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Science Matters with Lawrence Krauss

Airdate: September 6, 2016
Arizona State University physicist Lawrence Krauss will explain the latest science news, including the discovery of a habitable planet circling a neighboring star.

Guests:
  • Lawrence Krauss
Category: Science

Keywords: science, planet,

View Transcript
TED SIMONS: Coming up next on Arizona Horizon, world-renowned physicist Lawrence Krauss tells us about the discovery of a nearby earth-like planet. And we’ll hear about a “housing- first” approach to ending homelessness. Those stories next, on Arizona Horizon.

ANNOUNCER: Arizona Horizon is made possible by the contributions by the friends of Arizona PBS, members of your PBS station. Thank you.

TED: Good evening and welcome to Arizona Horizon, I’m Ted Simons. Congressional candidate Christine Jones filed a lawsuit today, asking a judge to order Maricopa County to hold off on processing the results of the Republican primary in Congressional District 5. Unofficial results show that Jones lost the race to Senate president Andy Biggs by 9-votes out of over 85-thousand votes cast. Jones contends in the lawsuit that the county failed to count hundreds of ballots of eligible voters and may have allowed improperly identified people to vote.

Yes, it’s time again for our monthly look at science news as explained by physicist Lawrence Krauss. Tonight we learn about an earth-like planet orbiting a nearby star, among other things. Here he is, cosmologist, astrophysicist and all-around man about town, Lawrence Krauss.

LAWRENCE KRAUSS: It’s nice to be about town here tonight.
TED: It’s nice to have you here! We were supposed to have you a couple of weeks ago.

KRAUSS: Well, a little bird flew into the engine of my jet—happily, when it was on the ground.

TED: All right, let’s get it going. An Earth-like planet circling a nearby star… what are we talking about here?

KRAUSS: Well, the nearest star to us around the system of Alpha Centauri is a star called Proxima Centauri, and what was discovered by looking at the planet—at the star wobbling, when the planet goes around the star, the star wobbles back and forth—and by looking for that wobble we were able to measure the mass of the star and the mass of the planet and the period of orbit. We discovered a planet that is about 1.3 times the mass of the Earth, so it’s just a little bigger. It is really close to the star however. It is so close that it orbits it once every 11 days. Now you might say, well, that it is not a fun place to be because that is even closer than Mercury is to our sun, but that star is far less bright and strong than our sun. It a very small star, so if you work out the amount of sunlight hitting that planet’s surface, it’s the same amount of sunlight hitting our Earth. And since it’s probably earth-sized and Rocky like it, we think it is in what is called the “habitable zone,” a region where liquid water might exist.

TED: Now am I correct here... It doesn't circle the sun, it’s like the moon does with us how the same side is always seen.

KRAUSS: It is so close to the sun that, like our moon, the same face is always pointing toward the sun. So if you lived in there, it might seem like Arizona – and you might say, well, you cannot have life there. But there are a few reasons you might think we might. First off, the star is actually much redder than our sun, so the light coming out is very red.

TED: It is a red dwarf.

KRAUSS: Very good! It is nice to see that knowledge coming through. In fact, actually, that means there wouldn’t be ultraviolet light coming from that star. So in terms of plants and other things, that would affect things. But the point is there could be currents, if there is an atmosphere that can actually—so the front side need not be that much hotter than the backside. Even with Venus, the heat gets distributed. And there is a region with where the high property values are, which is on the equator or on the ecliptic. So there is a region where you are almost always at sunset. That will be a beautiful place to live. The bottom line is, look, we say it is inhabitable, but we don't know we yet—we don't know anything about the star. Really we need to take pictures of that planet.

TED: Yeah, that was an artist’s rendition that we were seeing there. 4.2 light years away, so we’re talking, what 25 trillion miles away… as you said, obviously we can’t see it. We just know it by wobbling and by gravitational forces.

KRAUSS: Exactly. We are inferring something about the planet. What makes it so exciting is it is the closest star to us and it has what may be a sort of Earth-like planet. If you are thinking about exploring the universe for life, that is where you would want to go.

TED: 4.2 light years away, that’s a long ways away. The idea of spacecraft even getting out that far—

KRAUSS: Conventional spacecraft would take 50-100 thousand years to get there. A couple of years ago I would have said, we’re never going to visit it, but it isn’t a few years ago.

TED: You have a “breakthrough starshot initiative”.

KRAUSS: Yes, a Russian billionaire named Yuri Milner decided that it would be interesting to consider whether we might send a spacecraft to the nearest star before, even before this planet was discovered and put together an advisory group with Stephen Hawking, and others including yours truly. The idea is not to send a spacecraft with people, not with James D. Kirk in it, but a spacecraft with a one gram payload to the nearest star.

TED: And we have a video…

KRAUSS: There it is. You see, what we will do is— you cannot have a rocket ship, it would need an enormous amount of fuel to get to the nearest star. So what we want to do is have an amazing array of lasers that will point to a sail one meter by one meter across, shoot ten gigawatts of power toward the sail. The light bounces off the sail and and within two minutes the little spacecraft will get to twice the distance of the moon, traveling at 20 percent the speed of light and taking about 20 years.

TED: You talk about the things on the ground are shooting up into the sky?
KRAUSS: Exactly, and that sail has to reflect 99.99999 percent of the light—otherwise it will burn up. it is the pressure of the light that will knock the whole thing and accelerate it at about a million gs, and it will get to twice the distance of the moon, at which point the lasers can't reach it… and hopefully it will accelerate at that time to 20% the speed of light which is far faster than any spacecraft we have ever built.

TED: It can go past suns, it can go past planets…

KRAUSS: The great thing is it will be a challenge. It is at the edge of modern technology. We are thinking 10-15 years to see if we can do that. The laser array is pushing. The satellite has to be small, but still take pictures. The solar cell will have to be made of new materials. But if we can do it, the cheap part is the sail and the spacecraft. Yes, maybe the goal is to travel and take a picture of the planet, but even if we cannot do that, we can send satellites out to Pluto in less than a week. We can explore the whole solar system in a few weeks.

TED: And these things are the size of a smartphone, maybe?

KRAUSS: Much smaller. The sail is a meter, but the satellite is one gram, one cubic centimeter. Micro-miniaturization is allowing us to do a lot with small things. Mass is the enemy of space travel. That is why you don't want people out there, you need something light. It is turning—I wrote about this a long time ago. If we ever explore stars other than our own, we will not be sending people out there, we’re going to be sending very small objects. This is the first effort to do it. Is it plausible? It’s possible—It doesn't violate any laws of physics.

We certainly cannot do it with the technology we have today. SO the timeline is, 10-20 years of R&D, 20 years of travel, then four years take the signal back. And so in 39 years, you and I will be doing this program in our wheelchairs, and hopefully you will have pictures instead of the artist’s rendition.
TED: And something else has happened—we have a close-up image of the north pole of Jupiter.

KRAUSS: Yeah, I think we talked earlier in the episode about the Juno spacecraft, It is orbiting Jupiter… and here is a picture taken from about 2500 miles. Notice Jupiter here is blue because the north pole of Jupiter is blue and there are incredible storms that have never been predicted to be seen on it. It also took a picture of the South pole of Jupiter, which is this beautiful aurora. It is pictures of Jupiter we have not seen. This spacecraft will take every month or so to do an orbit, but when it gets close each time we will see Jupiter as we have never seen it before, and eventually it will crash. Every time we open a new window on the universe you are surprised.

TED: Something else that is surprising, at least to me, a missing spacecraft the size of a washing machine was found on a comet the size of Central Park. There it is.

KRAUSS: Here is a picture. You may remember this lander was released from the Rosetta spacecraft, which was doing a rendezvous with the comet as it was orbiting around the sun. It was supposed to land on the comet; what happened was it bounced a few times and it ended, as luck would have it, in the crevice and in the shadow. It is supposed to operate using solar power. It only operated a little time and sent back data but we didn't know where it was. And the Rosetta spacecraft is approaching that comet—it’s now about a kilometer and a half away—and it was able to see that spacecraft. And it’s useful because we can interpret the data that came from the 60 hours before it died because we know where it is. Eventually the Rosetta spacecraft itself is going to gently crash—in fact, at a lower velocity then that lander was going at—into the comet so maybe it will survive.

TED: So there are going to be two spacecrafts on the comet.

KRAUSS: …as it goes around the sun and eventually, you know, it heats them off, and probably it would become very volatile. But it’s amazing that we are able to do that.

TED: I love this stuff. Okay, before you go, we have a couple minutes left here. I understand that Lucy, for the 3.2 million years old, fell from a tree and now we know how we died?

KRAUSS: No way. Lucy, our famous ancestor, is 3 million years old. Some people recently saw that her shoulder was fractured, and the kind of fracture they thought she had by asking orthopedics could only come from a car accident—which is unlikely—or a fall from a tree. But the point is, as my colleagues pointed out, almost all of the fossils they find in that region have similar things including the hippos and other things, which probably weren’t climbing a lot of trees. When you’re under the earth for 3,000 years, there are a lot of geological forces that can produce these things. So to say Lucy fell from a tree is absolutely outrageous.

TED: A passing hippo could have gotten stepped on the bones.

KRAUSS: Yes, exactly. And the hippo itself died and had similar problems! So, It is a nice idea but there is really no evidence for it. When you make extraordinary claims, they require extraordinary evidence… and as we will be talking about tomorrow night at our Origins Project event here downtown, which is political bodies, gender, sex and reproductive rights… it will be a really fiery event and I hope people come to it.

TED: So that’s happening. Alright, of all things that we talked about, and you wrapped it up quickly --

KRAUSS: Thank you. Well, I didn’t want to go over time for you.

TED: Of all the things we talked about, what is the most exciting?

KRAUSS: For me, the reason I got involved in the breakthrough starship is because I find the possibility so exciting. The idea that potentially in our lifetime, if we take care of ourselves, humanity may have sent an object to the nearest star… to me, is so inspirational. Even if it is a long shot—literally as well as metaphorically—it is just amazing to think about, and I think inspiring. Can you imagine having a picture of the planet we can show?

TED: And we should mention, Alpha Centauri, isn’t that where Proxima is?

KRAUSS: They are all in the same region. Alpha Centauri actually is a double star. If you actually lived on the planet, you would see these two huge stars that are incredibly bright, much brighter than any star in our sky, because they are so close to Proxima. And by the way, just because the star is much smaller than the sun, because this object is closer to the sun, its sun would be ten times bigger than our sun in the night sky.

TED: Unless you live in the areas with the nice sunsets, then you could break open a bottle of wine.

KRAUSS: That is where you want to live.

TED: It is good to see you.

KRAUSS: It is great to see you.

TED: Thanks man.