ok I have listened to the first 32 podcasts and this episode is the one that I have a question about. I am asking this from a point of knowing I do not understand a lot, but here goes...
Why do super large galaxies have an elliptical shape and smaller ones are disc shaped?
Here is why I ask, the milky way, for example is spiraling around a super massive black hole, so is the Andromeda Galaxy. Systems within the Galaxies have stars rotating around stars, planets rotating around stars, black holes consuming gas in a spiraling accretion disk etc. The effects of angular momentum is readily apparent on scales as small as a planet/moon relationship, all the way up to our galaxy.
So why is it, that large galaxies lose this trait? For that matter, why are galaxies clustered in a sponge-like pattern instead of in an ever larger spiral? Is there an upper bound on the effects of angular momentum and ultra-large collections of mass or has there just not been enough time for these effects to take place? Or maybe they HAVE taken place but it hasn't reached us yet?
Also, in a similar vein, why are globular clusters not disk-shaped? what is it about their structure that keeps them from spinning up around a denser core group?
Awesome podcasts, by the way. I love this series, and have to say that Fraser and Pam discuss things on a level that isn't too high fr a layman such as myself to understand.
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