What is the coldest thing in the world? - Lina Marieth Hoyos

Translator: Jonathan Rebetz Reviewer: Polona Ramšak

The coldest materials in the world aren’t in Antarctica.

Najhladnejše snovi na svetu niso na Antarktiki.

They’re not at the top of Mount Everest

Niso na vrhu Mont Everesta

or buried in a glacier.

ali zakopane v ledenik.

They’re in physics labs:

So v fizikalnih laboratorijih:

clouds of gases held just fractions of a degree above absolute zero.

so oblaki plinov, ki jih ohranjajo le delček stopinje nad absolutno ničlo.

That’s 395 million times colder than your refrigerator,

To je 395-milijonkrat hladneje kot vaš hladilnik,

100 million times colder than liquid nitrogen,

100-milijonkrat hladneje kot tekoči dušik

and 4 million times colder than outer space.

in 4-milijonkrat hladneje kot vesolje.

Temperatures this low give scientists a window into the inner workings of matter,

Tako nizke temperature dajo znanstvenikom vpogled v notranje delovanje snovi

and allow engineers to build incredibly sensitive instruments

in omogočijo inženirjem, da sestavijo izjemno občutljive instrumente,

that tell us more about everything

ki nam povedo več o vsem

from our exact position on the planet

od našega točnega položaja na planetu

to what’s happening in the farthest reaches of the universe.

do tega, kaj se dogaja v najbolj oddaljenih kotičkih vesolja.

How do we create such extreme temperatures?

Kako pa ustvarimo tako ekstremne temperature?

In short, by slowing down moving particles.

Na kratko, tako da upočasnimo premikajoče se delce.

When we’re talking about temperature, what we’re really talking about is motion.

Ko govorimo o temperaturi, v resnici govorimo o gibanju.

The atoms that make up solids,

Atomi, ki so gradniki trdnih snovi, tekočin in plinov

liquids,

and gases

are moving all the time.

se nenehno premikajo.

When atoms are moving more rapidly, we perceive that matter as hot.

Ko se atomi snovi premikajo hitreje, dojemamo snov kot vročo.

When they’re moving more slowly, we perceive it as cold.

Ko se premikajo počasneje, jo dojemamo kot hladno.

To make a hot object or gas cold in everyday life,

Da ohladimo vroč predmet ali plin v vsakdanjem življenju,

we place it in a colder environment, like a refrigerator.

ga postavimo v hladnejše okolje, na primer v hladilnik.

Some of the atomic motion in the hot object is transferred to the surroundings,

Nekaj gibanja atomov v vročem predmetu se prenese v okolje

and it cools down.

in predmet se ohladi.

But there’s a limit to this:

Ampak pri tem obstaja omejitev.

even outer space is too warm to create ultra-low temperatures.

Celo vesolje je pretoplo, da bi ustvarilo ultra nizke temperature.

So instead, scientists figured out a way to slow the atoms down directly –

Namesto tega so se znanstveniki spomnili načina, da atome upočasnijo neposredno -

with a laser beam.

z laserskim žarkom.

Under most circumstances,

Pod običajnimi pogoji

the energy in a laser beam heats things up.

energija v laserskem žarku stvari segreje.

But used in a very precise way,

Ampak če jo uporabimo zelo natančno,

the beam’s momentum can stall moving atoms, cooling them down.

lahko žarkova gibalna količina ovira premikajoče se atome in jih ohlaja.

That’s what happens in a device called a magneto-optical trap.

To se zgodi v napravi, ki ji rečemo magnetno-optična past.

Atoms are injected into a vacuum chamber,

Atomi so vstavljeni v vakuumsko komoro,

and a magnetic field draws them towards the center.

kjer jih magnetno polje vleče proti središču.

A laser beam aimed at the middle of the chamber

Laserski žarek, namerjen v sredo komore,

is tuned to just the right frequency

je nastavljen na ravno pravo frekvenco,

that an atom moving towards it will absorb a photon of the laser beam and slow down.

da bo atom, ki se premika proti njemu, iz žarka absorbiral foton in se upočasnil.

The slow down effect comes from the transfer of momentum

Učinek upočasnitve izhaja iz prenosa gibalne količine

between the atom and the photon.

med atomom in fotonom.

A total of six beams, in a perpendicular arrangement,

Šest žarkov, razporejenih pravokotno,

ensure that atoms traveling in all directions will be intercepted.

poskrbi, da bodo prestreženi atomi, ko potujejo v kateri koli smeri.

At the center, where the beams intersect,

V središču, kjer se žarki stikajo,

the atoms move sluggishly, as if trapped in a thick liquid —

se atomi premikajo počasi, kot da bi bili ujeti v gosto tekočino.

an effect the researchers who invented it described as “optical molasses.”

To je učinek, ki so ga njegovi izumitelji opisali kot "optična melasa".

A magneto-optical trap like this

Takšnale magnetno-optična past

can cool atoms down to just a few microkelvins —

lahko ohladi atome na samo nekaj mikrokelvinov:

about -273 degrees Celsius.

to je približno -273 stopinj Celzija.

This technique was developed in the 1980s,

To tehniko so razvili v osemdesetih

and the scientists who'd contributed to it

in znanstveniki, ki so pri projektu pomagali,

won the Nobel Prize in Physics in 1997 for the discovery.

so za svoje odkritje dobili leta 1997 Nobelovo nagrado za fiziko.

Since then, laser cooling has been improved to reach even lower temperatures.

Od takrat so lasersko hlajenje izboljšali, da zdaj dosegajo še nižje temperature.

But why would you want to cool atoms down that much?

Ampak zakaj bi sploh želeli atome tako zelo ohladiti?

First of all, cold atoms can make very good detectors.

Prvič, hladni atomi zelo dobro zaznavajo.

With so little energy,

S tako malo energije

they’re incredibly sensitive to fluctuations in the environment.

so izredno občutljivi na nihanja v okolju.

So they’re used in devices that find underground oil and mineral deposits,

Uporabljajo se torej v napravah, ki iščejo podzemna nahajališča nafte in mineralov,

and they also make highly accurate atomic clocks,

in pa tudi v izjemno natančnih atomskih urah,

like the ones used in global positioning satellites.

kot tistih, ki jih najdemo v GPS satelitih.

Secondly, cold atoms hold enormous potential

Drugič, hladni atomi imajo izreden potencial

for probing the frontiers of physics.

za preizkušanje meja fizike.

Their extreme sensitivity makes them candidates

Zaradi izredne občutljivosti se lahko uporabljajo

to be used to detect gravitational waves in future space-based detectors.

za zaznavanje gravitacijskih valov v prihodnjih detektorjih v vesolju.

They’re also useful for the study of atomic and subatomic phenomena,

Ravno tako so uporabni za preučevanje atomskih in subatomskih pojavov,

which requires measuring incredibly tiny fluctuations in the energy of atoms.

kar zahteva merjenje izjemno majhnih nihanj v energiji atomov.

Those are drowned out at normal temperatures,

Ta se spregledajo pri normalni temperaturi atomov,

ko atomi brzijo naokrog s hitrostjo več sto metrov na sekundo.

when atoms speed around at hundreds of meters per second.

Laser cooling can slow atoms to just a few centimeters per second—

Lasersko hlajenje lahko atome upočasni do le nekaj centimetrov na sekundo -

enough for the motion caused by atomic quantum effects to become obvious.

dovolj, da postane očitno tisto gibanje, ki ga povzročijo atomski kvantni efekti.

Ultracold atoms have already allowed scientists to study phenomena

Ultrahladni atomi so znanstvenikom že omogočili študij pojavov,

like Bose-Einstein condensation,

kot je Bose-Einsteinovo kondenzacija,

in which atoms are cooled almost to absolute zero

v kateri se atomi ohladijo skoraj do absolutne ničle

and become a rare new state of matter.

in zavzamejo redko novo agregatno stanje.

So as researchers continue in their quest to understand the laws of physics

Medtem, ko se raziskovalci trudijo,

da bi razumeli fizikalne zakone in razkrili skrivnosti vesolja,

and unravel the mysteries of the universe,

they’ll do so with the help of the very coldest atoms in it.

jim bodo pri tem pomagali najhladnejši atomi, ki v vesolju obstajajo.