0:00

Hey, it's Lindsay and Marshall

0:03

It's been a really busy season for us and

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we're hard at work preparing the rest of season

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9 We wanted to thank

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you all for listening to tumble and

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give a very special Thank you to

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Just to say how much you love the

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it helps us keep making the show

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We're coming up on a hundred and

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fifty episodes now and to celebrate We're

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gonna be doing a quiz show featuring

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trivia from across all nine seasons of

0:42

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be giving our patreon members the chance to

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if you want the details on how to

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be on this quiz show and future quiz

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episodes All you need to do

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is pledge your support on patreon.com Tumble

0:59

podcast I also recommend brushing

1:01

up on your tumble listening over the

1:03

holidays So you can get the highest

1:05

score even if you're not on we'll

1:07

find a way for you to play

1:10

along Indeed. So to

1:12

get you started we have one of our

1:14

favorite episodes from last season do aliens

1:16

exist This episode made

1:19

us look at the stars and ask if

1:21

anything really is out there. So let's

1:23

listen in Hi,

1:29

I'm Lindsay and I'm Marshall welcome to

1:32

tumble the show where we explore stories of

1:34

science discovery How likely is

1:36

it that we'll find intelligent alien life

1:38

on other planets? And if we do

1:40

what will it be like will

1:43

they take us to their leader because I'm sure

1:45

they've got some great ideas In

1:48

this episode, we're going to discover how

1:50

a math equation and our own Evolution

1:52

can help us on our search for

1:54

intelligent life on other planets

1:58

you Okay,

2:02

Marshall, one of the greatest quests

2:04

in science is to find life on

2:06

other planets, and one of

2:08

the biggest questions in that quest is

2:11

whether there's life that's like us. You

2:13

mean like the kind that we see in science

2:16

fiction where people basically are human actors but they

2:18

have pointy ears? Pointy

2:21

ears are no. The technical

2:23

term is intelligent life. That

2:26

means life beyond Earth that

2:28

could build civilizations and technology

2:31

like us. Do you think

2:33

it exists? I mean I think given

2:35

the size of the universe there's no way

2:37

that it doesn't exist, but I just think

2:39

it's probably really really far away. But what

2:41

about you? Well, I just, I don't know.

2:45

That's why we asked some kids. So

2:48

let's hear what they think. Hi,

2:50

my name is Madeline. I'm eight years old.

2:53

I think that there may be living things

2:55

like bacteria on other planets, but I do

2:57

not think there are what we picture

2:59

aliens. My name is

3:01

Shepard. I'm six. I

3:04

think aliens would look like

3:07

three armed creatures

3:09

with six heads. I

3:13

think honestly Madeline seems to me like the

3:15

most realistic of the two kids, so I

3:17

like Shepard's idea a lot. There's

3:20

lots of cool ideas of what

3:22

aliens could be like. So let's

3:24

ask our listeners what they think.

3:27

Do you think alien life exists?

3:30

And how would scientists find out? Because

3:33

we're about to set off on our search

3:35

for the possibility of alien

3:37

life in the universe. So

3:49

that you've thought about your answer, where

3:51

do we start in our search for aliens? First,

3:54

we have to figure out what we're searching

3:56

for. And to do that, we're

3:58

going to talk to two scientists. The

4:00

first will help us figure out

4:02

where aliens could live, and the

4:04

second will help us see what

4:06

alien species could be like. Alright,

4:08

who's our first guest? We're about

4:10

to meet a planet hunter and

4:13

alien life expert named Caitlin Rasmussen.

4:16

There's just so many possibilities for

4:18

life to exist and for it

4:20

to be different and totally bizarre

4:22

and really cool, and I just

4:24

want to spend all my time

4:27

studying that. So, although life could

4:29

take many forms, Caitlin says scientists

4:31

don't really agree on how

4:34

much could be out there. So

4:36

if you ask a bunch of scientist

4:38

questions, you'll get a whole bunch of

4:40

different answers. Some people think that the

4:42

galaxy is just totally full of life,

4:44

like there's aliens everywhere and we could

4:47

talk to them. But other

4:49

scientists think the opposite. And some

4:51

people think that actually the

4:53

Earth is super rare, and we might not

4:55

have any other aliens in the galaxy at

4:58

all. Okay, wow. So

5:01

who's right? And how would we find out? Well,

5:04

that's a question that scientists have

5:06

been asking themselves for a really

5:08

long time. So, back

5:11

in 1961, an astronomer named

5:13

Frank Drake came up with

5:15

a math equation to try

5:18

and answer it. It's called

5:20

the Drake Equation. Ooh,

5:22

a cool equation that gets its own name. That's

5:25

because the Drake Equation is probably one

5:27

of the most famous math equations

5:29

in astronomy. It's a

5:31

way to think about the probability

5:33

of more likelihood that we will

5:35

find intelligent life on other planets.

5:38

There's really only a very small subsection

5:41

of scientists who actually study and use

5:43

the Drake Equation and try to figure

5:45

out exactly what those percentages might be.

5:49

Okay, so it's like trying to figure out

5:51

how likely it is that I'm going to get cookies

5:53

in the mail today. Right

5:55

now, I'm thinking it's like 30% not going to happen, 70% going

5:57

to the moon. to

6:00

happen. Why do you

6:02

think that? I'm just guessing.

6:07

Maybe today if I see a package arrive that

6:09

likely number gets like a lot higher. Well

6:14

the Drake Equation is a bit

6:16

more complicated because it's giving it

6:18

a bigger question. How many species,

6:21

how many intelligent alien people

6:23

are out there in the

6:25

Milky Way today that people could

6:27

talk to? So to figure

6:29

this out, Drake divided this

6:31

question into two parts. The

6:34

first asks how many planets intelligent

6:36

life could evolve on. So you

6:40

have to think about how big the Milky Way

6:42

is, how many stars are in

6:44

it, how many of those

6:46

stars have planets, how many

6:48

planets does each star have. Alright

6:51

so I'm keeping track here so we got to know

6:53

how big the Milky Way is which is like really

6:55

big. How many stars are

6:57

in the Milky Way and for every star

6:59

that has planets like we need to know

7:02

roughly how many planets do they have. Astronomers

7:04

have been working to fill in those blokes.

7:07

I think the most recent estimate is if

7:09

a quarter of all the stars in the

7:12

Milky Way have planets that are a good

7:14

distance away from their star to support liquid

7:16

water, that answers 25 billion planets

7:19

just in our own galaxy alone. It's a

7:21

really big number. I think

7:23

something our little human monkey brains have

7:25

trouble processing is exactly how big a

7:27

billion is. It's crazy! It would

7:30

take forever to search all those planets.

7:32

That's where Caitlin's work comes

7:34

in. With the help of high-powered

7:36

telescopes, she searches the galaxy for

7:39

planets with the right ingredients for

7:41

life like water and land and

7:43

elements like carbon and nitrogen. That

7:46

would be my dream. That would

7:48

be the coolest possible thing that

7:50

I could run into in my

7:53

career is another perfectly Earth-like planet.

7:56

So what if we find an Earth-like planet? What

7:58

would we even be looking for? for

8:00

and how would we know that it's

8:02

got intelligence, six-headed, three-armed creatures on it?

8:04

That's where the second part of Drake's

8:07

equation comes in. Right after this...

8:34

Tumble's brought to you with support from Spotify

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your first month

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at kiwico.com/tumble. Okay

10:15

so we just talked to Caitlin about

10:17

the first part of the Drake equation

10:19

where we could find alien life. The

10:21

second part of the equation is about

10:23

finding those aliens we can talk to

10:26

and our guide comes from kind of

10:29

an unusual place. So I study

10:31

how animals came to be the way they were

10:33

how they evolved to be the way that they

10:35

were. That's Eric Kirschenbaum. He's

10:37

a zoologist. Okay but as I

10:40

understand it a zoologist studies animals

10:42

and we're doing an episode about

10:44

aliens. Did we take a wrong

10:46

turn in the A science section?

10:49

Eric's name starts with A too

10:52

and he's an author of a

10:54

book called the zoologist guide to

10:56

the galaxy where animals on earth

10:58

reveal about aliens and ourselves

11:00

and he's thought a lot about the

11:03

Drake equation. Now while a lot

11:05

of them terms the Drake equation

11:07

are quite well understood like how

11:09

many planets there are some of

11:11

them are less well understood like

11:13

and what's the probability of life

11:15

evolving on the planet. But

11:18

in recent years we've made

11:20

a lot of progress in understanding that

11:22

and I think we feel a lot

11:24

more comfortable now that life is probably

11:26

not as extremely unlikely as people once

11:28

thought. So he's saying we're feeling

11:30

good about the first part of the Drake equation which

11:32

Caitlin took us through but what about the

11:35

second part? So here the big question

11:37

is how much of the

11:39

life we find is intelligent

11:41

enough to make technology

11:43

that could send out signals?

11:46

Yeah so like they'd be able to send

11:48

out distant beeps in the darkness of space.

11:51

Exactly. So Eric says

11:53

to know how likely it is

11:55

that we'll hear a message from

11:57

another civilization and what that

11:59

civilization would be like. We

12:01

need to look at Earth starting

12:03

with the story of how we

12:05

evolved. Well the fun thing about

12:08

studying how animals evolve on Earth is that

12:11

evolution is something that is common throughout

12:13

the universe. This is the way that

12:15

life arises. It's the way that life

12:17

arose on Earth. It'll be the way

12:19

that life arose on other planets. So

12:22

he's saying if you know something about evolution

12:24

on our planet, you know something about evolution

12:27

on other planets. Exactly, and that

12:29

means what the planet is like shapes

12:31

what its life is like. The

12:33

way that animals look is

12:35

very very much dependent on the kind of

12:37

environment that they live in. So

12:39

whether we have alien fish on

12:41

a watery planet or alien birds

12:44

or both. Or more. Eric says

12:46

that our Earth rules of evolution

12:48

apply to other planets because we

12:50

think there are universal rules behind

12:52

how the universe works. Which

12:55

goes back to math. So we

12:57

know that these laws of evolution, these

12:59

are mathematical laws just like the laws

13:01

of physics and just like the laws

13:03

of physics apply everywhere. Math

13:06

applies everywhere. I guess that

13:08

makes math a good way to think about the

13:10

universe. Drake was really onto something. Right,

13:12

because if math is the

13:14

same everywhere it means evolution

13:16

is the same everywhere. And

13:18

Eric says that means intelligence

13:20

might come about the same

13:22

way it did on our

13:24

planet. And that starts with

13:26

living in groups. Once you

13:28

live in a group you have a

13:31

huge advantage because you can cooperate. Eric

13:39

says that living in groups things can

13:41

get complicated. You need communication.

13:43

You need communication to tell

13:46

the other person in your group that you

13:48

are happy or that you are angry with

13:50

them. Or the classic I'm not angry. I'm

13:53

just disappointed. No

13:55

one knows for sure how human

13:57

language evolved. But a popular theory

14:00

says that our lives in groups had a lot

14:02

to do with it. And

14:04

what seemed to happen with humans was

14:06

that when our ancestors reached a certain

14:09

level of complexity of the groups in

14:11

which they live, then

14:13

our own language evolved

14:15

and was born. And our communication became so

14:18

complex that we could somehow get to say

14:20

anything. And that's why there are so many

14:22

podcasts, and so few of them are hosted

14:24

by dogs. Exactly.

14:27

Which leads us to technology.

14:30

What aliens would need to make in

14:32

order for us to find them? We're

14:35

not going to hear from or

14:38

speak to another alien civilization

14:40

unless they can build technology.

14:43

And you can't really build technology on your own. You need to

14:45

live in a group. You need to have people to help

14:47

you build things and lift things and pass you the tools

14:49

and things like that. Passing the tools

14:52

is one of the more important roles there is.

14:54

But maybe aliens have so many hands that they

14:56

don't need anyone to do it. Beyond passing

14:58

the wrench, technology like ours is

15:00

a big group effort. So

15:02

does Eric think that it's likely that an intelligent

15:04

species would evolve to make technology, which would allow

15:06

us to find them? That's kind of the whole

15:08

point of this equation, right? Right.

15:10

So let's recap Eric's theory.

15:13

It seems that on any planet

15:15

on which there is life, eventually

15:18

there will be animals, and there will

15:20

be plants, or they're equivalent. And

15:23

there will be complex interactions between these,

15:25

including animals that have

15:27

complex social interactions and complex communication.

15:30

In other words, we can imagine that

15:32

alien life might follow our path. So

15:35

like eventually they'd invent the alien

15:38

internet in alien Instagram? Maybe.

15:40

What would they share? Hashtag

15:42

blerp-werk. And

15:45

it's tempting to say that given enough

15:47

time, a species that's capable

15:49

of building machines and radios and spaceships

15:51

and so on would evolve.

15:53

The key here, though, that doesn't think you're

15:55

in the drinking place is

15:58

to let you give in enough time. What

16:00

does he mean by that? Eventually, give it

16:03

enough time. Well, to find

16:05

the rare intelligent life in our

16:07

galaxy, humans also have to be

16:10

using technology at the same time.

16:12

And there's been a

16:14

lot of time in the universe.

16:17

It's been over three and a half billion years since

16:20

life arose on Earth. And

16:22

we've got no way of knowing whether

16:24

that's fast or slow or anything

16:27

else. So we could be like

16:30

two ships passing in the night. Maybe aliens

16:32

were looking for us billions of years ago

16:34

when we were still like little single celled

16:36

life forms. We'll just never know. Well,

16:39

unless we get a message from them like now. So

16:41

how likely is that? My own personal

16:43

guess is I think it's quite unlikely. Certainly

16:46

unlikely in my lifetime. But again,

16:48

it could happen tomorrow. I

16:52

think the takeaway here is we should always be

16:54

prepared for an alien message, but like not that

16:57

hard. The other takeaway is

16:59

that we may never solve the

17:01

drink equation. But using math gives

17:03

us a way to think about

17:05

a scientific problem in creating ways.

17:08

And that's why we should consider what

17:10

a scientist who studies animals has to

17:13

say about aliens. So

17:16

my ideas are not controversial, but

17:18

they're very unusual. Because

17:20

no one's got to the stage yet of thinking

17:22

about, wait a minute, how are these

17:24

animals interacting with the plants and with the other

17:26

animals and what's that going to do to evolution? We'll

17:29

just have a stage yet. I think

17:31

it's time. I think it's time we start thinking about that.

17:34

I mean, I guess when aliens come to Earth and abduct people,

17:36

we usually don't think of them as being part of a whole

17:38

food web. When

17:41

you're being beamed up, you're usually not like, hmm.

17:44

I wonder what kind of

17:46

ecosystem developed this technology. Maybe

17:50

it's time. So

18:00

how do you imagine alien environments? Draw

18:03

a picture. Think about the landscape of

18:05

your alien planet and draw the types

18:07

of plants and animals with light bulbs

18:09

who live there. Label the different

18:12

parts of your drawing to explain how those creatures

18:14

evolved. And think about the food webs that they're

18:16

part of. Maybe they have

18:18

like big giant teeth to eat big giant

18:20

animals that need to be captured with big giant

18:22

teeth. It could be anything. And

18:25

send us your drawings

18:27

to tumblrpodcastgmail.com. We'll pop

18:30

this email. Thanks

18:32

today to Dr. Caitlin Rasmussen,

18:35

astrobiologist at the University of

18:37

Washington and the Virtual Planet

18:39

Laboratory. And also author of

18:41

the forthcoming book, Life in

18:43

Seven Numbers, The Drake Equation,

18:45

revealed. Thanks also

18:47

to Dr. Eric Kirshambomb, zoologist at

18:49

Cambridge University and author of The

18:51

Zoologist's Guide to the Universe, What

18:54

Animals on Earth Reveal About Aliens,

18:56

and Ourselves. And special thanks to

18:58

Shepard and Madeline for sending in your

19:00

answers. You can hear

19:02

more from our interviews with Caitlin and Eric

19:04

in our bonus interview episode, available on Patreon

19:07

when you pledge just $1 or more a

19:09

month at patreon.com. We'll

19:12

also have free resources to learn

19:14

more on the blog on our

19:16

website at www.siliencepodcastforkids.com. Sarah

19:19

Roberson-Lence edited this episode and created the

19:21

episode Art. Elliot Hichaj was our

19:23

production assistant. And Gary Calhoun-James

19:25

engineered and mixed it. I'm Lindsay

19:27

Patterson and I wrote this episode along

19:30

with Sarah. I'm Marshall Escamilla

19:32

and I made all the music and sound

19:34

design for this episode. Tumble is a production

19:36

of Tumble Media. And now you can listen

19:38

to our podcast on Amazon Music, as well

19:40

as Spotify, Apple Podcasts, and wherever you get

19:42

your podcasts. Thanks for listening and

19:44

tune in next time for more stories of

19:46

science discoveries. It

20:00

is time for the patreon people we got a

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we go To Irene mom and

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dad love your kind heart and your curious

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Robert numbers happy birthday on December

20:13

12th Which is a great number

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12 12 and

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keep on working on those math problems Anaya

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and brings so much brilliance creativity and

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enjoy your birthday on December 13th with

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love from kaffa and mama Max

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mommy mama and lane love you so much

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Desmond to always stay curious your imagination

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will take you to millions of worlds

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in your mind and worlds even beyond

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Earth I know I've been to

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those happy birthday on December 16th Lots

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birthday on December 16th as well Finn

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