Horizon, Host: Ted Simons

February 13, 2013


Host: Ted Simons

Lawrence Krauss on Science


  • Explore the often strange world of science as world-renown ASU physicist Lawrence Krauss discusses the latest science news in his monthly appearance on Horizon.
Guests:
  • Lawrence Krauss - Physicist, ASU
Category: Science   |   Keywords: krauss, innovation, technology, physics, science, ,

View Transcript
Ted Simons: Every month we hear the latest in science, as explained by ASU physicist Dr. Lawrence Krauss who joins us to talk about everything from black holes to Richard III. All right. We have it teed up.

Lawrence Krauss: My kingdom for a black hole.

Ted Simons: Let's start with black holes, and first, a general definition, what are they and, and why is it so important that we know how big that they are?

Lawrence Krauss: Well, that's a good question. The point is that black holes are fascinating because they are objects so dense that light can't escape from them. And it's, in fact, the first testament of that possibility was done hundreds of years ago before we really knew what they were because, we have an escape velocity from the Earth, 11 kilometers per second. We have to send rocket ships that fast to get out of the Earth's pull and over to the moon, and now, if I added a teaspoon full of material to the mass, the escape velocity would go up a bit more, and a bit more and a bit more. And eventually, the escape velocity will exceed the speed of light. And at that point, not even light can escape. Now we have a general theory relativity which says that space curves around a mass of object, and if it's massive or dense enough, light can't escape, that light, the -- if you shot a laser Beem out that would curve and come back down. Because the escape velocity is faster than light. And that's remarkable, and sexy and the word black hole, by the way, which was coined in 1965, by someone who did not believe in it at the time, and I think that, that there's been lots of movies because of that term, and in Russia, they call them frozen stars, and there is no movies --

Ted Simons: You mentioned movies and, and this will be a dumb question, I'm sure, but what is behind a black hole.

Lawrence Krauss: You know, that's another really good -- not a dumb question but a really good question because, of course, we cannot -- we don't know because nothing -- no light can get out to tell us and, and in fact, if you take the laws of generatively directly, at the center of the black hole is this infinitely dense singularly where matter is dense and the laws of physics break down, and some speculated it could be, basically, a portal to another universe. Because the laws of physics break down, but the thing about a black hole that I find so neat, and I want to tell you about, is that, that, and it fascinated me when I was in high school. Is that, is that you know, they are not as exotic as you would imagine in the sense that you have to think that they are incredibly dense, like if you took the sun, and collapsed it to the size of Phoenix, a million times the mass of the Earth, in a region the size of Phoenix, you have a black hole, and a teaspoon full of material would weigh thousands of tons. That's a black hole. But, as black holes get bigger, their properties change because it is easier for them to capture light if you want, so if you had a black hole the mass of our galaxy, the density would be that of water, like of the Earth. It's just so massive, that light can't escape, and this is the really neat thing. If you had a black hole, the mass of the universe, the density would be a factor of two of the actual density of the University. So we could be living in a black hole.

Ted Simons: And that was, I was going to ask, how, how come we don't see a black hole, and we stare and go, there's the black hole.

Lawrence Krauss: We do see them but not the, not our own universe, although, if the universe were closed, we would look far enough and see the back of our heads, which was telling us the light was going around the universe, a black hole, but we do see black holes in galaxies. That's one of the amazing discoveries of the last 20 years, we have the technology to look at galaxies, and how we see black holes if they don't shine? Well, you cannot see them, they are dark, but we measure things by looking at objects going around them. And so we look at the centers of galaxies and we see stars orbiting this thing, dark thing, so close that, that, that the matter in the center has to be dense, and by the speed of the stars, we can estimate, the mass of the object, and we find these objects are millions of times the mass of our sun, and sometimes billions, contained in a region so small that they can only be a black hole.

Ted Simons: And the new headline is, there's a newer way to measure these with, by way of gas? Like molecules?

Lawrence Krauss: That's the, the reason we're talking about it, obviously, the trick is to measure the material going around it, as accurate as possible in order to measure the mass. And we can briefly mention why we want to know that in a second. But measuring stars isn't always so good because they have random motions, but the gas has very circular motion, and it can emit, if it's cold, it can emit radio waves, and that's the new thing. By looking at these radio waves we can see how fast the gas is orbiting around and we can get a really good estimate of the black hole mass, at the center of the galaxy, there is a million solar mass black holes, at the center of several other galaxies there is billion black holes, and the big question, really unknown, is chicken or egg? Did galaxies form because the black holes were there or did they form after the galaxies? And we really don't know the answer. That's one of the reasons we want to build the telescope. We will look at the earliest galaxies and see if they have black holes in their center.

Ted Simons: That's fascinating. We need to keep moving. Anything else we need to know about black holes?

Lawrence Krauss: Nothing for the moment.

Ted Simons: I want to get to Richard III because the, they found his bones under a parking lot.

Lawrence Krauss: I think Jimmy Hoffa was with him.

Ted Simons: Yeah. And science did play a role in not only identifying him, but finding out what happened tomorrow.

Lawrence Krauss: And it's really -- it's a neat story because it is a mixture of science and drama. People thought he might be buried there. And there was, there were written records that he might have been buried to protect him from the advancing troops and, and the parking lot, of course, was built over there. They dug it up and found the bones, and then they tested the DNA some of his of some of his descendants. A few people known descendants of Richard III, and you can test the DNA, and work backwards, and basically, get a good confirmation that it was Richard III, and that several of the features we know about Richard III were there. For example, like Shakespeare said that he had a hunch back but you could see his curved spine.

Lawrence Krauss: And you could see it if you look online and you could see that curve, and his skull was rather in sad shape from getting hit as people thought that they saw him killed in battle, and probably got raw deal, because he was -- in fact, I heard the other day that he was the last King of England to ride in battle on a horse, and in the process, got killed.

Ted Simons: Back to the scientific aspect here, I read that it was mitochondrial DNA, from the maternal line. And which makes sense because probably the male heirs were, get him out of here, but the females.

Lawrence Krauss: We use mitochondrial DNA, the female line, and that's how we have inferred that everyone came from some eve, who was in Africa. You can -- using this DNA is a really good way to, to verify and, and follow back in time, lineages and look for the relationships. And, and a lot of interesting things have come out of that for humans, and now, of course, we're refining our genetic techniques and being able to use it for other species.

Ted Simons: And I read, this is a rare DNA type anyway for English folks so the fact that this connection was made, it all adds up.

Lawrence Krauss: You know, it's -- as I said it before, walks like a duck, quacks like a duck. If it had -- I think that there is a 1% chance that it could be someone other than -- that it could be someone unrelated to the people they tested. And if that's all that there was, we might say it's not convincing. But it's a 1% chance, 99% likelihood it was right but also found in the place he was buried, had the characteristics of the man. The wounds people claimed to have seen.

Ted Simons: And the carbon dating from a couple of rib bones suggested his death during that time span?

Lawrence Krauss: That's what's great, there is lots of signs you can apply. That's what makes it a neat science story. People are interested in Richard III, and this is science doing, you know, csi or whatever, but in the real sense, back a whole bunch of centuries.

Ted Simons: And now everyone gets to argue whether Shakespeare gave him a raw deal.

Lawrence Krauss: A lot of fun.

Ted Simons: Last thing before we go, apparently, there is, there has been found a common ancestor for all mammals and apparently, you and I come from an aardvark.

Lawrence Krauss: Something that looks like an aardvark. I don't think it's as pretty as that. It relates to the Richard III story, as far as I'm concerned. We are, because of modern computers, and our ability to, to sequence genomes, we can, in fact, begin to do the kind of things that never would have been possible before, and the new techniques are not just allowing us to follow humans back but look at the relationship between different species, and try and use the, the characteristics of different mammals to try and trace back and see what would be the characteristic of the single common ancestors of all mammals. The interesting thing about this aardvark-like thing is not only are we descendants from that, but before that, a fish and before that, a single celled animal, and we don't know the first ancestor of all of us, but, what's interesting is the dinosaurs were, were destroyed, apparently, due to a comet 65 million years ago, and that probably created an E. illusionary niche for mammals who would not otherwise have been able to survive well because the dinosaurs would have eaten them.

Ted Simons: Dinosaur birds survived and nothing else did.

Lawrence Krauss: Exactly but the question, is the common ancestor of all of us, all of us mammals, come from before that extinction or afterwards? There was two arguments, one, the look at fossils suggested the first mammal, and a mammal is animal that has their child in vitro, the offspring are born inside the uterus. And that the first mammal arose after that extinction. On the other hand there is a molecular clock, which really traces the rate of mutations in DNA going backwards, and have used that molecular clock, it happened before. So there is this debate. This new analysis, which is really comprehensive in using a whole bunch of new techniques, suggests it happened after, the extinction, that mammals could only arise after the dinosaurs, except for the birds.

Ted Simons: When the opportunity presented itself.

Lawrence Krauss: Instead of one mammal sneaking through the barrier, and people might have been these things differ, that means evolution doesn't work. At the forefront of science, we're always learning. And there are different techniques. Now what we're learning is it's probable the molecular clock mechanism has to be recalibrated a bit. It's evidenced not that evolution is weak, but once again that evolution happened.

Ted Simons: It's also evidence that this new system of looking at fossils and genetic data is light years ahead of what used to be done.

Lawrence Krauss: And it's all because of, basically, the ability to take new measurements and the ability to use large computers, and it's just the beginning. Our ability to use this incredible, I mean, this wealth of information, the genome, most of it we don't understand. And it's going to be a computational nightmare but as the computers are better and better, we can learn new things about not only our, our own ancestry but the nature of what makes us up and human, and other things not human.

Ted Simons: And again, this is like, like a rat-sized thing?

Lawrence Krauss: It looks like it has a long snout, and it's amazing to me, as a non biologist that you can take all these characteristics all the mammals, and use these mathematical models with the data and work backwards to find out what were the characteristics of our ancestors. And they can, apparently, do it in a way which convinces other scientists, which is more important because we're skeptical that this is reasonable, is amazing. And we know we came from this ugly looking thing. And I guess it's not too impossible.

Ted Simons: Well, now. But, and insects --

Lawrence Krauss: Lived on insects. And which is, you know, again not surprising.

Ted Simons: You mentioned a scientific theory, and theories need to be tested. That's what science is all about. And has this particular theory been tested?

Lawrence Krauss: No, this is the first example. It's compelling and interesting but others are saying we have to -- it's one bit of data and we need to do others before we can confirm it, and so I think that it's very, a very interesting proposal, a lot of science behind it. And a lot of interesting analysis but it's not conclusive. You hope your ancestor wasn't, was a little better looking.

Ted Simons: A little nicer. We're talking about how we're all aardvarks. Richard III, under the parking lot because of science, and things that we cannot see, we can now measure. So, wrap it all up in a bow, what is science telling us?

Lawrence Krauss: Science is extending our senses to tell us things about the University we never could have understood otherwise, and be able to test it. In many ways, from the nature of black holes to understanding the nature of Richard III, it's evidence that science means the University is more amazing than we would have imagined, and it is a tool to learn things and to, to reveal mysteries, and in fact, with every discovery, there is another mystery. The nature of this animal, and what the precursors were, I think that it's fair to say that before both evolutionary theory and modern genetics, no one might have guessed that your ancestor was an aardvark. They would be looking at you saying, I would never have guessed it.

Ted Simons: We're estranged. But, it's science expanded. And it's the nature of science, which a lot of people still have trouble with.

Lawrence Krauss: Oh, yeah, and I think that that's why I got to that point. The fact that these two dating mechanisms for where the earliest mammal came, from one from molecular genetics and one from the fossil record don't agree. You have some people jumping on and saying that means the whole thing is wrong. And the point, is at the forefront of science, we are always getting tentative data and we're learning some things are right and wrong. But if something is -- when we're pushing our knowledge to the edge, of course, there is controversy. But that controversy of whether the earliest mammal was before or after the extinction is fascinating from a scientific point of view, but, the fact that there is controversy there doesn't mean that the whole thing doesn't work. In fact, it points to the remarkable fact that, that we can, in fact, trace our evolution back. It is not a theory. It is a fact. The fact that we can trace the genetic relationships with different species and the fact that these two different ideas are, are different techniques to, to look backwards, all converge on close time, tells us, you know, it amazes me that somehow people argue that this remarkable science, it should be taught in school because it reveals a universe that we would not understand, that some want to suppress it because either they are afraid of it or they are suspicious of it.

Ted Simons: All right, you have given us quite a bit to chew on here. It's been fun, and I will never look at an aardvark the same again, thank you for joining us. That is it for now. I'm Ted Simons, thank you so much for joining us. You have a great evening.

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