Chapter 1: What are the implications of finding alien life versus being alone in the universe?
Chuck, that might have been the best Cosmic Queries ever.
Yep. Grab bag. It was certainly entertaining. And if you want to know what happened, well, you're going to have to listen. That's all there is to it. Not giving anything away. That's cold.
No, that's how good it was.
It's worth the listen. All right, coming right up.
Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Neil deGrasse Tyson, your personal astrophysicist. Chuck, you're the grab bag man. I'm the man with the bag.
This is Yousef Kazwini, who says, Greetings, StarTalkers. Yousef from Damascus, Syria. Here. Damascus? That's right. Whoa. That's right. Ancient, ancient city Damascus. I found your podcast recently and I joined the club. Welcome aboard, my friend. Here's my question. You often mention pro-photons travel at the speed of light at all times.
Working as an optics engineer and dealing with TIRF microscopes, I wonder how evanescent waves during total eclipse Internal reflection, TIR, is thought of from a particle physics perspective. Are the photons moving at the speed of light, but somehow without propagating? Or the photons don't exist at all. But then what is interacting with the sample on my microscope? Thank you. I love your work.
P.S. Chuck, you surely deserve an honorary PhD by now, my brother. Oh, look at that.
My brother.
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Chapter 2: How do photons behave in different mediums?
That's a dated reference to 55 miles an hour speed limit when we went out and said we're not going to go fast anymore. So that doesn't mean light always travels at that speed. Exactly. It means it will never travel faster than that speed. Right, because you can slow it down. So let's tell you do that. Okay, it turns out you sort of can slow it down. Right. I got you.
So the medium itself... can slow the travel.
Yes. The medium. Okay, but the way it slows it down is fascinating. Interesting. Okay? Okay. Okay, so I'm going to beam a light. Just going on about my business. Going about my business.
Look at me traveling at the speed of light.
Nothing can be faster. Nothing can be faster. Then you hit... the air, or you hit a piece of glass or a piece of water. This is for visible light going through what we would say are transparent objects. If you're transparent, it means the light stays coherent as it goes through. So that the waveform maintains its structure.
If it does not maintain its structure, light can still get through, but we would not call it transparent. Yes. You know the word we have for that? Translucent. Translucent. Yes. And lucent means light in Latin. Latin, yeah. Luce is light. Luce. So the light comes up to the boundary. Some light will get reflected. And optics people know and understand that, okay?
That happened, you can't do anything about that. You can try to minimize it by having what are called these coatings that will delete any attempt for the light to reflect back, right? And it's fun the way they do that. So you have a coating that's half the wavelength of the light that you're using. Interesting. Okay?
So then the light goes through, and by the time it wants to reflect back, the light that's coming in is out of phase with it.
oh so it creates a disruption and it flattens out it flattens the light look at that I never knew that isn't that brilliant that's god people are smart that
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Chapter 3: What is the significance of the speed of light in optics?
Right, right, right. And when I say it reflects, because light will reflect off of practically any surface, Whether or not it's a mirror. Yeah. That's what I'm saying.
As a matter of fact, in photography, they have something called a bounce board, and it's just a stark, stark white. I forget the color of white.
So it diffuses the light that comes back to you. That's all it does. Otherwise, a flash can be very harsh.
Right, exactly.
So you bounce it off of there, and you get the light without the harshness. Without the harshness. So now you took care of that. Now the light enters the medium. Between molecules. Okay. Okay. Light is moving at the speed of light.
Gotcha.
But it hits a molecule. I got to deal with the molecule. I got to go in and come out. Damn it. Yeah. Excuse me. Pardon me. Excuse me. I'm so sorry. Now I'm at the speed of light again until I hit the next molecule. Right. Oh, God. Here we go. Here we go again. Right.
It's like walking down New York City Street behind tourists.
Right.
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Chapter 4: How does total internal reflection work in optical systems?
Yeah, who does that? Who does that? Who does that? But a tourist who was just ambling, looking up, ambling. And so you can't predict what their next move is, but for other New Yorkers, you can. It's true. Not only that, there are people who are, I've walked perpendicular to people, they're on the sidewalk and I'm crossing the street. You time it. That's right. So that you know exactly when.
You know exactly. No, it's a dance.
It's a dance. You got to live here to know the dance. Whereas the tourists will stop. Right. Well, now they just messed up my timing. Exactly. Okay, they'll look, they'll say, excuse me, pardon me. Right. And you get people, I'm trying to get in the subway. Okay? And a train just lets out. Tourists will wait for everyone to clear from the stair. No, you don't do that. You make your path.
And they know you're coming down. They will move aside as they come down and you're going.
Right. Exactly.
Just because there's a mass of people.
You just made me miss my train.
You know that, right?
That's what you did. Waiting in line to get on the damn stairs. What the hell is wrong with you? I'm late for work. Get down. And by the way, stand back from the doggone platform. Not that I'm worried about you or concerned about your safety. I'm late for work. You follow on the damn tracks. Guess what? Now I'm late. Okay, anyway. How to give New Yorkers a bad name. Anyway, so.
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Chapter 5: What are the cosmic mysteries we may never resolve?
Ooh. Yeah, so. Ooh, I love it. And I'll tell you how it works. Go ahead. The index of refraction, you can use that in a formula to tell you how much the light will bend coming in or out of that medium. That's how you make a lens at all. Okay? But, The index of refraction, if you take the speed of light And divide by the index of refraction. Go ahead. That's the speed of light in that medium.
Ain't that something? That is really cool. Okay, so let's do the math. The index of refraction of diamond is 2.4. Mm-hmm. What is one divided by 2.4? One is like the speed of light. Divide by 2.4. Mm-hmm. What's the number? .4 something. Exactly. .4 something. About .4. Yeah. So light in diamond is going 40% as fast as it goes in a vacuum.
In a vacuum.
Isn't it? Oh, I love it so much. Yeah, yeah. And so diamond is one of the hardest natural substances known. Exactly. It's hard for light to get through as well. Yes, it is, yeah. And even though it's transparent. Right. And before we get all emotional about light trying to get through the medium, visible light can't get through most mediums. True. Like a brick wall. Right.
It's just like, damn it! That's light trying to get through a brick wall.
Gah!
Gah!
If light were given a voice. Right. Let's try the brick. Nope. Let's try the steel. Nope. Nope. Damn it. Damn it. But other wavelengths of light are transparent in these other substances, as you know. So your cell phone works in here because the walls are transparent to microwaves. Microwaves. Right.
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Chapter 6: How do gravitational waves affect our understanding of the universe?
Microwaves come right on through. No problem. No problem.
They don't travel well through plaster, though. What are you talking about? Because my house, the walls are plaster. My house was built in 1898. I think there might be something else in your walls.
Oh, you know what?
You're right.
It's a metal lathe.
Metal grid. Metal lathe. So here's what it is. It's plaster, then it's wood, then it's lathe, then it's metal. I bet there's a metal mesh.
It's a mesh, yeah. To hold up the plaster. To hold up the plaster. So you're in a Faraday cave, my son. Oh, my God. Faraday cage. That's what it is. That's right. If you are surrounded by a metallic anything, then the electrons in the metal will conspire to prevent electromagnetic energy from entering.
That's why I can only hear the voices when I go outside.
So that's why. Don't blame the plaster. Damn. Plaster ain't nothing to do with this. Wow, look at that. Okay. Yeah, back then they would put up the mesh. Yeah, you put the mesh. And they would hold the plaster up because all of the little, the grid of the metal. So if you have multiple internal reflections, that's the light just going back and forth. Oh, by the way, by the way, check this out.
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Chapter 7: What will Earth's future look like without humans?
It comes up and it bends. Right. Yes. Suppose I take the angle of the light and make it steeper like this.
Mm-hmm.
then that will keep this come further and further down. There is an angle at which the light never enters the next medium. Because this bend now takes it backwards into the medium itself. And it's called total internal reflection.
Oh, wow. That's something I avoid at all costs. That's why I can't sleep at night.
So that's that angle. It's still in the other medium. Bam! Now it's total internal reflection. That's pretty cool, man. It's very cool. I love that. And you can know exactly what that angle is, how to do that. And so if you have an optical system where the light is just bouncing back and forth, it is within the parameters of... Or you can have just a reflective surface as well. Right.
Just a mirror would do that. But anyhow... What you do inside your medium is your business. And what that then does to a beam of light. But yeah. Interesting.
There it is.
That's all I can do to illuminate. See what I did there? To illuminate that question. There may be other places to go in the physics of optics that I would not have known to touch.
Very cool, man. What a great question. And thanks, Yousef. And welcome to the club.
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Chapter 8: Which species might dominate Earth after humans?
That's interesting.
Yeah, yeah. You have to then explore the leak. You gotta explore the leak now. Okay, I can't top that. That's good. No, I would say I don't think we're going to know for sure if there's life in the universe in my lifetime.
Whoa. Intelligent life in the universe. Well, then you win the bonus points because that is something we are very, very close to. But it's very possible we may not find in our lifetime.
Yeah, I don't think in my lifetime we will know that. What we will know in our lifetime is if there's any life at all. Outside. No, in our own sources. In our own sources. Okay, because we're looking at Europa. Right. We did a whole episode. We went. To JPL. Right. Jet Propulsion Labs. That's right. NASA in Pasadena. That's right. Talked to the Europa Clipper people. That's right.
Talking about what are they going to do? How are they going to measure it? What's beneath the ice? So we will know whether or not there has ever been or is currently life- in our solar system other than on Earth. Yes. I think that will happen. But it would be sad if there is no life other than life on Earth. You know what has been said? Mm-hmm.
How profound it would be if we discovered intelligent life in the universe, but how more profound it would be if we discovered that we're alone.
Listen, the second one is far scarier than the first. It's a little scarier, isn't it? Because that means all of this was a mistake.
No, it would feed many religious thinking that the whole universe is just for us. Some branches of Christianity, and perhaps other religions as well, require that life on earth be the sole object of God's creation.
Okay, I'm just gonna say it, and please don't judge me here. I'm being logical, and I'm thinking like God. That's the dumbest crap I ever heard. And here's why it's stupid. I don't need to do all this, okay? I don't need to do- Oh, you're God.
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