SPEAKER_1: From the American Museum of Natural History in New York City, and beaming out across all of space and time.
SPEAKER_1: This is StarTalk, where science and pop culture collide.
SPEAKER_1: This is StarTalk.
SPEAKER_1: I'm your host, Neil deGrasse Tyson, your personal astrophysicist, and we're coming to you from my office at the Hayden Planetarium of the American Museum of Natural History, right here in New York City.
SPEAKER_1: And this edition of StarTalk, we're calling Summer School.
SPEAKER_3: Yeah.
SPEAKER_1: Who said yeah?
SPEAKER_3: The professor.
SPEAKER_1: Friend and colleague, Charles Liu.
SPEAKER_1: Charles, welcome.
SPEAKER_3: Thank you so much for having me.
SPEAKER_3: I love summer school.
SPEAKER_3: You love summer school.
SPEAKER_3: Absolutely.
SPEAKER_1: And I got my cohost for this episode, Matt Kirshen.
SPEAKER_2: Hey.
SPEAKER_1: Welcome back.
SPEAKER_2: Thank you so much.
SPEAKER_1: All right.
SPEAKER_1: Host of probably maybe science.
SPEAKER_2: Probably science.
SPEAKER_1: Could be science.
SPEAKER_2: Nearly science.
SPEAKER_1: Not sure if it's science.
SPEAKER_2: I can't believe it's not science.
SPEAKER_1: Probably science.
SPEAKER_1: Weekly review of science current events.
SPEAKER_2: That's exactly it.
SPEAKER_1: Excellent, excellent.
SPEAKER_2: That's the podcast.
SPEAKER_1: Keep that going, keep that going.
SPEAKER_1: Charles, professor at the City University of New York.
SPEAKER_2: So it kind of equals here.
SPEAKER_3: No, we are.
SPEAKER_1: So this is a Cosmic Queries version, but it's called Summer School.
SPEAKER_1: People just trying to catch up.
SPEAKER_3: That's right.
SPEAKER_1: With stuff they might have missed.
SPEAKER_3: Or get ahead.
SPEAKER_1: Or get ahead.
SPEAKER_1: I forgot, Summer School's forgetting ahead, too.
SPEAKER_1: For motivated students.
SPEAKER_1: That's right.
SPEAKER_2: And with that in mind, I think let's start off with quite an academically advanced question.
SPEAKER_1: Let's do it.
SPEAKER_2: I think, Cooper Holland on Instagram asks, how hard would I have to fart to knock earth into escape velocity?
SPEAKER_2: Also, wouldn't sunrise be a good time to try it?
SPEAKER_2: Mm, that's Cooper Holland from Arizona State.
SPEAKER_1: From ASU.
SPEAKER_3: I'm coughing because I'm imagining how much gas needs to be used to make that happen.
SPEAKER_3: But the reality is, first, I assume you have an escape velocity from the sun, right?
SPEAKER_1: No, he wants to escape from the earth.
SPEAKER_3: Oh, he wants to escape from the earth.
SPEAKER_3: I thought he wanted the earth to escape from the sun.
SPEAKER_3: Oh, that's different.
SPEAKER_3: Now that is a massive.
SPEAKER_2: Yeah, it says to look earth into escape velocity.
SPEAKER_1: That's harder than just if he wanted to escape.
SPEAKER_3: Right, right, if he wanted to escape, that's easy.
SPEAKER_1: Just a few cans of beans.
SPEAKER_3: Put them on a gantry.
SPEAKER_3: No, earth would be a lot harder.
SPEAKER_3: Because earth's orbital velocity is about.
SPEAKER_1: I just now can't get that picture out of my head.
SPEAKER_1: He's positioned on a gantry in Cape Canaveral.
SPEAKER_3: Yeah, three, two, one.
SPEAKER_1: Glass tube, a couple of beans, one.
SPEAKER_2: Long trip bulletin for weather.
SPEAKER_3: But is that solid fuel or a liquid fuel rocket?
SPEAKER_1: Oh yeah, that would be, no, that's just air pressure fuel.
SPEAKER_3: That's just pressure fuel.
SPEAKER_2: That's really a bottle rocket.
SPEAKER_1: It's a pneumatic rocket.
SPEAKER_1: A bottle rocket, pneumatic rocket.
SPEAKER_1: Or like a CO2 pellet rifle, it's pneumatic.
SPEAKER_3: Wow, no, see, earth's orbital velocity is about 30 kilometers per second, right?
SPEAKER_3: Around the sun.
SPEAKER_3: You have to take the square root of two of that, and so that makes time 1.4 times 30, so about 42 kilometers per second.
SPEAKER_3: Earth's mass is about six.
SPEAKER_1: Because it's a cute little fact that whatever is your orbital velocity around what you're orbiting, if you multiply that by the square root of two, that's the speed to escape that object.
SPEAKER_3: Yeah.
SPEAKER_1: It's a very cool fact.
SPEAKER_3: It is, it's neat.
SPEAKER_3: It's nice coincidence in math.
SPEAKER_3: And the Earth's mass of course is about 1.4, yeah.
SPEAKER_3: Earth's mass is six billion trillion tons, right?
SPEAKER_3: So to generate the amount of impulse necessary to get Earth that much mass up to that velocity, that's a lot of cans of beans.
SPEAKER_1: Yeah, because it's a momentum thing.
SPEAKER_1: So you need enough expelled gas so that the recoil of your planet can be meaningful and significant.
SPEAKER_2: Right, and correct me if I'm wrong, but you'd also have to make sure you're in some way tethered to the Earth so you're not just blasting yourself.
SPEAKER_1: You can drag the Earth with you.
SPEAKER_1: Otherwise you would just fly off at a tangent, right.
SPEAKER_3: Yes.
SPEAKER_1: Ideally you'd want to get all humans involved in this.
SPEAKER_2: Right, you don't need to be holding onto a tree or something.
SPEAKER_3: You'd also need every cow in the world.
SPEAKER_1: You have the cows.
SPEAKER_3: You put them all together, I think that's a very good summer school problem calculation to do.
SPEAKER_3: Yes, Cooper.
SPEAKER_3: Good luck with that.
SPEAKER_3: That's great.
SPEAKER_1: But in principle, yes.
SPEAKER_1: So in other words, if you are in space, there are various ways you can actually set yourself into motion.
SPEAKER_1: But to do so, you have to lose mass from your body.
SPEAKER_1: Either gas through gas, liquid or solid.
SPEAKER_3: And if you're at sunrise, that would be a good time because the best way to inject that extra velocity, the delta V, is in the direction of the orbit, the tangent to the orbit.
SPEAKER_3: So not straight out, as some people might think, but actually out at a 90 degree angle.
SPEAKER_1: So you can build to the speed that the Earth has itself.
SPEAKER_1: Yes.
SPEAKER_3: Right.
SPEAKER_1: By the way, but all that methane, that could be a pretty dangerous situation.
SPEAKER_3: It's true, one match and you've got, yeah.
SPEAKER_1: Then you have a bomb.
SPEAKER_3: That's a flare.
SPEAKER_1: That's a bomb.
SPEAKER_2: And also that's a greenhouse gas.
SPEAKER_1: Yes, it is.
SPEAKER_3: Oh yeah.
SPEAKER_1: Yeah, very potent, more potent than CO2.
SPEAKER_3: True, so you really have to light that thing.
SPEAKER_3: Yeah.
SPEAKER_2: But then light it if you can control that lighting.
SPEAKER_3: No, wait a minute.
SPEAKER_2: If that's a thrust.
SPEAKER_1: Wait, if you leave Earth, you need the greenhouse gas to retain the warmth.
SPEAKER_3: That's right.
SPEAKER_3: So it's the balance, it's the balance.
SPEAKER_3: Yeah, wow, that's very exciting.
SPEAKER_3: You know what, I think I'm gonna have to assign that to my astrophysics class next year.
SPEAKER_1: And then the dean will call you in the office and say.
SPEAKER_3: Well, maybe Cooper will help me out with that.
SPEAKER_2: Well, while we are doing calculations, Tom Forman on Facebook asks, is math a discovery or an invention?
SPEAKER_3: Beautiful, beautiful.
SPEAKER_1: Don't get me started, I want to hear Charles first.
SPEAKER_3: Well, remember that my wife is a mathematician.
SPEAKER_1: Yes, she is.
SPEAKER_3: Right, and so I'm-
SPEAKER_1: My wife has a PhD in mathematical physics.
SPEAKER_3: That's right.
SPEAKER_3: Twinsies.
SPEAKER_1: So we got math going in the family here.
SPEAKER_3: Yeah, and my son also, given a choice of either studying math or astrophysics in college, has chosen math.
SPEAKER_3: Anyway, that's okay, we still love you.
SPEAKER_1: Sorry.
SPEAKER_3: Yeah, I know, I know.
SPEAKER_1: Such a disappointment.
SPEAKER_2: When did you know?
SPEAKER_2: Were the signs always there?
SPEAKER_3: When he was a little kid putting refrigerator magnets in strange shapes, I knew that something was up.
SPEAKER_1: Something was up.
SPEAKER_1: He was hiding something in the closet.
SPEAKER_3: Anyway, math is something that exists by itself, but mathematics as we use it and formulate it today is an invention of humans.
SPEAKER_3: This is a clear reality of the universe because things will do what they're doing whether we understand them or not.
SPEAKER_3: And we created math in order to try to understand and reproduce and utilize those things that nature provides for us.
SPEAKER_3: So for example, when the ancients were building pyramids, they invented geometry, right?
SPEAKER_3: Those pyramids would have stood anyway if we had put them together and not known the equations, but with the equations, the ancients were able to build them properly.
SPEAKER_3: The same is true with, say, rocket equations that allow us to send things out into space.
SPEAKER_3: We could have sent things into space without knowing how to do the calculations, but we wouldn't have had much control over it.
SPEAKER_3: So bottom line, the math you see in textbooks today or in papers, we humans have invented that following a set of rules that nature has provided for us as a template.
SPEAKER_3: Neil.
SPEAKER_1: I'm okay with that.
SPEAKER_3: Okay.
SPEAKER_1: I'm okay.
SPEAKER_1: I don't like debates about whether one word or another word best describes it.
SPEAKER_1: I'd rather say that maybe our language needs yet a third word that perfectly accounts for it and then we get rid of the argument altogether.
SPEAKER_2: And would that word be a discovery or an invention?
SPEAKER_1: It's the word between the two that we don't have.
SPEAKER_3: Discovention.
SPEAKER_1: It's why we argue.
SPEAKER_3: Math, the max x, math, math.
SPEAKER_3: Oh yeah, yeah, you math.
SPEAKER_1: Is it a particle or is it a wave in quantum?
SPEAKER_1: Why are we arguing that?
SPEAKER_1: It's both, we just don't have a word.
SPEAKER_1: We tried.
SPEAKER_1: We tried wavicle.
SPEAKER_1: But it didn't catch on, a wave and a particle.
SPEAKER_1: So, I just don't-
SPEAKER_2: Sounds like some sort of branding exercise from the 80s.
SPEAKER_2: It's wavicle.
SPEAKER_3: 70s, 70s, discovention, okay?
SPEAKER_1: The fact that math works at all as a tool to decode the universe is evidence that the universe, at least the parts that have revealed itself to us, follows logical, repeatable patterns.
SPEAKER_1: And math is simply a way to code for logical, repeatable patterns.
SPEAKER_1: And if, so it's remarkable that math can describe the universe at all, except that math is a perfectly logical system and so is the universe, put them together, of course.
SPEAKER_1: It's a marriage made in heaven.
SPEAKER_3: Very much like music, right?
SPEAKER_3: Math, music, that kind of connection.
SPEAKER_3: And the Bee Gees understood that well with their song, Calculus, calculus, yeah, yeah, yeah, calculus.
SPEAKER_1: And I thought Calculus was an emperor of Rome.
SPEAKER_2: That's an old joke, I heard that a long ago.
SPEAKER_1: Calculus, the brother of Clavius, yes, yes.
SPEAKER_2: Matt, get us off this topic really fast.
SPEAKER_2: I'm going to combine two different questions together.
SPEAKER_2: So Eric Hanson on Facebook asks, I recently read that if all of the space were taken out of every human on earth, the resulting mass would be about the size of a cube of sugar.
SPEAKER_2: How, then, can anyone adequately explain how the entire mass of the observable universe was once a point only microns wide?
SPEAKER_2: And then I'm going to combine this with this other question.
SPEAKER_3: That's a beautiful question on its own.
SPEAKER_2: Yeah, yeah, yeah, yeah.
SPEAKER_2: Well, this is a little code of question.
SPEAKER_2: I could have thrown it out afterwards, but I thought I'm going to leave this just in your subconscious to bubble over while you're answering that one.
SPEAKER_2: From Ashton Norton also on Facebook, other than the Big Bang, are there any other scientific theories that have been discussed as possible explanations for where we came from?
SPEAKER_3: Well.
SPEAKER_2: So, those two together or separate as you choose?
SPEAKER_3: Okay, so this is basically a cosmology question, right?
SPEAKER_3: So, I'll take the cosmology question number one.
SPEAKER_3: You can take cosmology question number two.
SPEAKER_3: I'll answer each one half way.
SPEAKER_1: Okay, you answer each half.
SPEAKER_1: Leave me a little room at the end.
SPEAKER_1: Go.
SPEAKER_3: So, the reason the universe is so different now than it was back then is simply because there was some kind of physics that happened between the moment of the Big Bang and the present day that we still don't yet understand.
SPEAKER_3: It is completely true that the universe back then, the density of the universe right around that moment of the Big Bang at the plank time, we call it, was approximately 10 to the 97 kilograms per cubic meter.
SPEAKER_3: That's pretty dense.
SPEAKER_3: And even if we took all of humanity...
SPEAKER_3: We're back in the 60s now.
SPEAKER_3: We're going from the 70s to the 60s.
SPEAKER_3: Absolutely.
SPEAKER_3: You said it.
SPEAKER_3: We have a circumstance where the matter of that density is so removed from anything we can think of that human beings the size of a cube of sugar analogy when you move all the space, that density is still only about 10 to the 15 kilograms per cubic meter.
SPEAKER_2: So there was just another state of matter or the matter itself.
SPEAKER_1: I thought it's not even that complicated.
SPEAKER_1: If it stays as solid matter, just taking out all the space between the particles, yeah, you're not going to get much smaller than that.
SPEAKER_1: But at the temperatures of the early universe, matter is not stable as solid matter.
SPEAKER_1: It's energy and you can pack energy into any kind of small volume you want.
SPEAKER_1: So is that a fair way to characterize it?
SPEAKER_3: It is a completely fair way to say it.
SPEAKER_3: And so as a result, the laws of physics that were governing that behavior produced something that eventually evolved into our universe today.
SPEAKER_3: And we have yet to decipher scientifically the processes that went from that to now.
SPEAKER_1: Wait, wait, I have to tighten that.
SPEAKER_1: It's not that it went from then to now.
SPEAKER_1: It went from then to a little bit after then.
SPEAKER_1: Because we know what happened a little bit after then until now.
SPEAKER_3: Yeah, that's fair.
SPEAKER_1: That's good physics.
SPEAKER_3: And by a little bit after, Neil, I think you're referring to 10 to the minus 30 seconds, right?
SPEAKER_3: So 0.00000.
SPEAKER_1: A gazillionth of a second.
SPEAKER_2: So we've managed to trace it back a very long way.
SPEAKER_3: Yes.
SPEAKER_3: But that last little bit.
SPEAKER_2: That last gazillionth of a second just really confusing it.
SPEAKER_3: And that segues into that second part of the question.
SPEAKER_3: Where what is going on in that tiny, tiny fraction of a second that is so different from what we know today in our universe?
SPEAKER_3: And so that's where the speculation can lie, right?
SPEAKER_3: What could have happened other than a big bang as we understand it today?
SPEAKER_3: Could something else have generated the kinds of energies and effects that have led to the way the universe expands today?
SPEAKER_3: There's lots of speculation.
SPEAKER_3: It was really, really hard to be able to decipher or to pinpoint the physics involved.
SPEAKER_3: We're adding extra dimensions.
SPEAKER_3: We're adding extra particles.
SPEAKER_3: We're adding all kinds of extra crazy ideas.
SPEAKER_3: And none of them have yet panned out in a scientifically verifiable way.
SPEAKER_1: And let me just say, do you think we're happy about a big bang?
SPEAKER_3: Yeah.
SPEAKER_3: That's a great point.
SPEAKER_1: This is like weird stuff.
SPEAKER_1: But evidence points to that.
SPEAKER_1: The universe we now occupy can be described by what happens if you had a big bang as accounted for with a small, dense, hot early beginning.
SPEAKER_1: And it gives us the amount of the hydrogen and helium and neutrinos and the age and the density and the distribution.
SPEAKER_1: All of this comes out of that.
SPEAKER_1: If you have a better idea, fine.
SPEAKER_1: We'll take it.
SPEAKER_1: But until then, we're stuck with the big bang.
SPEAKER_1: Is that another way to think about it?
SPEAKER_3: I think that's a great point.
SPEAKER_3: The imperfections of a scientific theory drive people nuts.
SPEAKER_3: We want theories to be perfect, but they're not.
SPEAKER_3: And that's where the science and the learning happens.
SPEAKER_1: But what you don't know is whether the addition is just an add-on or whether you have to throw out everything and come up with a new idea.
SPEAKER_2: Do you think that last gazillionth of a second will be explained or is it even explainable?
SPEAKER_1: We've got top people working on it right now.
SPEAKER_1: They're called string theorists.
SPEAKER_1: Top people.
SPEAKER_3: And cosmologists in general.
SPEAKER_1: Top people.
SPEAKER_3: String theorists is just one group of promising paths.
SPEAKER_3: But all of cosmology is really about trying to get that last little tiny bit.
SPEAKER_2: Question.
SPEAKER_2: This is...
SPEAKER_2: I'm going to stay on this theme for one more question.
SPEAKER_2: Because Chris Carlton on Facebook asks, why aren't we expanding with the universe if we are part of the universe?
SPEAKER_3: I get asked that question a lot by my students.
SPEAKER_2: And I'm going to add a coda to that.
SPEAKER_2: Will I ever break six foot?
SPEAKER_1: Are you still growing?
SPEAKER_2: Hopefully still expanding.
SPEAKER_1: The machines that can help you there.
SPEAKER_1: We will get to the answer to that when we return for our second segment of Summer School StarTalk.
SPEAKER_3: The future of space and the secrets of our planet revealed.
SPEAKER_1: This is StarTalk.
SPEAKER_1: We're back in our second segment of StarTalk Summer School.
SPEAKER_1: When you have to go to summer school, you gotta bring in the big guns.
SPEAKER_3: Charles Liu, professor.
SPEAKER_3: Thank you, Neil.
SPEAKER_1: Professor Charles Liu, CUNY Staten Island.
SPEAKER_1: Matt Kirshen.
SPEAKER_2: The little gun.
SPEAKER_2: The littlest gun.
SPEAKER_1: Wait, so how tall are you?
SPEAKER_1: How tall are you?
SPEAKER_2: Like 5'5.
SPEAKER_1: 5'5, and 120 pounds.
SPEAKER_3: Eight and a half stone, let's be specific.
SPEAKER_1: Excuse me, excuse me.
SPEAKER_1: Eight and a half stone?
SPEAKER_2: Yeah, because Britain really doesn't know what units to use.
SPEAKER_2: We're metric sometimes, and sometimes we're at...
SPEAKER_1: You know?
SPEAKER_2: In some cases, we're ahead of you.
SPEAKER_2: We do fruit and veg and metric.
SPEAKER_2: We normally do Celsius for temperature, but then we'll do stones.
SPEAKER_1: Yeah, you have issues.
SPEAKER_1: You have metric issues.
SPEAKER_2: We're comparing things to the size of animals.
SPEAKER_3: Oh, that's where the stones come from.
SPEAKER_2: I don't even know what a stone originally is.
SPEAKER_1: No, that's where the hands.
SPEAKER_2: Hands and, yeah.
SPEAKER_1: Who's hands?
SPEAKER_1: Who's feet?
SPEAKER_1: So, we left off at the first segment a question about...
SPEAKER_2: Yes, if the universe is expanding and we are part of the universe, why are we not expanding?
SPEAKER_3: And the answer is electromagnetic forces.
SPEAKER_3: See, the expansion of the universe is its own thing, but it does not counteract on small scales things like atoms and molecules pulling one another or electrons and protons or even...
SPEAKER_1: Literally, the atoms and molecules in his pinky that he was pulling.
SPEAKER_1: As he picks his fingers on his hands.
SPEAKER_3: That's an excellent point.
SPEAKER_3: Yeah, so the reason my pinky nail is not expanding away from my pinky finger is because they're being held together by other kinds of forces.
SPEAKER_1: Way stronger forces.
SPEAKER_3: In the shorts.
SPEAKER_1: In the short distance.
SPEAKER_3: In the short distances.
SPEAKER_3: So, out at the distances of millions or billions of light years, the expansion of the universe dominates, even galaxies are carried along for the ride.
SPEAKER_3: But on scales of humans or even planets, really, those other forces are much stronger.
SPEAKER_1: Even the solar system is not expanding.
SPEAKER_2: Okay, because I always, I've been given the analogy in the past of the blowing up the balloon and watching the dots get further apart.
SPEAKER_1: On the surface, yeah.
SPEAKER_3: That's right.
SPEAKER_2: But is it then almost more like sort of blowing up a globe that has ice sheets floating on it, but the ice sheets stay in one clump?
SPEAKER_1: That is a correct, better assessment.
SPEAKER_2: And they become further apart as the globe expands.
SPEAKER_1: Yeah, on a balloon, if you drew a galaxy on it, that galaxy would actually get bigger.
SPEAKER_3: So if you put little sticky notes on the balloon, then that would work.
SPEAKER_2: Right, sticky notes have the ability to slide.
SPEAKER_1: Life savers, you glue them on and they'll just stay in one shape as the thing goes on.
SPEAKER_2: So the sticky notes themselves, the life savers would become further apart, but within themselves, they would stay the same size.
SPEAKER_3: Correct.
SPEAKER_1: You got it.
SPEAKER_2: Okay.
SPEAKER_2: So I understand something a lot better now.
SPEAKER_3: We got good question people out there.
SPEAKER_3: What an excellent audience StarTalk has.
SPEAKER_1: This is an excellent audience, unless they just called.
SPEAKER_3: No, no, no, no.
SPEAKER_3: We'll check with our researchers to find out.
SPEAKER_1: Matt, next.
SPEAKER_2: All right, from Ben Ratner, at Ben Makes TV on Twitter.
SPEAKER_3: Oh, that guy.
SPEAKER_3: I've heard of that guy before.
SPEAKER_2: Ben says, please describe the laws of physics.
SPEAKER_2: It sounds like we're doing Ben's homework.
SPEAKER_1: Oh, here's what I'm doing.
SPEAKER_1: I'm going to pull rank here.
SPEAKER_1: You ready?
SPEAKER_3: Go ahead.
SPEAKER_1: In one of my books, I have a chapter called, On Earth as in the Heavens.
SPEAKER_1: That is all about the effort to discover laws of physics on Earth and the question about whether they apply in places other than Earth.
SPEAKER_1: And it's not a given that that should be the case.
SPEAKER_1: It might have been that something you discover on Earth is different on Mars or different on, but it turns out it's not.
SPEAKER_1: It's the same.
SPEAKER_3: What I would be interested in is not necessarily the laws of physics because that's what I live with all my life.
SPEAKER_1: Do you?
SPEAKER_3: Yes.
SPEAKER_1: Do you have a choice?
SPEAKER_3: What are the laws of psychics?
SPEAKER_1: Okay, I've never been curious about that.
SPEAKER_3: Really?
SPEAKER_1: Maybe I should be.
SPEAKER_3: I don't know.
SPEAKER_1: Yeah.
SPEAKER_3: Here's the thing.
SPEAKER_1: Okay, the headline you've never seen.
SPEAKER_1: Psychic predicts winning lottery number a second time.
SPEAKER_3: That's true.
SPEAKER_1: You don't get that.
SPEAKER_3: That's true.
SPEAKER_1: But otherwise, the laws of physics are very simple.
SPEAKER_1: I mean, they fit.
SPEAKER_1: I remember I was in school and somebody was taking an accounting class.
SPEAKER_1: I saw the book that they were carrying.
SPEAKER_1: It had like a million pages in the book.
SPEAKER_1: And my book, which was on all of gravitational physics, had like a third that many pages.
SPEAKER_1: So I can understand the whole universe based on what's in my book, but they need a book four times the fat just to be able to do somebody's taxes.
SPEAKER_3: Fair enough.
SPEAKER_2: Because you can't deduce the tax code.
SPEAKER_3: You can't deduce it?
SPEAKER_1: Thank you.
SPEAKER_1: That's the difference.
SPEAKER_1: The good thing about physics is you learn some rules and then all the rest derive from them.
SPEAKER_3: Pretty much.
SPEAKER_1: Very powerful.
SPEAKER_2: And then every so often someone comes along and goes, actually those rules are all slightly wrong.
SPEAKER_3: Yeah.
SPEAKER_1: Well, we have Newton's F equals ma, you got equals mc squared, you got Maxwell's equations.
SPEAKER_1: We're done practically.
SPEAKER_1: Throw in a few quantum physics equations.
SPEAKER_1: Schrodinger equation?
SPEAKER_3: Yeah.
SPEAKER_3: Years worth of physics study is just F on one side, force, and then ma, mass times acceleration on the other side.
SPEAKER_3: And you just change F in a gazillion different ways.
SPEAKER_3: You change ma in a gazillion different ways.
SPEAKER_3: And that spring, from that springs force for physics.
SPEAKER_1: And the universe unfolds for free.
SPEAKER_3: Yeah, absolutely.
SPEAKER_1: Yeah, it's beautiful.
SPEAKER_1: It's beautiful.
SPEAKER_3: Great question.
SPEAKER_2: I really enjoy this question because apart from the thing else, it came from a four-year-old.
SPEAKER_3: Oh.
SPEAKER_2: The four-year-old son.
SPEAKER_1: You should tell us after when we're stumped.
SPEAKER_3: Yeah, yeah, yeah.
SPEAKER_2: The four-year-old son of Pinty from Laos asks.
SPEAKER_2: Mm-hmm.
SPEAKER_1: Nice.
SPEAKER_2: Why do punctured balloons fly around chaotically?
SPEAKER_2: Why doesn't it fly on a straight line?
SPEAKER_3: Wonderful question.
SPEAKER_3: When you have a rocket, actually, you know how they travel in straight lines and we're always very impressed, right?
SPEAKER_3: But what we don't see is the amount of control mechanisms and structures within the rocket that make sure the exhaust comes out in a very orderly and a very directional fashion, right?
SPEAKER_3: When you puncture a balloon, the exhaust that's coming out is coming out in a way that's poorly controlled.
SPEAKER_3: It's not a pinpricked hole, for example.
SPEAKER_3: There's a difference.
SPEAKER_3: You can try this.
SPEAKER_3: You put a little tiny hole in a balloon as opposed to a large hole in the balloon.
SPEAKER_3: The larger the hole, the more chaotic the flow goes.
SPEAKER_3: So it's a matter of whether or not you can control the air coming out in a reasonable or a linear way compared with whether it's just rushing out all at once.
SPEAKER_1: Well, also, you'd want the movement of the air to line up with the center of mass of the balloon.
SPEAKER_1: Yeah.
SPEAKER_3: Okay?
SPEAKER_1: So if that lines up, then the balloon will just be pushed in one direction.
SPEAKER_1: If the jet's air is coming out at an angle different from straight to the center of mass, you'll start rotating the balloon.
SPEAKER_3: Right.
SPEAKER_1: Plus, the balloon is not symmetric.
SPEAKER_1: There's the little, the bottom of it where you got the knot.
SPEAKER_3: The knot, yeah.
SPEAKER_1: The knot.
SPEAKER_1: So the balloon's weight is not symmetric.
SPEAKER_2: And the center of the mass of the balloon would also move around as the balloon deflates.
SPEAKER_2: Yes!
SPEAKER_1: So, what you have to do is configure something, like get a straw, maybe, to guide the air a little better, have some stabilizers, and then you can make a balloon rocket.
SPEAKER_3: Yeah.
SPEAKER_3: That would be a lot of fun.
SPEAKER_1: But I love that question.
SPEAKER_2: It's a great question.
SPEAKER_1: That sounds like a kid that's tearing up birthday parties.
SPEAKER_3: I want that kid on my research stand.
SPEAKER_1: By the way, most of the time when you pinprick a balloon, it blows up.
SPEAKER_1: So you have to do this carefully.
SPEAKER_3: I learned as a child, if you put a piece of tape on the balloon, then you poke the hole through the tape.
SPEAKER_3: Then the rubber or the outside flexible stuff doesn't rupture in a rip, and you just get a little hole, then you can have it go around.
SPEAKER_1: So you've done this before.
SPEAKER_3: Of course, hasn't everybody?
SPEAKER_1: No, I haven't put tape on a balloon to puncture it.
SPEAKER_3: Oh, give it a try sometime.
SPEAKER_1: But it's way more fun to just pop them.
SPEAKER_3: It's too fast.
SPEAKER_1: It is too fast.
SPEAKER_3: It's too fast.
SPEAKER_1: You are correct.
SPEAKER_1: I will try this from now on.
SPEAKER_1: Masking tape?
SPEAKER_3: I use like plastic invisible tape.
SPEAKER_3: Scotch tape.
SPEAKER_2: So Pulsar Priv.
SPEAKER_1: Now you put on both sides of a balloon.
SPEAKER_3: There you go.
SPEAKER_3: That's it.
SPEAKER_2: It won't go away.
SPEAKER_3: It'll start spinning.
SPEAKER_3: That would be fun.
SPEAKER_3: All right.
SPEAKER_3: Four-year-old balloon experiments.
SPEAKER_2: Yeah, I like that.
SPEAKER_2: So Pulsar Priv on Instagram says, Hi, quick question.
SPEAKER_2: How would you explain neutrinos to dumb teenagers who know nothing about astrophysics?
SPEAKER_3: Okay, okay.
SPEAKER_2: And the question, it doesn't make clear whether they themselves are the dumb teenager or trying to…
SPEAKER_1: It's a friend.
SPEAKER_1: A friend.
SPEAKER_1: I would explain to a friend.
SPEAKER_3: Let me jump in right now and say that there are no dumb teenagers.
SPEAKER_3: There just aren't.
SPEAKER_3: I'm an educator and maybe I'm showing my bias here, but I've never found an actual dumb teenager.
SPEAKER_3: They can pretend to be dumb.
SPEAKER_3: They may think they're dumb, but they're not actually dumb.
SPEAKER_3: I want people always to feel like that they are smart because they are and not have to act dumb or pretend to be dumb to be cool.
SPEAKER_3: So there's no such thing as a dumb teenager.
SPEAKER_3: That's just my opinion.
SPEAKER_3: Sorry, I had to get it out there.
SPEAKER_3: Now to answer the question, a neutrino is just a little tiny particle that comes out so that in atomic interactions, nuclear interactions, energy is properly balanced, both in the motion and in the amount.
SPEAKER_3: I think that's really what a simple way of describing a neutrino is.
SPEAKER_1: It's a pretty weird particle because no one knew they existed and there was an imbalance in the experiments that were being done in nuclear physics.
SPEAKER_1: And it was Enrico Fermi who said, there's got to be a particle carrying away this momentum.
SPEAKER_1: There has to be.
SPEAKER_1: We're looking.
SPEAKER_1: We don't find it.
SPEAKER_1: It's got to keep looking.
SPEAKER_1: It's got to be.
SPEAKER_1: What properties would it have?
SPEAKER_1: We can't have any charge.
SPEAKER_1: It's got to be neutral.
SPEAKER_1: And it's got to be really low mass, a little.
SPEAKER_1: So it's got to be a little and neutral.
SPEAKER_3: Well, the funny thing is, of course...
SPEAKER_1: And so in Italian, neutrino, like bambino, neutrino.
SPEAKER_2: So it's just the diminutive version of neutral.
SPEAKER_1: Of neutral, or of a neutron, right, right.
SPEAKER_3: But the funny thing is, when this was first proposed, the neutron had not yet been discovered.
SPEAKER_3: So when the neutron was discovered, people were like, oh, is this it?
SPEAKER_3: And did more calculations, no, still not it.
SPEAKER_3: There's something that's even smaller than a neutron.
SPEAKER_1: That has no charge, that has no charge.
SPEAKER_1: So yeah, it's necessary to what's going on in the universe, but it's very hard to stop, it plows through anything.
SPEAKER_1: What's the number of neutrinos that go through your thumb every second from the sun?
SPEAKER_3: Many trillions.
SPEAKER_1: Trillions.
SPEAKER_3: Many, many trillions.
SPEAKER_3: Matt, can you feel it?
SPEAKER_2: I'm gonna kinda bit.
SPEAKER_2: It could be the air conditioning, I don't know.
SPEAKER_2: So how do you...
SPEAKER_1: They don't interact, and that's why they were so hard to detect.
SPEAKER_2: But they do interact very minimally, right?
SPEAKER_2: We can detect them.
SPEAKER_3: And it was one of the great experiments in astrophysics that allowed us to find neutrinos coming out of the sun.
SPEAKER_3: What happened was that people took a very large vat of dry cleaning fluid, very pure, put it down more than a mile below the surface in South Dakota, and surrounded it.
SPEAKER_1: I think it was just a pre-existing salt mine, wasn't it?
SPEAKER_3: It was a gold mine.
SPEAKER_1: Oh, gold mine.
SPEAKER_3: The Homestake gold mine.
SPEAKER_1: Gold mine, not a salt mine, okay.
SPEAKER_3: And it was sunk all the way down to the bottom.
SPEAKER_3: They put it there, and they surrounded it with a lot of cameras.
SPEAKER_3: And so they just watched this tank of very pure cleaning fluid.
SPEAKER_3: And when a neutrino hit, even though trillions and trillions pass through every second, they might only get one neutrino hit every long once in a while.
SPEAKER_3: And when that happened, there would be a flash of light.
SPEAKER_3: And so they'd watch it and make sure that the flash of light is not caused by anything other than a solar neutrino.
SPEAKER_3: And that's what they were.
SPEAKER_2: So it was amazing.
SPEAKER_3: It turns out that that particular molecule, perchlorate.
SPEAKER_1: I think it needed the chlorine in it.
SPEAKER_3: Had a special nice property that it would, when hit by a neutrino and with that interaction, very rare occasional interaction would cause a flash of light.
SPEAKER_2: And how long ago did that experiment happen?
SPEAKER_2: Was it recent?
SPEAKER_1: A couple of decades.
SPEAKER_3: That was several decades ago.
SPEAKER_3: It was still 70s.
SPEAKER_3: Ray Davis Jr.
SPEAKER_3: was the experimentalist.
SPEAKER_3: John Bacall was the theorist that was involved with that.
SPEAKER_1: Ray Davis got the Nobel Prize, I think, for that.
SPEAKER_1: But not John Bacall.
SPEAKER_3: Yes, yes.
SPEAKER_1: People didn't fully understand that.
SPEAKER_1: You have the theory and the experiment and the observations.
SPEAKER_1: They all have to come together to make that discovery.
SPEAKER_3: That's correct.
SPEAKER_3: But that was a real triumph.
SPEAKER_3: And it led to a secondary discovery, actually, because it turned out that the number of neutrinos that were being detected from the sun were fewer than we expected.
SPEAKER_3: And so for a moment, people thought, wait a second, is the sun dead and we just don't know it yet?
SPEAKER_3: It was known as the solar neutrino problem because those neutrinos had to be produced in order for nuclear fusion to be going on.
SPEAKER_3: So if they were half as many as we expected, then maybe the sun itself was starting to run out of fuel.
SPEAKER_1: Scary prospect.
SPEAKER_3: Yeah, scary prospect.
SPEAKER_3: Turned out, though, that it was just something happening in our upper atmosphere called neutrino oscillations.
SPEAKER_3: Another amazing discovery.
SPEAKER_1: Yeah, so it'd be, I throw you a basketball, but you catch a football.
SPEAKER_1: Right.
SPEAKER_1: So the experiment was designed to detect basketballs and what you were actually receiving, footballs.
SPEAKER_2: And what it is is someone in between is just swapping them out.
SPEAKER_3: And it was amazing.
SPEAKER_3: That was what was happening.
SPEAKER_3: Yeah, these neutrinos come in different flavors, it turns out.
SPEAKER_3: Who knew?
SPEAKER_1: Who knew at the time?
SPEAKER_2: Oh, okay, so there isn't just one neutrino particle, there's three.
SPEAKER_3: Yeah, three different kinds.
SPEAKER_3: Electron neutrinos, tau neutrinos and mu neutrinos.
SPEAKER_1: And their antimatter counterparts.
SPEAKER_3: And their antimatter counterparts.
SPEAKER_3: Yeah.
SPEAKER_1: Yeah, it's pretty cool.
SPEAKER_3: Physics is amazing, isn't it?
SPEAKER_3: I love summer school.
SPEAKER_3: Great question.
SPEAKER_1: Summer school, next question.
SPEAKER_2: All right, Kyle Ryan Tuff on Patreon asks, ignoring the cold, could a settlement survive on the surface of Pluto?
SPEAKER_2: What would radiation levels be like?
SPEAKER_2: Are there any useful resources other than water ice?
SPEAKER_1: Hold me back.
SPEAKER_1: We'll get to that question when we return.
SPEAKER_3: The future of space and the secrets of our planet revealed.
SPEAKER_3: This is StarTalk.
SPEAKER_1: Matt, before the break, you had a Pluto question.
SPEAKER_2: It is, yeah.
SPEAKER_1: I mean, Pluto have history.
SPEAKER_1: But we buried the hatchet long ago.
SPEAKER_2: Well, whether it's a planet or not, could a settlement survive on it?
SPEAKER_3: Oh.
SPEAKER_1: Well, you can ask why would you want to do such a thing.
SPEAKER_3: Right.
SPEAKER_1: Because, but just take for example, Charles, is there a line of people waiting to settle in Antarctica?
SPEAKER_3: No.
SPEAKER_1: And Antarctica is warmer and is balmer and wetter than Pluto.
SPEAKER_2: And there's penguins.
SPEAKER_2: So the best in my knowledge there are not.
SPEAKER_1: In a pinch, we can eat a penguin, right?
SPEAKER_1: So Pluto, in principle, Charles, in principle, we could just pitch tent anywhere.
SPEAKER_1: We just bring enough resources, right?
SPEAKER_3: Yeah, the settlement could survive there as long as you could shield yourself from the cosmic rays that hit it and as long as you can keep yourself warm because the temperature is so low out at that distance.
SPEAKER_1: And food, you need no way to generate food.
SPEAKER_2: How faint is the sun?
SPEAKER_2: If I was standing on the surface of Pluto and staring straight at the sun, which I presume I would be safe to do.
SPEAKER_3: The flux is only about 1,600th the amount of flux that we get from the sun here on Earth.
SPEAKER_1: Is it only that much?
SPEAKER_1: I thought, I'm going on a memory now, not on a calculation, that the sun from Pluto is about like a full moon night here.
SPEAKER_3: Let me do that quick calculation there.
SPEAKER_3: Well, absolute magnitude negative 26 for the sun, minus 15 for the moon.
SPEAKER_1: No, 12.
SPEAKER_3: Minus 12 for the moon.
SPEAKER_3: So that's 14 magnitudes.
SPEAKER_1: 14.
SPEAKER_3: So that's a factor of 10.
SPEAKER_1: So seven, so 10 of the 14, that's 10 of the 14.
SPEAKER_3: No, not quite that much.
SPEAKER_1: Yeah, seven magnitudes.
SPEAKER_1: Oh, no, five, five.
SPEAKER_1: Five, so it's a factor of 100,000.
SPEAKER_3: So it's a little bit.
SPEAKER_1: And you said it's.
SPEAKER_3: I said 1600 because it's a 40 AU, right?
SPEAKER_1: Oh, you just divided it out.
SPEAKER_3: So.
SPEAKER_1: I think we need HuffPo to find out if we're.
SPEAKER_1: You're in the middle of an active calculation here.
SPEAKER_1: You pull up a HuffPo page?
SPEAKER_3: No, no, this actually brings up a very good point and I teach this to all my students.
SPEAKER_3: Since this is a summer school episode, it's quite appropriate.
SPEAKER_1: We are 40, Pluto's 40 times farther away from the sun than Earth is on average and so it's one over that square.
SPEAKER_3: That's right.
SPEAKER_1: So that's where you get the 1st 1,600th as bright.
SPEAKER_3: That's right.
SPEAKER_3: But the idea that a person.
SPEAKER_1: Inverse square law of light, very cool.
SPEAKER_3: The idea that a person can just pull up the answer on Google faster than we can do the calculation brings up a really important point about school in general and education in specific.
SPEAKER_3: You might agree with this, Neil.
SPEAKER_3: We can no longer think that we are educated if all we can do is memorize facts or calculate things that can already be calculated and sit on a database.
SPEAKER_3: We have the world's information at our fingertips.
SPEAKER_3: The only way that we can remain viable as a productive member of society or as a civilization is if we are better than Google.
SPEAKER_3: We have to do that.
SPEAKER_3: And I'm just not picking Google specifically.
SPEAKER_1: Sounds like he doesn't want to be replaced with a robot.
SPEAKER_1: Matt, does that sound like that to you?
SPEAKER_3: It is absolutely right.
SPEAKER_3: We all can easily be replaced by a search engine.
SPEAKER_3: Our education system, our learning, our interaction with nature and with the world and with other people must be better than a search engine.
SPEAKER_1: Charles for president.
SPEAKER_2: Charles for president.
SPEAKER_2: We know that Charles is a better singer than Google.
SPEAKER_1: I think that was Charles' stump speech right there.
SPEAKER_2: Well, we are talking about singing and the like.
SPEAKER_2: Marcus, and I'm going to apologize for butchering this name, but Gui Mares, I apologize if that is way off, on Patreon, asks, I had a debate with a friend of mine where he said that scientists hate arts in general.
SPEAKER_2: I think that's not true, says Marcus.
SPEAKER_2: Dr.
SPEAKER_2: Tyson loves arts and he loves The Starry Night by Van Gogh.
SPEAKER_2: Could you please tell us something about the subject?
SPEAKER_2: Charles, are you okay there?
SPEAKER_2: You seem put out somehow.
SPEAKER_3: Science hates art?
SPEAKER_3: No way.
SPEAKER_1: First, I don't know any scientists who hates art.
SPEAKER_3: A.
SPEAKER_1: Many scientists I know not only just don't hate it, but love it.
SPEAKER_1: One of the books behind you on a shelf is called Mathematics and Art, a book written by an art curator who has fascinated by the role of science as it has influenced art.
SPEAKER_1: And I was privileged to be asked to write the foreword to that book.
SPEAKER_1: And, as the writer knows, I'm a big fan of The Starry Night by Vincent van Gogh, 1889.
SPEAKER_1: And I'm not unusual in this regard.
SPEAKER_1: Our colleagues love music, I love art, on levels that you might not even know or suspect.
SPEAKER_1: Because generally, if they're in the news, it's not because of that, it's because of the science they're doing.
SPEAKER_1: Oh, no, no, we're art-loving community all the way back.
SPEAKER_1: And why do you think universities, they're called the schools of arts and sciences?
SPEAKER_1: We go way back.
SPEAKER_1: Two sides of a coin, each the pinnacle of human creativity and expression.
SPEAKER_1: One constrained by the universe, the other constrained by imagination itself.
SPEAKER_1: Science and art.
SPEAKER_3: I could not say it better, Neil.
SPEAKER_3: It is absolutely true, science and art are inextricably intertwined.
SPEAKER_3: There is no scientist I know that doesn't like art.
SPEAKER_1: Have him take up that question with Leonardo da Vinci.
SPEAKER_3: Absolutely.
SPEAKER_3: And Albert Einstein himself wrote in 1930 that the sense of the mysterious, the wish to be awed by things we don't know is the root of all great art and science.
SPEAKER_3: And I agree with that statement.
SPEAKER_2: Trina Jennings on Facebook asks, if we can figure out the center of the Milky Way galaxy smells like raspberries, can we figure out what things would smell like elsewhere?
SPEAKER_2: Would the center of all galaxies smell like raspberries?
SPEAKER_1: Who said the center of the galaxy smells like raspberries?
SPEAKER_3: Oh, it's an acute press release about people who are looking at molecules in gas clouds.
SPEAKER_3: And it turned out that they detected certain aromatic compounds, which are found in raspberries.
SPEAKER_3: So they said, oh, it smells like raspberries.
SPEAKER_3: Oh, it smells like raspberries because there are these volatile organic compounds that are in gas clouds near the Milky Way galaxy center.
SPEAKER_1: There's also a lot of ethanol there, too.
SPEAKER_3: It would smell like a brewery.
SPEAKER_1: There's a lot of organic molecules in space.
SPEAKER_3: And there's even a sunless tanning lotion, too.
SPEAKER_3: DHA in molecules over there.
SPEAKER_3: So you can not only get a great sun tan, you can also smell.
SPEAKER_1: I didn't know such a thing existed.
SPEAKER_3: Yeah, yeah, sorry.
SPEAKER_1: Up in the hood.
SPEAKER_1: The CVS doesn't have that on the front counter.
SPEAKER_1: Not in the hood.
SPEAKER_1: So it's a little deceptive to say that space smells like that.
SPEAKER_1: Space smells like nothing unless you put molecules where you're sniffing and there are molecules everywhere.
SPEAKER_1: And so there it is.
SPEAKER_1: Then you're smelling molecules in space rather than space itself.
SPEAKER_3: So to answer that question constructively, the answer is yes.
SPEAKER_3: As long as we can find the molecules that create certain smells in our brains through our noses in a location, we can tell you exactly what that smells like.
SPEAKER_3: But there are a lot of particles out there, and they can smell like a lot of different things.
SPEAKER_1: Indeed.
SPEAKER_2: Nice.
SPEAKER_2: All right, who wants a relativity question?
SPEAKER_2: Hussain Sajwani on Twitter says, I am still having a hard time understanding the concept of how if your twin is on Earth and you travel at almost the speed of light, you will not age as much as them or something like that.
SPEAKER_2: Can you really try to dumb it down or using analogies?
SPEAKER_1: Again, before Neil says anything.
SPEAKER_1: I'm out of this one.
SPEAKER_2: Go.
SPEAKER_3: Please don't use the term dumb down.
SPEAKER_3: We are not dumbing things down.
SPEAKER_3: We are merely translating the concept into a language that everyone can understand.
SPEAKER_2: In that case, can you smart it up?
SPEAKER_3: Thank you, Matt.
SPEAKER_3: Okay, here's the basic point.
SPEAKER_1: Smart it down.
SPEAKER_3: Time is experienced at different rates for people who are traveling at different rates of speed.
SPEAKER_3: That's a very, very complicated concept if you're trying to lock it into our idea in our regular time that a second is a second is a second.
SPEAKER_3: But the moment you acknowledge the possibility that time is a dimension like length, width and height, and you can move through it at different speeds, then the twin paradox that is described here or other paradoxes become not too difficult because what you're doing is measuring time intervals.
SPEAKER_3: You're not measuring actually the amount of time at this very instant, but you're measuring the time from the time you experience one minute ago to the time you experience a minute from now.
SPEAKER_3: That person who is traveling at a different rate through time and space will simply experience a different interval.
SPEAKER_1: And you'll both call it a minute.
SPEAKER_1: But relative to each other, they're different lengths.
SPEAKER_2: And you only realize that once you come back into contact with each other.
SPEAKER_1: Correct.
SPEAKER_1: Yeah, that's right.
SPEAKER_1: That's right.
SPEAKER_1: And the way to know who will be younger, because both of them in motion will say that the other one is ticked, their opposite clock is ticking slower, is that the, your twin who went out had to slow down, turn around and come back.
SPEAKER_1: And that breaks the symmetry.
SPEAKER_1: It's called a paradox because if I see you traveling and your time is ticking more slowly and motion is relative and you see me, I'm actually standing still, but as far as you're concerned, you're standing still and I'm moving, you see my time ticking slowly.
SPEAKER_1: How is it that at the end of this exercise, one person is younger than the other?
SPEAKER_2: Right, how do we not know, like if, yeah, the train is going past the platform rather than the platform is going past the train?
SPEAKER_1: That's one of the great jokes against Einstein.
SPEAKER_1: He said, hey, Einstein, when does Grand Central Station arrive at the next train?
SPEAKER_1: Everyone was trying to get their head around this.
SPEAKER_2: So it's specifically the acceleration of the one train who goes out on the spaceship and goes out and then turns around and comes back.
SPEAKER_1: That breaks the symmetry.
SPEAKER_2: Is that acceleration and then deceleration?
SPEAKER_1: Yeah, the whole thing is either positive or negative acceleration, but it's just, it wouldn't matter, it's an acceleration.
SPEAKER_3: The one that leaves and comes back, that's the one that is the thing that appears to be wrong.
SPEAKER_1: So it's an uncomfortable concept because we don't experience that in everyday life.
SPEAKER_1: As active senses do, it was not necessary to know this on the plains of the Serengeti.
SPEAKER_1: To avoid getting eaten by a lion, you didn't need to know relativity.
SPEAKER_3: But it's absolutely necessary in this day and age of atomic energy and very, very high speeds.
SPEAKER_1: Yeah.
SPEAKER_1: Matt, it's time for lightning round.
SPEAKER_3: Oh yeah.
SPEAKER_1: See if the bell works.
SPEAKER_1: It does.
SPEAKER_1: So Charles and I will try to answer in sound bites.
SPEAKER_2: All right.
SPEAKER_2: Well, we're going to jump back from Einstein to Newton.
SPEAKER_2: DJ Milky on Instagram says, I read a few years back that the Earth is technically falling into the sun, but doesn't actually go into the sun.
SPEAKER_2: Is that true?
SPEAKER_3: Yes.
SPEAKER_3: And the reason it doesn't go in is because it's traveling at orbital velocity around the sun.
SPEAKER_1: Yeah.
SPEAKER_1: If we traveled any slower sideways, we would fall towards, get closer to the sun.
SPEAKER_1: So we are falling towards the sun, but we're being held up, if you will.
SPEAKER_1: By our very high sideways speed.
SPEAKER_1: So yeah, we got this.
SPEAKER_1: And Isaac Newton first demonstrated this in...
SPEAKER_1: Principia.
SPEAKER_1: And first drew it in the system of the world.
SPEAKER_1: That was his Cliff Notes for his Principia.
SPEAKER_3: Terrific.
SPEAKER_1: Written in English.
SPEAKER_3: Very cool.
SPEAKER_1: All right, you got it.
SPEAKER_2: All right.
SPEAKER_2: Codemonkeyia on Instagram says, What causes the Earth's magnetic poles to move and what would cause the magnetic north and south to flip?
SPEAKER_3: Ah, very good question.
SPEAKER_3: Our magnetic field is created by the dynamic motion of ferromagnetic materials inside our Earth.
SPEAKER_1: Iron.
SPEAKER_3: Yeah.
SPEAKER_3: Almost all iron.
SPEAKER_1: It's almost entirely iron.
SPEAKER_3: Almost all iron.
SPEAKER_3: And because of that, because it's fluid and it moves, that's why our poles move.
SPEAKER_3: It's as if you had a dancing magnet inside, but it's kind of somewhat semi-solid, somewhat liquid.
SPEAKER_1: And it rotates, but not exactly the same rate that Earth does.
SPEAKER_1: So all these dynamics influence which direction on Earth's surface you find the North and South Pole, and whether the North is up or down relative to it.
SPEAKER_1: And history has shown that the poles have flipped multiple times in the past.
SPEAKER_1: Next.
SPEAKER_1: Oh, by the way, if Earth cools completely and the core becomes solid, the magnetic field shuts off.
SPEAKER_3: It's frozen, yeah.
SPEAKER_3: It's done.
SPEAKER_1: Good.
SPEAKER_2: All right.
SPEAKER_1: It wouldn't shut off the magnetic field.
SPEAKER_1: It just changes the movement of the magnetic field.
SPEAKER_1: Good.
SPEAKER_2: Good.
SPEAKER_2: Evan Howington on Facebook says, If the universe is infinite, then how could time exist other than the meaning we give it?
SPEAKER_3: If the universe is infinite is the key point.
SPEAKER_3: We don't know necessarily yet that the universe is infinite.
SPEAKER_1: He's saying if it's infinite, let's change the question.
SPEAKER_1: Suppose the universe had no beginning and no known end, is infinite in time and space.
SPEAKER_1: What does it even mean to have a calendar?
SPEAKER_3: Great point.
SPEAKER_1: What are you measuring?
SPEAKER_1: Is that kind of the paraphrase of that question?
SPEAKER_2: I think so, yes.
SPEAKER_3: I think so, yeah.
SPEAKER_3: That's a good way to put it.
SPEAKER_3: And what we would be measuring in time is the various atomic processes going on in our bodies.
SPEAKER_3: And a clock, like the definition of a second, is just a way to macroscopically allow us to know whether we're getting older or whether we're not.
SPEAKER_1: So you need vibrating repeating phenomenon to measure time accurately at all.
SPEAKER_1: So in a universe where nothing repeats, there can be no measurement of time.
SPEAKER_1: What do you think of that?
SPEAKER_3: If you can measure the passage of time, or define the passage of time as the expansion of the universe, then you don't have to have a vibration.
SPEAKER_3: You can just have the change that's going in a single direction from smaller to larger.
SPEAKER_1: Okay, so time then gets measured by size.
SPEAKER_1: Size of things.
SPEAKER_1: Interesting.
SPEAKER_3: Rather than repetition.
SPEAKER_1: Matt, last question.
SPEAKER_1: Go for it.
SPEAKER_2: Alright, I'm going to go with this one then.
SPEAKER_2: Billy from Queens here out of Hunter College.
SPEAKER_3: Hunter College, City University of New York.
SPEAKER_2: Cosmically curious on Instagram.
SPEAKER_2: What are some tips for an everyday astrophysics student who wants to become an extremely successful science educator?
SPEAKER_3: Oh, read Neil's books.
SPEAKER_3: I really love it when educators express their knowledge in the language of the people who are listening.
SPEAKER_3: In other words, a really good science educator is essentially a very good interpreter, a very good translator.
SPEAKER_3: Not someone who just dumps things down, not just someone that turns things into sound bites, but someone that can really take a concept that's sort of described by math and science and turned into English or French or whatever language that the person is fluent in.
SPEAKER_3: That is the mark of a true science educator, thinking about the audience and not necessarily about the source.
SPEAKER_1: Oh, I can't touch that.
SPEAKER_1: I can't touch that.
SPEAKER_1: Other than to add punctuation and say that Galileo, an academic fluent in Latin, when he decided to write about whether Earth was in the center of the known universe or it orbiting the sun, he wrote that in Italian, knowing that the common folk would be able to then embrace and appreciate the discoveries he was making.
SPEAKER_1: And so that was quite a striking...
SPEAKER_1: That's like Carl Sagan appearing on The Tonight Show.
SPEAKER_1: Yeah, yeah.
SPEAKER_1: You're crossing...
SPEAKER_3: A pivotal moment.
SPEAKER_1: You're crossing boundaries there.
SPEAKER_1: And then he became a regular guest on The Tonight Show, coming to the people.
SPEAKER_1: Where the people are.
SPEAKER_3: Right.
SPEAKER_3: And never claiming that he was somehow smarter or better than they were.
SPEAKER_1: Empowering people to think even more highly of their own intellect that maybe they only just discovered for the first time.
SPEAKER_3: Well said, sir.
SPEAKER_1: We got to end it there.
SPEAKER_1: Charles.
SPEAKER_3: Neil.
SPEAKER_1: Love you, man.
SPEAKER_3: Love you, too, man.
SPEAKER_1: Family, everybody's okay?
SPEAKER_3: Everybody's good.
SPEAKER_3: Last I checked.
SPEAKER_1: Excellent.
SPEAKER_1: Matt.
SPEAKER_2: It's been a joy.
SPEAKER_1: Probably science is going strong.
SPEAKER_2: That is the podcast.
SPEAKER_3: Yeah, please check it out.
SPEAKER_1: We look for that on the podcast.
SPEAKER_1: And you've been watching, more likely perhaps listening, to this episode of StarTalk, our edition called Summer School.
SPEAKER_1: I've been your host, Neil deGrasse Tyson.