloud determines whether you get an elliptical galaxy (slow rotation) or spiral (fast rotation.)
"Bottom-up" galaxies are formed by the attraction of a number of small clumps. As the clumps, uh, clump together it draws more clumps. If this theory is correct, then the universe would exhibit more small galaxies than larger ones and superclusters would still be in the process of forming. Both of these things are true.
The upcoming-and delayed-James Webb Telescope could provide the answer here.
6.) What came first-the galaxy or the supermassive black hole at the center: this question becomes more intriguing when you consider the mass of the black hole seems to have some correlation with the mass of the galaxy that surrounds it.
More specifically, it relates to the mass of the bulge. The bulge refers to a tightly packed group of stars when viewing a galaxy. It gets a little esoteric with elliptical galaxies (or maybe I'm just tired) as they say the whole structure is the bulge but you can easily see it here in this image of the spiral galaxy Messier:
The bulge can be said to begin where the spiral structure appears to end.
The supermassive hole equates consistently to around 1/1000 the mass of the bulge. So, did one precede the other or did they form in concert somehow? This is another question that they hope the James Webb will answer as we'll be able to look further away at more galaxies and see if the presence of the black hole and the ratio holds constant.
7.) Whither the green galaxies
8.) Dark matter: you can't have dark energy without bringing up dark matter. The good news is that while we are a ways away from figuring out dark energy, we are evidently close to a breakthrough hopefully on dark matter. The notion of dark matter, like dark energy, again comes from an observation of something moving too fast. In this case, it's the rotation of galaxies that are rotating faster than their observable mass should allow.
When it's existence was first hypothesized, one of the competing theories was that gravity acts unpredictably over long distances. At least they've been able to can that theory. Unpredictable fundamental forces stress me out. And whatever dark matter is, it appears to be non-baryonic in nature; that is, not made up of things made up of quarks-protons and neutrons essentially. And needless to say, it doesn't interact with the electromagnetic spectrum hence its name. Apparently using neutrino detectors, they are getting some nibbles.
Related question, where then are the dark matter galaxies?
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