Let There Be Light

Are you on our wavelength? Learn about the many ways the electromagnetic spectrum infiltrates our lives and illuminates the universe.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Neil deGrasse Tyson?

  Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. Welcome back to StarTalk Radio. I'm your host Neil deGrasse Tyson. I'm an astrophysicist and director of New York City's Hayden Planetarium. And today's subject, let there be light. Joining me as my co-host is Lynn Koplitz. Lynn, welcome back to StarTalk Radio.

• 0:32Speaker 01

  Hello Neil.

• 0:33Neil deGrasse Tyson?

  You're a founding co-host of mine on this program.

• 0:36Speaker 01

  That's right.

• 0:37Neil deGrasse Tyson?

  And welcome back.

• 0:38Speaker 01

  Thank you, it's exciting to be back.

• 0:39Neil deGrasse Tyson?

  I know, you think about light all the time. This whole show is on light. And what we would otherwise call the electromagnetic spectrum, but it's light to most people. But to the astrophysicist, light is not just like the colors of the rainbow. Roy G. Biv, have you ever heard of Roy G. Biv?

• 0:53Speaker 01

  Of course.

• 0:54Neil deGrasse Tyson?

  I don't know what you've heard of.

• 0:55Speaker 01

  I'm not special needs.

• 0:56Neil deGrasse Tyson?

  Okay, can you recite that?

• 0:57Speaker 01

  I'm not a genius.

• 0:58Neil deGrasse Tyson?

  You're not special needs.

• 0:59Speaker 01

  Red, orange, yellow, indigo, blue, violet.

• 1:02Neil deGrasse Tyson?

  What happened to green?

• 1:04Speaker 01

  Well, that's obvious.

• 1:06Neil deGrasse Tyson?

  Okay.

• 1:07Speaker 01

  That's the G.

• 1:08Neil deGrasse Tyson?

  Right, red, orange, yellow, green, blue, indigo, violet. That's the visible part of the electromagnetic spectrum.

• 1:13Speaker 01

  I didn't know there was a pop quiz.

• 1:15Neil deGrasse Tyson?

  And then it goes in either direction. So you go beyond the red, beneath the red, it's infrared. Infrared means less than, back when they first laid this out. You can't see infrared. And you go beyond infrared, you get two microwaves and radio waves. We've all heard of these, maybe you didn't know it was part of the family of light that we call the electromagnetic spectrum. And you come out the other side, beyond violet, what do you find there?

• 1:36Speaker 01

  Beyond violet?

• 1:37Neil deGrasse Tyson?

  Yes.

• 1:38Speaker 01

  Uh, headache?

• 1:39Neil deGrasse Tyson?

  Ultraviolet, and you go beyond ultraviolet, X-rays and then gamma rays. There's the entire electromagnetic spectrum, and the astrophysicist is an expert in each of these bands, and the universe talks to us. And each one of those bands telling us something different. But what we should do is sort of start off with...

• 1:55Speaker 01

  I know, I'm gonna be patient, because I don't understand half of what you just said.

• 1:58Neil deGrasse Tyson?

  Let's start out, let's see what Bill Nye...

• 2:00Speaker 01

  He lost me at bands.

• 2:01Neil deGrasse Tyson?

  Let's see if we can get Bill Nye to just sort of warm us up with just an encounter with what our telescopes do for the universe.

• 2:09Speaker 02

  We're on the radio. What better time to ponder what we cannot see? If you start counting, you'd say you see a lot of things. Tiny things, like pistols between petals of petunias. And big things, like fantastically faraway stars. But now, try the eyepiece of an instrument: a telescope. The moon's not smooth. It's a mess. Those aren't just bright dots. They're worlds with rings and weather. Some of the dots aren't just worlds. They're galaxies full of worlds. And so far, we've just talked about rays of light, visible to human eyes. It turns out that even though we see thousands and millions and billions of things, we hardly see the energy of the universe at all.

• 2:52Speaker 02

  Visible light waves, and microwaves, and X-rays, and cosmic rays, even heat waves are manifestations of both electricity and magnetism at the same time. Electromagnetism. It radiates all over the place, or places, all over space, the universe. By building remarkable instruments to detect all these wavelengths of electromagnetic energy, we discovered planets, stars, and galaxies. Now, as we build better and better instruments, we found that we don't know the half of it, actually about the ninety-four percent of it. We've detected a great deal of energy from vast reaches of space, but there just has to be so much we don't yet see. Let's look into the sky, and stay tuned.

• 3:36Speaker 02

  For StarTalk Radio, I'm Bill Nye the Science Guy.

• 3:40Neil deGrasse Tyson?

  Bill Nye, always telling it like it is. Lynn, welcome with me, one of our guests tonight.

• 3:46Speaker 01

  We have cool guests today, and they're all here.

• 3:49Neil deGrasse Tyson?

  And they're all here, in studio. First up, in this segment, is Michael Benson. Michael, welcome to StarTalk Radio.

• 3:56Speaker 03

  Hey, how you doing? Thanks for having me.

• 3:57Neil deGrasse Tyson?

  Now, how do I characterize you as like a journalist, a photographer, a photojournalist, a astro-nut? Because everything you write about, and everything you publish books on, is about the universe.

• 4:07Speaker 03

  Yeah, the answer is yes. That's how you can characterize me. Thank you very much.

• 4:11Neil deGrasse Tyson?

  An astro photojournalist.

• 4:12Speaker 03

  I'm an astro-nut photojournalist.

• 4:14Neil deGrasse Tyson?

  I first met you many years ago. I think you were preparing one of your earlier books called Far Out. Was that one of them?

• 4:22Speaker 03

  No, the first one was, Far Out is the last one. And that covers basically everything from... Just at the gates of our solar system, all the way to the Big Bang.

• 4:31Neil deGrasse Tyson?

  Okay, so this is a book where you have collected images together with narrative that where you're just bringing the universe to the public.

• 4:38Speaker 03

  Yes, and then the first book was called Beyond, and that's the one you probably saw.

• 4:41Neil deGrasse Tyson?

  Beyond.

• 4:42Speaker 03

  We collaborated a little to put a show up. I don't know if you remember, we put a show up at the hated.

• 4:46Neil deGrasse Tyson?

  No, no, I do remember. So Beyond, Beyond was, those were the space probes that then put up, got images of the planets. So I'm, I'm fortunate as an astrophysicist to have journalists who care about the universe, because then you get to do some of the work that we would otherwise try to do, but would, wouldn't necessarily succeed. And you've been eminently successful at this. Beautiful books that you've published.

• 5:06Speaker 03

  Thank you.

• 5:07Neil deGrasse Tyson?

  So, so what about the universe attracts you? Is it just because the stuff looks cool? Or, and you're a photographer too, so you know, you think about light and what it does and how it, and, and there's a little bit of artist in you, so you think about how light affects the viewer and images.

• 5:20Speaker 03

  I like to think there's a lot of artists in me, Neil, but I'm just teasing you here.

• 5:24Neil deGrasse Tyson?

  All right.

• 5:24Speaker 03

  What about the universe attracts me? That kind of question, um, it's almost impossible to answer that because everything is the universe, so anything that's attractive is the universe. But what about the universe attracts me?

• 5:35Speaker 01

  Wow, you just blew my mind socks off. What does that mean?

• 5:38Speaker 03

  Oh my God, I think I did.

• 5:40Neil deGrasse Tyson?

  Well, he's saying even people sitting next to him is part of the universe.

• 5:44Speaker 01

  That's part of the universe, okay.

• 5:44Neil deGrasse Tyson?

  So, images of him, right.

• 5:46Speaker 01

  Oh, my universe is just my little universe.

• 5:48Neil deGrasse Tyson?

  All right, uh huh.

• 5:49Speaker 03

  No, I don't know, it's probably, it's probably quite large. No, but what attracts me to the universe? I mean, I think that part of it, to be moderately serious here is that, you know, in the last 50 years, um, we have seen things that everybody prior to 50 years ago could only dream of seeing, which is highly detailed images of all the planets, you know, um, of the solar system. And then also after the Hubble was launched and so on, incredibly detailed pictures of, of the origin, you know, the beginnings of solar systems in Orion and this kind of thing. So, my question is, how is it possible really for people not to be attracted?

• 6:25Neil deGrasse Tyson?

  So when he says beginnings of solar system in Orion, the constellation Orion has one of its stars is actually a region of the galaxy where stars are being born, and that's what you meant when you said.

• 6:35Speaker 03

  The Orion Nebula.

• 6:36Neil deGrasse Tyson?

  The Orion Nebula, very famous place in the, in the solar system. A stellar nursery, in fact. And so, so, so all these places excite you, and so you... You, but you didn't take any of these pictures. You assembled them from public sources, right?

• 6:51Speaker 03

  Well, thanks for pointing that out.

• 6:52Speaker 01

  I was just gonna say, wow, what a CB, what a blocker.

• 6:58Speaker 03

  Yeah, well, no, no, I mean, look.

• 7:00Neil deGrasse Tyson?

  So what do we need you for?

• 7:01Speaker 03

  Uh, well, I'll tell you.

• 7:03Neil deGrasse Tyson?

  Why'd I even invite you on the show?

• 7:04Speaker 03

  I was wondering that too when I got the call, you know, but then I decided I would play along. I would play along with you guys. Um, you know, part of it is that, um, uh, you know, it's true, I didn't take, uh, the individual shots. In fact, it's impossible. No human being has been in orbit of Jupiter, for example, or, or orbiting Saturn. But what I do do.

• 7:23Speaker 01

  Tell him, tell him.

• 7:24Speaker 03

  Tell it like it is.

• 7:25Speaker 01

  Go ahead, go ahead. Pull the gloves off, Michael. Don't take that from him.

• 7:29Speaker 03

  Take that, man.

• 7:30Speaker 01

  He's no genius in here. He's just a guy. I'll hold him, you hit him.

• 7:34Speaker 03

  Oh, I don't know. I mean, I think he's, he's certainly got elements of genius, you know? I mean, just the way all of us do.

• 7:40Speaker 01

  Pick a side, pick a side.

• 7:41Speaker 03

  Uh, I'm on your side, baby. Um, okay, let me, let me, let me just say this, you know, um, what I do is go into archives that have hundreds of thousands of, of raw images and I look for extraordinary frames, which I can then mosaic together.

• 7:58Neil deGrasse Tyson?

  Mosaic means they're, they're, you tile them together and make a bigger picture than what the single image was.

• 8:03Speaker 03

  Yes, and I composite them to get color and, and so, um, you know, I feel very much, I, I feel almost authorial towards them because some of them really wouldn't exist if I had. Authorial, like I'm the author.

• 8:16Neil deGrasse Tyson?

  Oh, okay.

• 8:16Speaker 03

  You know, I feel, I feel, I feel like the author of, of quite a number of them, even though of course, anybody can go into the archives and I encourage this very much, to go into the archives of raw data.

• 8:27Neil deGrasse Tyson?

  So the point is, anyone can do it, but they didn't, you did.

• 8:29Speaker 03

  Right.

• 8:30Neil deGrasse Tyson?

  And so you then had the privilege of being the first in and therefore the first out with these beautiful books that you've published.

• 8:36Speaker 03

  I mean, I'll tell you a story.

• 8:37Speaker 01

  It's like you make a collage almost, but you put it all together.

• 8:39Speaker 03

  Yeah, I'll tell you a story. I mean, recently I had a show in Chelsea in, in my gallery, which is Hasstead Krautler Gallery on West 24th Street. And, um, because I had the deadline of February 3rd to have an opening, I went into the archives and I started digging in Cassini material. Cassini is the spacecraft orbiting Saturn right now. And I started looking for extraordinary images.

• 8:57Neil deGrasse Tyson?

  Tons of images are there.

• 8:58Speaker 03

  Yeah, and I found, um, I found these amazing images of the dark side of Saturn, which was not dark. It was not dark because there's so much indirect light bouncing off the rings and so on. And I put together a multiple frame mosaic. And, and, you know, as it emerged in color and I made it seamless and everything, I had the very real sensation that I was the first human being to see-

• 9:21Neil deGrasse Tyson?

  To see the backside of Saturn.

• 9:22Speaker 03

  To be, see, yeah, you can put it that way. The backside of Saturn, I saw the rear side of Saturn in a way. Um, you know, and I had this amazing sensation that, you know, I was a privileged person because I had done this. And then, of course, for me, part of the fun of it is to get it out there and, and show it to people.

• 9:38Neil deGrasse Tyson?

  Let me bring in my second of three-

• 9:39Speaker 01

  It's beautiful.

• 9:40Neil deGrasse Tyson?

  It is, it is. Let me bring in my second of three guests. His name is Brian Abbott. Brian, welcome to StarTalk Radio, your first appearance.

• 9:47Speaker 04

  Thank you, Neil. Thank you. It's a pleasure to be here.

• 9:49Neil deGrasse Tyson?

  Brian, I, I, you have to tell this to the audience. Tell me, tell everyone, because I know in advance, tell everyone what it says on your business card, what it is that you do. You are what?

• 9:58Speaker 04

  Well, I have a business card that reads, "Manager of the Digital Universe."

• 10:02Neil deGrasse Tyson?

  Manager of the Digital Universe, that is so cool. That's like, does that get you dates in the bar?

• 10:07Speaker 04

  It doesn't hurt.

• 10:08Speaker 01

  It's better than Staples. Manager of Staples.

• 10:11Neil deGrasse Tyson?

  So, so Brian, you, you come to this, you have a huge science background, you're computer literate, and you put together data sets for the Hayden Planetarium that enables people to sort of take journeys through those data. And so, what are some of your challenges collecting them scientifically? Because Michael Benson is, is mining the archives, and, and that's cool, but at the end of the day, they're still just photographs. Still photographs, 2D photo, sorry, Michael, I'm sorry.

• 10:41Speaker 01

  It's art, too.

• 10:42Neil deGrasse Tyson?

  Yeah, it is art, it is art, but Brian, you take another dimension here. So where do you take it?

• 10:47Speaker 04

  But that's just another dimension. That's a hard dimension. You know, astrophysicists have a hard time getting distances.

• 10:54Neil deGrasse Tyson?

  Distances is everything.

• 10:55Speaker 04

  Taking pictures of something in the night sky, seeing the, the sort of 2D sky, if you will, from Earth is great, but-

• 11:01Speaker 01

  The whaty sky? Oh, 2D.

• 11:02Neil deGrasse Tyson?

  2D.

• 11:03Speaker 04

  But getting distance to that object is very challenging.

• 11:06Neil deGrasse Tyson?

  And once you get the distance, then you can create a journey through it, right?

• 11:09Speaker 04

  That's right.

• 11:10Neil deGrasse Tyson?

  Okay, so now, now, it's not just visible light data that you've got, because we've got telescopes in every band of light of the electromagnetic spectrum. We have ultraviolet telescopes and infrared tel-, we got a telescope in every band that we cannot see. So what do you do with those data?

• 11:25Speaker 04

  We show them.

• 11:26Neil deGrasse Tyson?

  How do you show them if we can't see them?

• 11:27Speaker 04

  Well, that's the challenge is.

• 11:28Neil deGrasse Tyson?

  Actually, I know the answer to that question, but I want you to say it because you've got the title manager of the digital universe.

• 11:33Speaker 04

  How do you reconcile showing something that we should be seeing with our eyes visible, like the stars in the sky?

• 11:38Neil deGrasse Tyson?

  Yeah.

• 11:38Speaker 04

  With something that is invisible to our eyes?

• 11:40Neil deGrasse Tyson?

  That's what I'm asking you.

• 11:41Speaker 01

  Like?

• 11:41Neil deGrasse Tyson?

  Yeah, thank you, Lynn.

• 11:42Speaker 01

  What's invisible?

• 11:44Speaker 04

  Like microwave radiation, or infrared, or ultraviolet.

• 11:47Speaker 01

  Right, so how do we see that? How do you make it visible to us?

• 11:51Speaker 04

  We, the scientists, and we take, and our third.

• 11:55Speaker 01

  You're the manager.

• 11:56Neil deGrasse Tyson?

  You're the manager. I want to see the manager on this.

• 12:00Speaker 01

  I want to see the manager. I want to see your manager, manager.

• 12:02Neil deGrasse Tyson?

  Take me to your leader.

• 12:04Speaker 01

  For real, I want to know.

• 12:05Speaker 04

  We, we essentially decide how it looks. You get a sense of how it looks from the instrument, and then you decide how you want that to look. And that relates to how we see things as humans. So, it's, it's always a judgment call.

• 12:19Neil deGrasse Tyson?

  So you're converting invisible light into light that we can see, but then you have to be honest and say, you actually can't see this. This is what it would look like if you could see in those bands of light, correct?

• 12:29Speaker 04

  Exactly, yes.

• 12:30Speaker 01

  Like when they tell you this is how a dog sees things. You don't really know that.

• 12:33Neil deGrasse Tyson?

  I guess not, but you can study.

• 12:36Speaker 01

  Yeah, but, but somebody has to decide what, what would it look like on the scientific data that they have.

• 12:41Neil deGrasse Tyson?

  Somebody's got to make that judgment, exactly.

• 12:43Speaker 04

  Then you need to make a dog hearing simulator, or a dog seeing simulator.

• 12:47Neil deGrasse Tyson?

  Right, which is essentially.

• 12:48Speaker 01

  You're that guy?

• 12:49Neil deGrasse Tyson?

  That's essentially what you've done, Brian.

• 12:51Speaker 04

  Yes.

• 12:51Neil deGrasse Tyson?

  You've made a simulator that allows us to see in bands of light we cannot.

• 12:55Speaker 04

  Correct.

• 12:55Neil deGrasse Tyson?

  And so what's your favorite data set in a band we can't see?

• 12:57Speaker 04

  Well, I love the WMAP.

• 12:59Neil deGrasse Tyson?

  The WMAP, so this is of the microwave?

• 13:01Speaker 04

  Microwave radiation.

• 13:02Neil deGrasse Tyson?

  Of the, of the entire universe?

• 13:04Speaker 04

  The baby picture of the universe.

• 13:05Neil deGrasse Tyson?

  Of the universe, born, the light cast forth.

• 13:09Speaker 04

  Thirteen point four billion years ago.

• 13:11Neil deGrasse Tyson?

  So you're just digging it.

• 13:12Speaker 01

  So the big bang picture, like when there was, when God said, "Let there be light"?

• 13:16Speaker 04

  Baby picture.

• 13:16Speaker 01

  You're like what it looks like when it turned it on?

• 13:18Speaker 04

  Well, it's as far back as we can see.

• 13:21Speaker 01

  I know, with a room full of scientists. Oh, God, what does that mean?

• 13:24Neil deGrasse Tyson?

  We've got to take a quick break. More on the science of light when we come back.

• 13:55Speaker 04

  We're back. Let me reintroduce my guests.

• 13:58Neil deGrasse Tyson?

  Michael Benson, journalist, photographer, space geek, all the way. And not a month goes by where I don't read one of your op-eds or editorials criticizing NASA and the nation's priorities. Maybe we'll get back to that a little later.

• 14:11Speaker 01

  Wow, there is some weird tension with you guys.

• 14:14Neil deGrasse Tyson?

  Brian Abbott, manager of the Digital Universe at the Hayden Planetarium. Thanks for being on StarTalk. And of course, my inaugural co-host, Lynn Copelitz.

• 14:25Speaker 03

  Weird tension between you two.

• 14:26Speaker 01

  The light of your life.

• 14:28Neil deGrasse Tyson?

  Yes.

• 14:28Speaker 01

  Second light.

• 14:29Neil deGrasse Tyson?

  So we are here talking about "Let There Be Light," the light of the universe, and how it's created, what it's all about. Let me just sort of reset some of the physics of what's going on here.

• 14:39Speaker 01

  I have some questions.

• 14:40Neil deGrasse Tyson?

  Sure, sure. So light is energy. It's a form of energy. There are a lot of kinds of energy. There's kinetic energy of motion, there's potential energy. You get that in where you are in the universe. Or you have chemical potential energy. That's the energy that shows up when a bomb explodes. But in the universe, light is a form of energy. And we call it electromagnetic energy.

• 15:00Speaker 01

  And that's from the Big Bang?

• 15:02Neil deGrasse Tyson?

  Yeah, so at the Big Bang, you have all of this energy in a very small volume, and it is so hot, it is so energetic, that matter is forming out of the energy, according to equals mc squared. And the matter that's forming-

• 15:18Speaker 01

  According to the Bible, God just says, "Let there be light," and then the light turned on. But you're saying he threw a bunch of crap together.

• 15:24Neil deGrasse Tyson?

  Yes, I'm saying something different from that. I am indeed saying something different from what you read in Genesis. Yes, so what we have here is this soup. It's a matter/anti-matter-energy soup. And then as it expanded and cooled, all the matter and antimatter particles collided with each other and annihilated and created light. Except some matter was left over out of this. One out of 100 million particles was left over, and that is the matter that you and I are made of. And all the other matter/anti-matter collisions created the light of the universe, now visible as microwaves, at the distant, most distant regions of the universe. We call it the famous microwave background, the baby picture of the Big Bang.

• 16:06Neil deGrasse Tyson?

  And so, this is light. It all travels at, of course, the speed of light, which in miles per second, one hundred and eighty-six thousand, two hundred and eighty-two miles per second. And if you want to get really geeky at home, uh, one, one nanosecond, that's a billionth of a second, light travels one foot. So if you're standing a foot away from someone, you can say, "I see you not as you are, but as you once were, a billionth of a second ago."

• 16:30Speaker 01

  So if you were gonna time travel, would that be the speed of light like in Back to the Future?

• 16:35Neil deGrasse Tyson?

  Uh, that, well, it'll be exactly, yeah.

• 16:38Speaker 01

  I like my really serious questions. Look at all of our scientists, really, all of our really smart people in the room. We're like, "Who is this hooker and why is she in here?"

• 16:45Neil deGrasse Tyson?

  Yeah, it's exactly like that minus the flux capacitor. Yes, we, no, so telescopes are kind of like time travelers, because as you see far out in space, you see far back in time. You, I see you as you once were, like I said, two billionths of a second ago. You're two feet away from me. Uh, you, you are younger as I see you than you are at that moment that I see you. Yes.

• 17:05Speaker 01

  I can't believe you just said that.

• 17:06Neil deGrasse Tyson?

  Yes. The moon, the moon is, uh, like, a little more than a second, light second away. The sun, five hundred light seconds away. We have galaxies, here's a cool one. We have galaxies that are sixty-five million light years away, which means if they had a powerful telescope, they could look to Earth, and they can see the dinosaurs going extinct, as it's happening, as it's unfolding.

• 17:26Speaker 01

  You're blowing my mind.

• 17:27Neil deGrasse Tyson?

  They would need super duper telescopes for that.

• 17:28Speaker 01

  Can we go back to something simple for a second?

• 17:30Neil deGrasse Tyson?

  What's that?

• 17:31Speaker 01

  Uh, 'cause, let's break it all down for me. Okay, um, first of all, like, you said, light and energy. Is that why we can see lightning?

• 17:40Neil deGrasse Tyson?

  Well, light, well, so, yeah, so lightning is a lot of energy in a small spot, which rapidly expands the air, and it creates, creates basically a shock wave, so you hear the thunder, and it's very, yeah, it rapidly expands the air, and that creates, it's a shock wave, okay? And so, that, that's why you hear it. And of course, you hear it later than you see it, but it is very high temperature, and when you bring anything to high temperature, it glows. You see the sun, because it is at a high temperature, it glows. You heat anything to high enough a temperature, it will glow, period. Whether or not it's a gas, solid, it'll, it'll, it'll, it'll glow. That's correct.

• 18:14Speaker 01

  How interesting.

• 18:15Neil deGrasse Tyson?

  And there, and there's a guy from the nineteenth century who put together all our current understanding of the behavior of light, and he's, he's called Maxwell, James Clerk Maxwell. And they call Maxwell's equations, one of the most beautiful set of equations there are in all of physics. Have you ever heard of Maxwell?

• 18:31Speaker 01

  You know, the only Maxwell I know is a coffee guy.

• 18:34Neil deGrasse Tyson?

  I'm just checking. I, in fact, I don't know if it's the same guy. Probably not, though.

• 18:38Speaker 01

  Did he, who discovered x-rays?

• 18:40Neil deGrasse Tyson?

  Who discovered x-rays? Wilhelm Röntgen. In fact, in Germany, they're not called x-rays. They're called Röntgen rays. Yeah, so they, they still, I don't know if I'm pronouncing any Germans out there.

• 18:48Speaker 01

  Is that who I get to thank for my mammogram?

• 18:50Neil deGrasse Tyson?

  Uh, yeah, basically. Wilhelm Röntgen. And was actually discovered quite by accident. He was working with sort of high-energy emissions from tubes, and his hand happened to be in the way of a photographic plate, and he developed the plate and saw his bones on that photograph. It's completely creepy. I would have freaked out if that had happened.

• 19:10Speaker 01

  And then he did it again?

• 19:12Neil deGrasse Tyson?

  Not knowing that this is the kind of thing you, things you die from, you know, too much exposure to x-rays. You've been in the x-ray room, and what does the x-ray technician do right before they flip this switch?

• 19:20Speaker 01

  They all leave.

• 19:20Neil deGrasse Tyson?

  They leave, close the door, shut the door. That's what they do.

• 19:24Speaker 01

  The CAT scan's the worst. They go like down the hall and talk to you through a thing. They're like, are you okay? No, I'm not okay. I'm alone in, obviously, what's a really frightening room.

• 19:34Neil deGrasse Tyson?

  So these are just bands of light that actually are in our everyday lives. So your cellphone uses microwaves.

• 19:39Speaker 01

  Why, tell me this. Cause I, and now I've got all of you here in this little light summit meeting. I wanna know, when, like, I, I travel all the time when I'm on the road, and I'm gonna be doing it this week. Wednesday I'll be at the Orlando Improv. Um, but anyway, my question is this, um...

• 19:56Neil deGrasse Tyson?

  And for those who are listening on Time Delay iTunes Podcast, which Wednesday was that? Yeah, that Wednesday's like a month in the past by then.

• 20:03Speaker 01

  It's somewhere in June. Whatever, just go, go online and look for it. But, um, the Orlando Improv.

• 20:10Speaker 01

  But here's my question. They're making me now at the airport walk through those body scan things?

• 20:16Neil deGrasse Tyson?

  Yeah, that's where they, someone else sees you naked, and the person that sends you through doesn't see it. Yeah, they try to split the person who knows who you are from the person who sees your body parts.

• 20:23Speaker 01

  You know, I don't care about people seeing me naked. That is enough of that. If someone wants to see, by all means, they can take a look. But I'm more concerned, like, can it kill me? Like, how? Why does this light hurt us?

• 20:33Neil deGrasse Tyson?

  I haven't formally studied that scanning process and

• 20:38Speaker 01

  So you don't know? That means DK in genius speak.

• 20:40Neil deGrasse Tyson?

  What they don't know, they claim that it's not any more dangerous than than a plane flight that you might be taking.

• 20:47Speaker 01

  You guys know?

• 20:48Neil deGrasse Tyson?

  Exposure to radiation on that. Brian?

• 20:50Speaker 04

  This is exactly what I've heard, that when you fly in a plane, you're actually exposed to more radiation than you would be on Earth.

• 20:55Neil deGrasse Tyson?

  Right, on Earth's surface, because the atmosphere protects you from, it shields you from a lot of radiation that's coming from space.

• 21:01Speaker 04

  Exactly.

• 21:02Neil deGrasse Tyson?

  And notice that the doors of it are open. By the way, in your microwave oven, which also uses microwaves, by the way, I should have led off by saying, what's the difference from one band of light to the other? The length of the wave itself. Microwaves are about a half an inch, a third of an inch long, in a little wave shape. So if you want to block microwaves, just put a screen where the mesh is smaller than that size, and the microwaves can't get out. So take a look at the door of your microwave oven.

• 21:30Speaker 01

  Oh yeah, it's got that screen.

• 21:30Neil deGrasse Tyson?

  It's a screen that's got holes. Why don't the microwave come through the holes? Because the wavelength is bigger than the holes themselves. And are you old enough to remember how people used to receive TV signals? Rabbit ear antennas?

• 21:42Speaker 01

  Oh yeah.

• 21:42Neil deGrasse Tyson?

  Exactly. Why are the antennas that long? They're about a meter, you know, about a yard long. That's the length of a radio wave. Radio waves are longer than microwaves. And you want to capture radio waves, you get a, the antenna has to be about that length. So walkie talkies, which use microwaves, how big is their antenna? It's much stubbier. It's like, you know, it's like an inch.

• 22:02Speaker 01

  Wait, if they use microwaves, then can't that be bad for you to talk into them?

• 22:06Neil deGrasse Tyson?

  Well, if you create a cavity and zap you with much greater power than what goes on in a walkie talkie, then it would boil your blood, and that would be bad. Right?

• 22:15Speaker 01

  Yeah, because the

• 22:16Neil deGrasse Tyson?

  That's not what happens otherwise.

• 22:17Speaker 01

  Microwaves cook things from the inside out, right?

• 22:18Neil deGrasse Tyson?

  Yeah, so, microwaves, what happens is, the water molecule really likes microwaves. They have a deep cozy relationship with each other. Which is one of the reasons why, when we try to observe the universe in microwaves, you want to get above the cloud forming layer of Earth's atmosphere, because clouds wreak havoc on microwaves. Your cellphone signal is worst during thunderstorms. And all microwave signals are corrupted in the presence of water and we exploited that with microwave ovens. Because most food that you'll ever consume has water in it and the water absorbs the microwaves, it vibrates them real fast and it's friction that cooks your food and nothing else. And so people who think of microwave ovens as nuking the food, not, it's just the vibration

• 23:00Neil deGrasse Tyson?

  of the water molecules all next to each other vibrating ferociously, creating heat. And it's microwaves in our, in our life and in our culture. That, and, and microwaves, Brian, you've got microwave data sets telling us what's going on in the early universe.

• 23:13Speaker 03

  That's right.

• 23:14Speaker 01

  What kind of light is it in night, when you use night vision goggles?

• 23:17Neil deGrasse Tyson?

  It depends. So, what, the kind that you flick the switch on your camcorder? That one is like infrared.

• 23:22Speaker 01

  No, but that's night, night mode. I'm talking about the kind Buffalo Bill wore in Silence of the Lambs.

• 23:27Neil deGrasse Tyson?

  Oh, okay, so that would be like an image intensifier? So that takes a very low, those are developed in wartime, by the way, so you can like shoot people in the dark of night.

• 23:34Speaker 01

  Like what the SEALs use.

• 23:35Neil deGrasse Tyson?

  A lot of this is military technology and so very, very low light situations, you can greatly magnify it electronically. So you have, it looks like it's broad daylight to you and someone else is groping in the dark.

• 23:47Speaker 03

  Groping, do you mean that literally?

• 23:48Neil deGrasse Tyson?

  You mean what literally?

• 23:49Speaker 03

  Groping, the groping.

• 23:51Neil deGrasse Tyson?

  Uh, yeah, yeah.

• 23:52Speaker 03

  Just trying to make an intervention here.

• 23:54Speaker 01

  Mike is getting a feel for the show.

• 23:55Speaker 03

  Yeah, getting a feel for the show.

• 23:56Neil deGrasse Tyson?

  So, so Mike, on any of your photos, do you, do you, do you have a relationship with other bands of light? Or you probably aren't really visible?

• 24:02Speaker 03

  What kind of relationship do you need? Oh, um, no, I'm, I'm going, I'm, I'm trying to stay with, with vis- visible, uh, spectrum.

• 24:10Neil deGrasse Tyson?

  So you're a visible guy?

• 24:12Speaker 03

  I'm a visible light guy.

• 24:13Neil deGrasse Tyson?

  That's okay.

• 24:14Speaker 03

  But, um.

• 24:15Neil deGrasse Tyson?

  But you realize the, the human eye sees in one octave of light and we have detectors that see in 64. So what you're telling me now is that all of your books basically are demonstrations that we're actually mostly blind in the universe.

• 24:26Speaker 03

  Oh, but we're mostly blind in the universe anyway. I mean, you know, 99.9% of the universe is made out of stuff we don't even understand.

• 24:32Neil deGrasse Tyson?

  That's a whole other.

• 24:33Speaker 03

  I can't believe I have to tell you that.

• 24:34Neil deGrasse Tyson?

  Point of ignorance going on there.

• 24:35Speaker 01

  Speaking of ignorance, I have another question.

• 24:37Neil deGrasse Tyson?

  Oh, you have another question? We might have to save it for the third segment. Get it in real quick, go.

• 24:40Speaker 01

  No, I, I want to ask about photosynthesis.

• 24:42Neil deGrasse Tyson?

  Oh, cool. Yes, we can so go there. We've got to take a quick break, but more StarTalk when we return.

• 25:09Neil deGrasse Tyson?

  This is StarTalk Radio. Welcome back. Today's subject, "Let There Be Light." I've got Michael Benson, author and journalist. I've got Brian Abbott, manager of the Digital Universe at the Hayden Planetarium, and of course, the light of StarTalk, Lynn Koplitz herself.

• 25:26Speaker 01

  Hello.

• 25:27Neil deGrasse Tyson?

  Lynn, you had a question just before the break. What was that?

• 25:29Speaker 01

  I did, but I have to tell our guests that Neil tells me there are no stupid questions, although sometimes I feel uncomfortable because I do feel like there are things I should've listened to in science class.

• 25:38Neil deGrasse Tyson?

  Let me just say, you ask the best stupid questions there ever were.

• 25:40Speaker 01

  Okay, thank you.

• 25:41Neil deGrasse Tyson?

  Okay, if that's how you have to feel about it.

• 25:42Speaker 01

  Having preempted that, I will say, I've now, I never used to be able to like let plants live in my care, and I've just started raising some little plants, and I've given them all names, which is kinda weird, but I'm 43 and single.

• 25:55Neil deGrasse Tyson?

  You've named your plants, okay.

• 25:56Speaker 01

  Yeah, anyway, so I put them on the fire escape, and they're doing quite well, but I've noticed, because I've been home, I haven't been on the road for a month or so, and I've been able to watch them, that, you know, I know that photosynthesis is what it is.

• 26:09Neil deGrasse Tyson?

  Yeah, they like light. Yes, they need light.

• 26:11Speaker 01

  But some of them, like Steve, he's foliage, he leans toward the light.

• 26:16Neil deGrasse Tyson?

  Steve leans.

• 26:17Speaker 01

  But what I thought it was just sunlight.

• 26:18Neil deGrasse Tyson?

  Steve is the name of one of your plants.

• 26:19Speaker 01

  Yes, but I thought it was just, Steve is, he's very cute, but Steve leans towards the light, but I thought it was just sunlight, but I bring him in at night.

• 26:27Neil deGrasse Tyson?

  Any light that, so actually...

• 26:29Speaker 01

  So any, any light, and the pansies open up at night when I turn the little light on at night?

• 26:34Neil deGrasse Tyson?

  So you're messing with their biorhythms.

• 26:36Speaker 01

  Well, that's my question, am I screwing them up?

• 26:38Speaker 03

  Is pansy the name of a plant, or is that the type of plant?

• 26:41Speaker 01

  Their name's Panzal, Michael.

• 26:42Speaker 03

  Oh, okay, well, I should've known.

• 26:44Speaker 01

  Why would you name them pansy? They are pansies.

• 26:46Neil deGrasse Tyson?

  Duh.

• 26:46Speaker 01

  It'd be like me calling you Man-Man.

• 26:49Neil deGrasse Tyson?

  Most people think that plants like light, but in fact, it's the light that's inhibiting the growth of the plant on the side of the plant that faces the light, allowing the far side of the plant to outgrow the side of the plant that's nearest the light, and so we then say, "Oh, it's leaning towards the light." In fact, the light is inhibiting the growth of the plant on that side.

• 27:08Speaker 01

  Oh, no, I'm stunting their growth.

• 27:09Neil deGrasse Tyson?

  Well, actually...

• 27:10Speaker 01

  This is why I can't have children, because I don't know how to take care of it.

• 27:14Neil deGrasse Tyson?

  I don't see that connection. I'm sorry.

• 27:15Speaker 01

  Because I could stunt their growth.

• 27:16Neil deGrasse Tyson?

  Yeah, because you have to do more than just water the children, yes.

• 27:19Speaker 01

  But here's my, well, you have to do more than just water a plant. Here's my question, so when it's leaning, then why does it say to plant things in direct sunlight?

• 27:28Neil deGrasse Tyson?

  Uh, there's some plants that prefer direct sunlight rather than diffuse sunlight or indirect sunlight. So it just depends on how the plant evolved.

• 27:35Speaker 01

  So if I don't have sunlight, can I just put them in a pot and put a regular light on them?

• 27:40Neil deGrasse Tyson?

  Uh, if, you want a light that's close to the spectrum of the sun, and you can buy sun lamps. Oh, yeah. Yeah, yeah. But you could, you can completely, you don't even need the out, outdoor sun. Just go for it.

• 27:49Speaker 01

  Interesting.

• 27:50Neil deGrasse Tyson?

  Yeah, just put in a light that, you don't want a regular incandescent bulb. It's not blue enough for what the plant would thrive on.

• 27:55Speaker 01

  What happens to people if they're never, if they never have any sunlight?

• 27:57Neil deGrasse Tyson?

  Uh...

• 27:58Speaker 03

  Vitamin D? What, which, what's the vitamin that you're supposed to take in the winter?

• 28:02Speaker 01

  Vitamin D, yeah.

• 28:03Speaker 03

  Yeah, so you don't get vitamin D. You don't produce vitamin D.

• 28:05Neil deGrasse Tyson?

  Yeah, if you have light skin, yes, that's a, that's a rule.

• 28:08Speaker 01

  So what happens to you?

• 28:09Neil deGrasse Tyson?

  Well...

• 28:10Speaker 01

  Like, can you die from not getting any light?

• 28:12Speaker 03

  You get scurvy.

• 28:12Neil deGrasse Tyson?

  Yeah, you, well, no, scurvy's vitamin C.

• 28:14Speaker 03

  Okay, but I'm improvising.

• 28:16Speaker 01

  Are you like powder?

• 28:17Neil deGrasse Tyson?

  Uh, well, so, so, yeah, so you, that sun helps you, the body produce vitamin D. That's correct.

• 28:22Speaker 01

  But what happens if you don't have vitamin D? What happens to you?

• 28:24Neil deGrasse Tyson?

  Your bones weaken.

• 28:25Speaker 01

  Really?

• 28:26Neil deGrasse Tyson?

  Yeah.

• 28:26Speaker 03

  And if you get depressed and you drink...

• 28:28Neil deGrasse Tyson?

  And if you're developing, then you, you're, you get rickets.

• 28:30Speaker 01

  I think I have that.

• 28:31Neil deGrasse Tyson?

  And you look like the cowboy with the bowed legs. Well, let's get back to the universe, if we may.

• 28:35Speaker 01

  Please.

• 28:36Neil deGrasse Tyson?

  Just let's, let's understand how this works. So we have objects in the universe that emit light. And the visible part, that's easy to understand because our eyes see visible light. Many really cool things in the universe don't know anything about visible light, and they're trying to talk to us in bands of light we cannot see. And it's a triumph of 20th century astrophysics that we've been able to build specialized telescopes with detectors that can reveal the universe in all these bands of light. Ultraviolet, X-rays, gamma rays, radio waves, all these bands of the electromagnetic spectrum that tell us what the universe is actually doing, because we are practically blind.

• 29:11Speaker 01

  Who came up with black light?

• 29:13Neil deGrasse Tyson?

  Black light, that's just ultraviolet light. And the part of the ultraviolet light you, the part of the black light you see is just violet. But it's really doing its job in the part of the spectrum you can't see, the ultraviolet. And bug zappers?

• 29:24Speaker 01

  Oh, that's right, because the ultraviolet, that's right, because black light, you can see all the lint and all the dust.

• 29:29Neil deGrasse Tyson?

  Yeah, well, so, yeah, so that's the ultraviolet sort of make, rendering that aglow. So...

• 29:33Speaker 01

  Is that what you use to find DNA on things, like the crime scene people use?

• 29:37Neil deGrasse Tyson?

  Uh, the crime scene people will use ultraviolet light to see different things that are, might be left on your sheets. Yes.

• 29:42Speaker 01

  Interesting.

• 29:43Neil deGrasse Tyson?

  And a quick thing about bug zappers, did you know that bug zappers are violet, basically, because bugs just love violet light. They come out in the early evening where the sky has a higher fraction of the total light represented in ultraviolet. And so you simulate the twilight sky with a bug zapper and the bug says, "I'm flying to the light," and it just gets zapped. And it's great, it's evidence that we're smarter than bugs, that we can exploit the fact that they are sensitive to ultraviolet light, even though we're not. I gotta bring in our third guest here. This guy, there's no one like him in the universe last I checked. Carter M. Art. Carter, you are Director of Astro-Visualization of the

• 30:25Neil deGrasse Tyson?

  Roast Center for Earth and Space. Welcome to StarTalk Radio. And you just gave a presentation at the World Science Festival last night, bringing the universe to the public as never before. You were born an artist with deep interest in the cosmos. You became a computer literate and you transitioned what used to be canvas and paint for planetary shows into the 21st century. So, welcome to StarTalk Radio. And tell us what you did last night.

• 30:53Speaker 05

  Thanks a lot, Neil. Yeah, actually, at the Hayden, we had a program that was looking at, it started off with a 60s-era light show, from the Joshua Light Show. And then we went in-

• 31:05Neil deGrasse Tyson?

  60s era had lasers and stuff, right?

• 31:06Speaker 05

  Well, no, it was pre-laser.

• 31:07Neil deGrasse Tyson?

  Pre-laser light show, okay.

• 31:09Speaker 05

  And the Joshua Light Show actually backed up Jimi Hendrix and other bands.

• 31:13Neil deGrasse Tyson?

  So, were people getting high in the dome?

• 31:15Speaker 05

  Well, 10 minutes of that. And then, basically, I took us in a piece where we leave, we go from the Earth on out to the cosmic microwave background.

• 31:27Neil deGrasse Tyson?

  So, you zoom, a zoom, a powers of 10 kind of zoom?

• 31:30Speaker 05

  Yes, we do. And then we actually travel all the way back to Earth and through the atmosphere and down to the town of Norsjipping, Sweden, where I actually directed this film last year. And we fly all the way down. To quarks in a carbon nucleus.

• 31:44Neil deGrasse Tyson?

  So these are Swedish quarks.

• 31:46Speaker 05

  Yes, in that case. It's a strand of DNA.

• 31:50Neil deGrasse Tyson?

  So as you zoom out, there'd be some familiar things. We'll see Earth from a distance, like the Apollo images. But rapidly, those images would become unfamiliar because you're zooming through a three-dimensional space that telescopes can't provide.

• 32:04Speaker 05

  Yes, but it's a data map, thanks to my work with Brian. Brian, taking data sets, academic data sets, catalogs of various objects that we see and we observe with light, and their signature from the light gives us distance information. We're able to plot that.

• 32:20Neil deGrasse Tyson?

  In three dimensions?

• 32:22Speaker 05

  In three dimensions. A revolution in planetariums really occurred from that of showing the sky to now showing space three dimensionally.

• 32:28Neil deGrasse Tyson?

  And, yeah, Lynn?

• 32:29Speaker 01

  I just have a question, because we're talking about the universe, it's just so humongous, the idea of like you creating a show, a light show, that represents certain parts, how do you decide exactly what you want the show to be? Like, it's hard enough, like, when you're putting together a musical or something, how do you decide what parts of the universe are interesting and how you're going to use them?

• 32:50Neil deGrasse Tyson?

  Well, another way to say that, how do you know what to not include?

• 32:52Speaker 01

  Exactly, that's what I'm trying to ask.

• 32:54Speaker 05

  The idea of the digital universe is to include everything.

• 32:57Neil deGrasse Tyson?

  That's a cop-out. I mean, it's the right answer, but you choose a pathway to take the visitor on it. And you're invoking an artistic eye to this.

• 33:05Speaker 05

  We were also, yes, and design and movement is a big part of it, and that goes to the heart of what our space shows are and how we create them and how to display the data.

• 33:17Neil deGrasse Tyson?

  Because a pure scientist wouldn't necessarily know the best way to look at their own data, right? And you have an artistic eye for this.

• 33:24Speaker 05

  Well, and also, it's a matter of putting the pieces together. If you look at any one data set, say, stars, that'll be very interesting to the people that study the stars. But to put that in coordination to our solar system or the galaxy at large that those stars are part of is our job.

• 33:39Neil deGrasse Tyson?

  So now you get the whole sweep of the universe. So Lynn, it's the whole freaking universe.

• 33:43Speaker 05

  So also, I should say that the program last night, after bringing us back down in light, essentially, from the most ancient light we can see, which is the cosmic microwave background.

• 33:56Neil deGrasse Tyson?

  In microwaves, yes.

• 33:57Speaker 05

  Because as we look farther out, we're looking farther back into the past. That as we come down, we then hand it over to Joy Hirsch, who's the director of the Columbia Brain Lab. And she talked about, really, the difference between photons and essentially the light in our mind in a sense of understanding. And so that mind, so we're really trying to address this issue of the universe around us and the universe that we know in our brains.

• 34:24Neil deGrasse Tyson?

  So you went from the outer universe to the universe of our inner mind? Correct.

• 34:30Speaker 01

  You know, that reminds me of when I used to, when I was in college, I took a lot of drawing. I was like an art minor. And I remember one of our teachers telling us to squint our eyes because what we thought we were seeing and what we were seeing were different things. And he said, "If you squint your eyes and you just draw the shadows and draw, you know, the shadows and the light." And then it was so weird because you look up and all of a sudden you have a whole image. And it's what you were really seeing.

• 35:00Neil deGrasse Tyson?

  Yes, so Brian, how do we know? I mean, how do you distinguish? I mean, both of you, Brian and Carter. So there's what is and there's what our perception is. And how do you make the two work to get the most effective show?

• 35:14Speaker 05

  Well, you know, when we look up and we see stars, we can sort of have a sense that they're different distances. But to really see the layout and the distances or say where the planets fall and this, because look up in the night sky tonight and you'll see one of those bright stars, so to speak, is Saturn.

• 35:31Neil deGrasse Tyson?

  It's Saturn, in the evening sky. Beautiful sight tonight.

• 35:34Speaker 05

  And we were showing that with the World Science Festival just on Friday night, which was wonderful.

• 35:38Neil deGrasse Tyson?

  Right under the Brooklyn Bridge. That was a beautiful setting. If people don't know, this time of year, every year in New York City, there's the World Science Festival and some of the greatest scientists in the nation and in the world descend on New York and bring science to the public in many different venues, one of which was the Hayden Planetarium last night.

• 36:24Speaker 05

  This is Startoff Radio. Welcome back.

• 36:27Neil deGrasse Tyson?

  Brian Abbott, manager of the Digital Universe, you had some comments just before the break about the difference between how a scientist views data and how you guys make it alive.

• 36:37Speaker 05

  Yeah, what struck me when I started working on this project is that scientists see their data not only as a 2D graph, but also they only see their data. They don't see it in the bigger picture, the bigger context of where that fits in the universe.

• 36:49Neil deGrasse Tyson?

  So the visually...

• 36:51Speaker 01

  2D is in two dimensional, right?

• 36:53Neil deGrasse Tyson?

  Yeah, of course.

• 36:55Speaker 01

  This is 2D.

• 36:56Neil deGrasse Tyson?

  Sorry, it's not 2D, 2D fruity. 2D, yes, two dimensions, yes. So it's a really boring way to look at the data and you might miss the bigger picture.

• 37:04Speaker 05

  Yes.

• 37:05Neil deGrasse Tyson?

  And so Carter, you make the big picture is what you do.

• 37:07Speaker 05

  Right. The scientists understand the bigger picture and that's their job. And it's our job to, again, create that continuous experience from Earth all the way out.

• 37:15Neil deGrasse Tyson?

  One of the most moving moments in this journey is when we pass by the radio bubble. Tell us real quick about that.

• 37:22Speaker 05

  So, yeah, if you actually look out into the stars, you can say, okay, how many different distances? But if you stand away from the Earth, let's stand away from the Earth about 100 light-years, you would look back and you'd see a sphere, about 70 light-years in radius.

• 37:38Neil deGrasse Tyson?

  That's if you had radio-sensitive eyes, you'd see a sphere.

• 37:40Speaker 05

  Well, no, you'd have to actually be detecting it in the atmosphere, essentially.

• 37:45Neil deGrasse Tyson?

  Atmosphere, okay.

• 37:45Speaker 05

  But what we do is we draw a graphic of a sphere, and that indicates how far radio signals have traveled since the Earth became radio-bright. You had Tesla and Marconi in early radio that bounced around inside the ion...

• 37:56Neil deGrasse Tyson?

  It's not when Earth became radio-bright, it's when human beings on Earth became radio emitters, right?

• 38:01Speaker 05

  Yeah, that's right.

• 38:01Neil deGrasse Tyson?

  With their apparatus.

• 38:02Speaker 05

  Yes, with radars and television carrier waves. And so you can see that moving out. So if you parked next to Arcturus tonight, which is up in our sky, you would be...

• 38:12Neil deGrasse Tyson?

  Lynn would plan to do that, yeah.

• 38:13Speaker 05

  You would be hearing radio broadcasts or TV from 40 years ago.

• 38:18Speaker 01

  Yeah, see, I have that question. If there's all this stuff that we can't see, all these waves and, and, and light waves and things.

• 38:26Neil deGrasse Tyson?

  Penetrating your body right now.

• 38:27Speaker 01

  And don't they all bump into each other? When is there too much and what happens?

• 38:31Neil deGrasse Tyson?

  Yeah, no, the good, interesting thing about, right, is they can interfere, but they can, they only interfere if they're sort of coherent. So a laser, you can make lasers interfere and you get like what's called fringe patterns.

• 38:41Speaker 01

  Oh, before we leave, I have to know. Are there lightsabers?

• 38:44Neil deGrasse Tyson?

  Oh, you mean like in Star Wars?

• 38:45Speaker 01

  Yeah.

• 38:45Neil deGrasse Tyson?

  No. Okay. So now.

• 38:49Speaker 01

  He told me to wait and ask on the air.

• 38:51Neil deGrasse Tyson?

  No, no, here's the thing. No, you can make a, you can make a beam of light that would be visible, such as lightsaber.

• 38:56Speaker 01

  Like your light beam thing that you use to point.

• 38:58Neil deGrasse Tyson?

  Ever, and I even tweeted this a few weeks ago, lightsabers would not hit each other. They would just pass right through one another and they wouldn't have these sword fights the way they would show it. They would just pass through one another.

• 39:09Speaker 01

  What kind of light is lasers made out of?

• 39:11Neil deGrasse Tyson?

  Uh, it's, it's visible light. You can make, you can make other kinds of laser light, but the ones we're most familiar with are visible.

• 39:17Speaker 05

  The, the, the radio sphere sort of sets us up in a sense that if you go away from the earth far enough, you're going far enough back in time. Everything we see, you know, a star twice the distance away is twice as far in the past essentially. So if you look far enough, you're actually seeing the cooling off of the universe or the transition between when it was a plasma and opaque to where it became clear space. And that's the microwave background that we see.

• 39:42Neil deGrasse Tyson?

  So you not only show us the radio bubble that we created that's now about 100 light years out.

• 39:48Speaker 01

  That's cool.

• 39:48Neil deGrasse Tyson?

  And all of our civilization, as we've communicated it through each other, has leaked into space and is contained within this bubble.

• 39:54Speaker 01

  So you show like if God were to look at it.

• 39:56Speaker 05

  Yeah, but those are, those are, those are waves moving out, our radio sphere. But the stuff that's coming to us is essentially, you can imagine a sphere, very large, um, that's a microwave background and everything that we can observe is contained within it. And it's centered on us, but that's just because it's us observing it. If you moved anywhere else, you'd also see a sphere around you.

• 40:16Neil deGrasse Tyson?

  You'd be feel like you're in the center of that. So now we're in-

• 40:18Speaker 01

  So Carter creates like accurate art.

• 40:20Neil deGrasse Tyson?

  Yes, yes, and that is the hallmark of the 21st century.

• 40:24Speaker 05

  Pictures from data.

• 40:25Neil deGrasse Tyson?

  That's ex- and like the, as the, he gave the analogy a moment ago with the dioramas, something that the American Museum of Natural History pioneered 100 years ago, where you create, it's not just an animal stuffed on a, on a pedestal. You put it in an environment that transports you to that local, to, to, to that, to that location. So now we're, we're in an expanding universe and this microwave light, and all the light in the universe is getting diluted in space, and its energy is dropping. And so the universe, I don't know if you knew this, is approaching, uh, the universe will not end in fire, it will end in ice. Not with a bang, but with a whimper. And all-

• 41:03Speaker 01

  I saw that movie.

• 41:03Neil deGrasse Tyson?

  You, yeah, well, well, it's, it's a poem, you know, it's a T S Eliot poem as well. So, they call it a heat death, but it's really a cold death.

• 41:11Speaker 05

  How do you equate that with global warming, Neil?

• 41:13Neil deGrasse Tyson?

  Yeah, so-

• 41:14Speaker 05

  I mean, I don't know, I mean, does that mean that you don't believe in global warming?

• 41:18Neil deGrasse Tyson?

  Earth is insignificantly small compared to the scale of the universe on which I'm referring. And so, so the temperature of the universe of this cosmic microwave background, you can actually stick a thermometer in it and get a reading, it's about three degrees absolute, uh, absolute temperature. Three degrees above absolute zero. So, and we're about 14 billion years old. When we're 28 billion years old, we'll be one and a half degrees. And it'll scale right on down until we asymptotically approach zero, and the day will come.

• 41:45Speaker 01

  Really asymptotically?

• 41:46Neil deGrasse Tyson?

  Yeah, well, as we, you approach it without ever actually hitting it. As, it's asympt- you get closer and closer without-

• 41:52Speaker 01

  Everyone just looked at you like they knew what you were talking about. I'm like, asymptotically?

• 41:57Neil deGrasse Tyson?

  Asymptotically, it's, you learn that in, in Algebra II and trigonometry.

• 42:00Speaker 01

  Oh, okay.

• 42:01Neil deGrasse Tyson?

  In high school, yeah, so-

• 42:02Speaker 01

  I skipped it.

• 42:04Neil deGrasse Tyson?

  So, all I'm saying is that, so the universe, the temperature of the universe will continue to thin out and get cooler and cooler and cooler. Stars, well, yeah, I think so, yeah.

• 42:13Speaker 01

  Sounds bad.

• 42:14Neil deGrasse Tyson?

  Stars will eventually run out of their fuel. They will die, even the clouds- They'll make whatever stars they can, and then they'll die out, and then all matter will be left, uh, will be, will be left in the, in the remnants, the dead cold remnants of stars that once were.

• 42:32Speaker 01

  The universe sounds feminine, it sounds like women, like you have to work really hard and then the earth is just mending around.

• 42:38Neil deGrasse Tyson?

  Well, once the energy sources run out, the stars will turn off one by one, the galaxies will shut off, and the universe will turn dark for the remainder of eternity. Brian, you, you, how can you say anything after what I just said? Downer!

• 42:52Speaker 04

  Well, it's fascinating that future astrophysicists will not know anything about cosmology, because they will not see any of the galaxies out past our local

• 43:00Neil deGrasse Tyson?

  Oh, because we will expand so fast that our galaxies will expand beyond the horizon.

• 43:05Speaker 05

  But that's not true, because if you look far enough away, you will see some of that radiation coming toward you.

• 43:11Neil deGrasse Tyson?

  Well, it's, well, it, yeah, I, we, we, uh, this is another show!

• 43:16Speaker 03

  By then, by then, we're gonna have, you know, faster than light travel, and we'll have sources, we'll be able to make our own stars, and we'll be able to zap around.

• 43:24Neil deGrasse Tyson?

  And Michael Benson's been reading tons of science fiction.

• 43:26Speaker 03

  Yeah, of course, you know, I mean, come on.

• 43:28Neil deGrasse Tyson?

  That's all the time we have, this has been StarTalk Radio. I want to thank my guests, and as always, I bid you to keep looking up.