What a planet needs to sustain life | Dave Brain

Prevodilac: Milenka Okuka Lektor: Mile Živković

I'm really glad to be here.

Baš mi je drago što sam ovde.

I'm glad you're here,

Drago mi je što ste vi ovde,

because that would be a little weird.

inače bi bilo malčice čudno.

I'm glad we're all here.

Drago mi je što smo svi ovde.

And by "here," I don't mean here.

A pod "ovde", ne mislim na ovde.

Or here.

Ili ovde.

But here.

Već ovde.

I mean Earth.

Mislim na Zemlju.

And by "we," I don't mean those of us in this auditorium,

I pod "mi" ne mislim na nas u auditorijumu,

but life,

već na život,

all life on Earth --

sav život na Zemlji -

(Laughter)

(Smeh)

from complex to single-celled,

od složenog do jednoćelijskog,

from mold to mushrooms

od buđi preko pečuraka

to flying bears.

do letećih medveda.

(Laughter)

(Smeh)

The interesting thing is,

Zanimljivo

Earth is the only place we know of that has life --

da je Zemlja jedino poznato mesto na kom ima života -

8.7 million species.

8,7 miliona vrsta.

We've looked other places,

Tražili smo druga mesta,

maybe not as hard as we should or we could,

možda ne onoliko koliko smo trebali ili mogli,

but we've looked and haven't found any;

ali tražili smo i nismo našli bilo šta;

Earth is the only place we know of with life.

Zemlja je jedino nama poznato mesto sa životom.

Is Earth special?

Da li je Zemlja posebna?

This is a question I've wanted to know the answer to

Odgovor na ovo pitanje sam želeo da znam

since I was a small child,

od svog ranog detinjstva,

and I suspect 80 percent of this auditorium

i pretpostavljam da 80% ovog auditorijuma

has thought the same thing and also wanted to know the answer.

je pomislilo isto to i takođe je želelo da zna odgovor.

To understand whether there are any planets --

Da bismo razumeli ima li još nekih planeta -

out there in our solar system or beyond --

u našem solarnom sistemu i dalje -

that can support life,

koje mogu da održavaju život,

the first step is to understand what life here requires.

prvi korak je u razumevanju šta je neophodno za život.

It turns out, of all of those 8.7 million species,

Ispostavilo se da su za život svih 8,7 miliona vrsta

life only needs three things.

potrebne tri stvari.

On one side, all life on Earth needs energy.

S jedne strane, svem životu na Zemlji je potrebna energija.

Complex life like us derives our energy from the sun,

Složeni život poput našeg dobija energiju od sunca,

but life deep underground can get its energy

ali život duboko pod zemljom dobija energiju

from things like chemical reactions.

od, recimo, hemijskih reakcija.

There are a number of different energy sources

Ima više različitih izvora energije

available on all planets.

dostupnih na svim planetama.

On the other side,

S druge strane,

all life needs food or nourishment.

svem životu je potrebna hrana ili ishrana.

And this seems like a tall order, especially if you want a succulent tomato.

A ovo se čini kao težak zadatak, naročito ako želite sočan paradajz.

(Laughter)

(Smeh)

However, all life on Earth derives its nourishment

Međutim, sav život na Zemlji dobija hranu

from only six chemical elements,

iz svega šest hemijskih elemenata,

and these elements can be found on any planetary body

a ovi elementi su prisutni na bilo kojoj planeti

in our solar system.

u našem solarnom sistemu.

So that leaves the thing in the middle as the tall pole,

Te je zbog toga ovo u sredini težak zadatak,

the thing that's hardest to achieve.

nešto što je najteže postići.

Not moose, but water.

Ne los, već voda.

(Laughter)

(Smeh)

Although moose would be pretty cool.

Iako bi los bio baš super.

(Laughter)

(Smeh)

And not frozen water, and not water in a gaseous state, but liquid water.

I to ne zamrznuta voda, i ne voda u gasovitom stanju, već tečna voda.

This is what life needs to survive, all life.

Ovo je potrebno životu za opstanak, svem životu.

And many solar system bodies don't have liquid water,

A mnoga tela u solarnom sistemu nemaju tečnu vodu,

and so we don't look there.

te zato tamo ne tražimo život.

Other solar system bodies might have abundant liquid water,

Druga tela u solarnom sistemu mogu da imaju obilje tečne vode,

even more than Earth,

čak i više nego Zemlja,

but it's trapped beneath an icy shell,

ali je ona zarobljena ispod ledene opne,

and so it's hard to access, it's hard to get to,

te je teško njoj pristupiti, teško je doći do nje,

it's hard to even find out if there's any life there.

teško je čak i saznati da li tamo uopšte ima života.

So that leaves a few bodies that we should think about.

Stoga nam ostaje nekoliko tela o kojima bi trebalo da mislimo.

So let's make the problem simpler for ourselves.

Zato pojednostavimo problem zbog nas.

Let's think only about liquid water on the surface of a planet.

Razmišljajmo jedino o tečnoj vodi na površini planete.

There are only three bodies to think about in our solar system,

Možemo da razmišljamo o svega tri tela u našem solarnom sistemu,

with regard to liquid water on the surface of a planet,

u smislu tečne vode na površini planete,

and in order of distance from the sun, it's: Venus, Earth and Mars.

a prema udaljenosti od sunca to su: Venera, Zemlja i Mars.

You want to have an atmosphere for water to be liquid.

Potrebna vam je atmosfera da bi voda bila tečna.

You have to be very careful with that atmosphere.

Morate da budete veoma oprezni s tom atmosferom.

You can't have too much atmosphere, too thick or too warm an atmosphere,

Ne treba vam previše atmosfere, pregusta ili pretopla atmosfera

because then you end up too hot like Venus,

jer bi bilo suviše vrelo, kao na Veneri

and you can't have liquid water.

i ne biste imali tečnu vodu.

But if you have too little atmosphere and it's too thin and too cold,

Ali ako imate premalo atmosfere i ona je suviše retka i hladna,

you end up like Mars, too cold.

završite kao Mars, suviše hladni.

So Venus is too hot, Mars is too cold,

Dakle, Venera je pretopla, Mars je prehladan,

and Earth is just right.

a Zemlja je potaman.

You can look at these images behind me and you can see automatically

Posmatrajući ove slike iza mene, možete automatski da vidite

where life can survive in our solar system.

gde je moguć opstanak života u našem solarnom sistemu.

It's a Goldilocks-type problem,

To je tip problema "Zlatokosa",

and it's so simple that a child could understand it.

i toliko je jednostavan da dete može da ga razume.

However,

Međutim,

I'd like to remind you of two things

voleo bih da vas podsetim na dve stvari

from the Goldilocks story that we may not think about so often

iz priče o Zlatokosoj o kojima možda ne razmišljamo tako često,

but that I think are really relevant here.

ali smatram da su zaista važne ovde.

Number one:

Pod jedan:

if Mama Bear's bowl is too cold

ako je činija mame medved suviše hladna

when Goldilocks walks into the room,

kad Zlatokosa uđe u prostoriju,

does that mean it's always been too cold?

da li to znači da je oduvek bila hladna?

Or could it have been just right at some other time?

Ili je u nekom drugom vremenu bila baš kako treba?

When Goldilocks walks into the room determines the answer

Kad Zlatokosa uđe u prostoriju određuje odgovor

that we get in the story.

koji nam priča pruža.

And the same is true with planets.

A isto je tako i s planetama.

They're not static things. They change.

One nisu nešto statično. Menjaju se.

They vary. They evolve.

Variraju. Razvijaju se.

And atmospheres do the same.

A isto je i sa atmosferama.

So let me give you an example.

Stoga ću da vam dam jedan primer.

Here's one of my favorite pictures of Mars.

Ovo je među mojim omiljenim slikama Marsa.

It's not the highest resolution image, it's not the sexiest image,

Nije to slika naročito visoke rezolucije, nije ni naročito seksi,

it's not the most recent image,

nije najskorija slika,

but it's an image that shows riverbeds cut into the surface of the planet;

ali je slika koja pokazuje rečna korita kako seku površinu planete;

riverbeds carved by flowing, liquid water;

rečna korita koja je urezala tekuća, tečna voda;

riverbeds that take hundreds or thousands or tens of thousands of years to form.

korita koja su se oblikovala stotinama ili hiljadama ili desetinama hiljada godina.

This can't happen on Mars today.

Ovo više nije moguće na Marsu.

The atmosphere of Mars today is too thin and too cold

Danas je atmosfera na Marsu suviše retka i hladna

for water to be stable as a liquid.

da bi voda bila postojana kao tečnost.

This one image tells you that the atmosphere of Mars changed,

Ova slika vam govori da se atmosfera na Marsu promenila,

and it changed in big ways.

i to se promenila uveliko.

And it changed from a state that we would define as habitable,

A promenila se iz stanja koje bismo odredili kao nastanjivo,

because the three requirements for life were present long ago.

jer su tri uslova za život nekad davno bila prisutna.

Where did that atmosphere go

Gde je nestala ta atmosfera

that allowed water to be liquid at the surface?

koja je omogućavala vodi da bude tečna na površini?

Well, one idea is it escaped away to space.

Pa, jedna od ideja je da je izmakla u svemir.

Atmospheric particles got enough energy to break free

Atmosferske čestice su dobile dovoljno energije

from the gravity of the planet,

da se oslobode gravitacije planete,

escaping away to space, never to return.

izmičući u svemir, bespovratno.

And this happens with all bodies with atmospheres.

A to se dešava svim telima s atmosferama.

Comets have tails

Komete imaju repove

that are incredibly visible reminders of atmospheric escape.

koji su izuzetno očiti podsetnici izmicanja atmosfere.

But Venus also has an atmosphere that escapes with time,

Ali Venera takođe ima atmosferu koja vremenom izmiče,

and Mars and Earth as well.

kao i Mars i Zemlja.

It's just a matter of degree and a matter of scale.

Prosto se radi o stepenu i razmeri.

So we'd like to figure out how much escaped over time

Pa bismo voleli da otkrijemo koliko je izmaklo vremenom,

so we can explain this transition.

kako bismo mogli da objasnimo ovaj prelaz.

How do atmospheres get their energy for escape?

Kako atmosfere dobijaju energiju za beg?

How do particles get enough energy to escape?

Kako čestice dobiju dovoljno energije za beg?

There are two ways, if we're going to reduce things a little bit.

Postoje dva načina, ako bismo želeli da malo sažmemo stvari.

Number one, sunlight.

Prvo: sunčeva svetlost.

Light emitted from the sun can be absorbed by atmospheric particles

Svetlost koju odašilja sunce mogu da apsorbuju atmosferske čestice

and warm the particles.

čime se one zagrejavaju.

Yes, I'm dancing, but they --

Da, plešem, ali one -

(Laughter)

(Smeh)

Oh my God, not even at my wedding.

Oh, gospode, nisam ni na svom venčanju.

(Laughter)

(Smeh)

They get enough energy to escape and break free

Dobiju dovoljno energije da umaknu i oslobode se

from the gravity of the planet just by warming.

od gravitacije planete, pukim zagrevanjem.

A second way they can get energy is from the solar wind.

Drugi način na koji mogu da dobiju energiju je solarni vetar.

These are particles, mass, material, spit out from the surface of the sun,

Ovo su čestice, mase, materijali koje su ispljunute sa površine sunca

and they go screaming through the solar system

i one jurcaju kroz solarni sistem

at 400 kilometers per second,

400 kilometara u sekundi,

sometimes faster during solar storms,

ponekad i brže tokom solarnih oluja

and they go hurtling through interplanetary space

i one hrle kroz međuplanetarni prostor

towards planets and their atmospheres,

ka planetama i njihovim atmosferama,

and they may provide energy

a mogu i da pruže energiju

for atmospheric particles to escape as well.

atmosferskim česticama da bi i one umakle.

This is something that I'm interested in,

Ovo je nešto za šta sam zainteresovan

because it relates to habitability.

jer ima veze s nastanjivošću.

I mentioned that there were two things about the Goldilocks story

Pomenuo sam dve stvari iz priče o Zlatokosoj

that I wanted to bring to your attention and remind you about,

na koje želim da vam skrenem pažnju i da vas podsetim na njih,

and the second one is a little bit more subtle.

a druga je malčice finija.

If Papa Bear's bowl is too hot,

Ako je činija tate medveda suviše vrela,

and Mama Bear's bowl is too cold,

a činija mame medveda je suviše hladna,

shouldn't Baby Bear's bowl be even colder

zar ne bi trebalo da je činija bebe medveda čak i hladnija,

if we're following the trend?

ukoliko pratimo trend?

This thing that you've accepted your entire life,

Nešto što ste prihvatili čitav vaš život,

when you think about it a little bit more, may not be so simple.

kad razmislite o tome malo više, možda i nije tako prosto.

And of course, distance of a planet from the sun determines its temperature.

I naravno da udaljenost planete od sunca određuje njenu temperaturu.

This has to play into habitability.

Ovo se odražava na nastanjivost.

But maybe there are other things we should be thinking about.

Ali možda ima nešto drugo o čemu bi trebalo da mislimo.

Maybe it's the bowls themselves

Možda se radi o samim činijama

that are also helping to determine the outcome in the story,

koje takođe pomažu u određivanju ishoda priče,

what is just right.

šta je taman kako treba.

I could talk to you about a lot of different characteristics

Mogao bih mnogo da vam govorim o različitim osobinama

of these three planets

ove tri planete,

that may influence habitability,

koje možda utiču na nastanjivost,

but for selfish reasons related to my own research

ali iz sebičnih razloga u vezi s mojim istraživanjem,

and the fact that I'm standing up here holding the clicker and you're not --

i zbog činjenice da ja stojim ovde gore i držim daljinski, a ne vi -

(Laughter)

(Smeh)

I would like to talk for just a minute or two

želeo bih da govorim samo minut ili dva

about magnetic fields.

o magnetnim poljima.

Earth has one; Venus and Mars do not.

Zemlja ga ima; Venera i Mars nemaju.

Magnetic fields are generated in the deep interior of a planet

Magnetna polja nastaju u dubokoj unutrašnjosti planete

by electrically conducting churning fluid material

električnim provođenjem uskovitlanih tečnih materijala

that creates this big old magnetic field that surrounds Earth.

što stvara veliko staro magnetno polje koje okružuje Zemlju.

If you have a compass, you know which way north is.

Ako imate kompas, znate na kojoj strani je sever.

Venus and Mars don't have that.

Venera i Mars to nemaju.

If you have a compass on Venus and Mars,

Ako imate kompas na Veneri i Marsu,

congratulations, you're lost.

čestitam, zalutali ste.

(Laughter)

(Smeh)

Does this influence habitability?

Da li ovo utiče na nastanjivost?

Well, how might it?

Pa, kako bi moglo?

Many scientists think that a magnetic field of a planet

Mnogi naučnici smatraju da magnetno polje planete

serves as a shield for the atmosphere,

služi kao štit za atmosferu,

deflecting solar wind particles around the planet

koji odbija čestice solarnih vetrova oko planete

in a bit of a force field-type effect

u nekoj vrsti blagog efekta sile polja

having to do with electric charge of those particles.

koja je u vezi sa električnim nabojem tih čestica.

I like to think of it instead as a salad bar sneeze guard for planets.

Pre to vidim kao o zaklonu od kašlja za planete u vidu šanka za salatu.

(Laughter)

(Smeh)

And yes, my colleagues who watch this later will realize

I da, moje kolege, koje će ovo kasnije da gledaju, će uvideti

this is the first time in the history of our community

da je ovo prvi put u istoriji naše zajednice

that the solar wind has been equated with mucus.

da je solarni vetar poistovećen sa sluzi.

(Laughter)

(Smeh)

OK, so the effect, then, is that Earth may have been protected

U redu, posledica toga je da je Zemlja možda zaštićena

for billions of years,

milijardama godina

because we've had a magnetic field.

jer ima magnetno polje.

Atmosphere hasn't been able to escape.

Atmosfera nije mogla da umakne.

Mars, on the other hand, has been unprotected

Mars, s druge strane, je bio nezaštićen

because of its lack of magnetic field,

zbog nedostatka magnetnog polja,

and over billions of years,

i tokom milijardi godina

maybe enough atmosphere has been stripped away

je možda dovoljna količina atmosfere guljena

to account for a transition from a habitable planet

do te mere da on pređe iz nastanjive planete

to the planet that we see today.

do planete koju vidimo danas.

Other scientists think that magnetic fields

Drugi naučnici smatraju da magnetna polja

may act more like the sails on a ship,

možda deluju poput jedara na brodu,

enabling the planet to interact with more energy from the solar wind

koja omogućuju planeti da interaguje s više energije iz solarnih vetrova

than the planet would have been able to interact with by itself.

nego što bi planeta sama bila u stanju da interaguje.

The sails may gather energy from the solar wind.

Jedra možda sakupljaju energiju iz solarnog vetra.

The magnetic field may gather energy from the solar wind

Magnetno polje možda sakuplja energiju iz solarnog vetra

that allows even more atmospheric escape to happen.

koja omogućuje da se još više atmosferskog izmicanja desi.

It's an idea that has to be tested,

To je zamisao koja mora da se testira,

but the effect and how it works

ali njeni efekti i to kako deluje

seems apparent.

se čine očiglednim.

That's because we know

To je zato što znamo

energy from the solar wind is being deposited into our atmosphere

da se energija iz solarnog vetra skladišti u našoj atmosferi

here on Earth.

ovde na Zemlji.

That energy is conducted along magnetic field lines

Ta energija se sprovodi duž linija magnetnog polja

down into the polar regions,

dole do polarnih oblasti,

resulting in incredibly beautiful aurora.

rezultirajući predivnom polarnom svetlošću.

If you've ever experienced them, it's magnificent.

Ako ste to iskusili, veličanstveno je.

We know the energy is getting in.

Znamo da energija dolazi unutra.

We're trying to measure how many particles are getting out

Pokušavamo da izmerimo koliko čestica izlazi napolje

and if the magnetic field is influencing this in any way.

i da li magnetno polje na bilo koji način utiče na to.

So I've posed a problem for you here,

Dakle, postavio sam vam problem ovde,

but I don't have a solution yet.

ali još uvek nemam rešenje.

We don't have a solution.

Nemamo rešenje.

But we're working on it. How are we working on it?

Ali radimo na tome. Kako radimo na tome?

Well, we've sent spacecraft to all three planets.

Poslali smo kosmičke brodove na sve tri planete.

Some of them are orbiting now,

Neki od njih upravo kruže,

including the MAVEN spacecraft which is currently orbiting Mars,

uključujući svemirski brod MAVEN koji trenutno kruži oko Marsa,

which I'm involved with and which is led here,

u to sam uključen i time se upravlja odavde,

out of the University of Colorado.

sa Univerziteta u Koloradu.

It's designed to measure atmospheric escape.

Dizajniran je da meri atmosferska izmicanja.

We have similar measurements from Venus and Earth.

Imamo slična merenja sa Venere i Zemlje.

Once we have all our measurements,

Čim dobijemo sva merenja,

we can combine all these together, and we can understand

možemo da kombinujemo sve njih zajedno i možemo da razumemo

how all three planets interact with their space environment,

kako sve tri palente interaguju sa svojim svemirskim okruženjem,

with the surroundings.

sa okolinom.

And we can decide whether magnetic fields are important for habitability

I možemo da odredimo da li su magnetna polja važna za nastanjivost

or not.

ili nisu.

Once we have that answer, why should you care?

Zašto biste marili za taj odgovor?

I mean, I care deeply ...

Mislim, ja veoma marim...

And financially as well, but deeply.

I finansijski, ali veoma.

(Laughter)

(Smeh)

First of all, an answer to this question

Pre svega, odgovorom na ovo pitanje

will teach us more about these three planets,

ćemo više naučiti o ove tri planete,

Venus, Earth and Mars,

Veneri, Zemlji i Marsu,

not only about how they interact with their environment today,

ne samo kako interaguju trenutno sa svojim okruženjima,

but how they were billions of years ago,

već kakve su bile pre milijardu godina,

whether they were habitable long ago or not.

da li su nekad davno bile nastanjive ili ne.

It will teach us about atmospheres

Naučićemo o atmosferama

that surround us and that are close.

koje nas okružuju i koje su blizu.

But moreover, what we learn from these planets

Ali, štaviše, ono što naučimo od ovih planeta

can be applied to atmospheres everywhere,

može da se primeni na atmosfere svuda,

including planets that we're now observing around other stars.

uključujući planete koje trenutno posmatramo oko drugih zvezda.

For example, the Kepler spacecraft,

Na primer, kosmički brod Kepler,

which is built and controlled here in Boulder,

koji je napravljen i njime se upravlja odavde iz Boldera,

has been observing a postage stamp-sized region of the sky

posmatra predeo neba veličine poštanske markice

for a couple years now,

već nekoliko godina,

and it's found thousands of planets --

i otkrio je na hiljade planeta -

in one postage stamp-sized region of the sky

u jednom predelu neba veličine poštanske markice

that we don't think is any different from any other part of the sky.

koji ne smatramo iole različitim od bilo kog drugog dela neba.

We've gone, in 20 years,

Prešli smo, za 20 godina,

from knowing of zero planets outside of our solar system,

od poznavanja nula planeta van našeg solarnog sistema,

to now having so many,

do toga da ih imamo toliko,

that we don't know which ones to investigate first.

da ne znamo koje prvo da istražujemo.

Any lever will help.

Svako oruđe može da pomogne.

In fact, based on observations that Kepler's taken

Zapravo, na osnovu zapažanja koja je napravio Kepler,

and other similar observations,

i drugih sličnih zapažanja,

we now believe that,

trenutno verujemo da,

of the 200 billion stars in the Milky Way galaxy alone,

od 200 milijardi zvezda samo u galaksiji Mlečni put,

on average, every star has at least one planet.

u proseku, svaka zvezda ima bar jednu planetu.

In addition to that,

Uz to,

estimates suggest there are somewhere between 40 billion and 100 billion

procenjuje se da ima otprilike između 40 milijardi i 100 milijardi

of those planets that we would define as habitable

planeta koje bismo odredili kao nastanjive

in just our galaxy.

samo u našoj galaksiji.

We have the observations of those planets,

Imamo zapažanja s tih planeta,

but we just don't know which ones are habitable yet.

ali prosto još uvek ne znamo koje su nastanjive.

It's a little bit like being trapped on a red spot --

Pomalo podseća na zarobljenost na crvenoj tački -

(Laughter)

(Smeh)

on a stage

na sceni

and knowing that there are other worlds out there

i saznanje da postoje drugi svetovi tamo negde

and desperately wanting to know more about them,

i na očajničku želju da znate više o njima,

wanting to interrogate them and find out if maybe just one or two of them

želite da ih ispitate i otkrijete da li možda bar jedan ili dva od njih

are a little bit like you.

bar malo liče na vas.

You can't do that. You can't go there, not yet.

Ne možete to da učinite. Ne možete i dalje da odete tamo.

And so you have to use the tools that you've developed around you

Te morate da koristite oruđa oko vas koja ste razvili

for Venus, Earth and Mars,

za Veneru, Zemlju i Mars,

and you have to apply them to these other situations,

i morate da ih primenite u tim ostalim situacijama,

and hope that you're making reasonable inferences from the data,

i da se nadate da izvodite razumne zaključke iz podataka

and that you're going to be able to determine the best candidates

i da ćete biti u stanju da odredite najbolje kandidate

for habitable planets, and those that are not.

za nastanjive planete, i one koji to nisu.

In the end, and for now, at least,

I, naposletku, bar za sad,

this is our red spot, right here.

ovo je naša crvena tačka - tačno tu.

This is the only planet that we know of that's habitable,

Ovo je jedina planeta za koju znamo da je nastanjiva,

although very soon we may come to know of more.

iako ćemo veoma brzo saznati za mnoge druge.

But for now, this is the only habitable planet,

Ali za sad, ovo je jedina nastanjiva planeta

and this is our red spot.

i ovo je naša crvena tačka.

I'm really glad we're here.

Baš mi je drago da smo ovde.

Thanks.

Hvala.

(Applause)

(Aplauz)