Horizon, Host: Ted Simons

May 8, 2014


Host: Ted Simons

Krauss on Science


  • Arizona State University physicist Lawrence Krauss makes his monthly appearance on Arizona Horizon to discuss the latest science news.
Guests:
  • Lawrence Krauss - Physicist, Arizona State University
Category: Science   |   Keywords: science, asu, news, latest, krauss,

View Transcript
Ted Simons: Good evening, and welcome to "Arizona Horizon." I'm Ted Simons. ASU physicist Lawrence Krauss joins us each month for an enlightening discussion on the latest science news. Tonight that news includes climate change concerns and the evolution of the universe. Here now is Lawrence Krauss. Good to see you.

Lawrence Krauss: Good to be back here. On this cool day.

Ted Simons: Nice cool day for the time being. We'll get to climate change in just a second, but I want to start with the evolution of -- This idea that MiT scientists put all we know what a super computer and BA-boom!

Lawrence Krauss: Well, it’s a large group, it’s not just MiT, but it's kind of appropriate that we're talking about it in the context of climate change. These are models of the universe. You put in all the physics you know, and you let things evolve. And since I've been a physicist, those simulations have been changing tremendously. Because computer power has been changing tremendously. And what these people have done is now take the best possible simulation we can do, putting in gravity, and the dynamics of magnetic fields and gasses and explosions from associated with large black holes and putting it all in and following I think 12 billion mass points over a region the size about 300 million light years across, and the simulation I think would take something like two-thousand years on a desk top computer. So it's the most complex simulations that ever been done and it's amazing to look at. I know we have the video.

Ted Simons: Let's look at it. Tell us what we're seeing. It starts about 12 or 13 million years in.

Lawrence Krauss: We're seeing the dark matter, which dominates the universe. Dark matter has begun to collapse, and normal matter, the matter makes up you and I begins to fall into those dark matter potential wells and you can see the blue is the dark matter, the other material is regular matter and you can see these explosions that are happening. As we now are several billion years after the big bang, massive black holes have formed at the center of galaxies and as they eat material, it blows the gas out and you see these immense explosions. Kicking out diffused gas into the interstellar medium and that's producing hydrogen gas but it’s also, as stars are evolving, producing all the elements that make you and I up. And you can see now from the dark matter now you can begin to see the regular matter, the stuff at the center of these dark matter potential wells, and all of the heavy elements. And what's amazing, the heavy elements are this diffused material on the outside of that cosmic web of galaxies. And what is amazing is that this simulation has reproduced the characteristics of our universe extremely well. The ratio of so-called elliptical galaxies to spiral galaxies. Here's the dark matter. We come back now almost at the present time. The dark matter that dominates the universe, but now you're going to see the dark matter disappear and there's the remnants. That's what we can see with telescopes. That's what you would see with a telescope in that hypothetical universe, and remarkably, it is what with very close to what we see with telescopes today. Our galaxy is a spiral galaxy, most galaxies are spirals, 15% are ellipticals. The ratio of heavy elements, the stuff that make you and I up compared to hydrogen and helium in the big bang, this simulation appears to reproduce pretty well everything we see, which is amazing when you think about it, that we can now numerically do that kind of intense, what we can more or less recreate the evolution years. Now I must say, when you look at that, it looks like it reproduces everything exactly. But the individual points that are used in that, the individual mass points, are each a million solar masses. So we can't yet have a simulation that would go from looking at all these clusters of galaxies down to individual stars, that would take right now longer than the age of a universe with a current computer.

Ted Simons: Ok, so these scientists take everything we know, this is what we see. Now can they take everything we know, this is what we see, project into what's going to happen?

Lawrence Krauss: Of course they can. But that's the easy part.

Ted Simons: I want to see that video!

Lawrence Krauss: There are videos of showing how one of the things we can do, there's a nice simulation, maybe next time I'll bring it, showing our cluster of galaxies. Cuz our Milky Way is part of a cluster of galaxies. And eventually we're going to collide in billion years with the Andromeda galaxy. They'll all collide together and eventually produce one massive galaxy. No longer a spiral galaxy. From what we see now, it's easy to sort of predict what can happen in the future. The hard part is to start from a big bang with dark matter, and dark energy, and see if the physics that we understand produces what we see, and also what's really interesting about the simulation, it tells us that somehow the ratio of normal matter, we call it baryonic matter, to dark matter, changes dramatically over scale. So as we try and look for dark matter in the universe, we can use this simulation to predict how much dark matter there may be in the solar neighborhood and to guide experimentalists as they look out in the universe.

Ted Simons: Last question on this before climate change. How accurate can something like this be when you're dealing with dark energy and dark matter? We don't even know what that is! Do we?

Lawrence Krauss: We don't know what it is, but it is amazing. You don't have to know what it is. You just have to know its gravitational properties. Because it turns out the dark energy, its dominant effect is causing the expansion of the universe to speed up. Dark matter, it's dominant effect is due to gravity, creating these potential wells that normal matter fell into to form galaxies. The hard part, the stuff that couldn't have been known 20 years ago is to take into account the complex interactions of normal matter, gas expanding, heating up, explosions, stellar explosions, those are the hard things, and it's only recently the simulations have been able to include those. How accurate are they? It’s an interesting question because it used to be when the numerical simulations disagreed with evidence from reality, they'd say look our models are wrong. But what we inevitably found was they weren't including all the physics in the simulations. So what they're trying to do is test to see if the simulations reproduce what we can see, and if they do it well enough, we can have the simulations tell us about things we can't see, and that we can look for. So the tests are that this amazing new simulation is -- Produces a universe that looks remarkably like our own, and I critically like seeing those huge explosions that come from -- And what they are, black holes, eating up stars and gas and causing huge shock waves. And pushing out material which tells us there's lots of diffused gas in the interstellar medium.

Ted Simons: I think it's fantastic.

Lawrence Krauss: I like watching it a lot.

Ted Simons: Alright, let's get to climate change here because the national climate assessment has come out, climate change impact region by region. Give us a general overview, what do we have to worry about here in the southwest? What are we talking about here?

Lawrence Krauss: Well, look, the first thing is interesting because we're talking about modeling with galaxies and how accurate they can be. We try and model the climate, we, meaning climate change modelers and those models have gotten much much better in the last 40 years. They used to be relatively course grained, like the galaxy simulations, they're now much much better. So our ability to model what going to happen is much better, but most importantly, over the last 40 years, the data has gotten much better. What this new assessment is telling us, unequivocally is that climate change is happening and it's human induced. There's no doubt, there’s no debate. You'll hear it in the media, you'll hear climate change deniers, but the point is, the scientific data tells us that these things are happening, and they're accelerating at exactly the kind of rate or better faster, not better, but worse, faster than you might expect on the basis of human induced climate change carbon dioxide in the atmosphere. We're seeing -- We've seen these incredible storms in the northeast, 71% more rain in the northeast, 21% more in the southeast. It's also telling us that not only are the oceans getting more acidic, but forest fires have increased at a great rate, droughts have increased, the average temperature in the southwest has gotten worse, in fact there have been in Texas and Oklahoma, two consecutive periods of days with more than degrees heat. It's telling us that the effects are different in each place. But the effects are already happening. It's not as if we need to predict into the future. And people who claim that human induced climate change isn't happening, you just have to look around, and it means that we -- Look, it's not all doom and gloom. But it means we have to realize these are real effects, we're fortunate, one of the predictions here is that we've already seen that sea levels have risen by nine inches or so, but they could rise up to four feet. Or six feet. Sorry six feet. A lot of southern Florida is only four feet above sea level. So that's a real concern there. You might say we're lucky in Arizona. But we've got real worries, because allergens are are increasing, as biodiversity is changing and as frost-free periods are going away, new pests, new insects, new allergens, mountain beetle is now able to survive in regions of the southwest that it couldn't before. And forest fires, you could show in fact that something like there's now based on the existing data, there's twice as great a probability of major droughts and forest fires now as there was 40 years ago. This is 40 years, this is a period that's relevant for humans. But you know, of course there have been major periods of climate change in history, but this kind of intense period, which is predicted by the fact we are continuing to dump more carbon dioxide in the atmosphere. One of the things showed in this report is the U.S. is producing three times as much carbon dioxide as is taken by all the forests and biomass in the U.S.

Ted Simons: I'm going to get all the emails and all the calls.

Lawrence Krauss: I'm glad you will.

Ted Simons: And one of them I get a lot is that CO2 as a pollutant is silly, the plants need it, we need it, because -- We and the plants have a symbiotic relationship with CO2 why do you want to take it away?

Lawrence Krauss: Well, look. It's true that plants use CO2 and in fact they help moderate the amount of CO2 in the atmosphere, unfortunately we're producing it at a faster rate than the plants can take it up. Which is until humans were doing that, there was a kind of greater balance. And CO2 has other effects. By the way, the effects are not all good in plants. CO2, it turns out a recent study showed CO2 can cause plants to grow faster, but just because they grow faster doesn't mean they have more nutrients. In fact, they're less efficient at producing nutrients the faster they grow. So if you’re interested in food production, you're finding, yeah CO2 makes things grow faster, but the food that comes out of it isn't necessarily any better. And the main thing is that CO2, besides -- In some areas of the country this report points out there will be longer growing seasons, but it's more than outweighed by the incredible potential disasters of sea level rise, also extreme storms. Again, not just a prediction of the future, the number of extreme storms over this period, we've been measuring for 40 years during a period when we've been dumping huge amounts of carbon dioxide in the atmosphere, and it hasn't gone down. It's continuing to go up. What this report, and I recommend people look at it, because the data, there's too much here to go into in this program, but what it really shows is that the data is not only validating the models, but the data is showing that climate change is happening. Carbon dioxide, here's one thing it isn't good for, it isn't good for the oceans. It produces carbonic acid. It makes the oceans more acidic. It destroys coral reefs. The data are that the oceans are 30% more acidic than they were in 1970, I think, because of the effects of carbon dioxide. Coral reefs are dying, habitats for fish are dying. Now, again, this – What we have to do is not say, you know, throw up our hands and say I give up, the future is miserable. We have to say these things are happening, we're producing this stuff, it's having this effect, we can't bury our heads in the sand, and we can't pretend for political reasons that it's not happening, what can we do to protect people from these effects? What can we do to produce a better infrastructure-- For example droughts in the southwest are going to produce more demand and heat waves, more demand on power, but the more power we need the more demands there are on water. And we're going find periods where there may not be enough water flowing to produce a sufficient power. We have to fortune favors the prepared mind and we have to think about how we can use our technology for better or worse—-. And of course we have to reduce our dependence on fossil fuels that produce carbon dioxide. But equally important is we have to look at new technologies that can address these real problems that are happening today.

Ted Simons: Last question, we only got about a minute left. Last question, how do you balance hey, if it's going to happen, mankind is smart enough, wise enough and genius enough to adapt and perhaps thrive in a future world that's very different than ours because of global warming, as opposed to, making a lot of changes that opponents of this idea say will kill economies and kill the process the that current economy world economy seems to allow to progress?

Lawrence Krauss: Well, you know, we have lived in a world of cheap oil. And abundant oil. Now we have to live with the fact not only is that resource getting scarcer, but the effects are producing disastrous effects on the economy. The economy of New York, when there was that flooding, believe me it wasn't a positive effect. The money needed to be spent to fix that was immense. Much -- It's much more efficient to spend money to produce technologies to address it. And I agree, we are ingenious enough in our principle to address this situation, but we can't address it if we deny that it's happening. That's the big problem.

Ted Simons: All right. Well it’s good to talk with you again. It's good to see you again.

Lawrence Krauss: It's good to see you again too.

Ted Simons: Alright, take it easy.

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