Fritz Zwicky + Coma Cluster origin of dark matter

4:14>> Yes. >> This one has a few. >> And so that was what they were. Is this the first relic which was the abbreviation? >> Um and so but this is different than Cloud9. >> This Yeah, this this could be a proper galaxy and there there are differences that we're going to highlight. >> Okay, perfect. >> Okay, so let's give some historical context. There was this guy Fritz Vicki. He was at Caltech. He coined the term dark matter >> in 1933 because he observed this particular cluster called the Koma cluster. M he observed a bunch of galaxies in the coma cluster and he figured out what the velocities of these galaxies were >> and he figured out that how fast these

4:54galaxies were moving around some central mass distribution >> it didn't make any sense they were moving way too fast he used something called the viral theorem which is a theorem in basic physics that connects kinetic energy to potential energy okay you can apply the varial theorem to the solar system for example And everything makes sense because the farther you are out, the slower you move. That's a the farther you are out, the more potential energy there is. So the less you have for kinetic energy, right? When he applied it to the coma cluster, those observations didn't make any sense. There was way more potential energy from gravity than what he saw. And so he said, there's got to be some dark matter

5:34there that we can't see that is providing the gravitational potential energy. There has to be a source for the pole that creates these orbitals. >> Yes. >> And normally we can see where the source >> of the gravity is. >> Yeah. Normally it's stars, right? And it'll be bright >> and you can't miss it. >> Yeah. >> So the thing that's weird about this is we're looking things are moving in very fast. >> Very fast. >> But the thing we can see that would drive that movement