Making Sense - Sam Harris - #252 — Are We Alone in the Universe？

00:00:00.000 Welcome to the Making Sense Podcast.

00:00:08.860 This is Sam Harris.

00:00:10.900 Just a note to say that if you're hearing this,

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00:00:46.380 Today I'm speaking with Neil deGrasse Tyson.

00:00:50.060 Neil probably needs no introduction.

00:00:53.060 He's been on the podcast before,

00:00:54.880 and he's been everywhere else before.

00:00:57.640 He is an astrophysicist who hosts his own podcast,

00:01:03.360 StarTalk Radio,

00:01:04.860 as well as the Emmy Award-winning National Geographic shows,

00:01:08.320 StarTalk and Cosmos.

00:01:10.420 He is the author of more than a dozen books,

00:01:13.200 including Astrophysics for People in a Hurry,

00:01:16.300 and most recently, with his co-author, James Treffel,

00:01:19.860 Cosmic Queries.

00:01:22.880 StarTalk's guide to who we are,

00:01:24.540 how we got here, and where we're going.

00:01:26.800 He's also the director of the Hayden Planetarium in New York.

00:01:30.820 And today we talk about our place in the universe.

00:01:33.880 And we spend much of the time on the question

00:01:37.660 of whether or not we are alone here.

00:01:41.300 So we discuss the famous Fermi problem,

00:01:44.880 i.e., where is everybody?

00:01:47.060 And that naturally grades into a conversation

00:01:50.000 about recent events on Earth

00:01:53.380 where a renewed interest in UFOs

00:01:55.940 has captured a lot of mainstream attention.

00:01:58.720 We also cover the public understanding of science a bit,

00:02:03.960 the impossible existence of flat-earthers

00:02:06.900 who still live among us.

00:02:09.960 And then I try to lead Neil once again

00:02:12.980 into a conversation about politics

00:02:15.640 and attendant moral panics.

00:02:19.200 And you can judge the results of that for yourselves.

00:02:22.800 Anyway, it's always great to speak with Neil,

00:02:25.060 and I hope you enjoy the conversation as much as I did.

00:02:28.720 And now I bring you Neil deGrasse Tyson.

00:02:37.500 I am back once again with Neil deGrasse Tyson.

00:02:40.480 Neil, thanks for joining me.

00:02:42.540 Yeah, Sam.

00:02:43.360 I mean, you know, I love your show,

00:02:45.040 and I never think of myself being on it

00:02:47.460 so that when I'm on it, it's like,

00:02:49.440 ooh, what am I going to talk about?

00:02:50.900 Because all of your guests

00:02:52.460 and all of your conversations are,

00:02:56.380 you know, anything that I do,

00:02:59.320 just as a scientist and as a popularizer,

00:03:02.060 you kick it up a notch,

00:03:03.540 and you just inject it into

00:03:05.440 all of the most controversial things going on in society,

00:03:08.320 and I'm just not that brave.

00:03:10.880 So I feel like I don't, you know,

00:03:13.480 I should not be on your show.

00:03:15.380 I just feel that way sometimes.

00:03:17.020 Well, I hope not to confirm that hypothesis,

00:03:19.800 but I will lead you to the edge of your courage,

00:03:23.140 and you can pull me back.

00:03:25.760 Okay.

00:03:26.360 But it's great to hear your voice,

00:03:27.920 and before we go all over the place here,

00:03:30.380 I want to just touch upon your book,

00:03:32.260 because you have a new book out,

00:03:33.980 which is Cosmic Queries,

00:03:36.540 StarTalk's Guide to Who We Are,

00:03:38.440 How We Got Here,

00:03:39.300 and Where We're Going.

00:03:40.140 And let's start with the area

00:03:45.140 of just pure scientific interest,

00:03:47.240 and then we can go to points of controversy

00:03:50.100 or not as the hour unfolds.

00:03:53.460 But this is really a gorgeous book.

00:03:55.780 It's published by National Geographic,

00:03:57.900 so it's really well illustrated,

00:04:00.620 and in reading it,

00:04:02.540 I confess I have not read all of it,

00:04:04.740 but I've read a lot of it,

00:04:06.820 and it just struck me immediately

00:04:09.260 that this is the book you would want to hand

00:04:11.420 to a smart, inquisitive,

00:04:14.900 science-interested teenager,

00:04:18.120 anywhere from, I don't know, 14 on up.

00:04:21.700 It's just perfectly pitched to

00:04:23.560 a person's first book on science.

00:04:26.980 Was that at all your intention in writing it?

00:04:30.360 It's interesting you say that,

00:04:32.000 because what I learned from my very first book,

00:04:35.460 which was many, many moons ago,

00:04:37.420 I wrote a book, and I said,

00:04:38.480 well, if I'm going to write a book on science,

00:04:40.080 I want to make sure everyone understands

00:04:43.480 everything that's in it, right?

00:04:45.220 And so my first book was a question-and-answer book

00:04:48.560 on the universe,

00:04:49.740 and I wrote it in a playful way.

00:04:52.760 I had a pen name for Merlin,

00:04:55.980 dear Merlin, how does the universe work?

00:04:59.000 And Merlin would recall a conversation with Einstein.

00:05:01.920 It was a fun, playful thing,

00:05:03.720 and all the questions were asked by full-up adults.

00:05:06.300 When the book came out,

00:05:08.040 I found that when adults read it

00:05:10.260 and they understood everything in it,

00:05:12.360 they thought to themselves,

00:05:13.360 well, this is clearly not for me.

00:05:14.980 This is for someone younger.

00:05:16.980 And I said, wow.

00:05:18.820 So people are accustomed to,

00:05:20.580 when they encounter adults,

00:05:22.080 when they encounter a science book,

00:05:23.580 they expect some of it to sit above their head.

00:05:26.400 And so I said, oh, okay,

00:05:28.720 so my next book,

00:05:29.980 I'm going to have two chapters

00:05:30.800 that's guaranteed to be above everybody's head,

00:05:33.120 and no one thought about giving those to kids.

00:05:35.580 But Cosmic Queries, I think,

00:05:37.320 is a celebration of the deepest sources of curiosity

00:05:42.120 that exist within us as humans.

00:05:45.580 And all of those cylinders,

00:05:47.640 if I'm allowed to use

00:05:49.240 an internal combustion engine reference,

00:05:51.180 all of those cylinders are firing

00:05:53.480 for all of us when we were younger, right?

00:05:57.480 Every day is, oh, what is that?

00:05:59.660 And it's a flower and a tree and a rock,

00:06:01.860 and why is this?

00:06:03.560 And why is that?

00:06:04.760 And some of those questions get very deep.

00:06:07.780 Like, how did it all get here?

00:06:09.260 And why are we all here?

00:06:10.440 And are we alone?

00:06:11.700 How will it all end?

00:06:13.440 And so that deeper category of question

00:06:16.440 got elevated and put into this book.

00:06:19.420 But the whole concept of Cosmic Queries

00:06:22.120 is stoked monthly in our podcast, StarTalk.

00:06:27.780 StarTalk, we interview celebrities,

00:06:31.800 and I have a comedian who's a co-host,

00:06:34.160 so it's very, they're a force of levity

00:06:37.520 on a show where content might have

00:06:39.940 their own force of gravity,

00:06:41.500 and I dial those in

00:06:43.320 so that we have a consistent product each time.

00:06:45.680 But one of the more successful variants

00:06:47.900 on that show is called Cosmic Queries,

00:06:49.720 where our fan base just simply asks us questions.

00:06:52.420 And we cull the deepest subset of those

00:06:55.480 and put them into this book.

00:06:58.580 So for me, it's a celebration

00:07:00.520 of what it is to be human

00:07:02.360 and be on one side of knowing something

00:07:04.860 and want to cross over into another side

00:07:07.000 of enlightenment.

00:07:08.360 And yeah, it serves the curiosity in us all.

00:07:11.320 I think some adults, they've lost it.

00:07:14.580 And so maybe it'll fan the embers

00:07:16.240 and maybe ignite a flame once again

00:07:19.280 because you know it was there when you were younger.

00:07:21.740 So I think that's how you,

00:07:22.620 I think that's why you were feeling that way about it

00:07:24.940 because it makes you feel young again

00:07:26.700 and wide-eyed.

00:07:28.520 And thanks for noticing the National Geographic DNA

00:07:31.840 in the book.

00:07:33.200 It's a beautiful book.

00:07:34.740 And we didn't stop at just science illustrations.

00:07:37.560 There's art as well.

00:07:38.540 Yeah, yeah.

00:07:40.020 Carefully chosen artwork

00:07:41.660 that evokes the themes or the ideas

00:07:44.900 in the narrative.

00:07:46.360 So yeah, so thanks for calling that out.

00:07:49.060 Yeah, so is it always an exciting time

00:07:52.260 in astronomy and astrophysics

00:07:54.100 or have there been periods of stagnation

00:07:57.260 analogous to those in physics?

00:07:59.180 I get the sense that in physics,

00:08:03.080 certainly in any given generation,

00:08:06.140 there's an impressive feeling of

00:08:07.780 at least on the theory side

00:08:10.880 of spinning your wheels

00:08:12.960 and not necessarily making discernible progress.

00:08:17.060 But I just intuitively,

00:08:19.020 it seems like it could be different

00:08:20.560 in astronomy and astrophysics.

00:08:23.260 Is there...

00:08:23.740 That's a perceptive point.

00:08:25.920 And let me attempt to address it,

00:08:28.500 whether or not I fully answer it.

00:08:30.960 In physics, what you're referring to,

00:08:32.820 I think, is sort of the revolution

00:08:35.460 or evolution of ideas, right?

00:08:37.700 And you don't get those every day.

00:08:39.640 You know, you get them

00:08:40.700 maybe once in a generation.

00:08:43.260 And all the years in between

00:08:45.420 are filling in the gaps

00:08:46.600 between those ideas.

00:08:47.980 And those don't tend to get headlines,

00:08:49.560 even if they're intrinsically exciting

00:08:51.780 to a physicist.

00:08:53.680 So in astrophysics,

00:08:55.780 occasionally ideas matter deeply, yes.

00:08:58.440 But what happens more frequently

00:09:01.280 is that weird stuff gets discovered, right?

00:09:05.900 Or interesting stuff.

00:09:07.720 Water on the moon,

00:09:09.420 on the craters of the moon,

00:09:10.860 a black hole in the galaxy,

00:09:13.040 in the center of the galaxy.

00:09:14.580 Photograph of the black hole

00:09:15.900 in the center of the galaxy.

00:09:17.300 I mean, so things that exist in the universe,

00:09:20.680 because the universe is so vast

00:09:22.260 and it has so many different kinds of objects,

00:09:24.980 that in all of our catalogs,

00:09:27.300 we probably missed something

00:09:29.320 that is one in a million

00:09:31.600 or even one in a billion.

00:09:34.140 And when that gets discovered,

00:09:35.520 that's headlines.

00:09:36.700 And so, no,

00:09:37.140 it doesn't rethink the whole field,

00:09:38.780 but it is definitely fun to inventory

00:09:41.160 and talk about and characterize it

00:09:43.100 and try to figure it out.

00:09:44.760 Now, I did do one thing.

00:09:46.300 For a while,

00:09:47.060 I was a postdoc at Princeton

00:09:48.300 and Princeton has our feature journal,

00:09:52.000 the astrophysical journal,

00:09:53.520 all on one wall.

00:09:55.320 Okay?

00:09:55.960 From this very first episode,

00:09:58.440 for this very first issue,

00:10:00.560 1895,

00:10:01.520 the astrophysical journal,

00:10:02.740 up to the present.

00:10:03.900 And I thought to myself,

00:10:05.320 hmm, let me do this experiment.

00:10:07.600 And I found the exact middle

00:10:09.500 of that wall,

00:10:12.240 of all the journals.

00:10:13.400 And I said,

00:10:13.960 I wonder what date this is.

00:10:15.580 And it was-

00:10:17.180 Five years ago.

00:10:18.520 No.

00:10:18.740 So this would be sort of the halfway point.

00:10:26.880 And as I did this,

00:10:27.940 and I kept having it,

00:10:29.900 what I found is that

00:10:31.360 the halfway interval of time

00:10:34.840 was 18 years.

00:10:36.540 It fluctuated between 15 and 18 years.

00:10:39.200 So the total amount that was published

00:10:41.780 doubled every 15.

00:10:43.400 Now, not all of it is quality.

00:10:45.720 You get that.

00:10:46.360 I understand.

00:10:46.980 But as a first-pass measure

00:10:49.100 of the pace of things,

00:10:51.240 this was highly illuminating to me.

00:10:53.700 And it said that,

00:10:54.500 yeah,

00:10:54.960 I mean,

00:10:55.380 if you're living on the exponential curve,

00:10:58.560 every day looks like

00:10:59.960 you're living in special times.

00:11:01.980 And I remember going back,

00:11:03.160 I have a book on the sun

00:11:04.960 written by an astronomer

00:11:06.880 named Charles Young.

00:11:08.420 In fact,

00:11:08.680 he was at Princeton in his day.

00:11:10.100 I have two versions of the book.

00:11:11.800 One that came out in like the 1880s,

00:11:13.500 late 1880s,

00:11:14.180 and another one came out in the 1890s.

00:11:16.340 It was like the second edition.

00:11:18.380 And like,

00:11:19.020 you know,

00:11:19.620 five years or eight years had gone by.

00:11:22.220 And you read the preface

00:11:23.480 in the second edition,

00:11:24.340 it said,

00:11:25.000 our advances are so great

00:11:27.300 in our understanding of the sun.

00:11:28.980 We had to come out with another.

00:11:30.740 And I'm thinking,

00:11:31.700 you guys have no clue

00:11:33.280 what a great advance is.

00:11:36.000 Yet, of course,

00:11:36.500 that's what it felt like

00:11:37.480 when you're on

00:11:38.860 an exponential growth curve.

00:11:40.600 Everybody feels like

00:11:41.540 they're living in special times.

00:11:44.320 The biggest change,

00:11:45.740 again,

00:11:46.040 I have a layperson's view

00:11:48.960 of advances in astronomy,

00:11:52.420 really,

00:11:53.160 to take the observational side

00:11:54.960 of things for a moment.

00:11:56.020 The biggest news

00:11:57.540 in my lifetime,

00:12:00.040 I think,

00:12:00.600 I mean,

00:12:00.780 leaving aside

00:12:01.420 very sexy things

00:12:03.240 like gravitational waves,

00:12:04.980 is just that

00:12:05.980 the fact that

00:12:07.480 we crossed over

00:12:08.700 from

00:12:09.200 talking merely

00:12:11.440 about

00:12:12.040 planets

00:12:13.500 in our solar system

00:12:14.800 to confirming

00:12:16.100 their existence

00:12:17.620 elsewhere.

00:12:19.720 I mean,

00:12:19.860 so we lost Pluto

00:12:20.940 quite famously,

00:12:22.020 but we gained,

00:12:23.420 I don't know how many planets

00:12:24.300 at this point,

00:12:24.860 how many extra solar planets

00:12:26.260 have been cataloged?

00:12:26.780 Over 4,000,

00:12:28.140 yeah,

00:12:28.400 and it's rising fast.

00:12:29.840 Yeah.

00:12:30.240 And so,

00:12:30.580 what's the safe assumption now

00:12:32.300 that our own galaxy

00:12:33.640 has hundreds of billions

00:12:35.560 of planets,

00:12:36.280 and what's the number?

00:12:38.340 Yeah, so we do

00:12:39.800 that calculation

00:12:40.600 and you,

00:12:41.920 in the section,

00:12:42.880 you know,

00:12:43.240 are we alone

00:12:43.840 in the universe?

00:12:45.120 But you can ask

00:12:46.020 a different set

00:12:47.060 of philosophical questions,

00:12:48.440 something that might

00:12:49.100 titillate you.

00:12:51.040 You can look at

00:12:51.980 all of the layers

00:12:53.380 of bias

00:12:54.080 that are inherent

00:12:56.080 in how we even

00:12:57.920 go about answering

00:12:58.980 those questions.

00:13:00.160 Because even

00:13:00.760 in your very statement,

00:13:02.100 you said,

00:13:02.540 well,

00:13:02.640 how many planets?

00:13:03.280 Because the life

00:13:04.560 that you know

00:13:05.200 and the life

00:13:05.660 that I know

00:13:06.020 lives on a planet.

00:13:07.620 But maybe life

00:13:08.820 also lives on moons.

00:13:10.760 Maybe it lives

00:13:11.700 in atmosphere.

00:13:12.780 Maybe it lives

00:13:13.300 in gas clouds.

00:13:14.700 So,

00:13:15.380 we go through

00:13:16.200 all of the biases.

00:13:17.580 There's a carbon bias,

00:13:19.220 right?

00:13:19.480 We are carbon-based life.

00:13:21.260 Some of these biases,

00:13:22.180 I think,

00:13:22.440 are fully legitimate.

00:13:23.900 But if you really

00:13:24.980 want to search

00:13:26.620 with as wide

00:13:27.880 a net as possible,

00:13:29.620 also consider

00:13:30.440 the Goldilocks zone.

00:13:33.240 So much was written

00:13:34.380 and talked about

00:13:35.160 for decades

00:13:36.300 from the 1950s

00:13:37.700 and 60s

00:13:38.300 when this concept

00:13:39.360 was first formulated

00:13:40.300 where we know

00:13:41.740 life thrives,

00:13:42.840 needs,

00:13:43.300 and thrives

00:13:43.720 on liquid water.

00:13:44.880 So,

00:13:45.020 if you're going to

00:13:45.240 stick a planet

00:13:45.860 in a star system

00:13:47.460 not too close,

00:13:49.240 it'll evaporate

00:13:50.380 the water.

00:13:50.760 Not too far,

00:13:52.020 it will freeze

00:13:52.740 the water.

00:13:53.260 So,

00:13:53.460 there's this zone,

00:13:54.820 this belt

00:13:55.380 around any star

00:13:57.020 where a planet

00:13:58.440 would naturally

00:13:59.500 have liquid water.

00:14:00.980 And you need

00:14:01.460 atmospheric conditions

00:14:02.700 to sustain it,

00:14:03.520 of course,

00:14:03.820 but you're not

00:14:04.460 fighting it.

00:14:05.340 It would happen

00:14:06.300 naturally

00:14:06.820 if the conditions

00:14:07.960 allowed.

00:14:08.860 And so,

00:14:09.200 then we learned,

00:14:09.940 wait a minute,

00:14:10.820 the sun is not

00:14:11.520 the only source

00:14:12.260 of energy

00:14:12.740 in town.

00:14:14.140 All right?

00:14:14.600 Jupiter

00:14:14.980 and its tidal stresses

00:14:16.880 on its surrounding moons

00:14:18.820 is a source

00:14:19.720 of energy.

00:14:20.720 So,

00:14:21.060 one of Jupiter's moons,

00:14:22.220 Io,

00:14:22.820 is the most

00:14:23.320 volcanically active

00:14:24.600 place in the entire

00:14:25.620 solar system

00:14:26.300 because Jupiter

00:14:27.160 is pumping it

00:14:28.020 with energy.

00:14:29.500 And so,

00:14:30.060 now we have to think

00:14:30.980 if life needs

00:14:32.340 the warming energy

00:14:34.020 of a heat,

00:14:34.940 of a,

00:14:35.860 it just needs

00:14:36.300 an energy source,

00:14:37.540 why does it have

00:14:38.260 to have a star?

00:14:39.560 And so,

00:14:39.920 you just,

00:14:40.360 and then we learn

00:14:41.160 every model

00:14:42.260 of the solar system

00:14:43.120 that we construct

00:14:44.180 that of any star system

00:14:46.020 when it's born,

00:14:47.280 most of the planets

00:14:48.320 that formed

00:14:48.820 are on unstable orbits

00:14:50.200 and they fly out

00:14:51.680 into interstellar space.

00:14:54.320 It may be that

00:14:55.120 there are more

00:14:55.700 vagabond planets

00:14:57.160 than there are planets

00:14:58.860 bound to their

00:15:00.040 local star systems.

00:15:01.640 So,

00:15:01.900 you say,

00:15:02.160 well,

00:15:02.200 that's not a good

00:15:02.720 prospect for life.

00:15:03.800 However,

00:15:04.840 Earth still has

00:15:05.820 energy sources

00:15:06.720 in its core.

00:15:08.180 Yeah.

00:15:08.540 Is this how you get

00:15:09.620 volcanoes

00:15:10.120 and all these

00:15:12.500 mid-sea vents

00:15:14.120 that are pumping

00:15:15.300 very hot waters

00:15:16.220 into the bottoms

00:15:17.360 of the oceans?

00:15:18.200 If you're a life form

00:15:19.320 thriving on that,

00:15:20.640 you don't even care

00:15:21.640 if you were ever

00:15:22.260 orbiting a sun.

00:15:23.060 You could be

00:15:24.340 a frozen lake bed,

00:15:26.340 a frozen ice on top,

00:15:29.480 but down below,

00:15:31.000 you could be

00:15:31.560 doing the backstroke

00:15:32.580 in your warmed hot tub.

00:15:34.760 So,

00:15:35.180 this notion

00:15:36.420 that we want

00:15:36.980 to look for planets

00:15:37.780 and look for

00:15:38.280 a habitable zone,

00:15:39.460 a Goldilocks zone,

00:15:40.560 may be needlessly

00:15:41.800 restrictive

00:15:42.300 as we go forward.

00:15:44.420 Hmm.

00:15:45.160 So,

00:15:45.460 now,

00:15:45.620 what are your,

00:15:46.320 how have your intuitions

00:15:47.240 been pushed around

00:15:48.320 with respect

00:15:48.860 to the prospect

00:15:50.400 that we are alone

00:15:51.880 versus the prospect,

00:15:53.540 seemingly equally

00:15:54.620 astonishing

00:15:55.100 that the galaxy

00:15:57.220 and the universe

00:15:58.240 is teeming

00:15:59.460 with life?

00:16:01.700 Have you had

00:16:02.900 changes in your,

00:16:05.840 the way you weight

00:16:06.740 those probabilities

00:16:07.580 over the course

00:16:08.260 of your life?

00:16:09.800 Yeah,

00:16:09.940 that's a great way

00:16:10.800 to ask that question.

00:16:11.880 I would say

00:16:12.300 the probabilities have,

00:16:14.780 as they've changed,

00:16:16.320 they've changed only

00:16:16.860 because we learned

00:16:17.580 new things,

00:16:18.680 but not because

00:16:19.200 I had to re-evaluate

00:16:20.280 what I was already

00:16:21.060 thinking.

00:16:21.880 I've always been

00:16:22.880 very open

00:16:24.120 to possibilities

00:16:25.920 of the universe,

00:16:28.000 just given the size

00:16:29.480 and the diversity

00:16:30.840 of objects

00:16:31.760 and the age,

00:16:33.440 you know,

00:16:33.720 practically anything

00:16:34.760 you can imagine

00:16:35.420 being possible,

00:16:36.320 we think is going

00:16:36.900 to be possible.

00:16:37.940 But there's some

00:16:38.540 other really good

00:16:39.620 reasons for some

00:16:41.660 of the bias

00:16:42.280 that we are invoking

00:16:43.380 here.

00:16:43.760 For example,

00:16:44.900 there's a famous

00:16:46.340 episode of the

00:16:47.380 original Star Trek

00:16:48.320 where they encounter

00:16:49.820 a life form

00:16:50.480 that's basically

00:16:51.060 made of rock.

00:16:51.880 And it moves

00:16:53.420 through rock

00:16:54.220 like we move

00:16:54.880 through air.

00:16:56.200 And it's rock-based

00:16:57.680 life.

00:16:58.540 And an active

00:16:59.400 ingredient in a lot

00:17:00.480 of minerals

00:17:01.620 is silicon.

00:17:02.800 So it's silicon-based

00:17:04.580 life.

00:17:04.920 And this was their

00:17:05.460 attempt to do this

00:17:06.340 in the 1960s.

00:17:07.440 And this was silicon-based

00:17:09.500 life as opposed to

00:17:10.380 carbon-based life.

00:17:11.540 Well, they didn't

00:17:12.060 pull silicon out

00:17:13.360 of their ass,

00:17:14.040 right?

00:17:14.300 Why do people

00:17:15.160 think of silicon-based

00:17:16.120 life?

00:17:16.580 If you go back

00:17:17.280 to the periodic

00:17:17.920 table and remember

00:17:19.900 why elements

00:17:22.300 form columns,

00:17:24.820 the columns have

00:17:25.720 similar valence

00:17:27.300 electrons,

00:17:27.740 which means if

00:17:29.200 you're above or

00:17:30.480 below another element

00:17:31.480 in a table,

00:17:32.180 in the periodic

00:17:32.640 table, you can make

00:17:33.840 similar molecules

00:17:34.820 with all the same

00:17:35.900 other atoms.

00:17:37.300 Well, let's find

00:17:38.240 carbon.

00:17:38.880 Well, there it is

00:17:39.460 at the top of the

00:17:40.400 chart, number 12.

00:17:41.780 What's directly

00:17:42.660 below it?

00:17:43.680 Silicon.

00:17:44.900 So every atom

00:17:45.800 you can, every

00:17:46.440 molecule you can

00:17:47.440 make with carbon,

00:17:48.520 you can make with

00:17:49.480 silicon.

00:17:50.480 So why not create

00:17:51.460 an entire parallel

00:17:52.840 life system where

00:17:55.200 silicon is the base

00:17:56.320 instead of carbon?

00:17:57.880 And so that's a

00:17:58.520 perfectly legitimate

00:17:59.460 chemical broadening

00:18:01.460 of your bias as you

00:18:03.380 go search.

00:18:04.320 My rebuttal to

00:18:05.380 that is you don't

00:18:07.200 need to do that

00:18:08.660 because first,

00:18:09.820 carbon is hugely

00:18:11.020 sticky.

00:18:11.980 It sticks to itself

00:18:13.120 and multiple bonds

00:18:14.380 and silicon also,

00:18:16.400 but what you really

00:18:17.860 went out is that

00:18:18.740 carbon, depending

00:18:19.940 on where exactly

00:18:20.820 you are in the

00:18:21.380 universe, is between

00:18:22.240 five and ten times

00:18:24.380 as abundant.

00:18:26.480 So carbon is

00:18:28.020 already going to

00:18:29.260 be added before

00:18:30.760 silicon, you know,

00:18:32.020 figures out how to

00:18:33.140 put on its pants in

00:18:33.940 the morning.

00:18:34.860 And so I don't

00:18:35.880 need to really

00:18:37.240 think of life

00:18:38.980 forms based on

00:18:39.860 an isotope of

00:18:41.100 bismuth or even

00:18:42.060 silicon.

00:18:43.120 So I think carbon

00:18:44.040 is the way to go

00:18:45.320 here.

00:18:45.640 just given its

00:18:46.820 diversity of

00:18:48.060 chemistry that it

00:18:50.040 offers us.

00:18:51.460 And I don't know

00:18:51.840 if I directly

00:18:52.760 answered your

00:18:53.360 question.

00:18:53.740 Oh, have I

00:18:54.180 changed any of

00:18:54.780 my evaluations?

00:18:56.020 So the Fermi

00:18:57.900 paradox is what

00:18:58.720 you're dancing

00:18:59.180 around there.

00:19:00.080 And I want to

00:19:01.360 clarify the Fermi

00:19:02.560 paradox because I

00:19:03.360 don't think, I

00:19:04.860 think most people

00:19:05.520 who invoke it

00:19:06.200 don't know the

00:19:07.520 full weight that

00:19:09.520 it carries.

00:19:10.800 All right?

00:19:11.080 So you can do

00:19:12.180 the thought

00:19:12.560 experiment.

00:19:13.000 So Enrico

00:19:15.160 Fermi, the

00:19:15.620 physicist, famously

00:19:17.260 quipped, if

00:19:19.300 there's life in

00:19:20.220 the galaxy, then

00:19:23.260 the galaxy ought

00:19:24.380 to be teeming

00:19:24.960 with life and

00:19:25.680 they would have

00:19:26.060 visited us by

00:19:26.700 now.

00:19:27.420 Where are they?

00:19:28.580 Okay?

00:19:29.420 So maybe they're

00:19:29.960 not there at all.

00:19:30.600 It might be worth

00:19:31.260 spelling out why

00:19:32.560 that seems so

00:19:34.100 logical.

00:19:34.660 I mean, just with

00:19:35.260 respect to any

00:19:35.840 kind of time

00:19:36.380 window in which...

00:19:37.680 Exactly.

00:19:38.660 So you can ask

00:19:40.240 yourself, well, how

00:19:40.720 wide is the galaxy?

00:19:42.080 So 100,000 light

00:19:43.240 years.

00:19:43.940 Okay.

00:19:44.620 So that feels

00:19:45.260 intractable.

00:19:46.640 So let's say you

00:19:48.340 never get to the

00:19:51.280 speed of light.

00:19:51.820 But let's say we

00:19:52.400 get to 20% the

00:19:53.740 speed of light.

00:19:54.920 That means you can

00:19:55.600 cross the galaxy in

00:19:58.160 500,000 years.

00:19:59.860 All right.

00:20:00.360 But most stars are

00:20:01.620 not the diameter of

00:20:03.520 the galaxy away from

00:20:04.440 each other.

00:20:04.840 They're much nearer.

00:20:05.720 So for example,

00:20:07.580 Alpha Centauri system

00:20:08.820 from Earth, four

00:20:10.560 light years away, 20%

00:20:12.620 the speed of light.

00:20:13.240 You get there in 20

00:20:13.900 years.

00:20:14.940 Okay?

00:20:15.560 And you can star hop.

00:20:17.300 So imagine, this is

00:20:19.780 one of those...

00:20:21.440 I forgot whose

00:20:22.160 machine they got

00:20:22.960 named after.

00:20:23.820 You go to a

00:20:25.040 planet and then

00:20:26.460 it's with a robot

00:20:27.540 and then the robot

00:20:28.340 builds two copies of

00:20:29.400 itself and then they

00:20:30.340 launch to other

00:20:31.400 planets.

00:20:32.320 Okay?

00:20:33.280 And so...

00:20:34.240 So...

00:20:35.240 Or even people

00:20:36.100 or aliens.

00:20:37.200 So they arrive on a

00:20:38.460 planet and then they

00:20:39.960 say, okay, time to go

00:20:41.360 to more planets.

00:20:42.160 And now you go from

00:20:43.120 one planet to two to

00:20:44.280 four to eight.

00:20:45.460 The star systems.

00:20:46.760 It turns out, you...

00:20:49.200 If you did that, only

00:20:50.740 going to two once you

00:20:52.160 land on one, you can...

00:20:56.520 It's two to the n

00:20:57.760 power.

00:20:58.340 Right?

00:20:58.540 So, however many

00:21:00.500 years are loaded in

00:21:02.520 your n, you can

00:21:04.560 easily, completely

00:21:06.440 populate the entire

00:21:07.540 galaxy in an

00:21:09.080 evolutionary time

00:21:09.960 scale.

00:21:10.920 Easily.

00:21:12.300 And so, like, you

00:21:13.400 can do it within a

00:21:14.480 few, like, you know,

00:21:15.580 tens of millions of

00:21:16.460 years.

00:21:17.320 But the planet is

00:21:18.200 around for billions

00:21:19.180 of years.

00:21:20.460 So, where is

00:21:22.980 everybody?

00:21:24.280 That's the question.

00:21:25.820 And the other

00:21:28.020 intuition, the other

00:21:29.840 element to this

00:21:31.560 picture is that if

00:21:33.860 a complex life is

00:21:36.020 ubiquitous, you

00:21:37.400 would expect certain

00:21:39.200 civilizations to be

00:21:40.820 millions of years

00:21:42.280 ahead of us.

00:21:43.060 I mean, because

00:21:43.400 given, you know,

00:21:44.480 nearly 14 billion

00:21:45.700 years to start this

00:21:47.240 experiment, it would

00:21:48.620 just be a miracle if

00:21:49.920 all complex life

00:21:52.420 were at precisely

00:21:54.160 the same point in

00:21:55.320 its technological

00:21:56.040 evolution.

00:21:56.800 So, to find

00:21:57.420 ourselves not

00:21:58.940 surrounded by

00:22:00.160 evidence of

00:22:00.960 technological alien

00:22:03.340 life is to

00:22:04.920 suggest that it

00:22:06.360 might not exist

00:22:07.300 because, you know,

00:22:09.040 again, where is

00:22:09.860 everybody?

00:22:10.960 Yeah, and you're

00:22:11.920 right.

00:22:12.160 We are very

00:22:12.700 Johnny-come-latelys

00:22:13.760 in this.

00:22:14.620 First, you have the

00:22:15.200 14 billion-year-old

00:22:16.460 age of the universe.

00:22:18.020 Then you have the

00:22:19.060 five, four-and-a-half

00:22:20.200 billion-year-old

00:22:21.680 solar system.

00:22:22.960 And then ask, you

00:22:24.880 know, how old is

00:22:26.460 the branch of the

00:22:27.560 tree of life called

00:22:28.880 primates, right?

00:22:30.180 If primates were

00:22:30.920 your best chance, or

00:22:32.380 mammals, let's say,

00:22:33.260 were your best chance

00:22:34.040 of, quote,

00:22:34.580 intelligence on Earth,

00:22:36.500 we really didn't get

00:22:37.600 underway until after

00:22:38.600 the dinosaurs.

00:22:39.660 And that's basically

00:22:40.540 yesterday, 65 million

00:22:42.280 years ago.

00:22:43.080 And the Earth had been

00:22:44.100 around for hundreds of

00:22:45.160 millions of years,

00:22:46.900 cranking out life.

00:22:47.680 So imagine a

00:22:49.240 planetary system that

00:22:50.580 got a billion-year

00:22:51.680 head start on us.

00:22:52.960 If there's any

00:22:54.240 forcing vector towards

00:22:56.820 intelligence, we would

00:22:58.620 be dwarfed by any

00:23:01.000 such intelligence that

00:23:01.980 manifested itself.

00:23:03.580 And the comparison I

00:23:04.740 like making, and I'll

00:23:05.480 get back to Fermi in

00:23:06.380 just a moment, is this

00:23:08.360 comparison you always

00:23:09.460 hear about the DNA

00:23:11.440 between the chimp, a

00:23:13.240 bonobo, let's say, and

00:23:14.140 a human.

00:23:14.480 You know, it's some

00:23:15.860 high 90, 99, whatever

00:23:17.740 percent, identical DNA.

00:23:19.680 And the people who want

00:23:21.100 to keep thinking humans

00:23:22.580 are special will say,

00:23:24.280 but what a difference

00:23:24.960 that half a percent

00:23:25.840 makes.

00:23:26.840 And they crowd

00:23:28.260 themselves into that

00:23:29.120 half a percent and

00:23:31.020 celebrate all that we

00:23:33.040 are that chimps are

00:23:34.260 not.

00:23:35.160 But I'd rather pose the

00:23:36.500 question a little

00:23:37.020 differently and say,

00:23:39.020 suppose the difference

00:23:41.280 between humans and

00:23:42.140 chimps is as small as a

00:23:44.420 half a percent DNA in

00:23:46.920 the intelligence vector,

00:23:48.080 whatever that vector

00:23:48.740 is.

00:23:49.300 Suppose it is that

00:23:50.040 small.

00:23:50.860 What do you say?

00:23:51.320 Well, what do you

00:23:51.680 mean?

00:23:51.900 We have the Hubble

00:23:52.620 Telescope and poetry

00:23:53.820 and philosophy, and

00:23:55.220 they stick a twig in a

00:23:56.980 hole to get termites

00:23:58.180 out.

00:23:58.760 And I say, well, maybe

00:23:59.780 the difference between

00:24:01.300 those is small.

00:24:03.760 You don't want to think

00:24:04.700 that way, but imagine

00:24:05.480 it.

00:24:05.660 So now let's imagine an

00:24:06.720 alien who is 5% along

00:24:09.760 that same vector beyond

00:24:12.300 us that we are beyond

00:24:13.640 the chimp.

00:24:14.860 What would we look like

00:24:16.240 to them?

00:24:18.480 No reason for me to

00:24:19.600 think that we wouldn't

00:24:20.320 look any different to

00:24:21.140 them that chimps look to

00:24:22.240 us.

00:24:23.340 Because a smart chimp can

00:24:25.100 stack boxes and reach a

00:24:26.540 banana.

00:24:27.680 That's, toddlers can do

00:24:29.040 that.

00:24:30.060 So what does a smart

00:24:31.180 human do?

00:24:31.960 Well, we can, you know,

00:24:32.800 roll Stephen Hawking

00:24:33.700 forward.

00:24:34.080 Here's a smart human.

00:24:35.180 And they'll chuckle and

00:24:36.980 say, oh, he derives

00:24:38.880 black hole theories in

00:24:40.320 his brain, just like

00:24:41.800 little Timmy over here

00:24:42.780 who just came home

00:24:43.660 from preschool.

00:24:45.300 So, and that's a half

00:24:47.100 a percent.

00:24:48.280 So now imagine 5%,

00:24:50.100 10%.

00:24:50.940 And our, their

00:24:53.880 simplest expression of

00:24:55.680 an idea would

00:24:57.120 transcend our smartest

00:24:59.700 capacity to comprehend.

00:25:02.760 In the same way you

00:25:03.780 walk up to a chimp and

00:25:04.800 say, what time is it?

00:25:06.660 They have no idea what's

00:25:07.760 your time.

00:25:08.340 You know, want a cup of

00:25:09.220 coffee at a Starbucks?

00:25:10.260 Going to catch a plane?

00:25:11.340 Do you want to go to the

00:25:11.940 library?

00:25:12.680 None of this makes any

00:25:13.800 sense to them and they're

00:25:14.640 our simplest sentences.

00:25:16.560 So I think about this all

00:25:18.980 the time, leaving me to

00:25:20.740 wonder whether the search

00:25:22.460 for intelligent life,

00:25:23.860 SETI, is itself a bit of

00:25:26.260 hubris.

00:25:27.360 Because it assumes that

00:25:28.620 some other species has

00:25:31.140 our intelligence and not

00:25:33.640 something so far beyond us

00:25:35.480 that they would take no

00:25:36.640 interest in who and what we

00:25:38.160 are.

00:25:38.820 And one of the solutions

00:25:39.820 to the Fermi paradox is

00:25:42.120 that we are to the aliens

00:25:43.340 what worms are to us.

00:25:45.040 You don't walk down the

00:25:45.840 street and a worm crawls

00:25:47.940 out from the moist soil.

00:25:49.480 You'll say, gee, I wonder

00:25:50.140 what that worm is thinking.

00:25:51.440 Let me go understand that.

00:25:53.200 Unless you're a

00:25:53.740 wormologist, no, you're

00:25:55.560 not thinking that.

00:25:56.860 So one of them is that

00:25:58.020 they studied earth and

00:25:59.380 there's no sign of

00:26:00.640 intelligent life to

00:26:02.240 interest them.

00:26:03.200 But I have my favorite

00:26:04.700 explanation for the

00:26:06.020 Fermi paradox.

00:26:06.800 And forgive me for not

00:26:08.780 remembering who to credit

00:26:09.900 this to, but I don't take

00:26:11.340 ownership of this idea.

00:26:13.220 It's whatever drive is

00:26:16.640 required for you to want

00:26:19.560 to, quote, colonize

00:26:21.500 planets with abandon.

00:26:23.760 Right?

00:26:24.400 You go to a planet, you have

00:26:26.080 offspring, and they colonize

00:26:27.480 two planets, and they go

00:26:28.520 two planets.

00:26:29.080 Whatever that drive is, has

00:26:32.220 the seeds of its own

00:26:34.660 unraveling built within it.

00:26:37.540 Because what happens when

00:26:38.620 the planets start becoming

00:26:40.020 scarce?

00:26:40.900 Your urge to do this, risking

00:26:42.820 life and limb, that means

00:26:44.560 it's deep in you.

00:26:45.680 You need that planet.

00:26:47.020 You want that planet.

00:26:48.600 And so you go out, and then

00:26:49.960 there's somebody else trying

00:26:51.780 to claim the planet, and then

00:26:53.160 you have interstellar warfare

00:26:55.740 competing over the limited

00:26:58.720 real estate of the planets

00:27:00.240 in the galaxy.

00:27:02.240 Yeah.

00:27:02.340 And then you think, here's

00:27:03.200 It's a version of the great

00:27:05.800 filter argument that I

00:27:08.580 believe is original to Nick

00:27:10.460 Bostrom.

00:27:11.540 He's certainly spoken about

00:27:13.280 a lot.

00:27:13.600 He might have gotten it from

00:27:14.460 somebody else, but I think

00:27:16.120 it's Bostrom.

00:27:16.740 But the more generic idea

00:27:20.120 here is that it puts most of

00:27:22.680 the onus on technology.

00:27:24.060 Once you get technically

00:27:26.320 sophisticated enough, you

00:27:28.540 have almost certainly built

00:27:30.620 destructive technology.

00:27:33.840 And, you know, whether this

00:27:35.380 is specifically weapons of

00:27:37.400 war or artificial intelligence

00:27:39.380 or something that gets away

00:27:41.680 from you, and a sufficient

00:27:43.560 technical prowess to colonize

00:27:46.040 the galaxy becomes self-terminating,

00:27:49.260 almost by definition.

00:27:50.640 I mean, there's just too many

00:27:51.660 ways to kill yourself and to

00:27:53.120 have all your incentives as a

00:27:54.860 species not aligned, that you

00:27:57.500 just, you self-extinguish.

00:27:59.300 So I would say that was, that

00:28:00.760 would be a subcategory, or

00:28:02.220 maybe they're both categories of

00:28:05.020 the self-destruct phenomenon in

00:28:08.300 high-intelligent creatures.

00:28:10.180 Because what this specifically

00:28:11.880 implicates is the same urges that,

00:28:17.520 that infused colonial Europe, right?

00:28:21.580 So here you have Spain, Portugal,

00:28:24.520 England, the Netherlands, and they

00:28:27.800 all want to conquer the world.

00:28:31.180 So initially they have their own

00:28:32.640 territory, but then they encounter

00:28:35.420 each other.

00:28:36.660 And then the entire system implodes

00:28:39.520 because they can't share it,

00:28:42.440 because in them they want to own it.

00:28:44.260 And so this notion has already

00:28:46.700 played out in this world.

00:28:48.760 And that was the implosion of

00:28:51.260 Europe and its colonistic ways,

00:28:53.660 going from the age of the great

00:28:55.480 explorers to the age of the great

00:28:57.240 collapse of the colonial empires.

00:29:00.160 So it's not a stretch to imagine

00:29:02.960 this as sort of a fundamental truth

00:29:04.840 without having to analyze the

00:29:07.320 psychological profile of the alien.

00:29:09.300 It's just one of these basic simple

00:29:11.000 facts that might manifest no matter

00:29:12.920 the life form.

00:29:14.260 Well, to back up for a second and

00:29:16.300 to bring it back to Fermi,

00:29:18.260 how has your sense of the

00:29:21.380 proliferation of life or lack thereof

00:29:25.600 changed once we discover things like

00:29:29.560 amino acids in meteorites and in

00:29:32.780 the tails of comets, which is to say

00:29:34.800 that the building blocks of life seem

00:29:37.420 fairly ubiquitous?

00:29:38.820 Yeah, and that's part of what we all

00:29:42.820 find encouraging for those who are

00:29:44.680 rooting for life elsewhere, because

00:29:46.940 I can encapsulate that statement in a

00:29:53.000 simple fact.

00:29:53.780 If you rank order the abundance of

00:29:57.580 chemical elements in the universe,

00:29:59.920 the number one element is hydrogen,

00:30:02.480 which is chemically active.

00:30:04.580 The number two is helium, which is not

00:30:07.380 chemically active, but it's there, but

00:30:09.120 it's a big number two.

00:30:10.240 Number three is oxygen.

00:30:12.800 Number four is carbon.

00:30:15.400 Number five is nitrogen.

00:30:17.600 Oh, my gosh.

00:30:19.040 Yeah.

00:30:19.320 So everything's on the menu.

00:30:20.640 Out of the five top elements in the

00:30:24.660 freaking universe.

00:30:25.760 And the seventh is a ham sandwich.

00:30:29.660 Are contained in what we call

00:30:32.460 biochemistry.

00:30:33.800 And so that's why, you know, like I

00:30:36.360 said, if we were made of some exotic,

00:30:38.520 like I said, a isotope of bismuth, you

00:30:41.140 might have an argument to say God did

00:30:43.720 something special on earth because this

00:30:45.580 stuff is not found anywhere else.

00:30:47.720 But if we, so if anything, life is

00:30:51.360 opportunistic.

00:30:52.620 Okay.

00:30:53.400 It makes very good use of what it has.

00:30:56.860 And one other fact, which is not often

00:30:59.680 cited, but it has to be in the equation,

00:31:02.480 is, you know, the earliest fossil

00:31:04.840 evidence, it comes in, of life, it comes

00:31:08.400 in around 3.8 billion years ago.

00:31:10.880 And earth began 4.5, 4.6.

00:31:15.200 So for the longest while, decades, people

00:31:17.320 subtracted those two numbers and said,

00:31:19.420 all right, life took 600 million years.

00:31:22.140 That's still pretty fast, given that we're

00:31:25.800 four and a half billion years old.

00:31:28.080 Okay.

00:31:28.720 That's still pretty fast.

00:31:29.600 It's small compared to the life, the

00:31:31.580 life expectancy of earth.

00:31:33.340 But it's even better than that.

00:31:35.400 Again, I'm value judging the speed of

00:31:37.080 this because the early earth was subjected

00:31:40.460 to what we call the period of heavy

00:31:42.540 bombardment.

00:31:43.340 There were two such periods.

00:31:44.960 Heavy bombardment, earth is still, the

00:31:47.400 polite way to say it is, accreting

00:31:49.080 matter from the nascent solar system.

00:31:53.360 The more violent way to put it is it is

00:31:55.740 being slammed constantly by comets and

00:31:59.040 asteroids because it has a strong gravity

00:32:01.320 in its region.

00:32:02.180 It's clearing out its orbit and all that

00:32:04.660 material ends up going somewhere and it

00:32:06.480 lands back on earth.

00:32:08.480 And so the earth is gaining mass and by

00:32:10.660 gaining mass, it gains even more gravity.

00:32:12.780 It becomes even better at it.

00:32:14.640 And over that time, earth's surface is

00:32:17.600 sufficiently pelted that the temperatures

00:32:20.060 prevent the formation of complex molecules.

00:32:24.260 Because under high temperatures, the bonds,

00:32:26.920 the molecular bonds break.

00:32:28.340 And every time you try to experiment with

00:32:30.320 it, it gets broken apart.

00:32:31.400 So it's not conducive to the

00:32:33.980 experimentations of life.

00:32:35.500 So if you're going to start the clock,

00:32:37.900 wait until the period of heavy

00:32:39.440 bombardment is over.

00:32:40.280 That's like 4 billion years ago, not 4.6.

00:32:43.980 So now you start the clock.

00:32:46.060 Now earth has some chance of cooling down

00:32:48.620 and making complex molecules and starting

00:32:52.080 the birth of biochemistry.

00:32:54.000 And there it is.

00:32:55.880 Earth went from organic molecules to

00:33:00.040 self-replicating life within between 1 and

00:33:03.160 200 million years in the early universe,

00:33:05.460 in the early earth.

00:33:06.700 And that's stupefying.

00:33:08.740 So if it did it that fast, using native

00:33:11.200 ingredients on a planet, just formed like

00:33:14.920 anybody on any other planet, then no one

00:33:17.840 who studied this problem is walking around

00:33:19.480 saying we're alone in the universe.

00:33:21.420 Although there is the additional

00:33:23.680 improbability, whatever it is, of getting

00:33:26.900 from life, single cell and I guess

00:33:29.540 multicellular to technologically advanced

00:33:33.080 civilization.

00:33:34.160 I mean, you can argue that we have barely

00:33:36.920 accomplished it and there's really no sign,

00:33:40.720 but for us, there's no sign of natural

00:33:44.100 selection producing anything like

00:33:46.960 civilization without us.

00:33:49.020 So, again, we've got, we're sampling this in a

00:33:54.180 very narrow time window and who knows what the

00:33:56.760 next million years might bring, but I guess a

00:34:00.220 little bit, let me just sharpen up your, the

00:34:02.400 Fermi intuition here.

00:34:03.980 If you had to bet or assign a probability to

00:34:07.420 one of two outcomes or one or two states of

00:34:11.060 affairs, one, we're alone with respect to

00:34:15.340 complex life or technological sentient

00:34:20.040 civilization building life.

00:34:23.380 So there might be microbes elsewhere in the

00:34:25.520 galaxy, but there's nothing like us pining for

00:34:29.220 other star systems versus the galaxy was or is

00:34:34.820 teeming with advanced life.

00:34:38.740 And we, and for whatever reason, we don't see

00:34:41.340 it, which seems less astonishing to you or

00:34:46.140 less unlikely.

00:34:48.680 Yeah, I don't, I have to think about it the

00:34:51.740 way you worded it, but let me, it's because I

00:34:54.680 don't entirely agree with what part of your

00:34:56.520 premise.

00:34:57.140 So look at beavers or beavers are mammals

00:34:59.940 that large brain, like relative to other branches

00:35:02.780 on the tree of life.

00:35:03.920 And they fully exploit the resources in their

00:35:07.460 environment.

00:35:07.880 Oh, there's a tree.

00:35:09.480 I'm going to use that tree to dam this river and

00:35:13.820 I'm going to make an underground den.

00:35:16.180 All right.

00:35:17.120 Is that, are we any different from that?

00:35:19.960 We use trees.

00:35:21.060 Well, first we use grass to make huts that was

00:35:23.360 available.

00:35:23.900 Then we use trees.

00:35:24.820 That's pretty convenient.

00:35:26.220 Then we found metal.

00:35:27.620 Oh my gosh, let's use that.

00:35:29.280 Okay.

00:35:29.900 And then we learn how to, how to make alloys.

00:35:33.340 Let's do that.

00:35:34.460 And then we learned chemistry.

00:35:36.160 Let's do that.

00:35:37.840 So yes, it takes thresholds of intelligence to exploit your environment even more.

00:35:44.500 But the simple act of exploiting an environment is not unique to being human.

00:35:50.440 That's my first point.

00:35:51.640 Second, the Romans were no less smart than anyone who followed them.

00:35:57.300 All right.

00:35:57.780 Smart in terms of the, what their brain could figure out, but they didn't have alien communication

00:36:03.780 technologies.

00:36:04.520 They didn't have radio telescopes.

00:36:06.260 They didn't go into space.

00:36:08.080 So imagine the Roman empire and aliens are waiting for a return signal back through space

00:36:14.680 and no return signal.

00:36:17.860 So they'll say there's no.

00:36:19.100 They're still trying to do arithmetic with their Roman numerals.

00:36:22.880 That was the problem.

00:36:25.700 Yeah.

00:36:26.220 They needed the Arabic numerals for that one.

00:36:28.400 Yeah.

00:36:28.600 But people forget that Roman numerals do not have a zero.

00:36:31.040 You cannot represent a zero with Roman numerals, and that's why the calendar, the Christian

00:36:38.460 calendar, Gregorian calendar, and the Julian calendar, there's no year zero.

00:36:42.680 It went from 1 BC to AD 1 because no one could wrap their head around it.

00:36:48.320 So yeah, arithmetic is hard with Roman numerals.

00:36:51.180 I think they would have figured something out.

00:36:52.880 I think they were smart folks.

00:36:54.280 In the fullness of time.

00:36:55.220 Yeah, no, I mean, I take your point, and we should be humbled by how much change can

00:37:03.220 occur over vast timescales, right?

00:37:06.460 I mean, you look at the rest of what's on Earth with us now, and it's hard to imagine

00:37:12.960 anything evolving into the kind of species that could do more than we're managing to do.

00:37:21.200 But we're just looking at asynchronous lines of evolution, right?

00:37:25.080 And given millions of years, basically everything is potentially available.

00:37:30.980 And millions is short compared with billions, right?

00:37:33.180 A billion is 1,000 times longer than a million.

00:37:36.500 And here we were, some kind of fist-sized or smaller shrew or some kind of rodent running

00:37:43.940 underfoot, trying to avoid becoming hors d'oeuvres for T-Rex, and that's how it would have stayed

00:37:50.500 if the dinosaurs didn't just get unlucky and an asteroid takes them out, pries open the

00:37:57.140 niche, an ecological niche that allows mammals to evolve into something more ambitious than

00:38:03.060 a rodent.

00:38:03.960 Meanwhile, rodents are still among us.

00:38:05.720 So, I want to impress upon people, if they didn't otherwise sort of wrap their head around

00:38:11.920 it, that we went from rodents to humans in 65 million years, and that's a vanishingly

00:38:19.700 small fraction of a billion years, and Earth has been around for 4 billion years.

00:38:24.780 So, now here's the tricky part.

00:38:26.840 If you line up, this is a little thought experiment, if you just lay Earth's timeline out on the

00:38:32.700 wall, left to right, beginning to end, and then you blindfold yourself, like, you know,

00:38:38.300 pin the tail on the donkey, and just, and then you walk up to it, you don't know where

00:38:41.600 you are, and you pin the tail.

00:38:43.760 Most of the places on that timeline you pin it, Earth only had single-celled life.

00:38:50.060 Complex life was relatively late, last half a billion years.

00:38:53.620 And then what we call intelligent life in big brain mammals, even smaller than that.

00:38:57.840 But the point is, if it ever, if Earth is any indication, if it ever gets to that, then

00:39:04.920 it's fast.

00:39:06.640 So, imagine it got to that sooner.

00:39:10.180 Or the other side, flip coin, flip side of that is, imagine the asteroid never came.

00:39:14.980 There'd still be dinosaurs here today.

00:39:16.680 You know how I know that?

00:39:18.420 Because dinosaurs were around as a community for 300 million years before the dinosaur,

00:39:24.960 before the asteroid.

00:39:25.880 So, what's another 65 on top of the 300?

00:39:29.580 They'd still be here.

00:39:31.460 So, what this tells us is what we think of as intelligence clearly is not important for

00:39:37.700 survival.

00:39:38.680 Otherwise, roaches would have really big brains, right?

00:39:41.860 So, maybe the big mistake here is thinking that intelligence is an inevitable consequence

00:39:47.340 of evolution.

00:39:48.580 When all it would have taken was one broken branch, then that could have taken out all

00:39:54.360 the mammals from the vertebrate chain, and then we would not have anything like we think

00:39:59.280 of today as intelligent creatures.

00:40:02.520 Yeah, but if you run this experiment billions upon billions of times, it's just-

00:40:06.840 Well, there you go.

00:40:07.700 That's the answer.

00:40:08.140 As long as we have, on the assumption that we're in no way unique, and we being a species

00:40:17.060 of Earth, and if multicellular life is ubiquitous in the galaxy or in the universe, and you just

00:40:26.800 have those hundreds of billions, ultimately trillions of similar experiments to run, then it's very

00:40:35.500 difficult to imagine that you don't have, at minimum, tens of millions of cases of advanced

00:40:42.340 technological life.

00:40:44.760 That's how you get to win the argument in the end.

00:40:46.700 You say, oh, what are the chances of that happening?

00:40:49.120 One in a million?

00:40:50.160 Okay.

00:40:50.800 One in a million, and there's 100 billion star systems out there.

00:40:54.260 So, run the numbers.

00:40:57.720 No one is thinking we're alone out there.

00:40:59.420 But is that actually the opinion in the field?

00:41:03.460 If you polled people at a conference of physicists and astrophysicists and astronomers, you think

00:41:11.220 a large majority would say that advanced life is ubiquitous in the universe?

00:41:17.720 I think the only sensible way to do it is to just- we have a sample of one, so let's

00:41:24.140 just start with that and ask, what fraction of the total timeline of Earth has Earth had

00:41:30.160 what we would call intelligent life, or big-brained life?

00:41:34.300 Yeah.

00:41:34.640 And what fraction of that period has it had intelligent- the Drake equation?

00:41:39.060 And what fraction of that period has intelligent life with technology?

00:41:42.080 So, if you do that, then that gives you a set of fractions that you can layer onto the entire

00:41:50.200 stellar population of the galaxy.

00:41:53.260 And even using highly conservative estimates, you do not come up with us being the only life

00:41:58.760 form around.

00:42:00.080 And like I said, if you look at the actual map of the galaxy, where we have found these

00:42:05.480 4,000 exoplanets, it's this tiny little circle.

00:42:10.500 The star has to be close enough to get good data to know whether it has another planet around

00:42:14.400 it.

00:42:14.840 And you say to yourself, gosh, this is what leads to that analogy that comes from the

00:42:19.340 SETI Institute with Jill Tartar and Seth Shostak, where they say, if you're going to

00:42:24.500 say, well, how could- have we found life?

00:42:25.920 We haven't found life yet.

00:42:27.300 And that's like taking a cup, an empty glass, and scooping it into the ocean and pulling

00:42:33.840 it out and saying, the ocean has no whales.

00:42:38.300 From this tiny sample of the vast ocean that you know you have yet to search.

00:42:44.040 Yeah.

00:42:45.040 But what do you think the limit is on getting a truly optical look at an exoplanet?

00:42:53.280 I mean, any of these large telescopes that you describe in your book coming online, how

00:42:59.520 close are we to seeing anything of interest in another solar system?

00:43:05.700 Yeah, that's a great question.

00:43:07.960 So you can ask- let's ask it another way.

00:43:10.600 If you're on the moon, how well can you see sort of cities on Earth?

00:43:17.320 Not very well.

00:43:18.320 Those images you see on the screensavers where you have the space station orbiting, you know,

00:43:23.700 they've pumped up the brightness of those cities so they can stand out as beautifully

00:43:27.400 as they do.

00:43:28.320 But if you're going to go a quarter million miles away from them and stand on the moon,

00:43:32.340 you become much less visible.

00:43:34.000 And that's our nearest neighbor in space.

00:43:36.540 And allow me to quantify this.

00:43:38.480 Imagine a schoolroom globe.

00:43:39.780 And I'm always sad because there's always color-coded.

00:43:44.480 And so you think of Earth as a place divided by countries, not unified by land and water

00:43:49.600 and atmosphere.

00:43:50.860 That's just me getting sentimentally cosmic on it.

00:43:54.420 But you can ask, well, at what altitude above that globe would you find the International

00:43:58.600 Space Station?

00:43:59.900 Half the people I've asked that come away about a foot from it.

00:44:02.760 It's about a- no.

00:44:03.720 It's three-eighths of an inch above the surface.

00:44:06.520 All right.

00:44:06.660 Now, where would the moon be?

00:44:08.180 Well, we're so jaded by how often we see the Earth and moon drawn in a textbook.

00:44:12.400 People tend to put the moon maybe a foot or two away.

00:44:15.120 No, the moon is 30 feet away.

00:44:17.680 Where would Mars be?

00:44:19.700 A mile away.

00:44:22.880 Space is vast.

00:44:24.840 So to directly image a planet, yes, that could be on our horizon.

00:44:31.060 But to image it in a way where we're going to see roads and cities, I think that's unrealistic.

00:44:36.660 But I have a- I say that, but smiling because I know what we're already up to.

00:44:42.400 All right?

00:44:42.960 You want to see life forms waving back at you.

00:44:46.100 What I want to see is any evidence in the atmosphere that anybody's alive on that planet's

00:44:54.060 surface.

00:44:54.500 Yeah.

00:44:55.240 And these are- we call them collectively biomarkers.

00:44:58.580 Right?

00:44:59.000 So if you- so I didn't know this.

00:45:01.480 I had to figure this out.

00:45:02.380 One of these, my own- that I gleaned as I got older and wiser and learned.

00:45:06.400 And so you grow up and you see these science fiction stories.

00:45:09.580 And take Star Trek again, for example.

00:45:12.340 You know they never donned spacesuits.

00:45:15.900 Right?

00:45:16.160 You ever wonder about that?

00:45:18.120 Never.

00:45:18.860 Never.

00:45:19.160 They're walking around on all kinds of planets.

00:45:21.160 Yeah.

00:45:21.360 No spacesuits.

00:45:21.860 Okay.

00:45:22.000 I also wonder about the suits they were wearing, but that's not a matter.

00:45:26.400 That's the 60s.

00:45:27.800 You were too young.

00:45:29.260 Okay?

00:45:29.760 I remember.

00:45:30.980 All right.

00:45:31.700 So I get to pull rank on you with my age here.

00:45:35.280 So they never wear spacesuits.

00:45:37.460 Why?

00:45:37.700 Because they have sensors.

00:45:39.060 And they say, Captain, it's an oxygen-nitrogen atmosphere.

00:45:41.920 Okay, let's go down.

00:45:42.700 As though if you searched enough, you would just simply find oxygen-nitrogen atmospheres.

00:45:49.260 What I didn't know at the time, and I don't think they knew either, is that we only have

00:45:55.200 oxygen because we have life.

00:45:57.800 Right.

00:45:58.520 That's the only reason.

00:46:00.160 And not only because we have life, but life is constantly making oxygen.

00:46:03.940 Because oxygen chemically is highly reactive.

00:46:06.560 So if you start out with a planet that's born with oxygen, it'll go away.

00:46:10.940 It is going to react with all manner of things, and it'll go to zero in very little time.

00:46:16.520 So the fact that we have an active fraction, 20%, 21% air of oxygen tells you something is

00:46:22.800 constantly making it, and that's the photosynthesis in plant life.

00:46:26.980 So if you find a planet that has a stable supply of oxygen, oh my gosh, bump that to the top of

00:46:34.300 the list.

00:46:35.160 And there are other unstable molecules, like methane, although there are other ways you can

00:46:40.880 make methane.

00:46:42.200 But the people who are in the business of studying the chemistry of atmospheres, they've

00:46:46.420 got a laundry list of chemical, of molecules that will be the product of all kinds of life

00:46:54.220 that we know goes on here on Earth.

00:46:56.860 And one of them was phosphine.

00:46:58.520 You may remember the news stories.

00:47:00.140 They found phosphine in the atmosphere of Venus, where it's not so hot, scalding hot on the surface.

00:47:06.020 You come up a little, it's a little cooler.

00:47:08.180 Phosphine, no one can figure out how you make phosphine other than by the natural chemistry

00:47:14.800 of life itself.

00:47:17.000 So that made headlines.

00:47:19.260 It's been questioned for other reasons since then.

00:47:21.660 But so we have this cottage industry of people studying the atmospheres of exoplanets, now that

00:47:28.400 we have the catalogs of exoplanets ready for our perusal.

00:47:31.460 And I think that's where the answers are going to come.

00:47:35.400 And one last point about that is, I joke, that if you find a planet that has hydrocarbons

00:47:43.500 in their atmosphere, but also smog and soot and other things, that would be the sure sign

00:47:49.560 of the no intelligent life at all.

00:47:52.440 It is polluting its own air.

00:47:56.880 And one last thing I'll tell you about the atmosphere is the thickness of our atmosphere

00:48:00.940 is to Earth as the skin of an apple is to an apple.

00:48:06.140 So we think of this as this huge ocean above us when it's not, and it's actually quite

00:48:12.100 fragile.

00:48:12.440 So this connects rather nicely to recent news stories about the aliens in our midst.

00:48:22.040 And I got to imagine you were hit with all manner of communication of human origin about

00:48:29.440 this behind the scenes, because even I was, and this is not my wheelhouse.

00:48:35.760 So what we've had, you know, we're recording this in just edging into the second week of

00:48:43.380 June.

00:48:44.460 And so we've had recent disclosures in the press that the Pentagon and the Office of Naval

00:48:52.800 Intelligence primarily have thrown up their hands and have admitted that we are in the

00:49:00.140 presence of technology that they can't explain.

00:49:02.700 And they've put forward some classified evidence apparently that is supposedly better than the

00:49:09.060 stuff that has leaked out.

00:49:10.560 And the media has seized upon this really prominent stories that were not at all skeptical and not

00:49:18.480 marshalling any of the legacy of, you know, skeptical debunkings of this kind of material in their

00:49:25.360 reporting.

00:49:25.800 And so we have 60 Minutes and the Washington Post and the New Yorker, the New York Times,

00:49:33.900 I mean, really more or less everyone in sight has given a very fair and one might even say

00:49:42.900 credulous hearing to these reports.

00:49:46.160 To my eyes, it's just not really clear what's going on.

00:49:49.060 And I said this on someone else's podcast, on Lex Friedman's podcast, that I had received a sort of an

00:49:55.220 advanced communication, advanced with respect to the calendar, not with the details, that this was

00:50:01.860 coming.

00:50:02.700 And, you know, I was urged to sort of prepare my brain to receive these startling disclosures so

00:50:09.000 that I could help shape a public conversation about this new consensus, which purported to be, again, it seems

00:50:18.960 to me that the shoe really never quite dropped.

00:50:21.620 And I want to get your opinion on this.

00:50:23.640 But what I was asked to anticipate was that the people who are best placed to assess the evidence, the people

00:50:32.180 who have the radar evidence, the Navy pilots who have had the dash cam video, the analysts who have poured over

00:50:40.440 these data for now several decades, they have formed a consensus that there's no way what they're seeing is a mere

00:50:50.440 artifact of glitches in our technology.

00:50:53.760 It does not admit of any truly skeptical interpretation.

00:50:57.920 No, we are in the presence of technology that is so advanced that it could not be of human origin, and we don't

00:51:06.800 know what to make of that fact.

00:51:09.160 I guess my first question before we get your full download, Neil, did anyone contact you and ask you to sort of

00:51:15.860 prepare your head for what was coming?

00:51:18.900 Yeah, I've been interviewed at least a dozen times in the last 10 days.

00:51:23.000 Most recently, a few hours ago, for the daytime ABC show, The View, so that you are correct

00:51:31.100 to recognize that you are the rest.

00:51:35.160 If you'd like to continue listening to this conversation, you'll need to subscribe at samharris.org.

00:51:40.700 Once you do, you'll get access to all full-length episodes of the Making Sense podcast, along with

00:51:45.160 other subscriber-only content, including bonus episodes and AMAs, and the conversations I've been

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Making Sense - Sam Harris - June 10, 2021

#252 — Are We Alone in the Universe？

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