SPEAKER_1: Welcome to StarTalk, your place in the universe where science and pop culture collide.
SPEAKER_1: StarTalk begins right now.
SPEAKER_1: This is StarTalk, a Things You Thought You Knew edition.
SPEAKER_1: Chuck, is that your favorite format?
SPEAKER_2: No, Explainers are my favorite, but Things You Thought You Knew is my second favorite because I am aware, thanks to working with you for almost 12 years, that I don't know jack crap.
SPEAKER_2: That is what I have learned.
SPEAKER_2: And all this time we have spent together is that I don't, I used to think, I thought at one point I knew something.
SPEAKER_2: I thought I knew something.
SPEAKER_2: And then the universe sent a man named Neil deGrasse Tyson into my life.
SPEAKER_2: And then the universe said, boy, you don't know shit.
SPEAKER_1: Okay, so Things You Thought You Knew is like a superset of explainers.
SPEAKER_2: Yes.
SPEAKER_1: Okay, you ready?
SPEAKER_1: First one is going to be Rainbow.
SPEAKER_2: Okay, that sounds delightful.
SPEAKER_1: Nobody doesn't love rainbows.
SPEAKER_2: That's right.
SPEAKER_2: Sounds delightful.
SPEAKER_2: I love it.
SPEAKER_1: Okay, nobody doesn't love rainbows.
SPEAKER_1: Okay, I have a quick rainbow story.
SPEAKER_1: You ready?
SPEAKER_1: I knew a couple, they were dating.
SPEAKER_1: And the guy was a little high strung and she was sort of like normal, right?
SPEAKER_1: And she pointed, we were driving, I happened to be in the car with them, and there was a beautiful rainbow out the window.
SPEAKER_1: And the guy was speaking about something else.
SPEAKER_1: And I said, oh, look at the rainbow.
SPEAKER_1: And she said, oh, that's a beautiful rainbow.
SPEAKER_1: And he says, no, shut up, I'm talking about something else.
SPEAKER_1: And I said, what?
SPEAKER_1: Who doesn't like rainbows?
SPEAKER_1: And she turned to him and two months later they broke up.
SPEAKER_2: Yeah.
SPEAKER_1: So I don't know.
SPEAKER_2: He didn't know it, but they were already broken up.
SPEAKER_1: Chuck has seen some therapists.
SPEAKER_1: He knows the signs.
SPEAKER_2: Let me tell you.
SPEAKER_2: So what's number two?
SPEAKER_1: The second segment is just going to be about zero.
SPEAKER_1: All right.
SPEAKER_1: The number zero.
SPEAKER_2: The number zero.
SPEAKER_1: Zero is a number.
SPEAKER_1: Just get over it.
SPEAKER_2: OK, yeah, you never think of zero as a number.
SPEAKER_1: Yeah, yeah, yeah, but it is.
SPEAKER_1: And we need it, it turns out, for most of what we do in mathematics.
SPEAKER_1: And the third one is, what do Zoom calls and Einstein's theory of relativity have in common?
SPEAKER_2: All right, you've gone too far, Neil.
SPEAKER_1: I know, I stepped off the ledge.
SPEAKER_2: Seriously, bro.
SPEAKER_2: You are over the cliff.
SPEAKER_2: That's it.
SPEAKER_1: Give it a chance, Chuck.
SPEAKER_1: Let me try.
SPEAKER_2: How are you going to pull that rabbit out of your hat?
SPEAKER_1: All right, let's get to our first one in this first segment.
SPEAKER_1: So, Chuck, we're going to talk about rainbows.
SPEAKER_2: My eight-year-old daughter loves rainbows.
SPEAKER_1: Well, make sure she listens to this.
SPEAKER_1: All right.
SPEAKER_2: That's cool.
SPEAKER_1: So, it was not until Isaac Newton, my man.
SPEAKER_2: That's your boy.
SPEAKER_1: My man.
SPEAKER_1: OK.
SPEAKER_1: Early 1700s.
SPEAKER_1: He wrote a book in 1704.
SPEAKER_1: It was just called Optics, one of the rare books that he actually wrote in English.
SPEAKER_1: All his other books were in Latin, which was the language.
SPEAKER_2: Wow, he really was a nerd.
SPEAKER_1: But in there, he figured something out.
SPEAKER_1: Everyone, of course, had known about the colors of the rainbow.
SPEAKER_1: Red, orange, yellow, green, blue, violet.
SPEAKER_1: OK.
SPEAKER_1: And people have seen, you know, chandelier.
SPEAKER_1: Light will come through the chandelier, and you'd see rainbow colors come out one side or another.
SPEAKER_1: Everybody until Newton presumed that those colors were somehow getting generated inside the chandelier glass.
SPEAKER_1: Or inside the raindrop.
SPEAKER_2: Right.
SPEAKER_1: That it was some property of the medium itself.
SPEAKER_1: Nobody was thinking that pure white light is composed of those colors.
SPEAKER_2: Oh, if only we could learn that lesson in our society.
SPEAKER_1: Chuck Gettner, sociological.
SPEAKER_1: So imagine if Martin Luther King were more physics fluent.
SPEAKER_2: Right.
SPEAKER_1: In a whole different I Have a Dream speech.
SPEAKER_2: It's okay.
SPEAKER_2: Everybody would have tipped their head and said, what?
SPEAKER_2: I may not get there with you, but we'll all be white one day.
SPEAKER_1: Okay, so here's how he did it.
SPEAKER_1: Okay, so he puts white light through a prism, okay?
SPEAKER_1: And out the other side comes the colors of the rainbow, much as what we all remember from Pink Floyd's Dark Side of the Moon album cover.
SPEAKER_2: One of the best ever.
SPEAKER_1: All right, so he then, and this is what makes Newton, Newton, he said, let me take another prism and put it upside down next to it.
SPEAKER_1: Ooh.
SPEAKER_1: Okay, and this would kind of reverse what had just happened.
SPEAKER_1: And when he did that out, the second prism came white light.
SPEAKER_2: Okay, how did I not hear?
SPEAKER_2: In all the time we've been working together, this is the first time I've ever heard this story.
SPEAKER_1: Yes.
SPEAKER_2: This is brilliant.
SPEAKER_2: Yes, because in doing so, he proves that it has nothing to do with the actual medium itself, that the light coming in was merely separated.
SPEAKER_2: And then by coming out and going back into another medium, it combines, it's the light.
SPEAKER_2: It's just the light.
SPEAKER_1: That's why he is Isaac Newton and the rest of us aren't.
SPEAKER_1: It's that simple.
SPEAKER_2: That is brilliant.
SPEAKER_1: And it's simple and brilliant.
SPEAKER_2: Yes, yeah, exactly.
SPEAKER_1: That's what makes it extra brilliant, is how simple it is.
SPEAKER_1: Okay, so at that point, it's easy to sort of extrapolate that a rainbow is just sunlight broken up into those same colors that the prism did for you.
SPEAKER_1: So now what's going on inside a raindrop?
SPEAKER_1: So sunlight enters the raindrop at a particular angle.
SPEAKER_1: All right, actually comes in at all angles, but only one of those angles will internally reflect off the boundary between the raindrop and the air.
SPEAKER_1: Okay, this is one of the most fascinating features of optics.
SPEAKER_1: In other words, if I'm underwater and I, let's say I have a laser, so we get a nice sharp point, and I point it upwards, not straight up, but at an angle, at a slight angle.
SPEAKER_1: When that laser beam exits into the air, it bends.
SPEAKER_1: Okay, it's bent.
SPEAKER_2: Right.
SPEAKER_1: It's bent.
SPEAKER_1: Okay, you can picture this.
SPEAKER_2: Yes.
SPEAKER_1: You can try it yourself if you have a pocket laser.
SPEAKER_1: Okay, so it's easy then to expect that a similar thing is happening between sunlight and raindrops that was happening between your sunlight and your prism.
SPEAKER_1: But the fun part is the sunlight goes inside the raindrop and bounces around a couple of times before it exits again.
SPEAKER_1: And by the time it exits, all those colors have been separated out from the white light.
SPEAKER_1: And thus you have this participatory rainbow where all of these dots of, all these droplets of water participate in one coherent rainbow.
SPEAKER_1: Now, the angle the light exits creates a rainbow that you see.
SPEAKER_2: Right, okay.
SPEAKER_1: Right, you only see what enters your eye.
SPEAKER_1: You can't see what doesn't enter your eye.
SPEAKER_1: Correct?
SPEAKER_1: That makes sense.
SPEAKER_2: Makes sense.
SPEAKER_1: By the way, that itself was a discovery from a thousand years ago.
SPEAKER_1: Ibn al-Haytham was a Muslim scientist back in the golden age of Islam.
SPEAKER_1: He was the first to deduce that sight is not you beaming stuff out of your eyes.
SPEAKER_1: It's completely passive.
SPEAKER_1: Your eyeballs are just sitting there waiting for light to enter and for your brain to then make an image.
SPEAKER_1: This is profound because before then, you had these legends like Medusa.
SPEAKER_1: Yeah.
SPEAKER_1: All right.
SPEAKER_1: How does Medusa work?
SPEAKER_1: How does that work?
SPEAKER_2: Well, when you look her in the eyes, she turns you to stone, basically.
SPEAKER_1: She turns you into stone.
SPEAKER_2: Because she's casting whatever from her eyes.
SPEAKER_1: From her eyes, correct.
SPEAKER_1: You could only think that if you have no idea how vision works.
SPEAKER_2: Right.
SPEAKER_2: Or if you're creating X-Men, but that's a different story.
SPEAKER_1: Oh, yeah, he's got his little visor thing that can send out the beams.
SPEAKER_1: So what that means is all of the rainbow light that's coming to you is exiting those raindrops at the precise angle that enters your eyeballs.
SPEAKER_1: That means your rainbow is unique to you.
SPEAKER_1: When if I stand to your left or right or above, doesn't matter if I stand somewhere else, and we're looking at, quote, the same rainbow we tell ourselves, we're not.
SPEAKER_1: We are each looking at our own private rainbow.
SPEAKER_2: Oh my God, my own private rainbow.
SPEAKER_1: Now watch, if you keep moving to the side, you'll reach a point where they do not see the rainbow because there's no rainbow light coming to them.
SPEAKER_2: Right.
SPEAKER_1: So Chuck, you know what this fact means?
SPEAKER_2: I do not.
SPEAKER_1: Every rainbow you have ever seen has been exactly face on to you.
SPEAKER_2: Aha.
SPEAKER_2: And so I am, every rainbow actually was made just for me.
SPEAKER_1: Just for you.
SPEAKER_1: You have never witnessed a rainbow at an angle.
SPEAKER_2: Angle, right.
SPEAKER_1: So think about that, because if your rainbow was a real thing in the sky, I could move to another location and look at it from a different angle.
SPEAKER_2: Right.
SPEAKER_1: If it was an actual thing that was there.
SPEAKER_2: Like anything else, right?
SPEAKER_2: Like a mountain, a tree, or whatever.
SPEAKER_1: A mountain like anything else, okay.
SPEAKER_1: So, if you wanted to go to the base of the rainbow, you can't.
SPEAKER_1: Because that would be taking a different angle of view on a thing that does not really exist as a physical entity.
SPEAKER_2: And now you have just explained how I have wasted a significant portion of my life trying to find that pot of gold.
SPEAKER_1: If you're gonna hide a pot of gold, put it at the bottom of a rainbow, nobody will ever find it.
SPEAKER_2: Nobody's.
SPEAKER_1: Ever.
SPEAKER_1: Yeah, so just a little known fact.
SPEAKER_1: Now, the light that's inside the raindrop, this is like inside baseball here.
SPEAKER_1: You ready for this?
SPEAKER_1: This is like.
SPEAKER_1: This is rainbow 201, not 101.
SPEAKER_1: So the light inside the raindrop sends out not only one rainbow, but multiple rainbows, but each next one is a little weaker than the previous one.
SPEAKER_1: Okay, and because the second rainbow that comes out had an extra reflection to it, if you ever see a double rainbow.
SPEAKER_2: Ooh, it means that you're tripping on mushrooms.
SPEAKER_1: Oh, no, if you see it.
SPEAKER_2: Oh, double rainbow.
SPEAKER_1: Chuck, it's just physics.
SPEAKER_1: Sometimes it's actually just physics, not the mushrooms you're consuming.
SPEAKER_2: Go ahead, the double rainbow.
SPEAKER_1: So with that, two properties of that second rainbow is one, it's much dimmer than the first.
SPEAKER_2: Got you.
SPEAKER_1: It's always there, but generally it's very hard to detect because it's so dim.
SPEAKER_1: So it's much dimmer and the sequence of colors is reversed.
SPEAKER_2: Oh, no.
SPEAKER_1: From the original.
SPEAKER_2: That's, okay, that is, first of all, that's dope.
SPEAKER_2: Secondly, who knew?
SPEAKER_2: So the double rainbow is kind of like the reverse rainbow.
SPEAKER_1: It's an inverted rainbow to the first rainbow and it's dimmer.
SPEAKER_1: There's actually a third and fourth and fifth.
SPEAKER_1: They're called the orders of the rainbow.
SPEAKER_1: First order, second order, third order.
SPEAKER_1: But they're so dim that if the sky is bright, you just will never see them.
SPEAKER_1: So, and there's a famous YouTube video some years back.
SPEAKER_1: I think they just call it the double rainbow guy.
SPEAKER_2: Yeah, that's what I'm saying.
SPEAKER_2: He's tripping on mushrooms, that guy.
SPEAKER_1: And he sees two rainbows and he falls prostrate to the ground.
SPEAKER_1: And so there is a god and it's so beautiful.
SPEAKER_2: Double rainbow.
SPEAKER_1: And that's how you'll behave if you don't know physics, right?
SPEAKER_1: Right.
SPEAKER_1: It's just physics, really.
SPEAKER_2: That's all it is.
SPEAKER_2: It's just physics.
SPEAKER_2: You know, once again, Neil, way to ruin rainbows.
SPEAKER_1: I want you to reserve your sense of wonder for things for which we still do not understand.
SPEAKER_1: And not apply it for things that are completely understood.
SPEAKER_1: You know, there will always be a moving frontier of science where our area of knowledge grows, so too does the perimeter of our ignorance, leaving us with no end of this universe to stand in wonder as we gaze.
SPEAKER_2: Thank you, people.
SPEAKER_2: That's the show.
SPEAKER_2: Nothing left to say, nothing left to say.
SPEAKER_2: That's it.
SPEAKER_1: So Chuck, we gotta take a break.
SPEAKER_1: When we come back, we'll do a little bit more of this.
SPEAKER_1: We'll find some other subject, if you're game.
SPEAKER_2: Sounds great.
SPEAKER_1: Let's do it.
SPEAKER_1: Okay, StarTalk, stuff you thought you knew.
SPEAKER_3: Hey, I'm Roy Hill Percival, and I support StarTalk on Patreon.
SPEAKER_3: Bringing the universe down to earth, this is StarTalk with Neil deGrasse Tyson.
SPEAKER_1: Thanks for listening.
SPEAKER_1: We're back, Chuck.
SPEAKER_1: Things you thought you knew.
SPEAKER_1: You ready for another one?
SPEAKER_2: I'm ready, let's do it.
SPEAKER_1: Let's go there.
SPEAKER_1: And by the way, I picked these based on how familiar we think we are about the subject, and then throwing some things that you never knew.
SPEAKER_2: Which is why they work.
SPEAKER_2: I mean, if we were just gonna talk about, like, gravitational waves, of course we know we don't know none, you know what I mean?
SPEAKER_2: Like, who's an astrophysicist?
SPEAKER_2: There's like, what, 20 of you, you know what I mean?
SPEAKER_2: You know, like, seven of you sitting around, you know, drinking tea.
SPEAKER_1: Yeah, so this is not just, let me explain stuff that you can get on the Wiki page.
SPEAKER_1: It's like, just cool, fun stuff you never thought.
SPEAKER_2: No, it's the twist.
SPEAKER_2: The twist that gets you, man.
SPEAKER_2: Like, the inverted rainbow, who knew that?
SPEAKER_2: The orders of rainbow, who knew that?
SPEAKER_2: Like, I mean, that's stuff that you honestly, but everybody knows rainbows.
SPEAKER_2: So, yeah, you're right, it's like twist.
SPEAKER_2: It's the twist that gets you.
SPEAKER_1: So, for this segment, we're gonna talk about zero.
SPEAKER_2: All right, here we go again.
SPEAKER_2: This is gonna be tough for you, man.
SPEAKER_2: All right, here we go, zero.
SPEAKER_1: So, zero is a number, but it wasn't always a number.
SPEAKER_1: In fact, no one ever imagined it could be a number.
SPEAKER_1: In fact, no one even imagined how to imagine it.
SPEAKER_1: Why would you?
SPEAKER_2: Right.
SPEAKER_1: What were numbers for?
SPEAKER_2: Right, who counts nothing?
SPEAKER_1: Right, numbers are for counting.
SPEAKER_2: Right.
SPEAKER_1: Okay, how many chickens do you have?
SPEAKER_1: Three.
SPEAKER_1: How many cattle do you have?
SPEAKER_1: You count things.
SPEAKER_1: So nobody had any use to count zero.
SPEAKER_1: It just was not there.
SPEAKER_1: For most of civilization, this was the case.
SPEAKER_2: Right.
SPEAKER_1: Even through the Roman Empire.
SPEAKER_1: We think of them as highly civilized, the whole cities and hot baths and armies and if that equates to civilization.
SPEAKER_2: Ducks and they're so sophisticated, their numbers were letters.
SPEAKER_1: So, Roman Empire, they can count, they used Roman numerals.
SPEAKER_1: We learn Roman numerals in elementary school, don't we?
SPEAKER_1: Still, I think.
SPEAKER_1: And the reason why we learn Roman numerals is so that we know how to count Super Bowl games.
SPEAKER_2: That is kind of the only application left.
SPEAKER_1: No, one other, for some movie sequels.
SPEAKER_2: True, true.
SPEAKER_1: That's it, that's it.
SPEAKER_1: I don't know any other application.
SPEAKER_1: Oh, I know, also, lowercase Roman numerals are the page numbers in books before you get to the actual chapters of the book.
SPEAKER_2: Okay, yeah, that's true.
SPEAKER_1: Look at the bottom of the page, those are usually Roman numerals.
SPEAKER_1: And then they restart from one at the beginning.
SPEAKER_1: Okay, so I don't know if you've ever thought about this, Chuck, you can't write zero with Roman numerals.
SPEAKER_2: No, you can't, right?
SPEAKER_1: There is no symbol for zero.
SPEAKER_1: It's not because they didn't come up with it, it's that the concept of zero was not yet invented.
SPEAKER_1: So when they made the Julian calendar, that's the one that has a leap day every four years, and because they knew enough to know that the calendar needed it, that calendar, the Julian calendar, which anchored its starter date on the birth of Jesus, okay, so this obviously came later after Constantine, I think Constantine brought Christianity to the Roman Empire, so that they stopped feeding the Christians to the lions, that all turned around, right?
SPEAKER_2: Very bad development for the lions.
SPEAKER_2: They were like, damn, you know, we like that.
SPEAKER_2: I know, don't write people.
SPEAKER_1: Okay, so in the Julian calendar, they went from 1 BC, BC of course stands for before Christ, to AD 1, and AD is in Latin, Anno Domini, the year of our Lord, 1, and there was no year zero in that transition.
SPEAKER_1: So when would Jesus have been born?
SPEAKER_1: All right, and in the mythical year between the two, he can't be born in AD 1, because that's after, and he can't be born in BC, because that's before, so this was an issue.
SPEAKER_2: Oh, I got the answer.
SPEAKER_2: It's a miracle.
SPEAKER_1: Well, later biblical research would show that Jesus was probably born closer to 3 or 4 BC, and so, but the calendar was already in place, so you're stuck with that.
SPEAKER_1: There's a mismatch there.
SPEAKER_1: Three or four year mismatch.
SPEAKER_2: We've got to play this hand.
SPEAKER_2: We've got to play this hand, bro.
SPEAKER_1: We've got to play it.
SPEAKER_1: Okay, so now, move time forward.
SPEAKER_1: Going, is it in the 600s, 700s, I forgot exactly when.
SPEAKER_1: In India, there were great advances in mathematics there, where they even developed the numerals, early versions of the numerals we now use.
SPEAKER_1: Rather than Roman numerals.
SPEAKER_1: Roman numerals were letters.
SPEAKER_1: These are now sort of symbolic shapes that would then represent the numbers.
SPEAKER_1: And in this effort was the hint that maybe you might want a zero in there.
SPEAKER_1: So we're crawling now before we can walk, but the seeds are planted.
SPEAKER_1: These new mathematics worked their way to the Middle East.
SPEAKER_1: And Baghdad specifically, a big trading post.
SPEAKER_1: And there it was.
SPEAKER_1: Ideas were put across the table.
SPEAKER_1: This is the golden age of Islam, right?
SPEAKER_1: Major advances were made in engineering and astronomy and biology, physiology and vision.
SPEAKER_1: These were the discoveries that in vision is a passive phenomenon, not active.
SPEAKER_1: And so all of this is going on, and then the zero was perfected.
SPEAKER_2: Oh.
SPEAKER_1: The zero is perfected, and they call those numerals Hindu numerals.
SPEAKER_1: But we today call those numerals Arabic numerals.
SPEAKER_2: Right, yeah.
SPEAKER_1: So this is the full tracking there, because in the Middle East, an entire algebra rose up, and arithmetic and algebra rose up, invoking zero, and you have negative numbers, and so mathematics is off to the races.
SPEAKER_1: Algebra is one of very common words in English that has its roots in Arabic.
SPEAKER_1: A lot of the AL words, AL is the in Arabic, as I understand it.
SPEAKER_2: Yeah, algorithm.
SPEAKER_1: So algebra, algorithm, there's another one, alcohol.
SPEAKER_1: These are all traceable to that period.
SPEAKER_1: But all I'm trying to say, Chuck...
SPEAKER_2: The best of which is alcohol.
SPEAKER_2: There you go, way to do it.
SPEAKER_1: So I'm just saying zero, all...
SPEAKER_1: Just consider how late zero came in civilization.
SPEAKER_1: The Egyptians knew nothing of zero.
SPEAKER_1: But it's there and we've got it.
SPEAKER_2: So what is this I hear about the Mayans and zero, that they somehow had something to do...
SPEAKER_1: I don't fully know my Mayan history other than that their calendar was...
SPEAKER_1: They really worshiped Venus in the sky.
SPEAKER_1: And so the calendar was sort of Venus-based.
SPEAKER_1: The calendar in ancient Egypt was based on the star Sirius.
SPEAKER_1: I'm talking about the New Year, when they start the New Year.
SPEAKER_1: Because it's completely arbitrary when you say, here, the New Year just began.
SPEAKER_1: Completely arbitrary.
SPEAKER_1: Just pick a date and whatever matters in your culture, call it the beginning of the year.
SPEAKER_1: To this day, when is the Chinese New Year?
SPEAKER_1: It's in like late January, February, right?
SPEAKER_1: Everybody's got a different starter date.
SPEAKER_2: The Jewish New Year is another New Year.
SPEAKER_1: Yeah, everybody's got their New Year.
SPEAKER_2: Everybody's got their own New Year.
SPEAKER_1: The academic calendar has a New Year.
SPEAKER_1: It's September 1st.
SPEAKER_1: Even though they don't say it, it really is that.
SPEAKER_1: All the academic folks come back from summer vacation.
SPEAKER_1: Children buy their school supplies.
SPEAKER_1: That's, in a way, a New Year's Day for school.
SPEAKER_1: So anyway, I just want to just round out what Xero was all about.
SPEAKER_1: And by the way, so you know...
SPEAKER_1: Wait, one quick thing.
SPEAKER_2: Go ahead.
SPEAKER_1: One quick thing.
SPEAKER_1: You got $100 in your bank account, and you go and withdraw $100 from the cash machine, and the bank tells you what?
SPEAKER_2: Don't do this again, man, because...
SPEAKER_2: By the way, you think you have $100, and you don't.
SPEAKER_2: What you forgot was the electric bill came through yesterday.
SPEAKER_1: Before you withdrew the $100.
SPEAKER_2: Before you withdrew this $100.
SPEAKER_1: You sound like this has happened to you, Chuck.
SPEAKER_1: So here's the thing.
SPEAKER_1: You have no money left in the bank, and that's bad.
SPEAKER_1: But what's worse is to have negative money in the bank.
SPEAKER_1: And so this whole concept of negative numbers arose and made complete sense once you passed through zero, and now instead of something coming your way, you now owe it.
SPEAKER_2: Right.
SPEAKER_1: And so the mathematics began to mirror commerce and the needs of civilization as we move forward, because we're doing much more than just counting things.
SPEAKER_2: You know, so this is like the birth of modern accounting.
SPEAKER_2: Once you find zero, that's when you're able to actually have, you know, a leisure sheet that shows you minus and pluses and all that kind of stuff.
SPEAKER_1: Yeah, it's one of the few places in the world where it's really good to be in the black.
SPEAKER_1: Apparently, no other way is it good to be in the black except on the accounting sheet.
SPEAKER_1: So, now you can go into negatives, and this keeps going with math, and you find other needs of culture and civilization and science where whole other branches of math have to be developed.
SPEAKER_1: And so, this just went on and on, and then we got trigonometry.
SPEAKER_1: All the stuff that you thought the teacher was just being angry with you, giving you these assignments, these are entire branches of math.
SPEAKER_1: The zero started at all where it gives you deeper insights into the operations of nature.
SPEAKER_2: Absolutely.
SPEAKER_2: Wow.
SPEAKER_2: That's pretty cool.
SPEAKER_2: I mean, all this just from nothing.
SPEAKER_1: Yeah.
SPEAKER_2: All this came from nothing.
SPEAKER_1: And so, in this way, nothing means something.
SPEAKER_2: Right.
SPEAKER_1: It means something.
SPEAKER_1: And what's that song from the 80s?
SPEAKER_2: Nothing from nothing leaves nothing.
SPEAKER_2: You got to have something if you won't be with me.
SPEAKER_1: Nothing from nothing leaves nothing.
SPEAKER_1: I think that's a legit equation.
SPEAKER_1: I have to think about that.
SPEAKER_1: Zero minus zero.
SPEAKER_1: You just can't start dividing, right?
SPEAKER_1: Because then you end up dividing by zero, and that's illegal.
SPEAKER_2: Right.
SPEAKER_2: You've broken the law of the universe or something.
SPEAKER_1: If you do that too many times, Beetlejuice shows up and it implodes.
SPEAKER_2: Yeah, exactly.
SPEAKER_1: So Chuck, I just want to bring you up to speed on zero.
SPEAKER_1: That's all.
SPEAKER_2: Yeah.
SPEAKER_2: Yeah, I got to tell you, I've never been more impressed with nothing.
SPEAKER_2: So this is cool.
SPEAKER_1: This is very cool.
SPEAKER_1: So Chuck, we got to take a break.
SPEAKER_1: When we come back, one more stuff you thought you knew, we can fit it in.
SPEAKER_1: All right, we'll be right back.
SPEAKER_1: Chuck, we're back.
SPEAKER_2: Yes.
SPEAKER_2: What do we got?
SPEAKER_1: Yeah, I got another topic for you.
SPEAKER_2: All right.
SPEAKER_1: What do Zoom calls and Einstein's theory of relativity have in common?
SPEAKER_2: No one knows how either of them actually work.
SPEAKER_2: I'm gonna say that's gotta be the answer.
SPEAKER_1: That's a good answer.
SPEAKER_1: So here you go.
SPEAKER_1: You ready?
SPEAKER_2: Okay, let's do it.
SPEAKER_1: What we learned, what we affirmed in Einstein's theories of relativity is that space cannot be thought of just as space.
SPEAKER_1: Time is a fundamental coordinate right alongside space.
SPEAKER_1: Right.
SPEAKER_1: So that when you ever wanna think about events, phenomena, past, present, future, you have to think of space time.
SPEAKER_2: Right.
SPEAKER_1: You can't just think of space or time as separate things.
SPEAKER_1: And there's an entire set of equations that fold the two together.
SPEAKER_2: That's, see now, that's, the first part I am so cool with, I like literally get it, you know?
SPEAKER_2: But when you talk about proving it mathematically, I'm still just flabbergasted.
SPEAKER_1: That's how you know it's gonna be tight.
SPEAKER_2: Yeah, of course.
SPEAKER_1: That's how you tighten it up.
SPEAKER_2: It keeps moving, it keeps working.
SPEAKER_2: When the math works, it works.
SPEAKER_1: It keeps it tight.
SPEAKER_2: Yeah, that's cool, man.
SPEAKER_1: It works, right.
SPEAKER_1: Okay, so, let us, for those who might still be uncomfortable with the space-time concept, what you don't know, perhaps, is that you live that way.
SPEAKER_1: There's no other way you live.
SPEAKER_1: It's so intuitive, you think it's complicated, but it's easy.
SPEAKER_1: So if I say to you, Chuck, you ready?
SPEAKER_2: Yep.
SPEAKER_1: Okay, I'd say, Chuck, let's have lunch tomorrow at noon.
SPEAKER_2: I would say, oh my God, as long as you're paying, that is such a wonderful offer.
SPEAKER_1: Okay, Chuck, it's on me, let's have lunch tomorrow at noon.
SPEAKER_1: What is your next comment back to me?
SPEAKER_2: Where?
SPEAKER_2: Where you wanna eat?
SPEAKER_2: Where do you wanna eat?
SPEAKER_1: Because the time alone was insufficient.
SPEAKER_2: Of course, yeah.
SPEAKER_1: For your life and my life to intersect, time alone will not make that happen.
SPEAKER_1: You also have to give a spatial coordinate.
SPEAKER_2: Right.
SPEAKER_1: Is it the diner on the corner of Hollywood and Vine at 12 noon?
SPEAKER_2: Right.
SPEAKER_1: So you have a space coordinate and time coordinate so that we can both meet.
SPEAKER_2: Right.
SPEAKER_2: Leave it to you to give me a coordinate where you know I can't get to.
SPEAKER_1: So watch.
SPEAKER_1: If you go to the diner at the corner of Hollywood and Vine.
SPEAKER_2: Right.
SPEAKER_1: Yesterday, and I go there tomorrow, we were in the same place.
SPEAKER_2: We were.
SPEAKER_1: But not at the same time.
SPEAKER_1: Doesn't work.
SPEAKER_1: Let's keep going.
SPEAKER_1: You were at the diner yesterday, and I'm at the diner tomorrow.
SPEAKER_1: We're both in the same place, but not at the same time.
SPEAKER_2: Which is what I call Neil's favorite lunch.
SPEAKER_2: Chuck, you were here yesterday.
SPEAKER_2: Good.
SPEAKER_1: Okay, so now watch.
SPEAKER_1: So now you're at the diner in the corner, and I'm at, this works with Starbucks.
SPEAKER_1: You're in that Starbucks.
SPEAKER_1: I'm in a different Starbucks.
SPEAKER_1: We're at the same time, but not at the same place.
SPEAKER_2: Right.
SPEAKER_1: Right, okay, so you need to be at the same place and at the same time for anything to happen where you have two things that will coordinate together.
SPEAKER_1: Okay, all right.
SPEAKER_1: So how does this manifest?
SPEAKER_1: Let's go in the universe, and there's an asteroid headed towards Earth.
SPEAKER_1: You could do the Bruce Willis thing and what?
SPEAKER_2: Blow it up.
SPEAKER_1: Blow it out of the sky, which takes a lot of wasted energy, or you can deflect it.
SPEAKER_1: Well, how do you deflect an asteroid?
SPEAKER_2: Not a good movie.
SPEAKER_1: How do you deflect an asteroid?
SPEAKER_1: So here it is.
SPEAKER_1: If you left it alone, it will collide with Earth, which means it will be in the same place at the same time that Earth is, sometime in the future, at some point in the future, okay?
SPEAKER_1: So what I can do is I can speed up the asteroid.
SPEAKER_1: Oh, I love that, which you speed it up.
SPEAKER_2: Yeah.
SPEAKER_1: Then it gets to that location in my orbit before I do.
SPEAKER_2: Exactly.
SPEAKER_1: So we exist at the same time, but we're not in the same place.
SPEAKER_2: That's a whole nother way to look at deflecting an asteroid.
SPEAKER_1: That's what's going on when you deflect an asteroid.
SPEAKER_2: That's awesome.
SPEAKER_1: Or you could slow it down.
SPEAKER_2: Right.
SPEAKER_1: Then we get to that point before it does, we keep moving and it goes right on by behind us.
SPEAKER_2: Oh man, it's the proverbial mental exercise that everyone does when they have a car accident.
SPEAKER_2: If only I hadn't forgotten my keys.
SPEAKER_2: If only I had left a little bit earlier, I would have never had-
SPEAKER_1: And they wouldn't have been in that spot at that time for the drunk driver, correct?
SPEAKER_2: Right, yeah.
SPEAKER_1: It's a mental calculation you do, right, right.
SPEAKER_1: And it works in simple ways that we don't even talk about, but it's so simple.
SPEAKER_1: You cross the street, five minutes later, a bus drives down the street.
SPEAKER_1: You just say, oh my gosh, I was almost hit.
SPEAKER_1: No, you didn't.
SPEAKER_2: Oh, you're a bit of a drama queen.
SPEAKER_2: You know that, right?
SPEAKER_2: My God, I was almost hit by a bus, did you see that?
SPEAKER_2: What, no, it came by here five minutes ago.
SPEAKER_2: It was just barreling down the street.
SPEAKER_1: It was in the same spot I was in.
SPEAKER_2: I was right there.
SPEAKER_2: I could have died.
SPEAKER_1: Right, you would not have died.
SPEAKER_1: And by the way, in relativity, we call these world lines.
SPEAKER_2: World lines.
SPEAKER_1: Your world line is where you are in space and time, which is always in motion.
SPEAKER_1: Because time, even if you're sitting there on your butt, you're moving forward in time.
SPEAKER_2: Right.
SPEAKER_1: By the way, this affects time machines, all right?
SPEAKER_1: So I give you a time machine and you say, okay, you want to go into the future.
SPEAKER_1: How far do you want to go in the future?
SPEAKER_2: Oh, I'm going to go at least 200 years just to see if we're still here.
SPEAKER_1: Okay, but suppose you say, all right, I don't want to land in the winter, let me land in the summer.
SPEAKER_1: So I want to go 200 years in six months.
SPEAKER_2: Okay.
SPEAKER_1: Okay, let's say, because we're recording this, it's cold outside right now.
SPEAKER_1: So you do that, all right?
SPEAKER_1: So you go in your time machine, go 200 years, and then you walk out of the time machine, you will suffocate in the vacuum of space.
SPEAKER_2: Oh, because Earth is not just spinning.
SPEAKER_2: It's moving while it's spinning.
SPEAKER_1: Okay, so you will land in the same spot that Earth was in its orbit, which is a different place than where it is six months from now.
SPEAKER_2: Oh, man.
SPEAKER_1: Which tells you a time machine can only work if it's a space time machine.
SPEAKER_2: That's right.
SPEAKER_2: That's pretty awesome.
SPEAKER_1: You wanna move to a location in time and a location in space.
SPEAKER_1: And a location in space.
SPEAKER_1: Correct.
SPEAKER_1: All right, so.
SPEAKER_2: Oh, wow, that is really cool because, yeah.
SPEAKER_1: Okay, so now watch.
SPEAKER_2: Yeah, yeah, yeah.
SPEAKER_1: Watch how this plays out.
SPEAKER_1: Are we on the same page?
SPEAKER_2: I don't know.
SPEAKER_1: I don't wanna move forward until I hear Neil, I'm with you.
SPEAKER_2: I am riding this wave with you, buddy.
SPEAKER_1: So under normal circumstances, I'm in my office three or four days a week.
SPEAKER_1: I travel a lot.
SPEAKER_1: There are seminars and colloquia.
SPEAKER_1: Scientists come through the department and they give talks.
SPEAKER_1: You know, if I'm around, I'm gonna attend those talks, because they're good.
SPEAKER_1: They learn about the latest breaking discoveries made by my colleagues.
SPEAKER_1: So we have maybe three or four talks a week in our division at the American Museum of Natural History.
SPEAKER_1: I used to make maybe one of those a week.
SPEAKER_2: All righty.
SPEAKER_1: However, during COVID, I was making four out of four talks a week.
SPEAKER_2: Why?
SPEAKER_1: Because Zoom calls broke the space-time alliance so that now you only have to be at the same time and you do not have to be at the same place.
SPEAKER_2: Interesting.
SPEAKER_1: As a result, world lines can split and only conjoin on the time coordinate, rendering the space coordinate irrelevant.
SPEAKER_1: That is why probably more people attending more conferences, seeing more meetings than ever before.
SPEAKER_1: You can no longer use an excuse.
SPEAKER_1: Oh, I'm on a business trip.
SPEAKER_1: I can't come in.
SPEAKER_1: Zoom in.
SPEAKER_1: We have you on the Zoom call.
SPEAKER_2: I know, it's an electronic lease is what it is for most people.
SPEAKER_1: And that's how, Chuck, you spent how many months you were filming Brain Games for National Geographic.
SPEAKER_2: Yes.
SPEAKER_1: You're their new host in their new season, yet you didn't lose a bit of this schedule.
SPEAKER_1: Your background was different because you were recording with us via Zoom through your hotel rooms and other setups.
SPEAKER_1: And so you were still participating because your world line didn't need the space coordinate.
SPEAKER_2: That's true, yeah.
SPEAKER_1: And so this is the relationship between Zoom calls and Einstein's theory of relativity.
SPEAKER_2: That is a, that's pretty wild.
SPEAKER_2: And in a way, I have a new respect for Zoom now.
SPEAKER_1: Breaking the space-time continuum?
SPEAKER_2: Yes, exactly.
SPEAKER_2: It's like, who knew Zoom was so damn sci-fi?
SPEAKER_2: No, that's pretty, that's, I love it, I love it.
SPEAKER_1: Chuck, in all fairness to the history of communication that predates Zoom, the telephone was kind of like that.
SPEAKER_1: All right, and by the way, do you know what the word caller meant before there was a telephone?
SPEAKER_1: It was a visitor to your front door.
SPEAKER_2: I would say a handsome gentleman perhaps.
SPEAKER_1: Yes, you have a gentleman caller.
SPEAKER_2: Oh, I do believe you have a gentleman caller.
SPEAKER_1: Yes, exactly, that's the meaning of that with the original meaning of that word.
SPEAKER_1: And then Alexander Bell invents a telephone.
SPEAKER_1: And so what word are you gonna use when you show up at the front door of the telephone line?
SPEAKER_1: It's a caller.
SPEAKER_2: It's a caller.
SPEAKER_1: And now that's, we've been that way for 130 years or whatever.
SPEAKER_1: So we, 150 years now.
SPEAKER_1: So 1876 was the demonstration of the patent for the first telephone.
SPEAKER_1: And so that put people together in time without having to be together in space.
SPEAKER_1: So this is one of the great achievements and advances in modern civilization.
SPEAKER_1: And Zoom just did it full up with voice and sound and audio quality and saved files and everything.
SPEAKER_2: It's really funny because the video call was reported to be the thing that would change everything in society and...
SPEAKER_1: I remember seeing a video phone in 1964 World's Fair in New York.
SPEAKER_1: It was like, wow, that's the future.
SPEAKER_1: Then you realize you call someone at six in the morning, they don't want you looking at them.
SPEAKER_2: Yeah, exactly.
SPEAKER_1: People don't always want you looking at them anytime you happen to call them.
SPEAKER_2: What is that on your face?
SPEAKER_2: Don't look at my face.
SPEAKER_2: Let's just have a call.
SPEAKER_2: Stop looking at my face.
SPEAKER_1: So now you can pre-schedule Zoom calls and now you can get all dolled up and all purty.
SPEAKER_1: You can look Zoom purty.
SPEAKER_2: Yeah, you got to.
SPEAKER_2: That's pretty, yeah, that's great, though.
SPEAKER_2: I mean, who knew that you could link this back to Einstein?
SPEAKER_2: I said you had a tough one, but you did it.
SPEAKER_2: You linked it back to Einstein somehow.
SPEAKER_1: And now you know with asteroids, we're just changing his world line.
SPEAKER_2: Yeah, which, by the way, that is the coolest thing ever.
SPEAKER_2: The fact that, I mean, and the idea is you don't even have to knock it off course.
SPEAKER_2: You can just speed it up or slow it down.
SPEAKER_2: Because you always think of deflection as a change in the vector.
SPEAKER_2: Right, right.
SPEAKER_1: Well, a vector is direction and speed.
SPEAKER_2: And speed.
SPEAKER_1: Technically, a vector has both of those components.
SPEAKER_1: So if you change its direction or you change its speed, you have changed its velocity.
SPEAKER_1: The velocity is the combination of those two.
SPEAKER_2: Nice.
SPEAKER_1: So it's exactly right.
SPEAKER_2: That's great.
SPEAKER_2: It's like that.
SPEAKER_2: I mean, I am less scared of asteroids now.
SPEAKER_2: I don't want...
SPEAKER_1: That was not the point of this explainer.
SPEAKER_2: Oh, okay.
SPEAKER_1: No, you are heartened...
SPEAKER_1: Oh, by the way, a velocity vector is motion that has direction and speed as part of it.
SPEAKER_1: Like the asteroid, right?
SPEAKER_1: So right.
SPEAKER_1: You can change its direction or change its speed.
SPEAKER_1: Or both.
SPEAKER_1: Either of those are changing the velocity of the asteroid.
SPEAKER_1: Okay, so now watch.
SPEAKER_1: You can do that.
SPEAKER_1: So with a car, there are three ways to change its velocity.
SPEAKER_2: Right.
SPEAKER_2: You can slow it down, you can speed it up, and you can hit a wall.
SPEAKER_1: Ideally not.
SPEAKER_1: You can slow down.
SPEAKER_1: It reduces its speed.
SPEAKER_1: You can accelerate, increase its speed.
SPEAKER_1: Or you can change direction.
SPEAKER_1: All three of those can help you avoid an accident.
SPEAKER_2: Right.
SPEAKER_1: It's not just how good your brakes are.
SPEAKER_1: Do you have a place to steer so that your worldwide does not fully intersect with the one that would cause the accident?
SPEAKER_2: You know what?
SPEAKER_2: As a person who rides a motorcycle, you just explained how you stay alive on a bike.
SPEAKER_2: Those are the three things that are your friend, that they teach you all the time.
SPEAKER_2: The first is acceleration.
SPEAKER_2: Get up and get out of the way.
SPEAKER_2: The second is being able to brake properly, but now motorcycles have anti-lock brakes, so that used to be a big deal, not so much.
SPEAKER_2: But the most important is being able to maneuver.
SPEAKER_2: So, you know, to be able to...
SPEAKER_1: And motorcycles are particularly nimble in that regard.
SPEAKER_2: Right.
SPEAKER_2: Exactly.
SPEAKER_2: Yeah.
SPEAKER_2: Super cool.
SPEAKER_1: So, Chuck, we got to bring this to a close.
SPEAKER_1: This was stuff you thought you knew.
SPEAKER_2: And now I do.
SPEAKER_1: And the inventory was rainbows, zero, and Zoom calls and relativity.
SPEAKER_1: There it is.
SPEAKER_1: That's as motley a crew as you'll find.
SPEAKER_1: All right, Chuck, we're going to land this plane, and I'm going to get out, and so are you.
SPEAKER_1: Neil deGrasse Tyson here, your personal astrophysicist.
SPEAKER_1: Wait a minute, wait a minute, before I end.
SPEAKER_1: I did say it, didn't I?
SPEAKER_1: Chuck, your show premiered with National Geographic, Brain Games, the new host, oh my gosh.
SPEAKER_2: Yes, yes, please watch it, people.
SPEAKER_1: Don't sound that desperate, Chuck.
SPEAKER_2: Oh yeah, that's right, that's not the way.
SPEAKER_2: You're not supposed to promote a show by going, hey man, please watch it, I got kids.
SPEAKER_2: That's not the way you're supposed to.
SPEAKER_1: I got hungry kids.
SPEAKER_2: Hey man, these kids eat so much, please watch my show.
SPEAKER_1: No, Brain Games, it's a new season, 20 episodes, just dropped on National Geographic.
SPEAKER_1: You can get it through the Disney portal.
SPEAKER_2: That's correct.
SPEAKER_1: And check out our very own Chuck Nice.
SPEAKER_1: We take ownership of you, Chuck.
SPEAKER_1: We feel like you're ours.
SPEAKER_2: That's right, yeah.
SPEAKER_2: Well, that's right.
SPEAKER_2: I feel that way too.
SPEAKER_2: Thank you, yeah, thanks Neil.
SPEAKER_1: All right, all right, this has been StarTalk.
SPEAKER_1: Neil deGrasse Tyson here as always.