The most interesting segment was with Roeland van der Marel and about the estimated galaxy collisions in four million years. Excerpt.
FLATOW: Is this going to be a violent collision?
MAREL: Yeah, as these things go, it probably will be. Our Milky Way and the Andromeda Galaxy are roughly equally big. Both have lots of stars in them. Each galaxy has, you know, over, you know, 100 billion stars in them. These galaxies are going to run into each other, and this is going to totally reshape them.
So in that sense it's going to be very violent. It's not going to be violent in the sense that individual stars will run into each other because these galaxies have a lot of empty space in them, and most of the individual stars will actually pass by each other.
So our sun will survive, but our galaxy as a whole will be totally reshaped.
FLATOW: So we actually have a picture on our website, at sciencefriday.com, of what it might look like. It's a NASA drawing. Now, aren't there black holes at the centers of galaxies? I mean, don't we know one's at the Milky Way's? Is there one in Andromeda also?
MAREL: Yeah, we actually know fairly certain that both of these galaxies have a black hole in their center. That's not particularly unusual. We think many or maybe all galaxies have such a super-massive black hole in their center. The one in the center of our Milky Way is about a million times as massive as our sun. The one in the center of Andromeda is about 10 million times as massive as our sun.
When these galaxies run into each other, ultimately the black holes will slowly spiral in towards each other, and they will merge, and this will be a particularly interesting event. It'll lead to the formation of one bigger black hole, and it'll also produce what is known as gravitational radiation, gravitational waves, which astronomers have yet to detect, and physicists, but we are fairly certain exists based on Einstein's Theory of Relativity.
Do you ever wonder about that? We'll be gone. Maybe not you, the one reading who thinks he or she will live for 8 million years, but the rest of us, we'll be gone. Presumably, the earth will still have people on it (although if we don't address global warming, that's in doubt). It reminds me of Battlestar Galatica -- the original one. From the 70s, I think. With Lorne Green, Anne Lockhart, Richard Hatch, etc. And the attack on their world that takes place when they're lured away.
(That was another planet attacking. But I'm thinking of how they make it back and discover their friends, their families all gone, everything wiped out.)
This is C.I.'s "Iraq snapshot:"