Krauss on Science

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World-famous physicist Lawrence Krauss will discuss the latest in science news, including Laniakea, Earth’s home among galaxy clusters.

Ted Simons: It's time again for our monthly look at the latest in science news, including casual concerns that messing around with the Higgs Boson could result in the complete collapse of space and time. Joining us now as he does every month is ASU physicist Lawrence Krauss. Unless, you know, whatever time we got left.

Lawrence Krauss: Boy, I'd pay to hear you say that again.

Ted Simons: We'll get to that in a second.

Lawrence Krauss: We may not have time.

Ted Simons: Between now and then, who knows? I want to start with this business, and this is really interesting, the idea of the Milky Way, where we are located in the universe. What are we talking about?

Lawrence Krauss: Until about a month ago, or two weeks ago, did you feel lost? [laughter] What's really happened is we know that the Milky Way is part of a cluster of galaxies and there are clumps of galaxies throughout the universe. There are a hundred billion galaxies and they have a very interesting foamlike structure in terms of their clustering over large scales, over millions of light years or hundreds of millions of light years. And we've known that the Milky Way is part of a cluster of galaxies that are orbiting around each other and will collide together like the Andromeda Galaxy, about 2 million light years away, it's heading straight toward us in 5 billion years or so it will smash into the Milky Way. So we knew we were part after small cluster but we hadn't mapped it out. Recently some remarkable work has looked at 8,000 galaxies around us, and discovered that we're part of a system that we never knew existed before. Which -- Since it was Hawaiian astronomers, it's called Laniakea. We're looking now at a simulation, from the journal where it was produced, these are the galaxies now seen in space where the size of that box is about 100 million light years across and what you're seeing here are floes, the galaxies are moving. What they did is measure each galaxy at its motion, and therefore what they determined was that there's a large clump of galaxies, you see that little light spot where the Milky Way is and that around it? We thought that was the cluster we're in but we discovered there's a bigger cluster, our whole cluster is moving toward the left towards that convergence, and the left called The Great Attractor. And we're talking hundreds of millions -- About 100 million light years across. You can see the floes, it looks -- This is the images of galaxies in the universe. As we continue talking, you'll see the galaxies flow. It's like weather. It's like what we talked about here, with the moisture going from the west and coming into the east because the westerlies, because of gravity, because of a huge mass, our galaxy, all the galaxies around us are basically being sucked in by gravity towards this central region of this massive, we now understand our home is Laniakea. We live in an object called a super cluster, super clusters are the largest bound objects in the universe.

Ted Simons: Is this a super cluster?

Lawrence Krauss: Some of the galaxies are moving away, and some are moving toward each other, and the hard part is to determine which are bound and which aren't. The ones in blue are moving inward and red are moving away. What's neat at the end of this video, is the fact that you know, most galaxies are part of a super cluster and here's our flow. The flow of all those galaxies are bound together by gravity, and what's really neat is later on in this video you'll see the next neighboring super cluster. So because of all galaxies are part of super clusters and we can see just like in weather there are flows in one direction and flows in other directions and all of those galaxies have been mapped for the very first time in history, and we now know the object we live in, and more or less what it's doing. And I just found those flows beautiful. Here are all -- Where we are.

Ted Simons: The Great Attractor.

Lawrence Krauss: Very good, very good.

Ted Simons: Thank you.

Lawrence Krauss: Doesn't it look like a weather map, with all the --

Ted Simons: I thought it looked like a retina display, but what do I know.

Lawrence Krauss: What I like about this weather map, I can predict the weather 2 billion years from now, which is great, because unlike predicting the weather tomorrow, we could be proved wrong, but 2 billion years from now, we can't be proved wrong --

Ted Simons: Now are these super clusters together?

Lawrence Krauss: This is all of our super cluster, and I don't know if we'll get to this end --

Ted Simons: We'll try.

Lawrence Krauss: And the question is to map not just the position of each galaxy, but what it's doing to know whether it's being dragged into our super cluster or whether it's a nearby galaxy that is actually under the gravitational influence of the next one.

Ted Simons: How do you know when a super cluster starts and another ends?

Lawrence Krauss: If we could get to the end of the video you'd see that the difference is that all the galaxies in our super cluster are part of a clump of motion in one direction, and all the galaxies in the other, this is what we thought we lived in before. That little bit. But now we see that little bit is just a small part of this big thing. And if -- I keep previewing it, I don't know if we'll get to it -- There we go. You see? We can now see all of the stuff in the black is our super cluster and the nearby galaxies are in a whole different set of motion. And so it's like two different air masses, and the other galaxies are all moving around each other in one place, and our set of galaxies, those are our motion, are moving around from other places. We know we're bound in that black object and not in the red object. That's now called Laniakea.

Ted Simons: Where does this end? We're revolving around the sun, the moon revolves around us, the Milky Way revolves around Laniakea --

Lawrence Krauss: The buck stops here. Because we now -- This is -- This is relatively new. The question is the structure -- There are all these structures and does it keep going? But we now know the largest structures in the universe are super cluster size, because of that energy and empty space which we've talked about, which is producing a cosmic repulsion. Two galaxies are that farther apart that are about the size of a super cluster are being pushed apart by the expansion of the universe and can never clump together. So the largest structures that ever formed are these super clusters and no larger structures will ever form in the future history of the universe. So we are part of this structure and that structure is not part of any other gravitationally bound structure.

Ted Simons: How do you know that?

Lawrence Krauss: What --

Ted Simons: How do you know that?

Lawrence Krauss: It's physics. The point is, it's really forces. We're being pulled by this mass. But empty space has energy, and we can calculate the force it applies outward. And two objects that are far enough apart, the outward force beats the inward force and they can't collapse together. The antigravity of empty space, for objects farther apart than about 50 to 100 million light years apart, will never collapse together, because empty space has taken over. And unless that energy of empty space goes away, they'll be pushed apart forever. So Laniakea is it. We're not going to be part of anything else and we now know where our home in the universe was, and now when you turn on your GPS to go home tonight, you'll know exactly where you are.

Ted Simons: Turn right at Laniakea. OK. So all of this, obviously, this is a game-changer in understanding the universe.

Lawrence Krauss: It's -- Yeah. I don't know if it's -- It tells us where we are. In the sense that cosmology is giving us a perspective of our place in the cosmos, we now know what our place in the cosmos is. It's not changing any radically any laws of physics, but it really is reorienting us. If you look at that video we now understand where home is. It's really -- We never knew before.

Ted Simons: Well, it's nice that we have a home, but according to Stephen hawking our home could be destroyed in the great collapse of space and time if someone monkeys around with that Higgs Boson too much.

Lawrence Krauss: I wanted to talk about this, because every time Stephen says something the world jumps up and down. And I don't want people going out and jumping off buildings tonight because of the Higgs Boson. So I want to point out, we have now discovered the Higgs boson, which we've talked about before, which is fascinating. But the Higgs boson, you may remember, is related to a phenomenon that happened early in the history of the universe. Where this field, we call the Higgs field relax in addition some state so it's permeating all of empty space and that field which is everywhere, affects the properties of the particles that make up your and my body and this table, and gives it mass. And when it relaxed, it was like water freezing on a windowsill. It was -- Ice crystals forming. This field cooled down and relaxed. OK? So it formed this structure and that structure gives meaning and significance to everything we see. We wouldn't be here if the Higgs field wasn't here. But the question is, is that structure going to stay around forever? Ice crystals can change, melt, and do other things. And so it turns out that when we saw the -- Solve the equations associated with the Higgs field, something particular happens. What we call the potential of the Higgs field, the desire for it to stay in its current state can be stable or unstable. If it's unstable eventually it's going to change, and everything we see will disappear. That's what Stephen was talking about. What's amazing is it all depends on the mass of the Higgs field. The mass that's been discovered is right on the borderline between a stable Higgs field and an unstable one. And we don't know yet enough to know which is which. But it is possible that the Higgs field, if the Higgs Boson mass is what it is, is ultimately unstable and everything we see in the universe will eventually disappear. The good news is, however, that unstable in a cosmic sense is -- It doesn't matter. It's quite likely that if it's unstable the time period over which it would actually change and destroy everything is not billions of years or trillions of years, but much longer than that. So if the Higgs field is unstable, it's highly likely you'll have a lot more programs to do.

Ted Simons: It sounded like what Stephen Hawking was saying was you would need an accelerator, maybe the size of the Earth in order to get the highest energy needed to get this Higgs Boson unstable.

Lawrence Krauss: There's another -- Of course there's another way -- It's like a mountain. Here's the idea. I'll try and draw it. The Higgs field is like a valley and a mountain, and the Higgs field is stuck in that valley. The question is, does the mountain go down on the other side, and that would mean the Higgs field is unstable. Fit, it classily will still sit in the valley. Like if you put a bowling ball in a valley, it would sit there even if there was another valley that was deeper farther away. But quantum mechanics says the Higgs field can tunnel through that mountain and end up on the other side and decay. That involves the decay of the universe. That may be the case. But what Stephen is pointing out, is there's another way to end up in that valley. That's to kick it. If I kick the bowling ball I can kick it over the mountain. So it is possible you might imagine if you put enough energy in a large enough volume you could kick the Higgs field up over the valley into -- But I think that is so unlikely, that it was almost irresponsible of him to say it. Sorry, Stephen.

Ted Simons: Is this what theoretical physicists do, just sit around and think about things, make headlines --

Lawrence Krauss: We just have coffee and say how can we make a headline today. No, the nice things about this is in fact we can do calculation and we can test these ideas. And I can tell you on the basis of the calculations that we've done and the basis of the measurements that we know about the Higgs particle, it's extremely unlikely any kind of accelerator could ever -- You'd need to -- Could ever get the energy produced over a large enough region to do anything even if it was unstable, and we don't know if it's unstable yet. The good news is, the large collider is turning on and not going to destroy the world, but what it will do is tell us the parameters of the Higgs Boson, and we'll know, we'll know and be able to predict exactly whether the field is unstable. So the answer is stay tuned.

Ted Simons: All right. Stay tuned is fair enough. Good to have you here. We'll see you next month.

Lawrence Krauss: If there is a next month.

Lawrence Krauss:Physicist, Arizona State University;

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