Krauss on Science

June 18, 2013

Transcript:

Ted Simons: ASU physicist and bestselling science writer Lawrence Krauss appears on "Arizona Horizon" each month to discuss the latest science news. Tonight we touch on black holes, mass extinction, and apparent toboggan marks on Mars.Good to see you.

Lawrence Krauss: It's great to be here in cool Arizona.

Ted Simons: Speaking of cool and climate and stuff --

Lawrence Krauss: Exactly.

Ted Simons: -- there's new information on what 12,000-some-odd years ago something may have come close to hitting or hit -- what's this new information?

Lawrence Krauss: The new information is studying below the surfaces of the earth, rocks, and discovering that rocks melted, producing what are called these carbon ferrules that really only happen during this extreme heat. A large object hit the Earth or came close enough to produce enough heat to melt a lot of rock. There were a lot of extinctions around then, woolly mammoths. The claim is mainly it wasn't the impact itself that caused these extinctions, but the climate change after it. When there are large volcanoes on Earth, the climate changes. When there's a lot of particulate matter thrown up in the atmosphere, that changes the weather. The argument is that these ferrules, seen in four different continents, would say something happened to heat up rock enough to melt it. Also, threw up enough stuff in the atmosphere, million tons or some large amount --

Ted Simons: I think that's what it was --

Lawrence Krauss: -- that it blocked sunlight enough that it changed -- first there was a glacial period, then it was getting warmer. Then suddenly for a little while it got cold for a century or so. The argument is that material thrown up in the atmosphere made it colder and a lot of animals didn't survive. And the interesting thing is, people were around then, too.

Ted Simons: People survived, but the woolly mammoth shuffled off the mortal coil. Why does all that stuff going into the air mean severe climate change for a hundred years? Can't we get rid of that? Doesn't the wind blow?

Lawrence Krauss: The circulation time for the wind to get rid of stuff can be many years. The interesting thing is, there was a recent study in a related vein which should concern us. On a totally different vein, India and Pakistan have both increased their nuclear arsenals. Even a small nuclear war between India and -- small, nuclear weapons -- would produce enough stuff in the atmosphere that for a decade there would be climate change. A billion people would die because of starvation around the world. Especially when the material is small, and in this case there was a cold spell for 100 years. I think the fact that humans lived through it is a very interesting thing. Actually my colleague Curtis Marion and others have studied a cave in South Africa where humans occupied for a 100 thousand years. Humans have had to evolve. We are used to thinking -- in fact, many people don't even realize that we're producing climate change right now. But independent of humans and climate change, over a period of a century there's natural climate change. You have to be able to adapt to it or, like the woolly mammoth, you're history.

Ted Simons: The researchers here said we basically have three options for life You can relocate, downsize or die. We must have done one of the first two.

Lawrence Krauss: Over human history migrations have indicated that humans have in fact adapted very well. Having a brain that allows you to plan is really important. In fact, you know, the chicken and egg is an interesting question. But as fish died in South Africa, other foods had high protein, which meant that people could stay on top of the changing food environments. If your entire existence consists of looking for a certain type of food, you're cooked. Well, in this case you're frozen.

Ted Simons: Researchers call this the last gasp of the last Ice Age. What is the normal Earth temperature? Or is there a normal Earth temperature?

Lawrence Krauss: It varies over geological time. There are well-known cycles, Milanovich cycles, over periods of thousands of years. It can happen over centuries with small variations. The earth changes over time. Over millennia you can have periodic changes in temperature. That's not what's happening right now. The change happening right now is happening over decades, exactly correlated to carbon dioxide in the atmosphere. People say it's a natural phenomenon. It is true there are natural cycles. But other factors which we are only now studying. They happen over longer times. There was an Ice Age well before this 13,000 years that started to warm up over a period of several thousand years. Then there was this blip where things got cold again for a century or so. That's where certain animals weren't able to adapt. If things change for a long time, you have a lot longer for things adapt. If there's a sudden change, in a period that's short compared to biological time, then species can't evolve and natural selection doesn't play an active role, and you see a lot of extinctions. We're seeing those now that far exceed those of that time. Human industrial activities that produced a bigger mass extinction than that did.

Ted Simons: Are there adaptability lessons from 13,000 years ago that we can apply today?

Lawrence Krauss: We're going to have to adapt. We're already seeing it, in New York Mayor Bloomberg talks about new plans to protect New York against new storms. It's going to happen, the sea level rises, the storms get stronger. There's no doubt that climate change is not going to wipe out humans. But we have to adapt because -- and in a complex society where small events can produce vast economic changes, we have to be prepared for these things. So we may not have a commentary or we may, but we are doing a pretty good job on our own.

Ted Simons: We have apparently tracks on sand dunes on Mars.

Lawrence Krauss: It's surfers, sand surfers. They look like toboggan marks on Mars. It's one of the many things people think is showing life. You see these marks and you wonder, are they streams of water. Water is the thing we're looking for on Mars, because where there's liquid water, generically there seems to be life. These toboggan runs sort of go down and suddenly stop with a little indent. New studies have shown that it's probably dry ice, frozen carbon dioxide, that basically surged down the sand dunes. You've played with dry ice. It's a carbon dioxide, it freezes and goes directly to a gas form to a solid form, something called sublimation. It doesn't go through a liquid form at 110 degrees below Fahrenheit. You can get the stuff and, because it goes from solid to gas form, you put it on a surface and as it starts to sublimate, it basically creates a cushion, just like those air hockey tables. You have a small block of carbon dioxide, it creates a little air hockey table below it. Those patterns seem to be evidence of carbon dioxide. It tells you there's probably dry ice melting on the surface of Mars. Unfortunately, it also means that many of these surfer patterns or toboggan runs are not due to water, which is important if we want to know about life. There are some patterns on Mars that look like they were due to liquid. These aren't. We all want there to be water on Mars. We have to be honest, and if these things aren't water, it reduces one possibility. It would be great to look, see if conditions are there. We'll take what nature gives you and try and figure it out.

Ted Simons: I think would it be great to find air hockey on Mars.

Lawrence Krauss: Yeah.

Ted Simons: Goodness gracious. Yhey think they have solved it.

Lawrence Krauss: It looks just like dry ice. I was thinking we should have brought some dry ice and played some air hockey.

Ted Simons: We talk about black holes a lot. Seems like some scientists are making a big deal. 26 new black holes found in the Andromeda galaxy.

Lawrence Krauss: Black holes are fascinating. There are big questions about how and when they form and how they are related to the galaxies themselves. Pretty well every galaxy we know of appears to have a large black hole at its center. There's a million solar mass black holes, or what appears to be a million solar mass black hole in the center of our galaxy. We refer to them by -- they move around in this area where there's nothingthing, and we find out it's a million solar masses, but it's so small that our physics calculations tell us it must be a black whole--something so dense that light can't escape from it. There will be black holes in many different sizes. Some stars, we calculate, when they die, they collapse into what's called a neutron star. One idea, a nucleus, say, of an atom. At that point it stops and produces a supernova explosion. If the star is massive enough, we can calculate it won't stop there, it'll keep collapsing--nothing can beat gravity and will eventually become a black whole. Whether there are 10 solar mass or 20 solar mass black holes, you can look for them by watching material fall into them. And because material falls into a neutron star, it achieves a certain speed and emits a certain type of radiation. But if it collapses into a black whole, recent calculations. It gets near the speed of light and emits what are called hard X-rays more efficiently. Astronomers can try and look at the X-ray emissions. They are called black holes. It's one way to say that maybe there are a lot more black holes in our galaxy than we thought.

Ted Simons: The way they were found is the exciting part of the story.

Lawrence Krauss: Yeah, a lot of it depends on the theory, because you have to try and model what happens to gas if it falls into a black hole.

Ted Simons: I always try to ask about a black hole. It boggles my mind. I once asked what's behind the black hole, I don't know if it's a good question or not. Here's another one. Is a black hole forever? Does that part of space just not exist?

Lawrence Krauss: It's a region separated from all the rest of the universe, because nothing can get out of it. Some black holes are more exotic than others, they are fascinating to think about being that dense. They would be forever except for something discovered by Steven Hawking, who discovered that -- not that diamonds aren't forever, but black holes aren't forever. Even though classically nothing can get out of a black hole. When you apply the laws of quantum mechanics, basically material can leak out of a black hole and the black hole will evaporate, heat up and get hotter and hotter and hotter. If Steven's right, everyone -- a solar black hole will exist for trillions and trillions of years. A smaller one evaporates in a minute or so.

Ted Simons: Can there be a galaxy inside a black hole?

Lawrence Krauss: In some galaxy we may find a billion solar mass black holes, or billion solar mass black holes. That's almost the mass of a galaxy. That much material has fallen in and is inside. What happens at the very last stages? We don't know. Black hole physics is at the forefront of our study of nature right now. The whole universe could be a black hole. If there's enough matter to cause the universe to recollapse, we would be living inside of a black hole.

Ted Simons: Lawrence, let's talk about time next month. Thanks for being here.