Is Gravity Real? Neil deGrasse Tyson Debates Nature of Force

CHUCK: Is gravity truly a force? NEIL: The trajectory, it looked like a duck,  It talked like a duck, It acted like a duck. CHUCK: Right.

NEIL: As far as you're concerned, it's  gravity. Go on about your business. CHUCK: And the universe doesn't  care one way or the other. NIEL: I'm going to quote Einstein. "Time  is defined to make motion look simple."

CHUCK: Woah! That is effing crazy! NEIL: If I put you in an  elevator and cut the cable,   you will fall to Earth at 32  feet per second for every second.

GARY: So, it's no good if I just  before I hit the ground, I jump? CHUCK: Only if you're Bugs  Bunny or the Road Runner. NEIL: This is StarTalk's special edition,  

and I have no idea what we're  doing today, but Gary knows. Gary. GARY: You've put the burden  on me. Responsibility upon me. NEIL: They just told me to  show up for a special edition.

GARY: All right, so every year, we sit  patiently through hundreds of fans' questions,   and thank you so much. But now,  after a year of good behavior,   we get to ask ours. So I suppose it's that  time of the year when there's naughty and  

there's nice. So I guess... I'll be  nice. I'll be naughty. How about that? NEIL: So this is the third time, apparently. GARY: I know. It's become a  tradition, yes. In the making.

CHUCK: This one is the charm. NEIL: Founded in 2023. GARY: What a great year.

CHUCK: It just does not sound very impressive. NEIL: All right, so what happens now? GARY: Okay, before we get to our questions...

NEIL: She's a question. You have... GARY: The StarTalk family have, and Chuck  and I are part of the StarTalk family,   so we have our burning  questions. Burning questions.

NEIL: Okay, you have your burning questions,   and you're also delivering questions from  people who are in the StarTalk family. GARY: Oh yeah, oh yeah. I mean,  we are built on curiosity.

NEIL: Okay, if that's as it should be. GARY: Thank you. NEIL: But if I can't answer it, I will tell you.

GARY: All right, before we get to our  questions, we recently had a Patreon   whose question made the rounds. First it stumped  you, so then you passed it on to Brian Green,   who then recently passed it on to Brian Cox and  stumped two different theoretical physicists,  

so congratulations to Mitchell Adkins for  winning Cosmic Queries. Well done, you. CHUCK: Yes. GARY: Right.

NEIL: Is there some prize for that? CHUCK: You get to ask more questions. GARY: He gets the pat on the back for being...

CHUCK: I remember that, that's the quark  question that you were so enamored of. NEIL: Oh yeah. CHUCK: The quark question, like during  spaghettification, when we get down to  

particles ripping apart, when you rip  apart a quark, it makes two more quarks. GARY: So, what happened? NEIL: It's a quark catastrophe.

CHUCK: Oh great, a quark catastrophe. GARY: Here we go, asymptotic freedom. CHUCK: Asymptotic freedom.

GARY: Like I said. NEIL: So now you guys got  questions, let's bring them on. GARY: Chuck, you have a question here, I think.

CHUCK: Yeah, this was like a general kind of... GARY: Yeah. CHUCK: We'll keep it to this year. My  actual question was, what was your top  

non-astrophysics topic we covered this year? Or  the favorite thing that you learned in this year? NEIL: It would have to be our David  Chalmers interview on consciousness. CHUCK: Oh, okay.

NEIL: Yeah. He's an Aussie,  is that right? Yeah, yeah. GARY: But he's NYU, I think he's NYU. CHUCK: He is NYU.

NEIL: Right, right. So I just like  hearing an expert, so many people   are opining on what consciousness is and  the mind and the... And he just thought   a lot about it. And I enjoyed learning  about... And that was on Special Edition.

GARY: Yes, it was. NEIL: Not just any of the  flagship StarTalk content.   So I like learning stuff as much as I can.

CHUCK: I find that shocking. GARY: No. You're not the only one. Yeah. NEIL: No, if I'm at a party, for example,  and I learn that someone's like an expert  

on like bird wings or grasshopper legs, it  wouldn't matter. I got 100 questions for him. GARY: Yeah. NEIL: 100 questions.

CHUCK: Yeah. And why not take  advantage of the expertise? NEIL: Completely. CHUCK: Take advantage of the moment. Yeah.

GARY: All right, Chuck, you want  to follow up with your question? CHUCK: Here's my first question.  Is gravity truly a force?   Is it truly a force or is it just the bending of  time itself? Okay. Now, so clocks tick more slowly  

as they are closer to objects with more mass,  right? Okay. So if we look at a flat spacetime   graph, okay? So it's just two axis, all right? And  on the space axis, we take Earth and we shrink it   down so it's just a one-dimensional flat Earth,  which some people actually think is the case.

GARY: Yeah, idiot. CHUCK: Anyway, I take that back. You're not an   idiot. You're just stupid. I'm sorry.  That didn't come out right either. Anyway.

NEIL: No way for that to come out right. CHUCK: Oh, God. Okay. So the Earth  is now flat on the flat space axis,   okay? If you travel up, which is the time  axis, right? Which means Earth is stationary.

NEIL: Yeah, you're just moving in time. CHUCK: You're just moving in time now. NEIL: Right. That means you're not  moving. You're just sitting there.

CHUCK: You're just sitting there. NEIL: Yeah. CHUCK: The time axis then bends, okay? Which  means that you're bending space time, which  

we know actually happens, but how do we get  to that place in that example? You know what   I mean? How do we get to that place in that  example? So is it just the large mass object   bending time and dragging space along with it?  Is that the case? And I left out acceleration  

purposely just for this. This could never happen,  we know. But if it could, how do we get to that? NEIL: Well, so let me try to answer that. I  don't know if I'll succeed. So when you said   the time axis has bent, what you mean by that  is the amount of mass represented by Earth and  

its surface gravity has a certain slope of  that line that you would move at an angle,   so to speak, on that timeline, and that  would be either faster or slower than   the time that passes for someone on a more  massive object or a less massive object.

CHUCK: Correct. NEIL: Okay. I think you shouldn't overthink it. CHUCK: That could be an issue.

NEIL: So, I'm reminded of,  if it looks like a duck,   walks like a duck, quacks like  a duck, it's a duck. Okay. CHUCK: I got you.

NEIL: All right. So, have we ever  talked about the equivalence principle? CHUCK: Briefly, in an explainer. GARY: Not in a special edition.

CHUCK: Not in a special edition. NEIL: Let's do a special edition.  Okay. Special edition version   of the equivalence principle. Okay. So, we're  here and I'm on earth. There's one G. Okay.

GARY: That'd be me. One Gary. Is  that a new unit? A unit of metric. NEIL: So, it's one G. So,   all the mass of the earth is pulling on  you for you to then weigh what you do.

CHUCK: Right. NEIL: Okay. People say, well,  gravity is strong. No, it's not,   because I can pick something  up away from the earth.

CHUCK: You just violated gravity. No, that's  right. You just, like, take that gravity. NEIL: No, I just jumped. I could jump. CHUCK: I'm just like, yeah.

NEIL: All right. So, and objects accelerate. So,   if I toss something to you, it won't go  straight to you, gravity will bend it. CHUCK: Absolutely.

NEIL: Okay. GARY: So, it's the parabola. NEIL: Yes.

GARY: Right. NEIL: Yeah. Well, on an exam,  the answer would be parabola. CHUCK: Right.

GARY: All right. NEIL: Once you understood that, then you say the  real answer is, it's a segment of an ellipse. CHUCK: Right.

GARY: Oh, okay. So, it's constantly falling? NEIL: No. So, if you answer ellipse,   it means you know more than the  questioner who wrote the question.

GARY: That's not gonna happen, is it? No. NEIL: It can happen, like when they write the  New York State Regents in physics. I had to   watch out for knowing too much. You have to  answer what they think you should answer.

CHUCK: They want the answer, that's correct. NEIL: So, when you do calculations with  trajectories, it's approximated with a   parabola. They don't say approximate, they just  say it is a parabola. For it to be a parabola,  

it means the force is directly down at every  single point on the trajectory. However,   Earth is round. So, this vertical line is not  parallel to this vertical line because it's   moved along Earth's arc. They each point inward to  Earth's center. You can approximate it over small,  

this is why people think Earth is flat, because  sections of Earth you can approximate with a   flat surface. But if you did it precisely, you  would find that those directions that gravity   is pulling you angle towards the center of the  Earth and that shape is not a parabola. It is an  

ellipse. And how do we know it's an ellipse?  Because if all the Earth were shrunk to its   center, it would orbit the Earth. This ball you  threw to your friend would orbit the Earth in a   really elongated ellipse. It's a cool fact.  But it's like the crime of knowing too much.

CHUCK: All you have to do is visualize it as,   don't look at it as you're throwing something  and it's going along the ground. Look at it   as you're throwing something and it's  going along the curvature of the Earth.

NEIL: Or the curve that Earth's gravity gives you.  That's what I meant. And the force of gravity from   Earth, when you calculate with it, you put all  of the mass at the center of the Earth. So when   you say, in Newton's equation of gravity, force  equals big G, which is a constant, mass of me,  

mass of the Earth, divided by our distance  squared, what's our distance if I'm standing   on the Earth? The distance between the center  of my mass and the center of Earth's mass, which   is down in the center of the Earth.

GARY: So it's two constants, your center  of mass and the Earth's center of mass. NEIL: Correct, and that distance is that distance.  It's not, the fact that there's Earth between it   and me doesn't make any difference to  the math, it turns out. So point is,  

that's why this arc is not thinking that Earth is  there. It doesn't care. It just cares that Earth   is operating as though it's at its center.  If Earth's surface were not in the way,   it would continue in this arc. So here's my  point. So Einstein said, if I'm in a rocket,  

and the rocket is accelerating at 1G,  okay, that's a pretty fast acceleration. CHUCK: Right. That is. NEIL: Okay, so 1G in American units is  32 feet per second. For every second,  

you're subjected to the force. CHUCK: Per second, per second? NEIL: Per second, per second, right. So  after one second, you're going how fast?

CHUCK: 32 feet. NEIL: Per second. CHUCK: Per second.

NEIL: After two seconds, you're going how fast? CHUCK: 32 feet times 32 feet. No, 64 feet. NEIL: 64 feet.

CHUCK: 64 feet. NEIL: Per second. After three seconds? CHUCK: 128 feet. No, 64  times 30. No, you're right.

GARY: 96. CHUCK: See, I'm already confused. NEIL: 96.

CHUCK: Add another 32 feet. GARY: You're in trouble if I'm  getting it right. Just so you know. CHUCK: No, this is where my overthinking starts.

NEIL: Yeah, exactly. CHUCK: I start overthinking.  Okay. So it's 96 feet. NEIL: That's the recipe to get to  your speed after three seconds.

CHUCK: Right. And it will just  continue like that. The farther,   the longer you fall, it just keeps continuing. NEIL: It just gets faster and faster.  Faster and faster. Okay. So now,  

so that's earth's acceleration of gravity. CHUCK: Right. NEIL: Okay? All right. So in  fact, what you're standing here,  

and that's your weight. If I dropped you  from an elevator shaft, or put you in an   elevator and cut the cable, you will fall to  earth at 32 feet per second for every second.   So it takes four seconds to hit the  ground. How fast did you hit the ground?

CHUCK: Wait a minute. This is time's time. NEIL: Jeopardy Think music. GARY: Is it 128 feet?

NEIL: 128 feet? GARY: Chuck, you're 0 for 2 here. I wasn't  sure. That's why I sat on that answer,   thinking, he's gonna play the game with me.

CHUCK: 32, 32, 64, 96, and then  the 32 on top of that. That's 120. NEIL: Okay. So, and then you  die when you hit the ground. CHUCK: Right.

GARY: Or not. NEIL: But while you're falling,  you're weightless, just so you know. GARY: So it's no good if I,  just before I hit the ground,  

I jump in the elevator when I land  softer than if I was just on the ground. CHUCK: Only if you're Bugs Bunny or the  Road Runner. That's when that works. GARY: Just wanted to test that theory.

NEIL: Thank you, thank you. If you could  jump or you were as resistant to death as   Wiley Coyote. Right, yeah, okay. If you  jumped upwards at 128 feet per second,   that would counterbalance the fact that  you were falling at 128 feet per second.

GARY: I'm gonna hit my head on the roof. NEIL: And then you would, I guess, you would just  land softly. It's not a theory I want to test. CHUCK: You would be your own  retro rocker at that point.

NEIL: That's right, it's your own retro rocker. CHUCK: Yeah, your own retro rocker. NEIL: It's a retro rocker, all  right. So now Einstein said,  

now here's a rocket that's  accelerating at 32 feet per second. CHUCK: Okay. NEIL: We're in space.

CHUCK: Right. NEIL: Okay, you're on the other side of the rocket  and we're accelerating sort of this way, upwards,   let's say, I mean towards our ceiling. You are  across from me in the rocket and I take a ball  

and throw it to you. At the instant I let go  of the ball, it is going at whatever speed the   rocket was going at that moment, because  I'm in the rocket and my hand is touching   the ball. But if it takes one second to get to  you, what happened to the speed of the rocket in  

that one second? It went up, it went faster,  so this ball is not going to make it to you,   it's not going to go straight across to you,  it's going to curve down, it's going to curve   down exactly the way it curves down if you  threw the ball on earth. And Einstein said,  

could you tell the difference between these two  situations in a rocket or on earth? If the rocket   were sealed and just standing here on earth, and  you perform this experiment, the ball's gonna dip   before it reaches you. If I'm out in space at  1G, the ball will dip before it reaches you.  

He hypothesized, turns out correctly, that  those two situations are indistinguishable. GARY: So you're telling me  someone took a ball on a rocket? NEIL: A real? No, there's another way to test  this. Okay. These are two different masses we're  

talking about. One is your gravitational mass,  and that shows up in the FGMM over R squared. The   other is your inertial mass, which shows up  in your F equals MA, which is another one of   Newton's equations. And the question is, are those  two masses the same? There have been experiments  

that have shown they're the same to like nine  or 10 decimal places. Basically, it's a correct   understanding of the universe. So, you asked if  gravity is a force. You can think of it as a force   when you're sitting here on Earth, but when you're  just rocketing through space, is it a force? No,  

it's just the leftover speed the ball had over  here that gives the illusion that something   pulled it down. But in a sealed rocket, you cannot  tell the difference. And so, to say, is gravity   a force or is it just the curvature of space and  time, I'm saying that distinction is immaterial.

CHUCK: It doesn't really make a  difference. You want it to be,   because that is our natural  intuitive thought process. NEIL: They're experimentally identical.

CHUCK: Exactly. NEIL: And since one of them involves  no planet at all, all we can say is,   it's convenient to think of that as this thing  called gravity here on Earth. It's a convenience.

CHUCK: In space, it's not gravity,  but it's doing exactly the same thing. GARY: So when did Newton  get to his laws of motion? NEIL: 1687.

GARY: So since 1687, we've  been trying to break his laws. NEIL: They're not going to break in  the realm that they were testing. GARY: No, but I'm saying, people have  tried, and they still are holding true.

CHUCK: Oh yeah. NEIL: No, no, no, it's been verified. So it's  only break down at the limits, right? Where,   oh my gosh, you're really close to the  sun. The gravity of the sun is so strong,  

Einstein's, Einstein matters, okay,  in the general theory of relativity. CHUCK: Right. NEIL: And where time begins to get altered. And  then Newton's equations fail. They just fail.

CHUCK: Got you. NEIL: But they still work. CHUCK: They still work.

NEIL: We went to the moon on Newton's equations. CHUCK: Yeah. NEIL: Just so you know.

CHUCK: Yeah. NEIL: All right. So it's like saying,  is a hot dog a sandwich? At one point,   it's just semantic, but people want to argue  as though it's a deep philosophical fact.

CHUCK: Right. It only matters  for the sake of the argument. NEIL: Good way to put that. CHUCK: It only matters for  the sake of the argument.

NEIL: It does not matter in the universe, right? CHUCK: And the universe doesn't care one way  or the other because it works both ways. It's   indistinguishable. It works. So basically,  this is the spaceship. That's the problem.

NEIL: And, yes, and this thing about time. CHUCK: Right. NEIL: Okay? Because I was only just talking about  the trajectory. So if there's a spaceship going  

past you, sorry, now let's go back to what's  called uniform motion, so it's not accelerating. CHUCK: Right. NEIL: Okay, just easier to think about  this. Okay? So a spaceship going past you,  

you don't know if you are  stationary and it's moving,   or it's stationary and you're moving. You don't  know. There's no way to even determine that. CHUCK: It's like when you're  on a train and it pulls off.

NEIL: Real slow. CHUCK: Real slow. The other train you're  looking at, you're like, oh, wait, who's moving? NEIL: Right, who's moving? Right, because it's  real smooth. If it's smooth. In the old days,  

they didn't have smoothly paved roads, and they  just had horse-drawn carriages and chariots. And   so if you were moving, you knew you were in  motion. So how could Earth be in motion? We   would feel it. No, because it's moving through  space, not on your damn road with cobblestone.

CHUCK: They don't have a  Department of Transportation   in the universe that doesn't do its job. GARY: Well, they may do, we've  just not come across them yet.

NEIL: So here's the problem. If you want  to know how their time ticks, all right,   let's say they send out time signals, just one  every second, okay? Well, you'll get one of those   signals, okay? And the next signal that comes  to you, the interval between those two signals  

will not match the interval between those two  signals sent to you by the person on the ship,   because they're coming towards you and they'll  be shrunken or expanded. And so, we also know   that the speed of light is the same no matter the  reference frame. And so everything else adjusts  

to make that happen. And so when Einstein  published his General Theory of Relativity,   it took the uniform motion and generalized it to  any motion at all. That's why it's called general,   the general theory of relativity, which includes  accelerations, which then talks about gravity  

and the curvature of space and time. So  that's the best I can do with that answer. CHUCK: No, that's pretty good. And you're right,  the real answer is you're overthinking it. NEIL: Well, yeah, yeah, and like you said, on  the ship, the trajectory, it looked like a duck,  

it talked like a duck, it acted like a duck.  As far as you're concerned, it's gravity. CHUCK: It's gravity, right. NEIL: Go on about your business.

CHUCK: Yeah, okay. No, I'm satisfied.  We'll see with the next one. GARY: Okay. I'm satisfied with this. Okay. CHUCK: Yeah. I appreciate your thinking.

NEIL: Your curiosity here. <v SPEAKER_5>This is  Ken, The Nerdneck Zeberra from Michigan, and I   support Star Talk on Patreon. <v SPEAKER_5>This  is Star Talk Radio with Neil deGrasse Tyson. GARY: All right, next question from  me. Recently, Airbus grounded some  

6,000 of its aircraft for emergency computer  updates as a result of cosmic radiation. Why   was it just Airbus and not others? Is  this a one-off for commercial flight,   or will this become something that  will be a new normal for air travel?

NEIL: Great question. GARY: You're welcome. NEIL: Okay, so let's back up. There's high-energy  phenomena in the universe, especially in the  

centers of galaxies, and that high-energy  phenomenon accelerates charged particles,   and to stupendously high energies, like 99.999  percent the speed of light. They travel across the   universe, especially across the galaxy, and when  they arrive on Earth, we call them cosmic rays.  

They come from every direction. I would see them  in my data when I expose a digital detector to the   universe through my telescope. In fact, there are  utilities we have that correct for cosmic rays,   because the cosmic ray hits one of the pixels,  and it blows it out. So what you do is you take  

multiple images, and then you overlay them,  and then you take out the high and the low,   and you get the median of your images, and  that basically takes out all cosmic rays.   So when you see images reported, it's not the  raw image. Raw images are always contaminated  

with cosmic rays. And so they're everywhere.  Oh, by the way, the cosmic ray doesn't make   it to Earth's surface. It hits our atmosphere  and creates showers of other particles who,   in total, equal the energy of that one particle.  It's called a cosmic ray shower. You look it up.

GARY: It's like a diffuser. NEIL: It just comes down and it psh, psh, psh. GARY: See, this is our problem with space travel,  

the radiation. And now you're telling  me this radiation is penetrating. NEIL: Well, the total energy  does actually reach the Earth. CHUCK: Yeah.

NEIL: Okay. It gets... CHUCK: Just not as cosmic rays. GARY: Not as concentrated.

NEIL: Not as concentrated. Correct, correct.  Not as the original cosmic rays. We still   call them cosmic rays because of their effect on  this. All right. This tells you cosmic rays are   everywhere. Okay. Oh, and high-charge particles,  high-energy charged particles from the sun,  

we're just right now, we're at the end, recording  this at the end of 2025. We're on the down stroke,   the very upper down stroke of the solar maximum,  solar max in the last year and a half or so. And   we heard about aurora. Also, the North  Magnetic Pole, which when we grew up...

GARY: Right. NEIL: Was wandering around Canada  in the last 20 years has made a   beeline towards the North Pole. And it  just recently passed the North Pole,  

it's on its way to Siberia. So, Putin is going  to own the North Pole very shortly. Here, okay. GARY: Why are you laughing? I just don't  like the idea of that sentence at all. NEIL: You'd rather the Canadians  own the North Pole, isn't it?

CHUCK: Santa, those elves  are in for some slave labor. GARY: That's all I can tell you. NEIL: Wait, wait. So, as it  goes closer to the North Pole,  

it actually comes closer to the Northeast.  Here we are recording this in New England,   the Middle States, because it just brought it a  little closer. All those three factors combined,   plus we're monitoring the sun as never before. So,  we know exactly when it would happen. There was a  

day you didn't know, oh, we caught it here, you  check it out, call me. We now know. It's called   space weather. There's a whole branch of NASA,  if it's still funded as of today. The studies,   explosions on the sun. All right,  and one of our favorite guests, Lika.

GARY: Right, Guhatakuta. NEIL: That one. GARY: Well done, Chuck.

NEIL: She's a NASA solar astrophysicist, and  so she thinks about all of this. But anyhow,   so we have better predictions, better monitoring,  and so there's a greater awareness of aurora   today than ever before. But there are people  thinking, oh my gosh, things are getting worse,  

but it's not. And this maximum we're coming off  of, that max, what they do is counting sunspots.   When they get a lot, and then when they come down.  All right, this max was higher than the last max,   11 years ago, but both of these were lower than  the previous three, okay? So there's nothing,  

you know, if the sun is gonna kill  us, it would have happened already. CHUCK: We'd already be dead. NEIL: We'd already been in cycles.

CHUCK: It's like every villain in a movie,  if I wanted you dead, you'd already be dead. NEIL: Or let me put you in a  contraption that will kill you   in an hour after I'm gone, to give you  a chance to escape without me knowing.

GARY: I'm gonna go have lunch now. CHUCK: When I come back, I  expect you fully unalive. NEIL: The laser will slowly move its way across  you. So, that's a long preamble to the fact that,  

it seems to me that, given how many planes are  flying every day, there's like tens of thousands   of flights every day. There's a million people at  any given moment who are airborne in an airplane,   okay? That many flights that have been  flying for that long, okay, and one plane  

uncontrollably loses altitude then regains  control, you wanna blame that on the universe? GARY: Oh no, I'm just saying that happened. NEIL: No, no, no, they said  it happened. They blamed a  

cosmic ray. They didn't know it was a cosmic ray. CHUCK: I don't know about that because  that's not the only incident of charged   particles because when you look  at these circuitries, they're...

NEIL: Yes, of course. CHUCK: They're so small. It  also happened to a car company. NEIL: What I'm saying is...

CHUCK: Go ahead. NEIL: What I'm saying is, my chip, in my day,   the chips were little. About  this big. I take a picture,  

depending on the length of the exposure, I have  a half a dozen cosmic rays that hit that chip. CHUCK: Ah, I see what you're saying. NEIL: Yes, I'm higher up than you. I'm at  7,000 feet. The plane is at 30,000 feet.

CHUCK: Couldn't that make a difference? Because   we said that the cosmic rays come  in and hit these other particles. NEIL: You're missing my point.

CHUCK: Go ahead, I am. GARY: Because it sounds to me like you're making  his point. No, no, what I'm saying is, Go ahead. NEIL: If you're gonna blame it on the universe,  it would be happening to way more than one plane.

CHUCK: I see, the volume of cosmic rays bombarding   the Earth all the time. I get  what you're saying. I got you. NEIL: On top of how many flights there are.

CHUCK: Right. NEIL: So you have to be so confident in the wiring  of your plane that the tens of thousands of planes   that all have maintenance schedules and all of  this, you have to be so sure that there is no  

human error in any maintenance schedule for any  of those planes that are flying every single day.   And it happens to one of them, and you say, this  plane is perfect, therefore the universe isn't. CHUCK: So here, this is a convenient,  this is a convenient, I won't say excuse,  

but I'll say, yeah, convenient way for the... NEIL: Tell them what CYA is. CHUCK: Cover your ass. Is it convenient CYA  for them to say? Because this happened to a  

car company, and they made the same excuse,  that highly charged particles that bombard   the earth somehow hit the circuitry where  it's supposed to go to a zero or one, and it   changes it to a one or a zero. It changes  the bit, okay? And the changing of the bit,  

of course, changes everything that  the computer does at that time. NEIL: But it can't do  anything for that calculation. CHUCK: For that calculation. Yeah. And so that,  

you know, so... But now that  I'm hearing you say this... NEIL: So they updated the software.  I don't know what they did,   but I can imagine what I would have done.

CHUCK: Yeah. NEIL: Because I've written in my life about  50,000 lines of code, so I think about this,   but others, they're programmers who do 100 times  that. So I'm not bragging here. I'm just giving  

some street cred that this is what I would  do if I was worried about this in the future,   if it were really a cosmic ray.  Any truly critical calculation,   because planes are flown by  computers, let's be honest.

CHUCK: Yeah, that guy who comes  on like, ladies and gentlemen,   so great to have you all bored with us today,  by the way. I'm up here not doing a damn thing. GARY: I'll be taking a nap, by the way. Same  voice. Let's go to pilot school for a voice.

CHUCK: The pilot school voice. NEIL: Here's what I would do if I were the  program, because they said they uploaded program.   If there's any truly critical calculation that  affects the safety of the plane, and computers are  

fast, so you can do this in practically real time,  I would put a loop in there to do it three times. CHUCK: Redundancy. NEIL: Three times. Okay, and  whichever two of those are the same.

CHUCK: That's the right answer. NEIL: That's the right answer. CHUCK: Right, if all three are the same,  

it's the right answer. If two are  the same, it's the right answer. NEIL: Correct. CHUCK: Right, and if a particle actually  kicks something out, changes a bit.

NEIL: Because it's not gonna do two in one. CHUCK: It's not gonna do two. NEIL: Right, it's not gonna do two.

CHUCK: Yeah, the redundancy will cover that. NEIL: Correct. CHUCK: And why couldn't you  just harden the damn, like.

NEIL: That's what it's all about. Well,   you're hardening not only the  software, but also the hardware. CHUCK: Yeah.

NEIL: And like satellites know all about this,  because they're up there above the atmosphere. CHUCK: Yeah, they don't  have any protection at all. NEIL: Cosmere hit the hit.

CHUCK: They raw dog in the universe. GARY: Raw talking. Like, come  on, baby. Bring it on, radiation. NEIL: Raw talking.

GARY: I'm learning some new phrases. NEIL: I can't get that picture out of my head. GARY: Oh.

NEIL: Satellites, raw dog. That's what it  is. That's what they do. It's not just to   protect against the radiation, but they're  not protected against asteroids, meteors. CHUCK: That's right.

NEIL: You see, oh, what a beautiful meteor shower.   These particles hit our satellites,  especially the space station. GARY: I have that last message. Oh.

CHUCK: Oh, wow. Okay, cool. NEIL: Yeah, so if it's a cosmic ray,  that's how I would solve it. I'm glad   no one was harmed. In this, I  understand it dropped altitude.

GARY: I was looking at saying, is this a  distraction for something else or is this   someone being smart and getting ahead of a story  and future-proofing into it as much as they can? NEIL: Yeah, I think they originally wanted to  blame it on the sun because we're near solar  

maximum and people are heightened, have heightened  concern. And no one on the sun is concerned. But   it'd be the same cause and effect. I mean, the  high-energy particle is hitting your software. CHUCK: Cool. Okay. All right, here we go.

NEIL: You got another one. CHUCK: Here's another one. What's the most  straightforward explanation of the strong nuclear   force and the behavior of quarks and gluons?  Because they say gluons, and I think like, oh,  

that's a thing, like a quark, but it's not. It's  not a particle, but we call it a name like it is   a particle. And then when you think of the strong  nuclear force, this should not happen. I mean,   I know it's happening on the quantum, but these  protons, they're like, yo, yo, what's up, buddy?

GARY: Come on over here. CHUCK: Let's hang out, man. I love you, man. GARY: Like, yo, give me a hug.

CHUCK: But the truth is, they  shouldn't be doing that. They   shouldn't be doing that. You know what I mean? NEIL: Because they're like charged particles.

CHUCK: They're like charged  particles, and they should be like... NEIL: They should repel. CHUCK: Yeah, like who you looking  at? What you doing over here, man?

NEIL: You get out, I was here first. GARY: I was here, what you talking about? CHUCK: What you mean?

GARY: This is my space, you want my turf? CHUCK: Like, it should be straight up turf war.  But instead, they're all loving and hugging,   right? And then the electrons are  hanging out, just like, what's up,  

guys? You know, which makes sense, that  makes sense, the electron field makes sense,   okay? But what is the strong nuclear  force that this is able to happen? NEIL: Okay, so, the strong nuclear force is  

one of the fundamental forces of  nature. There are four, basically. CHUCK: Electromagnetism. NEIL: It's really three, this three, but. Right.

GARY: So, just for my benefit, thermodynamics? CHUCK: No, electromagnetism, weak nuclear  force, strong nuclear force, and then what   we just talked about, gravity, which we know is  a force just because, except a bitch, anyway.

NEIL: Because it walks like a duck. CHUCK: Because it walks like a duck. GARY: That's why it's a force.

NEIL: These are the fundamental forces of nature. CHUCK: Right. NEIL: And we didn't invent them,  we observed them, okay? And as I...

CHUCK: Once again, overthinking, see that? NEIL: The opening page of one of  my books that said the universe is   under no obligation to make sense to you.  Okay. Now here's something to think about.

CHUCK: Go ahead. NEIL: The electromagnetic force  weakens as the distance separates. CHUCK: Correct.

NEIL: Correct? Gravity  weakens as distance separates. GARY: Correct. NEIL: The strong force gets  stronger as the distance separates.

CHUCK: Right. GARY: Because? NEIL: Why did you ask because on the other one?

GARY: Because it didn't come into my head. NEIL: Because those other forces are, we  operate in your everyday life in ways that   the strong nuclear force isn't. So you can  ask, is there anything in your life where if  

you increase the distance, they are attracted  together more strongly? The answer is yes. CHUCK: A rubber band. NEIL: A rubber band. A spring.

CHUCK: A spring, yes. NEIL: In fact, in physics. CHUCK: But not a slinky. Because when  you stretch it, it just gives up.

NEIL: Yeah, slinky is a weak ass spring. CHUCK: You stretch it out and it's like, ah, okay. GARY: Slinkies are not. Can't  face another staircase. Help me,  

help me. I'm a slinky and they  stretched me. I'm no good. NEIL: So, if you look at the force equation for  a spring, it has a negative sign on it. F equals   minus KX is what it is. K is the spring constant.  X is how much you have displaced the spring, okay?  

The minus means, as X gets bigger, there's more of  an attractive force back in, okay? Whereas these   other forces, it's a positive, all right? So, it's  a contest of forces. A proton at a distance sees   another proton and say, I'm not coming near you.  You can't make me. I say, yes, I can. I'm gonna  

heat up the gas. Now, your movements are so fast,  you will get closer before you successfully repel.   Repel, okay? The temperature is forcing this,  it's like a shotgun wave. It's forcing it. Then   at a threshold temperature, it gets so close.  Strong forces, I got you. And the strong force,  

the strength of the strong force overcomes the  strength of the repulsive force in that instant.   And then it attracts. And then it ain't even  about the electromagnetic force at that point. GARY: We discussed earlier on about Newton's laws,  

how they've, for centuries,  they've stood the test. NEIL: Yeah. GARY: Are we likely to find new  or slightly varied laws of nature?

NEIL: Well, yeah, ideally, every time  that's ever happened, it's like, oh my gosh,   look how much more we now understand when we  were previously just touching the elephant,   not knowing the animal. So there's a lot we don't  understand today. The nature of dark matter,  

the nature of dark energy, what was around  before the universe, was there a multiverse,   how will the universe end, is there a big rip?  These are questions that are just dangling there. GARY: How about time?

NEIL: Possibly, the time, I wanna quote Einstein,  time is defined to make motion look simple. CHUCK: Whoa, dude, that is  effing crazy. Einstein said that? GARY: Yeah, yeah. He did come up with  E equals MC squared. Oh, he's, he's  

saying that's hilarious. He's saying that  oppresses you, but not E equals MC squared. CHUCK: I know, I should probably, I should  recalibrate my, I should measure my responses   there. Yeah, that's a great, time is defined to  make motion look simple. That's very elegant.

NEIL: And deep. CHUCK: That is really cool. NEIL: Okay, so, quarks are what protons are  composed of, as are neutrons, by the way,  

and quarks have charge, if you knew this. CHUCK: Yes, I do, but I'm not sure if  I understand them because when I was   reading about it, first of all, there's like,  Jesus Christ, like 13 or 16 different kinds.

NEIL: No, no, there's six kinds of quarks. CHUCK: Six quarks, but then there's another  levels, and then there's spins. I think   there's six. Well, maybe I'm thinking about  it. It's like two up, one down, and then.

NEIL: Right, right, so in a proton, it has  a charger plus one. And it has three quarks. CHUCK: Right. NEIL: So, it has two up quarks, I think it's  up, with a charge of plus two thirds. What's  

two thirds plus two thirds? Each of  them has a charge of plus two thirds. CHUCK: Two thirds plus two thirds. NEIL: Yes. Is, come on, help him out here.

GARY: Four sixths, which is 75. NEIL: No, it's not four sixths. GARY: Then it's not.

NEIL: You don't add up the  denominator. The denominator carries,   you add up the top. So just do that.  Two thirds plus two thirds equals? GARY: One and a third.

CHUCK: Four thirds. NEIL: One and a third. Okay. So the other quark  has to have what charge for it to be plus one? CHUCK: Two thirds.

NEIL: No. CHUCK: I mean, it has to be a minus. NEIL: Minus, minus what?

CHUCK: Minus a third. NEIL: Minus a third. CHUCK: Right.

NEIL: There it is. CHUCK: Minus a third. And then it  cancels out and now you're good. NEIL: It adds up to one.

CHUCK: It adds up to one. NEIL: Correct. CHUCK: Right. It cancels out, adds up to one.

NEIL: Correct. And a neutron has, I  forgot exactly what, but they cancel   out to zero charge. There's like plus two  thirds, minus one third, minus one third. CHUCK: Okay.

NEIL: Okay. CHUCK: And then. NEIL: So there's still charges within  a, there's still charges there.

CHUCK: Gotcha. NEIL: All right. Now, so  the quarks are fundamental. CHUCK: Protons and neutrons are not fundamental.  And then the electron is a negative charge.

NEIL: Forget the electron.  We're not talking about that. CHUCK: I know we're not even talking about it. NEIL: Electron only knows electromagnetic forces.

CHUCK: Right, that's all it knows. NEIL: Okay, and a weak force. CHUCK: See, this is my problem. Now you  see how my brain works. That's good. I'm  

glad, I'm glad, Chuck. Yeah, no,  I'm not, I'm not. This is very,   I'm a nut job. This is my problem.  I'm a fricking nut job, but go ahead. NEIL: The strong nuclear force  holds the quarks together.

CHUCK: Got you. NEIL: It's the strong nuclear force  that when you pull two quarks apart,   you have to get more and more energy to do that,  like the rubber band, and then it snaps creating  

two extra quarks, all right? So that's the strong  nuclear force at work. And the spillage out of   those particles to attract the other nucleons. So  the spillage of the gluon, did I say gluon yet? CHUCK: Yes, well, we didn't get to them.

NEIL: Oh, sorry, sorry. So the quarks  are held together by the strong nuclear   force. What propagates the strong nuclear force?   It is the gluon. What propagates the  electromagnetic force? It is the photon.

CHUCK: Right. NEIL: So there's something called a virtual  photon that gets passed between two objects,   if they have a charge, and they will feel that  and respond and either get repelled or attract.  

And they're called virtual photons. The photon  is the force carrier of electromagnetic energy. CHUCK: And the gluon is the force  carrier of the strong nuclear force. NEIL: Of the strong nuclear force. And  it's strongest within those particles,  

but enough spillage so that two protons can stick   together in a nucleus. But the real  action is inside the particle itself. GARY: Wow.

CHUCK: Damn. GARY: Happy now? NEIL: Yeah, it's weird.

CHUCK: It's freaky. GARY: All right, should we have another one?   Another question? This is from  Tamsin, one of our producers.

NEIL: Tamsin! CHUCK: Yeah. GARY: When approaching a physics, astrophysics  problem, how do you determine which mathematical  

equation, equations, to use? Depending  on your approach or on which aspect of   the overall problem you're looking  at, do you shift the equations you   use? Just explain how you apply all the  equation. Tamsin says thanks in advance.

NEIL: Okay. Great question. Of course. So, I  remembered learning physics for the first time.   And a lot of it is kind of like, it's a sliding  brick on an inclined plane, there's a pulley,   there's... These questions don't look relevant  to anything. I wanted to understand the universe,  

and physics is fundamental to that. That's  what kept my interest in these boring ass   problem sets. Okay? So, then you realize  it's not about the problem set. It's about   manipulating equations that exist only  in the service of the problem you are  

reading. And so you build this inventory  of things that can happen in the universe,   and the equations that matter to it.  So if it's motion, right off the bat,   I'm probably gonna need Newton's Laws of  Motion somehow. Is it moving really fast?  

I better know Einstein's equations, okay? Is  it dropping through a viscous medium? Okay? CHUCK: Right. NEIL: Oh, by the way, can I tell you, in high  school, I didn't know what the word viscous meant.

GARY: Why did you think it meant? NEIL: I got a 98 on my physics regents exam,   and I knew what question I got wrong, because  I didn't know what viscous meant. They said,  

plot the distance-time curve for a  rock falling through a viscous liquid. CHUCK: You were like, a vicious liquid? GARY: Vicious, vicious. What kind of  liquid is that? Shark infestation.

NEIL: So that was a vocabulary problem for me,  not a physics problem. So I just got that one   wrong. Had I known what viscous was, then  it's trivial, because what happens is you   drop it into the liquid. Normally, if you  drop something, it moves faster and faster,  

right? Because gravity is accelerating it.  But in a viscous liquid, it just descends. CHUCK: It descends, right. NEIL: Old timers will remember  the Prel shampoo commercial,  

where they dropped a pearl into the shampoo, and  it just gently descended. So what happens is... CHUCK: What did that prove? GARY: No!

NEIL: I felt the same way.  It meant your hair is back. CHUCK: How's that cleaned my hair? GARY: It was a physics problem.

NEIL: If something is moving through  a fluid where there's viscosity,   then there are viscosity equations. And if I  never did a problem set that involved viscosity,   I would not know to reach for that  formula, or that bit of mathematics.

CHUCK: And that's a real world problem too. NEIL: All of these become real world  problems. That's the point. So every week   there were typically six physics problems, each  testing different, for homework, each testing a  

different physical principle. You'd have to apply  a new formula you learned that week in order to   solve it. And when I say formula, that cheapens  it. You'd have to apply a new understanding of   the behavior of nature that you learned that week.  And here's the equation of that new understanding.

GARY: So that's your toolbox. NEIL: Toolbox! GARY: Yeah, that's it.

NEIL: Toolbox. So you look around and you say,  wait a minute, there's matter becoming energy   here. What's going on? Marie Curie, one of the  first to show, radioactivity is a source of   energy coming out of nowhere. There's no machine  or engine going in. What's going on? There was  

no way to understand that without an equation  that has energy on one side and mass on the   other. There was no way, you can just describe  it, but there's no way to calculate with it.   Until Einstein in 1905, equals MC squared. Oh my  gosh, a little bit of mass times speed of light,  

which is a big number, squared. You can get  a lot of energy out of that by doing so. So   if you have gaps in your physics knowledge,  there'll be some problems that are intractable   to you. Now here's what I wonder, we're  scratching our head today. What new physics  

lay undiscovered until it rises up and we say  that's the equation I need to figure this out   that I've been scratching my head on for the past  10 years. Maybe the equation does not exist yet. GARY: So we don't know the solution  until we're faced with the problem.

NEIL: Or if you're really clever, people  were simply not clever enough with the known   physics to solve the problem. For example,  superconductivity. If you cool down a metal   of your choice low enough, then electricity goes  through it without any resistance at all. Whereas  

any wire the electricity goes through,  there's resistance, which leads to what? GARY: Heat. Heat. NEIL: Heat. So this goes through and there's  no heat. Oh my gosh. What is that? It's a  

purely quantum physics phenomenon. Was there  enough quantum physics to figure it out? Yes,   but no one was clever enough to figure it out.  Okay, what they found was that as the electrons   get colder, their wavelengths get longer,  because of the wave-particle duality. As they  

get longer and longer, all the electrons end up  behaving like they're one particle, because all   of their waves line up. They come together.  And as one particle, there's no resistance. GARY: They behave themselves.  They behave themselves.

NEIL: And it comes through. So  the quantum physics was available,   but no one was clever enough  to know how to apply it. GARY: Didn't know where to point it.

NEIL: Where to point it. Where  to point the weapons of equation. CHUCK: That's a great example. NEIL: Great question too.

GARY: I have another question. This one is  from Lane, one of our other producers. She's   over in our LA office. With David Crackauer  and Brian Cox, we learned about the two main   pillars of emergence. It is something greater  than the sum of its parts, and secondly,  

possesses a distinct language to describe the  emergent behavior. The example David gives is   how fluid dynamics through its own formulas can  predict movements of groups of particles without   needing to know about each individual particle.  Given that we have a language for describing  

and predicting a person's volition that screens  off the microscopic factors in someone's life,   would that make free will just as real  as fluid dynamics? Is free will just an   emergent property of conscious thought?  And the finishing is please discuss.

CHUCK: That was nice. NEIL: We got good people working for StarTalk. GARY: I'm telling you.  Damn, why are you surprised?

CHUCK: I always knew I was dumber than the people   on the show. I didn't know I was dumber  than all the people who work here, too. GARY: The producer and the revenue team.

NEIL: So I love that  interpretation of what's going on. CHUCK: Yeah, that's cool. NEIL: And just to remind people, but you can dig  up the show, there are gas laws we might have  

learned about in chemistry, which are macroscopic  laws that describe the behavior of the entire gas,   okay? Pressure, temperature, this sort of thing.  And they work, and so we use them. And they're   called laws. Those were discovered before we  even knew about atoms. Successful laws of nature  

describing the behavior of atoms in this emergent  way. What they all do when they're sort of   together as a blob of gas. That's remarkable. So  I like the direction certain branches of research   are going, trying to wrap their head around the  meaning of emergence in understanding complex  

phenomena. And so yeah, free will is emergent.  It's an emergent feature of consciousness. I've   always been on the camp, even if it's not free  will, if it feels like free will, it's free will. CHUCK: I think it's a fascinating thought  experiment because you can say if it's  

not free will, it's still a choice that you're  making. So maybe it's the freedom of the choice,   but then if the choice is predetermined by other  circumstances, is it really a choice at all?   But if you alter the predeterminate  factors that cause the choice,  

who's to say that you did that  or did the circumstance do it? NEIL: It's so intertwined. CHUCK: Or did the gas law of your brain do it?  You know what I mean? Like did the neurosynaptic  

gas law property actually cause this to  happen? And I think that in some respects,   there's evidence for it all when you look at it. NEIL: Maybe the future of neuroscience,  I'm just pulling this out of my ass.  

Maybe the future is looking at the  electrochemical state of your mind,   okay? Just the way we look at the pressure,  temperature, volume, and we put those together   with equations that give the future state of  that system. Will it expand, will it contract?

CHUCK: So it becomes predictive. NEIL: Predictive. Maybe if we do a  download of your electrochemical state,   maybe there are macroscopic laws that tell  you what decision is coming out of that state.

CHUCK: That'd be great. NEIL: And if that's the case, I can say, well,  you have this much poverty, you grew up in this   situation, a single-parent household, you  didn't have food, but crime candidate to be  

committed. What is it, more than half of people  in prison are illiterate. Or come from poverty. CHUCK: Well, that's more that way. NEIL: And those are correlated.

CHUCK: Yeah, they are. The  illiteracy and poverty go together. NEIL: So you have the configuration  that then makes the gas law prediction. GARY: You're talking about mind reading, just  from being able to take that snapshot of it.

CHUCK: It's brain reading more than mind reading. NEIL: Better than mind reading. GARY: In the sense of being  brain reading, mind reading, yes.

NEIL: It's better than mind  reading, it's brain reading. CHUCK: It's brain reading. NEIL: Because the brain creates the mind.

CHUCK: Exactly. NEIL: So, yeah. So, then we're,  the Menardee Report all over again,   aren't we? The great sci-fi short  story writer Philip K. Dick.

CHUCK: What an unfortunate name. GARY: What have you got against  Philip? <v SPEAKER_5>Okay. CHUCK: Very nice, very good.

NEIL: So, in the Menardee Report, there were  these precogs. So, rather than doing a download   off your brain, there were these precogs who were  telepathic, basically. <v SPEAKER_5>Yes. And so,   that's how they got into your brain to  know what was going on. But same idea.

CHUCK: Yeah, it is. Except that you're  mapping the actual person's brain. NEIL: The actual. CHUCK: That's why this is better than  precogs. Oh, of course. Because precogs  

only happen because an event  precipitates their telepathic forcing. NEIL: Oh, they're not gonna know whether you're  gonna choose strawberry or chocolate for dessert. CHUCK: Yeah. They can't do that. But with brain  mapping, and also, yeah, you would be able to  

determine a person's possible path, but also  give them, equip them not to take that path. NEIL: But you might have to change the  state of the system, like changing the   gas. You'd have to change the temperature,  the pressure, the volume, so that a different  

outcome would come. I think once that state is  established, it's going where it's gonna go. CHUCK: Yeah, you can't  steam clean with cold water. NEIL: Oh, good. Your mama tell you that?

CHUCK: No, I just made it up. Very good,  you can't steam clean with cold water. NEIL: So, for example, the person who's  just about to jump off the bridge,   do they have the option to not jump off the  bridge? I don't think so. In that instant.

CHUCK: In that instant, I  don't think they do either. GARY: There's no ability to reset. Correct. NEIL: Not in that moment, correct. So,  that puts a greater burden on society as  

treatment of people who have behaviors that are  transgressive or psychopathic or sociopathic. CHUCK: We should have that burden anyway,  unfortunately. We don't. You're right. NEIL: More blame should be on the shoulders of...

CHUCK: And if you know somebody who's  in that position, believe me, intervene,   okay? You can do something, even though it  may still happen. I mean, I've lost family   members to death by suicide, and even despite  the intervention. But in one case, there was  

a ton of intervention, and the other case, it  was like, damn, I pretty much saw that coming. NEIL: You saw it coming, yeah. CHUCK: Saw it coming. So, yeah.

NEIL: Well, bum us all out, Chuck. CHUCK: I'm sorry. I know I  did bring us down, didn't I? GARY: Well, on a happy note, okay.

CHUCK: I'm just saying, if you see somebody,  don't be afraid to reach out. That's it. NEIL: Gotcha. We got one more, but we  only have two minutes, so let's try. CHUCK: This is from Matt the editor. He says,  this is quite literally, and Matt, our editor.

NEIL: Our editor, yes. CHUCK: This is quite literally a burning  question, as it has to do with firewood. I   once heard Neil mention in an explainer, some  time ago, the energy of the sun is contained  

within the trees that we cut down and chop  into lovely little pieces for the burning in   our fireplaces. Can you expound on this idea?  I found the fact fascinating and perplexing,   but during a recent camping outing, I chose not to  share it as I didn't want to sound like an idiot  

trying to explain this to my fellow guests as we  enjoyed the sun's transferred energy via campfire. GARY: Love it, love it. CHUCK: What a great question, Matt.

NEIL: So, you eat food that  was once alive. Everyone does. CHUCK: Yes. GARY: Plant all animals.

NEIL: Plant all animals was once alive. If you eat  plants, where'd the plant get this energy from? GARY: The sun. Thank you. NEIL: Okay. If you eat cow, where'd  the cow get this energy from?

CHUCK: The plants. NEIL: Plants. CHUCK: And the sun.

NEIL: The plants you fed it. CHUCK: Right. NEIL: Okay. So, we are solar  powered through that tracking.

CHUCK: Of course. NEIL: Now, plants use the sun to build larger  molecules that have energy contained within   them. Okay. So, the cellulose that  has energy. Cellulose burn. Paper  

burns. That's energy inside the paper. What  color does the paper turn after it burns? CHUCK: Black. NEIL: Black.

CHUCK: Because it wants to be cool. NEIL: The energy is not just sitting there in an  energy vessel. The photosynthesis takes sunlight   and creates energy-dense molecules out of it. Now,  here's the problem. Here's why we are not cows.  

Because cellulose has energy, we cannot digest  it. So, you have to be careful in your calorimeter   experiment. You don't want to burn things that  we don't have digestive enzymes to metabolize.   Right. Yeah, if I took straw and burned it,  it has a calorie content of no use to us.

CHUCK: Right. NEIL: Okay? CHUCK: Yeah.

NEIL: So, it has to be stuff you can  digest. Otherwise, the calorimeter   experiment is not meaningful to us. It was  still meaningful for physics and chemistry,   but not for us. All right. And  so, you burn it, it's solar power.

GARY: It is. CHUCK: Look at that. NEIL: There it is.

CHUCK: Well, Matt, there you go,   Matt. I hope that explanation you're able  to use at your next camping expedition. GARY: Take this recording and play it.

CHUCK: Yeah, that's it, you know. NEIL: That's it. All right.  That's all the time we have. GARY: Yeah.

NEIL: That was fun. I like  hearing from our people. GARY: No, no. They're great. NEIL: Can we do like another one of these?

CHUCK: We need to. GARY: We've got more than enough questions. NEIL: From our own people. Yeah.

CHUCK: Yeah. NEIL: Yeah. GARY: Yeah.

CHUCK: Yeah. NEIL: But you did your own questions first. GARY: Yeah, we're selfish.

NEIL: Chuck, always good to have you. GARY: Always a pleasure. NEIL: Gary. <v SPEAKER_5>Thank you, Neil.

CHUCK: All right. NEIL: Neil deGrasse Tyson here. You're a  personal astrophysicist. Keep up the n...