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October 29, 2013

Host: Ted Simons

Lawrence Krauss

  • Arizona State University physicist Lawrence Krauss will stop by the Arizona Horizon set for his monthly visit to discuss the latest science news and issues.
  • Lawrence Krauss - Physicist, Arizona State University
Category: Science   |   Keywords: krauss, science, ASU,

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Ted Simons: Astronomers have discovered the oldest galaxy ever found and it's producing stars at a surprising rate. There's also news regarding the oldest completely preserved human skull ever found. For details we welcome world renowned ASU physicist Lawrence Krauss. How are you doing?

Lawrence Krauss: I'm still here.

Ted Simons: And you've got a big ol' press conference tomorrow morning regarding dark matter.

Lawrence Krauss: There is, and that's not mine but it's going to either confirm or refute some tentative evidence that dark matter exists. The bet is that it will refute it.

Ted Simons: Next time you're on, we'll talk about it.

Lawrence Krauss: We'll pat me on the back for being right.

Ted Simons: Let's get your impressions now of a distant, and I mean distant, galaxy. And this human skull, old, old skull.

Lawrence Krauss: I'm really happy to talk about both of them. I want to talk about cosmic evolution and human evolution. More importantly, at the forefront, how can you tell when you find the oldest thing or a single thing, whether you're getting something characteristic? How can you generalize when you’re pushing the edge and you're just getting rare fossils? You're bound to continually revise your estimates. People shouldn't be surprised when we discover something new and it changes our minds a little bit. For example, if we are all destroyed today and the only fossil they found was of a Phoenix Suns basketball player. They’ll conclude that humans were all seven feet tall. They might find one of me and they'd say a different species completely. And we'll talk about that, because that's kind of what's been happening. We just discovered the oldest galaxy ever seen and it's surprising us. Is it characteristic of all galaxies or is it really rare? Can we make generalizations? We're making tentative evidence as we try and understand how the universe has evolved and how humans have evolved. We know there’s evolution, and our general picture is correct, but it’s bound to change. I thought we could talk about these tentative results and sort of show how our picture of evolution is itself evolving.

Ted Simons: Let's talk about this galaxy, looking at light that took 13 billion years to get here. And oh, by the way, that little red splotch there, that's moving away from us.

Lawrence Krauss: It's not even where it was. It's 30 billion light years away now. In those 13.1 billion years it took to get there, that galaxy has been moving and it’s been moving so fast that now it’s 30 billion light years away.

Ted Simons: How do we know that red splotch -- was 13 billion --

Lawrence Krauss: Doesn’t it look like 13 billion?

Ted Simons: Looks like a fun place to be. 13 billion -- how do we know?

Lawrence Krauss: The way we can tell is by looking at the universe expanding at a certain rate. We can look at how fast it's moving away from us. The rate at which the expansion of the universe has been changing over time, when we look at things that are further away they are moving faster. And the things further away emitted that light much earlier. So we can look at the amount by which the frequency of the light, from the time it was emitted to the time it's come here has changed. That tells us how long it took the light to get here. Earlier objects -- stars are like fingerprints. We're looking at certain frequencies of light, the same frequencies that are emitted by hydrogen gas in a laboratory on earth. When they’re emitted by objects moving away from us, all that light is stretched out. It’s really simple, we can see how much the light is stretched out. It’s called the red shift because the red light is the long wavelength into the spectrum. The more it's stretched out, the earlier it was emitted. From the red shift of this, it's about 7.5, which means the light is stretched by a factor of roughly almost a factor of 8 in wavelength compared to what it is today, that tells us how long ago the light was emitted.

Ted Simons: When you're looking at this thing, you are looking back at a time before our sun.

Lawrence Krauss: Way before our sun. It's only 4.5 billion years old. This galaxy was formed 700 million years after the big bang, an instant in cosmic time. The big surprise is not only that it's there but that it's generating stars like crazy.

Ted Simons: Why is that a surprise?

Lawrence Krauss: It should take time for gas to collapse, and the star formation rate should take time to build up. This is a rate of something like 100 times the star formation rate of the Milky Way galaxy. And normally, because this is 1/50 of the size of the Milky Way galaxy, the gas should be just beginning to collapse. And why it's generating stars at that kind of rate, and in fact it's produced a lot of stars because we can measure what are called heavy metals. All the stuff that makes up you and I is not produced in the big bang; it's only produced in the core of stars. So stars have to explode and inject that material into the galaxy. Then the next generation of stars comes through and it keeps going on and on. The stuff in your and my body may have gone through six or seven stars that exploded before it got to us. We’re seeing already that these stars have produced heavy elements, which means there’s been stars before that. This is a very surprising result. As I point out, the key question is you would expect not to see such a thing in the survey that’s been done. But you never know when you see one thing if you can be surprised. It could be a rare accident or it could mean the galaxies were forming much earlier than we thought and stars forming much earlier than we thought. And that could be interesting because we don't quite know what causes galaxies to form, whether big black holes form in their centers or whether the stars formed first. This is a very interesting result, but it's one galaxy. This is what I mean by tentative results. When you find one thing, you don't know if you're just lucky.

Ted Simons: That takes us now to the complete human skull to the country of Georgia, not Atlanta. We're talking Georgia here. It’s a 1.8 million-year-old complete skull.

Lawrence Krauss: This is a complete skull, along with four other really good skeletons. What's amazing about this is, because all five of them were found, and they are very well preserved, they were all from around the same time. In fact, they were all found in an underground den so probably beings, humans or at least homo, eaten by lions and tigers pulled into the den and they didn’t have a happy ending. What’s interesting is they were all found in the same place, and they differ by huge amounts. There’s a difference in size and difference in characteristics. What’s remarkable is if you found five individuals on the street here they might look very different too, but had those five beings or fossil skeletons been discovered in five different places we might have called them five different species. What’s been happening is we try and understand our lineage, homo sapiens, and the first beings called homo, homo erectus, an early species in Africa that eventually went out to the rest of the world, this preserved skull looks just like the homo erectus that was found in Africa. It’s 1.8 million years old. It was quickly spreading around the world. More interestingly, the variation in all of these things is so great, it’s greater in what we previously called the different species of homo. And that could mean that all of these different species discovered in Africa and throughout the old world are actually the same species, just different beings.

Ted Simons: Can't even keep track of how many ancestors we've had in terms of species, but no, it may have been fewer species just more diversification within.

Lawrence Krauss: This is the point. And that’s why I go back to that basketball player. If you discover the basketball player in one place and me in another, you probably might call them different species. But if together we were on the light rail in an accident and they discovered us 1.8 million years now in the remains of that. They might say, these guys were riding together, they were probably the same species.

Ted Simons: Was this a surprise? Were scientists surprised by this? Should scientists have been surprised by this?

Lawrence Krauss: We should always be prepared to be surprised especially when we’re pushing the forefronts of science. What's amazing is how well preserved these skeletons were and the fact that they were together. And the fact that something this old that looks just like the homo erectus in Africa actually made it out that far suggests that our ancestors were exploring the world much faster than we thought. In fact we were much more spread out. There are different species of chimpanzee on different sides of a river because they have evolved and don’t interbreed. If this is the case for humans, then humans weren't just separated by geological land masses and separate species. They spread out about as quickly as they could. Humans were adventurers early on. This is all fascinating. If it's true, it’s at the forefront; we're just learning. This does not invalidate evolution in any way. It just tells us we’re learning the details. It's not too surprising we’re surprised because the data is very sparse. And we’re filling it in and our ideas are changing. It doesn't invalidate the notion that they’re our ancestors, they’re definitely our ancestors. We’re just learning maybe we have many more close relatives than we thought.

Ted Simons: Alters the evolutionary tree, if you will.

Lawrence Krauss: Exactly. And it will be altered again. We're learning, and learning means changing your mind. And we're learning the details and we can expect in those areas where we only have one sample or two samples, that as we learn more, sometimes we find a rare accident or sometimes we’ll find our ideas are correct.

Ted Simons: What are the limits right now in terms of observable universe? How far can we go out there? And what are the limits just in terms of preservation, as far as hominids, if you will?

Lawrence Krauss: The answer to both is we don't know. We will not go back before the big bang, 13.8 billion years ago. We know in light we can’t see back before about 100,000 years after the big bang because the universe was opaque before that. It’s like looking at a wall, we can’t see back in light before that time. We can use other things to look back before that time, because other things can get to us, like gravitational waves and other things that can permeate those early times. With gravitational waves detectors, which we are building, maybe 20 years from now when we do this program we’ll have discovered gravitational waves; we could probe back to the early seconds of the big bang. So we might be able to get probes that take us right back to the earliest point of the big bang. As far as humans are concerned, it's an open question. We're discovering that luckily in this case they were underground when that cavern collapsed and preserved. We find objects in the ice all the time. It's hard to know, but one thing is for sure. We're just beginning to scratch the surface. I suspect this kind of find is just the beginning and we will -- we have a lot more to learn about our heritage, and it's exciting to think we do. The fact that we don't know everything is wonderful. It doesn't mean we don't know nothing, though. That's the really important thing and I don't want people to get the impression just because we change our minds that somehow everything is wrong. It’s not. The general characteristic of our lineage, the fact that we descended from earlier species and we have a common ancestor with chimpanzees, all of that is unambiguous and clear and that’s not going to change. The details will change as we discover new things.

Ted Simons: Dark matter: you say tomorrow they will find out the evidence is hooey.

Lawrence Krauss: We're looking for dark matter, the stuff that dominates our galaxy. If we're right, it's a new kind of elementary particle that's going in this room right now through you and I. We built detectors underground to look for it. It’s very hard to detect. It’s another kind of fossil, a fossil from the early universe. We might expect one event per year. When we see something, is it a background or a signal? It's like this stuff, with one event you never know. We're just beginning. New data will maybe surprise us.

Ted Simons: Looking forward to being surprised tomorrow. Always a pleasure to see you again.

Lawrence Krauss: It's great to be back.

Ted Simons: Wednesday on "Arizona Horizon," a top AARP official talks about proposed changes in Social Security and Medicare. We'll hear about a company developing technology for border security in the military, that's at 5:30 and 10 on the next "Arizona Horizon." That is it for now, I'm Ted Simons. Thank you so much for joining us. You have a great evening.