Dark matter: The matter we can't see - James Gillies

Translator: Andrea McDonough Reviewer: Jessica Ruby

Prevoditelj: Katarina Mikjel Recezent: Ivan Stamenković

The ancient Greeks had a great idea:

Stari su Grci imali sjajnu ideju:

The universe is simple.

svemir je jednostavan.

In their minds,

Mislili su

all you needed to make it were four elements:

da se sastoji od samo 4 elementa:

earth,

zemlje,

air,

fire,

zraka,

vatre

and water.

i vode.

As theories go, it's a beautiful one.

Lijepa je to teorija.

It has simplicity and elegance.

Jednostavna i elegantna.

It says that by combining

Prema njoj, različitim

the four basic elements in different ways,

kombinacijama četiri osnovna elementa

you could produce all the wonderful diversity of the universe.

nastaje sva divna raznolikost svemira.

Earth and fire, for example,

Zemlja i vatra, na primjer,

give you things that are dry.

tvore suhe stvari.

Air and water, things that are wet.

Zrak i voda – vlažne stvari.

But as theories go, it had a problem.

Ipak, postojao je problem s tom teorijom.

It didn't predict anything that could be measured,

Nije predviđala ništa što je moguće mjeriti,

and measurement is the basis of experimental science.

a mjerenja su osnova eksperimentalne znanosti.

Worse still, the theory was wrong.

Još gore, teorija je bila pogrešna.

But the Greeks were great scientists of the mind

No Grci su bili sjajni znanstveni mislioci

and in the 5th century B.C.,

te je u 5. stoljeću pr. Kr.

Leucippus of Miletus came up

Leukipu iz Mileta pala na um

with one of the most enduring scientific ideas ever.

jedna od najtrajnijih znanstvenih ideja u povijesti.

Everything we see is made up

Sve što vidimo sastoji se

of tiny, indivisible bits of stuff called atoms.

od sićušnih, nedjeljivih djelića tvari koji se nazivaju atomima.

This theory is simple and elegant,

I ova je teorija jednostavna i elegantna,

and it has the advantage

ali, za razliku

over the earth, air, fire, and water theory

od teorije zemlje, zraka, vatre i vode,

of being right.

ona je i točna.

Centuries of scientific thought and experimentation

Stoljeća znanstvene misli i eksperimentiranja

have established that the real elements,

utvrdila su da je prave elemente,

things like hydrogen,

kao što su vodik,

carbon,

and iron,

ugljik

i željezo,

can be broken down into atoms.

moguće rastaviti na atome.

In Leucippus's theory, the atom is the smallest,

Prema Leukipovoj teoriji atom je najmanji,

indivisible bit of stuff that's still recognizable

nedjeljivi djelić tvari koji i dalje ima osobine

as hydrogen,

vodika,

carbon,

ugljika

or iron.

ili željeza.

The only thing wrong with Leucippus's idea

Jedina je pogreška u Leukipovoj ideji

is that atoms are, in fact, divisible.

to što su atomi zapravo djeljivi.

Furthermore, his atoms idea turns out

Osim toga, njegova ideja o atomima

to explain just a small part

tek u maloj mjeri objašnjava

of what the universe is made of.

od čega se sve svemir sastoji.

What appears to be the ordinary stuff of the universe

Ono što nam se čini uobičajenim dijelom svemira

is, in fact, quite rare.

ustvari je prilično rijetko.

Leucippus's atoms, and the things they're made of,

Leukipovi atomi, i njihovi dijelovi

actually make up only about 5%

zapravo čine samo oko 5 %

of what we know to be there.

poznatog dijela svemira.

Physicists know the rest of the universe,

Fizičari smatraju

95% of it,

preostalih 95 %

as the dark universe,

tamnim svemirom,

made of dark matter and dark energy.

sastavljenim od tamne tvari i tamne energije.

How do we know this?

Kako to znamo?

Well, we know because we look at things

Pa, znamo jer gledamo u stvari

and we see them.

i vidimo ih.

That might seem rather simplistic,

To možda zvuči površno,

but it's actually quite profound.

no zapravo je vrlo duboko.

All the stuff that's made of atoms is visible.

Sve stvari sastavljene od atoma vidljive su.

Light bounces off it, and we can see it.

Odbijaju svjetlost, pa ih možemo vidjeti.

When we look out into space,

Kad gledamo u svemir,

we see stars and galaxies.

vidimo zvijezde i galaktike.

Some of them, like the one we live in,

Neke od njih, poput ove u kojoj živimo,

are beautiful, spiral shapes, spinning gracefully through space.

prekrasnog su spiralnog oblika i graciozno se vrte svemirom.

When scientists first measured the motion

Kad su znanstvenici prvi put mjerili

of groups of galaxies in the 1930's

kretanje skupina galaktika u 1930-ima

and weighed the amount of matter they contained,

i izmjerili količinu tvari koju one sadržavaju,

they were in for a surprise.

iznenadili su se.

They found that there's not enough visible stuff

Otkrili su nedovoljno vidljive tvari

in those groups to hold them together.

u tim skupinama da bi ih držala na okupu.

Later measurements of individual galaxies

Kasnija su mjerenja pojedinačnih galaktika

confirmed this puzzling result.

potvrdila taj zbunjujući rezultat.

There's simply not enough visible stuff in galaxies

U galaktikama nema dovoljno vidljive tvari

to provide enough gravity to hold them together.

koja bi osigurala gravitaciju što ih drži na okupu.

From what we can see,

Iz toga slijedi da

they ought to fly apart, but they don't.

bi se trebale raspasti, no to se ne događa.

So there must be stuff there

Znači, postoji nešto

that we can't see.

što ne vidimo.

We call that stuff dark matter.

To nešto nazivamo tamnom tvari.

The best evidence for dark matter today

Najbolji dokaz postojanja tamne tvari

comes from measurements of something

pružaju mjerenja kozmičkog

called the cosmic microwave background,

pozadinskog mikrovalnog zračenja,

the afterglow of the Big Bang,

zaostalog odbljeska Velikog praska,

but that's another story.

no to je druga priča.

All of the evidence we have

Svi dokazi upućuju na to

says that dark matter is there

da tamna tvar postoji

and it accounts for much of the stuff

i tvori veći dio

in those beautiful spiral galaxies

prekrasnih spiralnih galaktika

that fill the heavens.

što ispunjavaju nebo.

So where does that leave us?

Koji je, dakle, zaključak?

We've long known that the heavens

Već dugo znamo da se nebesa

do not revolve around us

ne okreću oko nas

and that we're residents of a fairly ordinary planet,

i da nastavamo prilično običan planet,

orbiting a fairly ordinary star,

koji kruži oko obične zvijezde

in the spiral arm of a fairly ordinary galaxy.

u spiralnom rukavcu prilično obične galaktike.

The discovery of dark matter took us

Otkriće tamne tvari odvelo nas je

one step further away from the center of things.

korak dalje od središta svega.

It told us that the stuff we're made of

Pokazalo nam je da je ono

is only a small fraction of what makes up the universe.

od čega smo sačinjeni samo djelić onoga od čega se sastoji svemir.

But there was more to come.

No to nije bilo sve.

Early this century,

Početkom stoljeća

scientists studying the outer reaches of the universe

proučavanjem dalekih predjela svemira znanstvenici

confirmed that not only is everything moving apart

su potvrdili ne samo da se sve odmiče

from everything else,

od svega ostalog,

as you would expect in a universe

što se i očekuje u svemiru

that began in hot, dense big bang,

nastalom vrućim, gustim velikim praskom,

but that the universe's expansion

već i da se širenje svemira

also seems to be accelerating.

naizgled ubrzava.

What's that about?

O čemu je riječ?

Either there is some kind of energy

Ili postoji neka vrsta energije

pushing this acceleration,

koja potiče to ubrzavanje,

just like you provide energy to accelerate a car,

kao što se automobil ubrzava s pomoću energije,

or gravity does not behave exactly as we think.

ili gravitacija ne djeluje onako kako mislimo.

Most scientists think it's the former,

Većina znanstvenika misli da je u pitanju ovo prvo,

that there's some kind of energy driving the acceleration,

tj. da je uzrok tom ubrzanju neka vrsta energije

and they called it <i>dark energy</i>.

koju nazivaju tamnom energijom.

Today's best measurements allow us to work out

Najbolja današnja mjerenja pokazuju

just how much of the universe is dark.

koliki je dio svemira taman.

It looks as if dark energy makes up

Izgleda da tamna energija čini

about 68% of the universe

oko 68 % svemira,

and dark matter about 27%,

a tamna tvar oko 27 %,

leaving just 5% for us

što ostavlja samo 5 % za nas

and everything else we can actually see.

i sve ostalo što doista vidimo.

So what's the dark stuff made of?

Od čega se sastoji tamna tvar?

We don't know,

but there's one theory, called <i>supersymmetry</i>,

Ne znamo,

ali postoji teorija tzv. supersimetrije,

that could explain some of it.

koja bi to mogla donekle objasniti.

Supersymmetry, or SUSY for short,

Supersimetrija (skraćeno SUSY)

predicts a whole range of new particles,

predviđa cijeli niz novih čestica

some of which could make up the dark matter.

od kojih neke možda tvore tamnu tvar.

If we found evidence for SUSY,

Dokažemo li SUSY,

we could go from understanding 5% of our universe,

mogli bismo, umjesto 5 % našeg svemira,

the things we can actually see,

onoga što zapravo vidimo,

to around a third.

razumjeti otprilike trećinu.

Not bad for a day's work.

Nije loše za tako kratko vrijeme.

Dark energy would probably be harder to understand,

Tamnu energiju vjerojatno bi bilo teže shvatiti,

but there are some speculative theories out there

no postoje spekulativne teorije

that might point the way.

koje nas mogu usmjeriti.

Among them are theories that go back

Među njima su teorije koje

to that first great idea of the ancient Greeks,

se vraćaju na onu prvu sjajnu ideju starih Grka,

the idea that we began with several minutes ago,

ideju kojom smo prije nekoliko minuta započeli:

the idea that the universe must be simple.

da svemir mora biti jednostavan.

These theories predict that there is just a single element

Prema njima postoji samo jedan element

from which all the universe's wonderful diversity stems,

od kojeg potječe sva prekrasna raznolikost svemira:

a vibrating string.

vibrirajuća struna.

The idea is that all the particles we know today

Ideja je da su sve danas poznate čestice

are just different harmonics on the string.

samo različite frekvencije na struni.

Unfortunately, string theories today

Nažalost, teorije struna

are, as yet, untestable.

još je nemoguće testirati.

But, with so much of the universe waiting to be explored,

No budući da je dobar dio svemira neistražen,

the stakes are high.

ulozi su visoki.

Does all of this make you feel small?

Osjećate li se zbog toga neznatnim?

It shouldn't.

Ne biste trebali.

Instead, you should marvel

Naprotiv, treba vas zadiviti

in the fact that, as far as we know,

činjenica da, koliko znamo,

you are a member of the only species in the universe

pripadate jedinoj vrsti u svemiru

able even to begin to grasp its wonders,

koja može barem donekle dokučiti njegova čudesa

and you're living at the right time

i živite u vremenu u kojem

to see our understanding explode.

možete svjedočiti naglom porastu naših spoznaja.