Lawrence Krauss on Physics

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World-famous physicist Lawrence Krauss of Arizona State University joins Arizona Horizon monthly to talk about the latest science and physics news.

Ted Simons: Once a month we have the privilege to talk about the latest in the world of science with renowned physicist , and Arizona State University professor Lawrence Krauss, who joins us now. Lawrence, good to see you.
Lawrence Krauss: great to be here.
Ted Simons: quickly, those scientists in Italy, they don't predict a earthquake well enough, they are off to jail.
Lawrence Krauss: Yes. Science has become a risky business. It's amazing and it's so upsetting. The scientists used the data they had for some small tremors in it lip and they announced they couldn't say it was likely there would be an earthquake there. An earthquake happened and they were tried and convicted of manslaughter and sentenced to six years in prison. It defies imagination, the fact that scientists using the best data tell the truth and are put in jail. It's just…
Ted Simons: It also suggests people have maybe more of a face in different aspects of science than perhaps they should?
Lawrence Krauss: It means people don't understand science. One of the great strengths of science is uncertainty, being able to state things without certainties. We can say things with confidence or not with confidence. They said we can't say with confidence there's going to be an earthquake. What this represented, this travesty, is the fact that judges don't understand science, but I guess we knew that already.
Ted Simons: let's try to leave the solar system. Voyager one, this was launched in the '70s, correct and now it's out of the solar system?
Lawrence Krauss: There's new evidence that's come in that Voyager one, Voyager one and Voyager two, they are both heading out, Voyager one has crossed the protective bubble that the sun -- like a placenta that the sun puts around the solar system. The sun is pouring out charged particles and they are pushing out against cosmic rays and magnetic fields from the rest of the galaxy to a certain region that is the territory of the sun, if you wish, and as Voyager is moving out one of the ways we would know that it's crossed that boundary is that it is seeing particles coming into it from - cosmic rays coming one direction as opposed to charged particles from the sun. It's seeing the number of charged particles in the sun dropping off. The real test would be if the sun as these magnetic fields around it and outside the fields would be in a different direction. They haven't yet analyzed the data but that would be the real smoking gun. Everything else looks like it's crossed the boundary. It's the first human made object to leave the solar system. In neighbor 50 or 100,000 years it will be passing by the nearest stars and it's going to continue to operate for another -- that's what's amazing about these things. In 1977 though were launched. They are still working. I love that.
Ted Simons: What can they tell us about interstellar space?
Lawrence Krauss: They can measure magnetic fields, cosmic rays, give us the first taste of what the environment is out there but with the two or three simple devices they have to measure it. And then of course, once they die out, once the batteries go they will just be traveling quietly through the galaxy. I find it very romantic to think of them even if they are not reengineered by some alien civilization like star trek.
Ted Simons: just as long as they don't bump into anything.
Lawrence Krauss: they could be, depending what we do here on earth, and who knows what's going to happen to us, it's nice to know there's some evidence somewhere in the galaxy that we existed once.
Ted Simons: that we were here. You mentioned the nearest star. An earth-like planet. Where is this exactly? This is the nearest star?
Lawrence Krauss: The nearest star system to is alpha Centauri. Alpha Centauri B, the very closest one, about four light-years away. Takes four years from the light from that star to get to us. I'm amazed because it turns out that that star has an earth-like planet around it. It's not an earth like planet you would want to visit because it's orbiting the star every 3.2 days and the surface temperature is about 1,000 degrees. You may say why haven't we found it before? But it turns out you can't see planets. Generally you can't. Sometimes you can see them reflect the light from the star. That's how we see the planets in our solar system. But these small planets we detect them by this amazing technique. As the earth moves around the sun gravity tugs at the star. You can calculate from this earth mass planet that it causes the star to wobble at a speed of 50 centimeters a second, about the same amount you'd walk. It's amazing that we can measure a star wobbling at 50 centimeters per second four lights years away. Blows me away.
Ted Simons:If it wobbles a certain way do we know about the mass of the planet.
Lawrence Krauss: We can work out the mass -- the speed, the period of which it wobbles will tell us the period of the planet how fast it's going around the star. The amount by which it wobbles tells the mass of the star. So that's how -- the mass of the planet, sorry. That's how we know it's an earth-like mass planet, but our period of our orbit is a year, so 365 days. This goes around the star every 3.2 days, but where there's one planet there could be more. So to me, the fact that even the closest star to us has a planet around it means that there's 100 billion stars in our galaxy. I suspect there's 100 billion solar systems. If there are rocky systems around the star, There may be another habitable planet. It's harder to find if it's farther out. An earth like planet an earth's distance away would cause the star to wobble once a year. To see it you would have to measure over many years. They could see the period because it was 3.2 days they could see it wobble along. If they look at the star for 20 years --
Ted Simons:If we want to find out more about this particular earth like planet, these nearby -- nearby stars. How long would it take to send something up there unmanned?
Lawrence Krauss: Unmanned is a reasonable way to do it. Voyager one is going out in the galaxy, but it's moving very slowly. It would take 50,000 years. You could imagine with technology doing something that might take 100 years to get out to the nearest star system. 100 years one way, which is amazing because it's manageable in the human lifetime. It's the first time I realized a rocky planet, that I began to think, maybe humanity might send out probes that might actually reach habitable planet someday. Before that it seemed like science fiction to me.
Ted Simons: again, of course you'd hate to send something over to this earth-like planet and 50 years later go, what about that one? That one might be more interesting. You have to commit.
Lawrence Krauss: but that's what's so good about unmanned objects. They are cheaper.
Ted Simons: That's true.
Lawrence Krauss: people, you have to worry about getting them back. They are just very complicated.
Ted Simons:I have a question from Mrs. simons, my wife. I thought she had a really good question. I certainly couldn't answer it. If energy is neither created nor destroyed, which we all learned way back when, what happens to photons? They seem like they are here, they're gone.
Lawrence Krauss: They get absorbed by your skin. It's not that energy is never created or destroyed, you can convert energy to mass. That's what Einstein's equation is. E=mc2. You can take energy and turn it into mass and Vice versa. The lights from your studio are absorbed in my skin they actually make me heavier. The energy from those photons when absorbed by the atoms of my skin, my mass actually increases a little bit. Not by a huge amount but it's that thinking your wife's thinking was great. It's that thinking of what happens to light when it's emitted by a source and absorbed by another object that caused Einstein to develop his theory E equals MC2. She's well on the way.
Ted Simons: Okay, don't say that! Everything we talked about today, it's interesting, especially regarding the Voyager one and this earth like planet. We really are stretching out, aren't we? Really learning things at a rapid pace.
Lawrence Krauss: Yes. It seems every moment when we meet there's something new and exciting and there is. That's why we have to keep looking at the universe. The universe continues to surprise us. I suspect that's going to continue. I always say, when I wake up I'm surprised if I'm not surprised.
Ted Simons: All right. It's good to have you here. Back again next month?
Lawrence Krauss: Yep.
Ted Simons: we'll do it. Good to see you.
Lawrence Krauss: Great.

Lawrence Krauss:Physicist, Arizona State University;

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