Last week scientists announced they had created a type of bacteria that could live on arsenic. For astronomers looking for life on other planets, it’s a reminder that life elsewhere may be remarkably different from the forms we know on earth. Astronomers have, so far, identified hundreds of planets beyond our solar system. The hunt is on to determine if any of those spotted so far could sustain some form of life. Join us to talk about the study of exoplanets, the mystery of dark matter, and what some current research efforts can tell us about both the past and future of our universe


  • David Aguilar Director of Public Affairs and Science Information, Harvard-Smithsonian Center for Astrophysics
  • Lori Feaga Assistant Research Scientist Department of Astronomy University of Maryland
  • Alan Boss Department of Terrestrial Magnetism, Carnegie Institution for Science


  • 11:06:55

    MS. DIANE REHMThanks for joining us, I'm Diane Rehm. Last year, a group of astronomers announced the discovery of a planet beyond our own solar system that could, they thought, support life. Subsequent investigators were not able to verify the findings, but we are, many say, on the verge of making any number of discoveries about our galaxy and those far beyond.

  • 11:07:28

    MS. DIANE REHMJoining me as part of our Environmental outlook series to talk about exoplanets, dark energy and some of the many other research areas in astronomy today, David Aguilar of the Harvard-Smithsonian Center for Astrophysics, Lori Feaga of the Department of Astronomy at the University of Maryland and Alan Boss of the Carnegie Institution for Science. I do look forward to hearing your questions and comments as we talk about the world beyond our own. Do join us, 800-433-8850, send us your e-mail to and you are welcome to join us on Facebook or send us a tweet. Good morning to all of you.

  • 11:08:32

    MR. DAVID AGUILARGood morning Diane.

  • 11:08:32

    MS. LORI FEAGAGood morning.

  • 11:08:32

    MR. ALAN BOSSGood morning.

  • 11:08:33

    REHMYou know when you think about arsenic-eating bacteria, I mean, the whole idea just sort of blows my mind, Alan. What do we know about what that actually indicates?

  • 11:08:53

    BOSSWell, Mono Lake in California has long been known to be an arsenic-rich lake and it has strange critters living in it, so this recent group has been culturing some of the bacteria that come from that lake and they've made the claim that they can make these things grow quite nicely with huge amounts of arsenic that would kill basically anything else on our planet.

  • 11:09:14

    BOSSThey've also made the claim that the arsenic may actually be replacing the phosphorus in the DNA backbone of the molecules and if that is truly true, then they really have, in essence, discovered a new form of life. However, other scientists who have looked at the same information are debating quite strongly whether or not the arsenic that they detect in their samples is really locked up in the DNA backbone or not. So I'm afraid the jury is out as to whether a truly different form of life has been found, but it is a very fascinating area of investigation. I'm sure lots of folks will be following up on this in the future.

  • 11:09:46

    REHMI should say. Lori, have you been looking into this at all?

  • 11:09:51

    FEAGAI have not, but you know we're studying comets with some of the missions I'm involved with and comets are also the formation, from the formation of the solar system and have organics on them, which are building blocks of life as we understand life currently and may have brought water to the earth. So we're definitely, you know, keeping our eye on this research. I myself am not involved with it.

  • 11:10:15

    REHMAnd David, I would think that perhaps your own institution is equally interested?

  • 11:10:22

    AGUILARWe're interested, but I think this proves more than anything else that Darwin was correct that evolution is happening all around us on this planet. It adapts to different environments. It takes advantage of changes within our environment and we should find this on other worlds, too. I would have been much more interested if they'd found something that was based on silicon instead of carbon. That, to me, would have been a very new life form which would have given us so many more possibilities in the universe for different forms of life.

  • 11:10:51

    REHMWhereas you think arsenic has true limitations?

  • 11:10:55

    AGUILARWell, it has limitations in the sense that I'm not sure how abundant we're going to find it on other worlds but secondly we have microbes that eat noxious things, plutonium. We -- this may be a cash future for us on this planet of creating microbes that eat all of our waste that we have and no idea how to get rid of them.

  • 11:11:16

    REHMDavid Aguilar, he's director of Public Affairs and Science Information at the Harvard-Smithsonian Center for Astrophysics. Back to you, Alan. What do we know at this point about planets beyond our own solar system? Much more than we used to, I gather.

  • 11:11:38

    BOSSExactly back in 1995, we really had no solid proof of any other planets outside of our solar system, but in 1995, the dam broke and the first planet around a sun-like star was discovered by a Swiss group. As of this morning, the Exoplanets Encyclopedia, which is sort of the unofficial world site for keeping track of how many planets there are, tallies 506 planets found so far. So we've gone from zero to 506 in just 15 years.

  • 11:12:06

    BOSSAnd those 506 planets include an incredible range of objects. A lot of them are what we call hot Jupiters, which are Jupiter-size planets which orbit very close to their star and make them very hot. Some of them are cold Jupiters, which are a little bit farther out. There are a number of Neptune-sized planets in terms of mass. And there's a whole new class of objects which we call super Earth, with masses perhaps 5, 10, 15 times the mass of the earth. And some of them are hot and some of them are cold and some of them may even be habitable, just like the ones referred to at the top of the show, Gliese 581g, which is good case for being the world's first habitable planet.

  • 11:12:41


  • 11:12:44

    BOSSThere are even planets you didn't mention. There are puffy planets, which we don't even have in our solar system and we're not quite sure what they are. They're bigger than Jupiter. They have the density of less than Styrofoam. We're not quite sure what these are...

  • 11:12:54


  • 11:12:54

    BOSS…but we weren't blessed with them in our solar system.

  • 11:12:57

    REHMBut why do we call them planets? How do we define the planet as it is...

  • 11:13:02


  • 11:13:03

    FEAGAWell, you know, they're orbiting around their star. We're watching their orbits and...

  • 11:13:16

    BOSSI can actually follow up on that because I happen to have been chair of the International Astronomical Union Working Group, which had the task of defining what a planet should be.

  • 11:13:24


  • 11:13:24

    BOSSAnd so on the question of the lower mass and which, of course, brings you into the Pluto debate, we basically punted and said, we'll just go with whatever the solar system people say. But on the upper mass end, what everyone agreed with was at the time, which was actually about eight years or so ago now, was that if you can be massive enough to burn some deuterium in the same way that the sun burns hydrogen...

  • 11:13:44

    REHMWhat's deuterium?

  • 11:13:44

    BOSSDeuterium is a hydrogen atom which has an extra neutron in it, so it's called deuterium instead of plain hydrogen.

  • 11:13:50


  • 11:13:50

    BOSSAnd so deuterium, you don't have much of it, so if you do burn deuterium, you can maybe burn deuterium for a few million years and stay warm...

  • 11:13:59

    REHMIs that in the dictionary yet, that word?

  • 11:14:03

    BOSSOh, definitely, as well as trillium, which is hydrogen with an extra neutron.

  • 11:14:06

    REHMOkay, okay.

  • 11:14:08

    BOSSSo, it's -- astronomers are quite familiar with it as well as physicists, so basically, once you get about as massive as 13 times the mass of Jupiter, you can burn deuterium and so we decided if you can burn deuterium, thou shall not be a planet, thou art a brown dwarf.

  • 11:14:22

    REHMAll right. So in terms of the number of planets out there now we think?

  • 11:14:33

    BOSSMy latest book for National Geographic says there are 13, because I did not agree with the IAU, which the majority of astronomers do not. It was a hasty vote. You don't vote for popularity of planets. The dwarf planets fit the definition of a planet if you want to talk about the three possibilities. They're round, they circle a star and the fact that they haven't cleared their orbit. Neither has Jupiter with all the asteroids that are locked in orbit with it. Neither does the earth that every once and awhile gets hit, gains a ton in weight every day from the stuff that rains in. We haven't cleared that orbit.

  • 11:15:10

    BOSSSo consequently, I'm with 13. The universe thinks small. We just triple the size of the universe with tiny stars. Tiny galaxies are the most common. I think dwarf planets are the most common planets out there.

  • 11:15:17

    REHMWhat do you think, Lori, as far as the number is concerned?

  • 11:15:21

    FEAGAWell, you know, I don't even like to think of the number, Diane. I like to just think of classify them as similarities, so Pluto is very much like the (word?) objects and other comets that we're studying, it's a very cold body. It's from the outer parts of the solar system and it's much different than our four giant planets, Jupiter, Saturn, Uranus and Neptune. And of course, it's also much different than the four terrestrial planets, so if you just classify them more with similarity, you know, in groups rather than calling, well, we have nine planets or eight planets or 13 planets.

  • 11:15:54

    REHMAnd you, Alan?

  • 11:15:58

    BOSSWell, if Dave is willing to accept calling objects like Pluto a dwarf planet, I am in vigorous agreement with him that yes, there are probably a lot more dwarf planets than there are what we might call regular planets, which is as Lori just mentioned the terrestrial planets and the gas-giant planets. That's clear because basically nature, at least for rocky, icy bodies tries to build from the bottom up, so you start with a whole population of smaller objects and you try to accumulate them in the larger, so you usually have a lot of leftovers in terms of number, maybe not in mass.

  • 11:16:27

    BOSSBut you have a lot more of the smaller guys, so I think that's probably true in our solar system and undoubtedly, that's gonna be true around other solar systems and on other stars as well. There's no reason to think we should be very different there.

  • 11:16:39

    REHMAlan Boss of the Carnegie Institution for Science, Lori Feaga, she's at the University of Maryland's Department of Astronomy, David Aguilar director of public affairs and science information at Harvard-Smithsonian Center for Astrophysics. Do join us, 899-433-8850. Tell us more about this Gliese 581g, David.

  • 11:17:12

    AGUILARWell, it was part of a distant solar system that we had discovered before and there was some controversy that a new planet possibly in an earth-like orbit or close to it, so it could have conditions that we would consider similar to a terrestrial planet. Then there was some discussion that maybe the data was not robust enough, that they couldn't be duplicated, but I think Alan should really comment on this because he was more intimately involved in this.

  • 11:17:41

    BOSSYeah. Gliese 581g has been filed for 11 years now with data by two different groups, basically the Swiss group who happened to be the one that found the first planet back in 1995 as well as a group here in the U.S. centered on UC, Santa Cruz and the Carnegie Institution, so the Swiss found the first four planets around Gliese 581 several years ago and published them. And they found two in particular that were sort of just on the inside and the outside of what we call the Habitable Zone.

  • 11:18:04

    BOSSThe Habitable Zone is the distance from a star where if you have a body in orbit around it, you might have water, liquid on the surface. So they found Gliese 581c and 581d. C was apparently just a little bit too hot. D was a little bit too cold.

  • 11:18:21

    REHMSounds like "The Three Bears."

  • 11:18:23

    BOSSExactly. And it's as often called "The Goldilocks Planet" because what was just announced a few months ago was the California Carnegie group found one right in the middle which they called "Goldilocks," which could be habitable.

  • 11:18:33

    REHMAlan Boss of the Carnegie Institution for Science, short break and we'll be right back.

  • 11:20:03

    REHMAnd we're back talking about what's outside our world -- our own world for a change with David Aguilar of the Harvard-Smithsonian Center for Astrophysics. Lori Feage, she's at the Department of Astronomy at the University of Maryland. Alan Boss, he's at the Carnegie Institution for Science. I have seen a number 50 with 21 zeros following it, which apparently is the number of earth-size planets now expecting to be orbiting distant suns. How do we calculate that number of zeros? Look at them pointing to each other.

  • 11:21:02

    AGUILARI haven't a clue how we came up with that number.

  • 11:21:05

    BOSSRecently there was a claim that there may be in elliptical galaxies maybe several hundred times more...

  • 11:21:10

    AGUILAROh, sure.

  • 11:21:11

    BOSS...low mass so-called red dwarf or end dwarf stars than what people thought previously, but we now know from surveys of those stars in our galaxy is that something like one-third or more of them seem to have these super earths that we were talking about earlier. In fact, the other system we were talking about before Gliese 581 is one of these red dwarf stars. That's roughly one-third the mass of our sun. It is eight billion years old, so it's almost twice as old as our solar system is and it does have the system of at least six planets around it, including one which might very well be the first habitable planet.

  • 11:21:43

    BOSSAnd so one just has to say, given these facts, that end dwarf stars do tend to have lots of planets, which we can call super-Earths. Some fraction of them will be orbiting at the right distance to be -- have liquid water on them, therefore they could be habitable, so some -- when you say that within the factor of two or something, whenever you have an end dwarf star it might very well have a habitable world around it and therefore, you get to the 50 times 10 to the 21...

  • 11:22:08


  • 11:22:08

    BOSS...earths in the universe.

  • 11:22:09

    REHMYeah, yeah.

  • 11:22:10

    AGUILARBut this is a guess. This is just -- any number we can hang on it. Let me say something very quickly about super-Earths. Alan has brought it up. These are very fascinating worlds, something we had not quite expected. There is a body of scientists today that believe the earth is a minimal size planet to support life because it has plate tectonics which are necessary for us to re-circulate the carbon dioxide and keep our planet happy. But these super-Earths, they talk about them as being two and three times more massive than our earth, which really means they're about one and a half to two times the diameter of our earth, so some of these earthlike worlds that we're finding out there are much bigger than our earth.

  • 11:22:49

    AGUILARSo you think it's tough to travel on the planet right now. It'd be three times as long on those worlds to travel the same distances.

  • 11:22:55

    REHMAnd considering how we are finding out about these, you've got an orbiting telescope, the Kepler Mission. Tell us about that, Lori.

  • 11:23:07

    MS. LORI FEAGESo the Kepler Mission is looking for these transiting planets. And a transiting planet basically goes in front of the sun, dims the light of the star that it's orbiting and we can see that little tiny difference in the brightness from the sun that we're studying. So the Kepler Mission was a NASA mission and it's up there looking for -- you know, doing a survey.

  • 11:23:31

    REHMSo last June, you had this release of information about 350 stars and now you're expecting many, many more?

  • 11:23:44

    FEAGERight. So if you think about this mission has only been looking for a year and as Alan mentioned at the very beginning, we've only been looking for the exosolar planets since 1995 and we've seen over 500 and we have six planets in one particular solar system, we're looking at the odds are very high of course that these are all over the place.

  • 11:24:04

    REHMHow many astrophysicists are out there looking for all these stars, all these new planets, all this new information, Alan?

  • 11:24:17

    BOSSBack in 1995, there were really only about a dozen or so. These days, there's probably closer to several hundred to a thousand because it's become a very major area of astronomy because people realize that this is a wonderful way of finding something really exciting that a lot of the people in the public resonate with, finding information about habitable worlds often is a lot more exciting to folks than some of the other things astronomers find. Astronomers find them all equally interesting, but we know the public is really excited about having other worlds.

  • 11:24:45

    BOSSIn fact, we mentioned the Kepler data release last June. There's going to be another major data release in February. And so the Kepler Mission's going to be releasing information on another 800 or so stars and is going to be, of course, a lot of really exciting discoveries. It will be associated with that data release.

  • 11:25:00

    REHMAnd who's funding all this, David?

  • 11:25:02

    AGUILARIt comes from NASA, it comes from private funding, it comes from different organizations, NSF. I think what's most significant about what we're going through right now is that astronomy is an odd subject. You can't touch these objects, you can't taste them, you can't smell them. You can see them, you can't hear them and yet it changes us as human beings and what we think about the universe, where we place ourselves in it. We have always speculated there were other worlds out there and other creatures with fantastic capabilities or knowledge to pass onto us. And yet we never had that opportunity to find them.

  • 11:25:38

    AGUILARWe are the generation, we are the human beings on this planet that are now doing that. We're opening the doors to the universe. What's out there, what's possible every day and we're doing it as teams. The day of Galileo, the day of Herschel, these astronomers, is almost over. There are huge teams working cross borders, cross languages together to discover these worlds.

  • 11:26:03

    REHMAnd the question is, is there enough money to keep this going, Lori?

  • 11:26:11

    FEAGEWell, it comes down to what's in the budget for NASA, what congress and the American public and international colleagues and international collaborations, what they think of what's important as far as what the money that is there, what it should be spent on. So there's all these new and upcoming, like exoplanet research and astrobiology. There's these new fields that are becoming more interesting that are opening different departments and realms within different universities, but then there's always the new research that people are finding that end up getting funding and new missions, so...

  • 11:26:51

    REHMAnd what about student interest in these fields?

  • 11:26:55

    FEAGEThere's a high interest right now for astrobiology and exoplanet solar -- you know, exosolar planets.

  • 11:27:01

    REHMWhen you say high, what does that mean?

  • 11:27:04

    FEAGEWell, I would say a typical astronomy department doesn't have that many students to begin with compared to several other majors that you could choose from in college. Any department could have anywhere from five to 40 or so majors in astronomy and a handful of grad students, five to 80 or so.

  • 11:27:23

    REHMWhere do you see it -- are you seeing...

  • 11:27:25

    FEAGEWe are seeing an increase in these particular fields. That also comes and goes as far as what people are majoring in.

  • 11:27:35

    REHMOf course. Alan.

  • 11:27:36

    BOSSMy understanding is that many of the major graduate schools in astronomy these days that there are more graduate students who want to work on exosolar planets than they have professors around to help guide the research. It really has become a major fascination for new students. I also wanted to return to the subject of the funding. In the United States, ground base searches for exosolar planets are primarily funded by NSF, though NASA also supports some of that work through its support for the Keck Observatory, but mostly what we're thinking about from the Kepler Mission, for example, which is roughly a $600 million mission, is support by NASA.

  • 11:28:08

    BOSSAnd while Kepler is a fantastic mission, there are plans to build even more precise powerful space telescopes that will allow us to actually take a picture of a nearby earth. And those missions have to be paid for by NASA, but unfortunately, NASA is pretty much broke at this point in terms of the astrophysics budget, in large part because of the James Webb Space Telescope, which is going to be a fantastic next generation space telescope. It's costing more than people thought it would. And because of that...

  • 11:28:33

    REHMEverything does.

  • 11:28:34

    BOSSEverything does indeed. James Webb Space Telescope is no exception. But because of that we're going to have to defer delay for a decade or more our hopes to fly some new space telescopes that will actually do some more surveys to try to find exosolar planets, as well as solve other problems in astronomy as well.

  • 11:28:51

    REHMI wonder if all of you as scientists involved in scientific outlook, research are as concerned as I am about how this planet may be affecting the worlds around us. Lori.

  • 11:29:12

    FEAGEWell, Diane, that's a good question and I'm not -- I don't know if I've ever looked at it that way, how we would be affecting what other things are going on. Definitely, when we think about our research and we go in one direction, we do have an observational bias. And what we can see or what our technology allows us to build and to go and do is, of course, what directs us into what our next field is or what our next discovery is, so we might be limiting ourselves without even knowing it.

  • 11:29:46


  • 11:29:47

    BOSSYou know, the Gliese 581 system we were talking about was known to have possibly habitable planets a few years back. And so a Russian scientist decided that Gliese 581 being a possible place where there could be intelligent life, he sent them a radio message about eight years or so ago, which is now eight years closer to Gliese 581 than it is to us. And Gliese 581 is roughly 20 light years away, so maybe 12 more years from now, if there's anybody on Gliese 581 that's listening for us, they'll find out about a Russian radio astronomer sending them a message, so we could have an effect on the universe that way.

  • 11:30:20

    REHMAll right. We're going to open the phones because there is so much interest here. We'll try to take as many calls as we can. First to Clifton, Ohio. Good morning, Nelson, you're on the air.

  • 11:30:37


  • 11:30:39


  • 11:30:39

    NELSONI would like to give you a real breakthrough message here about this subject. I'd like to first mention that I am a member of the Institute for Noetic Science founded by ex moon astronaut, Edgar Mitchell and several other astronauts. I'd just like to mention that you're not approaching this from probably an open scientific angle. When the Settee (sp?) broadcast was, you mentioned, from the station in southern England, I forget the exact name of that station, they broadcast a cartouche, a rectangular column with a lot of binary information including our physical makeup and our size and some statistical information about our planet.

  • 11:31:42

    REHMAll right, Nelson. I need you to get...

  • 11:31:44

    NELSONOutside the station...

  • 11:31:46 your question, please.

  • 11:31:47

    NELSONYes. Okay. I would like to...

  • 11:31:49

    REHMThank you.

  • 11:31:49

    NELSON...tell you that outside the broadcast station, the Settee station, within 28 minutes of broadcast of this cartouche, there appeared in the field outside the broadcast station where the scientists were, a large three football fields long cartouche, an exact answer to our cartouche, which was the total information on who was broadcasting it, all their physical attributes. They are silicon based, by the way, and this is what they continue to do for anyone not to scientifically analyze the phenomena of such things as crop circles...

  • 11:32:38

    REHMAll right, Nelson. Thank you. Any comment from anyone here? David.

  • 11:32:45

    AGUILARI think Noetic Sciences is very interesting. It's right up there with metaphysics. I'm not quite sure what the connection was and I'm just trying mentally to think if that message came back 28 minutes later, it was 14 minutes out and 14 minutes back, which means it was somewhere between here and the orbit of Mars. So -- and we would've picked up anything that was sitting out there, so I’m not quite sure where this was coming from.

  • 11:33:09

    REHMAll right. Let's go to Jeff in Tallahassee, Fla. Good morning, you're on the air.

  • 11:33:15

    JEFFThanks. I have a real question (laugh). I wondered if the panel would like to discuss the whereabouts of where the universe is. And if we are dealing with holding of dimensions in, you know, space in time, then how do we know we're not looking at outside of the Milky Way just a hall of mirrors of the universe?

  • 11:33:34

    AGUILARI haven't heard of hall of mirrors before. This is David Aguilar, but I think it's quite interesting. One of the main topics we're coming out of MIT and some of the organizations right now is the big question, are there multiple universes? Are we just one of many that exist out there? Which, if true, would be certainly a very large revelation for who we are, where we are and what we occupy. So questions like this are not out of the question, they're just big. And we're not sure right now that we have the tools to answer them.

  • 11:34:07


  • 11:34:08

    REHMThanks for calling. To Blanco, Texas. Julian, you're on the air. Let's try that again. Julian, you're on the air.

  • 11:34:21

    JULIANYes. Thanks for having me on the show.

  • 11:34:23


  • 11:34:24

    JULIANMy question is I find it fascinating that we're looking at exoplanets and further and further out in the universe, but what research is being done here in our own universe under the surface of Mars or on the moon, Europa, where we can reach these areas to look under the surface for chemosynthetic organisms or bacteria that eat off of anything?

  • 11:34:47


  • 11:34:48

    FEAGEWell, thank you, Diane and caller. I would like to go ahead and say, first of all, I'm a part of the EPOXI Mission which just had a flyby of a comet, Comet Hartley 2, on November 4 and of course, comets are the leftover materials from when the solar system formed and we see asteroid and debris disk around some of these other suns and stars that we're observing. So this is not just alone here in our solar system. And there are building blocks, water, carbon dioxide, things that we have here on the earth and on some of our other planets within the comets.

  • 11:35:24

    FEAGASo we also, besides EPOXI, we have several rovers on Mars that are, of course, looking into this and something being launched next year, the Mars Science Laboratory, and that will be doing a lot of research on Mars. So we're definitely looking into life here within our own solar system and how it got started and how it got delivered to the different planets.

  • 11:35:50

    REHMWhat's the difference between an asteroid and a comet?

  • 11:35:57

    FEAGEAn asteroid, basically, is a rocky, metal material. It's inactive and it's elliptical orbit, but much more circular between the orbits of Mars and Jupiter. A comet is an icy body of ice and dust and they orbit much further out in the solar system. They have ices on them because they exist further away from the sun and those volatiles and ices, like water and carbon dioxide, can exist in ice form and not have evaporated or vaporized away. And they come in to orbit around the sun and they could come in much closer to the earth than to the sun and as...

  • 11:36:33

    REHMAnd how close do they get to planet earth?

  • 11:36:37

    FEAGEWell, for example, Hartley 2, when we made our flyby back in November, it approached earth in October at about a 10th of the distance from the earth to the sun as close to the earth, so...

  • 11:36:51

    BOSSIn fact, of course, sometimes comets actually hit the earth. I mean, that's perhaps what killed the dinosaurs some 65 million years or so ago and what really protects us from having even more comet impacts than we do is having Jupiter out there. Without Jupiter, which can intercept the comets and have them smack Jupiter in the face occasionally, we'd probably have about a thousand times as many cometer impacts and so instead of having a dinosaur-killing event every 65 million years, it'd be every 65 thousand years, which would not exactly be a pleasant place to live.

  • 11:37:18

    AGUILARBut I wanna speak up for comets because I love them and many people feel they added significantly to the oceans of this earth and that's where the water came from that we find on this planet. A lot of it came from the interior, but comets helped us out, too, in the early formation.

  • 11:37:33

    REHMDavid Aguilar of the Harvard-Smithsonian Center for Astrophysics. Short break and then more of your calls. Stay with us.

  • 11:40:03

    REHMAnd as we talk about outer space, what's there, what we know about, what we are learning about, Susan asks, "Could your guests please address Stephen Hawking's thoughts on extraterrestrial life and the possible negative potential of broadcasting a roadmap to Earth. Alan.

  • 11:40:33

    BOSSStephen Hawking, of course, is a distinguished scientist, but somehow, I think he has gone a little bit beyond -- you know, beyond the border here about worrying about someone coming in to invade us. The problem is that you really cannot come close to accelerating any massive object too close to the speed of light and if you can't travel close to the speed of light, there's no way to get from star to star. Just to get to Gliese 581g, which we've been talking about earlier today, at the speed of our fastest spacecraft now would take you 500,00 years, that's one-way. And there's just no way, based on Einstein's theory of relativity, that you can accelerate something at the speed of light.

  • 11:41:15

    BOSSSo I personally am not worried about the interstellar air raid sirens going off in the middle of the night. I don't think anyone's ever gonna come find us. Only way to communicate is with light signals back and forth, not sending physical weapons.

  • 11:41:21

    REHMBut at the same time, if we're basing what we know as life to be based on who and what we are, couldn't some other form of life use that same method to find us and perhaps be part of the earth without our even knowing it?

  • 11:41:47

    AGUILARCertainly if they are listening to our radio and television broadcasts, they might listen to "The Diane Rehm Show" right now, would be wonderful, but...

  • 11:41:55

    REHMBut again, you're assuming ears and eyes and arms and legs...

  • 11:41:57

    AGUILARBut that's because that's the only method we have right now...

  • 11:42:01


  • 11:42:03 value or take a look at life. We look at all the different forms that are on this planet, but there's only one that has stood up, created tools that have evolved and changed and started unraveling the mysteries of this universe, at least that we're aware of. So we're a pattern, right now, that we use and as Hawkings was saying, we have a terrible record of cultures crashing, the one with the better technology seems to always come out on top.

  • 11:42:29

    AGUILARSo he was looking more on a scientific vein as to what we have out there. I have to say personally, I hope there's some sort of intelligent life we can speak to and communicate with out there, but given the distances and given the possibilities of all different times and periods life comes about, I think we may be more isolated than we really think.

  • 11:42:51

    REHMAll right. To Jacksonville, Fla. Good morning, Walter.

  • 11:42:56

    WALTERGood morning. You guys mentioned habitable a number of times and I was just trying to get a better definition of what habitable means. I mean, you know, you could live in Antarctica and you can live at the bottom of the ocean, but I'd rather live in San Diego.

  • 11:43:08


  • 11:43:09

    FEAGAWell, our typical astronomical definition of habitable is a certain distance from the orbiting sun, such that water can be in liquid form, because as we know it and as David stated, you know, we can only define life right now from what we do know and what we've studied here on Earth. And we think we need water for most of the life that we understand. And so to be at a certain distance so that the planet is a certain temperature that water can be sustained.

  • 11:43:38

    BOSSAnd it also depends on the properties of the planet itself because if a planet is massive enough, it'll have some reactivity which is generating heat in the planet, it should have an atmosphere to help trap some of the heat from the planet as well as from the star and so it's a combination of distance from the star as well as the properties of the planet that will really make it habitable. As David said earlier, you might even wanna have things like thick tectonics to really make it habitable.

  • 11:43:57

    REHMAnd here's an e-mail from a law firm here in Washington, Williams and Connelly, wonder how he's charging a client. He says, "I have a question about antimatter. If every bit of matter has an equivalent bit of antimatter, where is all the antimatter? Could it be in one of those other universes?"

  • 11:44:28

    AGUILARWell, we do know that the possibility of other universes exist where the laws of physics are not the same as they are here, but we have created antimatter quite recently for a very short period of time, microseconds, before it disappeared, so we do know that it does exist, but we don't see it in any abundant form in this universe. It would be catastrophic if we did because when they two come together, they just -- they annihilate each other. So consequently, it is something that can exist, but we don't see it in any large amounts in our universe.

  • 11:45:02

    REHMAll right. To Jaytee in Dayton, Ohio. Good morning to you.

  • 11:45:07


  • 11:45:10

    REHMYes. Go right ahead.

  • 11:45:11

    JAYTEEHi. Yes, I'm a high school biology teacher in Ohio and that my students struggle with observation versus inferences. And one of the things, when you're talking about the extra solar system planets out there, what is the wobble effect and how do I get that -- like, they struggle with that light years and how to comprehend that and that it would take that long to get to these. But we can't see these planets, but yet we observe that they're there, you know what I mean? And we infer, so that was my question.

  • 11:45:41

    REHMGood question. Alan.

  • 11:45:45

    BOSSThat's a good question. In fact, most of the planets that have been found so far have been discovered by what you call the wobble effect, which is the fact that if you have a Jupiter size planet orbiting around it's sun-like star, Jupiter is about 1,000 times less massive than it's sun and so it pulls on its star about 1,000 times less strongly, which means it -- even though Jupiter orbits around the star, the star also orbits around what is called the center of mass of the system, which is now 1,000 closer to the star than Jupiter is.

  • 11:46:18

    BOSSSo you can think of the wobble as being a star and a planet sort of balancing on a teeter-totter, going back and forth. In the case of Jupiter orbiting around the sun, the sun orbits around a distance basically equal to its own radius every 12 years and Jupiter goes around a distance 1,000 times larger, about five times farther away from the sun than the earth does, so that's the basic wobble. If you can detect that wobble, there's no reason for a star to be wobbling, other than having a planet around it.

  • 11:46:43

    AGUILARAll right. Here's how you do it in the classroom. You get the biggest student that you've got in the classroom and the smallest. You put them up in the front of the room, have them hold arms and move around in a circle and pull back and forth on each other, then pretend the smallest student's invisible. That's what we're seeing. The big student, the star wobble back and forth.

  • 11:47:02

    REHMHuh. Does that help, Jaytee?

  • 11:47:03

    JAYTEEOh, that's nice.

  • 11:47:03

    REHMThat's good.

  • 11:47:04

    JAYTEEThat was nice, yeah. Thank you.

  • 11:47:06

    REHMOkay. Thanks for calling. And to Juan in Plantation, Fla. Good morning, you're on the air.

  • 11:47:15

    JUANHi, good morning. Thank you for taking my call.

  • 11:47:17


  • 11:47:17

    JUANI had a question -- hi, I had a question, well, having to do with the contingencies that make possible life on Earth. From what I understand, it's supposed to be like in the thousands that are dependent and interdependent with each other to even consider life as we know it. Supposedly, we can even be -- everything can just go away by just some of those contingencies to no longer be there. I was told things like for example, the moon, the amounts of moons we have, the relationship altogether with our moon, with our sun, with our planets, the gravity involved with our solar system, so to -- is that all being taken in consideration when considering life on other planets or to even talk about it as life on other planets?

  • 11:47:57

    JUANI also had one other question, having to do with other universes and I know bringing, like, the skeptical side here, but I find it pretty interesting that there's no -- as I know it, no evidence for other universes yet, it's taken highly into consideration or at least speculated a lot as something that we should dabble into when I don't think there's any evidence at all for it or is there?

  • 11:48:27

    REHMAll right. David.

  • 11:48:30

    AGUILARVery quickly, "The Rare Earth" by Peter Ward was one of the first books that came out that talked about all of these variations that needed to happen for life to happen on an earth. It needed a moon, it needed a giant Jupiter out there to protect us, it went through a whole litany. Some of these may be quite true and yet I suspect life is more viable than we can ever imagine and we're going to find it on other worlds that don't necessarily have these different capabilities.

  • 11:48:55

    AGUILARI think one of the most interesting aspects about life is today, Jake Craig Venter's just came out with a very interesting idea that we are walking bags of life. Seventy percent of our body's salt water. It's water and yet, the microbes that inhabit our bodies are as important to life for us as we as living. I mean, they support us, they're part of us, so we are a walking colony. We probably will find that on other alien life, if we do discover it. And lastly, these multi-universes, yes. Mathematically, it looks great. So the mathematics are there, we just need to figure out how to prove it.

  • 11:49:29

    REHMLet me understand the new news we've heard about more water on the moon than we had heard before. Lori.

  • 11:49:39

    FEAGAYes, so last summer -- or last fall, there was an announcement that water was discovered on the moon by several space craft that were looking there for a signature of water. And now this is a very small layer of water that was discovered last year, basically just molecules thick of hydrogen and oxygen bonded together on the surface of the moon, but it was everywhere. It wasn't just migrating to the poles, it was not just in the cold jaded areas we saw it in in the daylight as well. This would not necessarily sustain astronauts for long periods of time, it wasn't gallons and gallons of water. If you took an entire football field, you would get one small bottle of water that you would have to excavate in order to get that.

  • 11:50:30

    FEAGABut water is there on moons. We've seen it on asteroids, the water signature. There's obviously the icy planets and icy moons that have water, so water is really all around the solar system and very close to us, not just here on the earth.

  • 11:50:45

    REHMOkay. So why are we so excited by this?

  • 11:50:50

    BOSSI think the main attraction of having water on the moon is not so much about that we think the moon might have some life of its own, but simply that if we decide to go back to the moon and put up a colony or something, we can use that water to generate our own rocket fuel rather than have to bring that up from the earth, so it has important consequences for colonizing the moon.

  • 11:51:06

    REHMIf it's only molecules thick...

  • 11:51:08

    BOSSSo you'd have to do a lot of work to get it...

  • 11:51:11

    REHMI would say.

  • 11:51:12

    BOSSIt would not be easy. On the other hand, lifting up from the surface of the earth and getting things up into that orbit...

  • 11:51:14

    REHMLittle more time.

  • 11:51:17

    BOSSYou have to do a cost to benefit analysis here, clearly.

  • 11:51:19

    REHMYeah, I gotcha. All right. To Manchester, N.H. Good morning, John.

  • 11:51:25

    JOHNGood morning. I'm curious about the next telescope that's going to replace the Hubble. Will this be able to see beyond the Big Bang and what are the implications of that?

  • 11:51:36


  • 11:51:38

    FEAGAWell, the James Webb telescope, I believe, is what you're talking about. Obviously, that one's still in the works, it has not launched yet and it is -- it's going to be a -- has infrared cameras on it, so it doesn’t have the exact capabilities as Hubble, as far as ultraviolet looking at the ultraviolet regimes and cameras, visible cameras. I don't believe we can look beyond the Big Bang, that is when we think everything started...

  • 11:52:10

    REHMAny other thoughts on that?

  • 11:52:11

    BOSSIt's -- yes, the main motivation for building the James Webb Space Telescope was to find the primeval galaxies, to push back and find galaxies which were actually quite bright in giving off optical and ultraviolet light, but seeing that light be red shifted into the near infrared where JWST would detect them, so that is the main motivation to see it, but as Lori says, that's not going back before the Big Bang, that's trying to get back as close to after the Big Bang as when galaxies -- or at least the smallest bits of galaxies first start forming.

  • 11:52:36

    AGUILARWhen we look at the Big Bang, one of our problems is there's -- it's been masked, it's been obliterated for us to ever see what happens at that moment. It -- the brilliance is so bright, it spreads across the universe, the Cosmic Background Explorer, one of the earlier satellites, saw this, so it's like it's been shielded from humans to ever see.

  • 11:52:57

    REHMAnd you're listening to "The Diane Rehm Show." Now to Sarasota, Fla. Good morning, Patrice.

  • 11:53:04

    PATRICEGood morning. Earlier, I believe Alan was mentioning that he'd hoped more for silicon tolerant life form or life form than arsenic and am I completely ignorant? I thought that some of those had been discovered in Juan de Fuca range off the coast of The Americas near the volcanic...

  • 11:53:26

    BOSSThat was actually David's comment, but let me (word?) up to...

  • 11:53:26

    PATRICEOh, I'm sorry.

  • 11:53:26

    BOSS...say that I think the closest thing we have to silicon based life form is human beings who live on iPods and PCs all the time, but...

  • 11:53:29

    BOSS...they may (unintelligible).

  • 11:53:31

    AGUILAR(unintelligible) Vegas (laugh).

  • 11:53:38

    PATRICEVery good answer. Thank you (laugh).

  • 11:53:38

    REHMYeah, I should say. Thanks for calling. And to Winchester, Va. Damon, thanks for joining us.

  • 11:53:46

    DAMONYes, I'm pretty much of a shortcut man or I like to take the shortcut. I was wondering if any of your guests have ever Googled Billy Meier of Switzerland and what is your -- their opinion of him? Thank you.

  • 11:53:58

    BOSSHe's our UFO guy that photographed all those beautiful UFOs which turned out to be models when they found them in his garage about a foot and a half in diameter, but I have to say, it was before Photoshop. He did a miraculous job of putting those into those images (laugh).

  • 11:54:13

    REHMWhoa. All right.

  • 11:54:16

    BOSSAnd the Swiss countryside was gorgeous.

  • 11:54:17

    REHMOkay. To Demitri in St. Louis, Mo. Last caller. You're on the air.

  • 11:54:23

    DEMITRIGood morning, Diane.

  • 11:54:24

    REHMMorning, sir.

  • 11:54:25

    DEMITRII have two quick questions.

  • 11:54:27


  • 11:54:27

    DEMITRIWhere did the ingredients come from that created the Big Bang? That's my first question. The second one is, the way a camera receives images via light, would it be possible or feasible to decipher the light that has left the planets off where we couldn't possible communicate with a slice that light and create images on the negative? I've been thinking about that and I just wonder if it's a ridiculous idea.

  • 11:54:55

    REHMAll right. Alan?

  • 11:54:59

    BOSSLet me just address the second question. Certainly NASA's for 20 odd years been planning to build space telescopes which will allow us to actually do as you say, take pictures of planets around nearby stars. It's not an impossible task. It's extraordinarily difficult, but we know how to build those telescopes. The problem is just we do not have the money to build them right now.

  • 11:55:18

    AGUILARI would say very quickly, we do not know where the material came from for the Big Bang and certainly it wasn't Walmart, but if you can come up with the answer, it's worth at least a Nobel Prize, if not a Nobel gift certificate (laugh).

  • 11:55:28

    REHMWhile he's thinking about it, I mean, you know, there are a lot of people out there thinking about these things. I give them lots of credit, I give you all lots of credit for doing this wonderful work which I think is so mysterious. We haven't talked about black holes. Do that quickly, Alan.

  • 11:55:55

    BOSSI'm not sure if I'm the person to talk about black holes, but in some sense, the Big Bang was the opposite of the black hole, it's where everything came from and I think one way of perhaps addressing that riddle that the previous caller made was about what came before the Big Bang is to think of that there was no before the Big Bang because the Big Bang occurred at what is effectively infinite time ago. It's mathematically a choice of your corner system for time, but in some sense, the Big Bang was infinitely long ago, therefore there was nothing before. That's sort of a mathematical answer, but it's one that at least keeps me from not being able to sleep at night.

  • 11:56:31

    REHMAlan Boss of the Carnegie Institution for Science, Lori Feaga at the University of Maryland, David Aguilar, Harvard-Smithsonian Center for Astrophysics. We haven't solved the problems of the universe, but you've spoken about them very interestingly. Thank you so much.

  • 11:56:56

    AGUILARThank you.

  • 11:56:57

    FEAGAThank you.

  • 11:56:58

    REHMThanks for listening, all. I'm Diane Rehm.

  • 11:57:01

    ANNOUNCER"The Diane Rehm Show" is produced by Sandra Pinkard, Nancy Robertson, Susan Nabors, Denise Couture and Monique Nazareth. The engineer is Tobey Schreiner. Dorie Anisman answers the phones. Visit for audio archives, transcripts, podcast and CD sales. Call 202-885-1200 for more information. Our e-mail address is and we're on Facebook and Twitter. This program comes to you from American University in Washington. This is NPR.

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