All language subtitles for How the Universe Works S01E03 Galaxies 1080p ENG

>> Narrator: BILLIONS AND

BILLIONS OF GALAXIES -- THE

UNIVERSE IS SO VAST, WE CAN'T

EVEN IMAGINE WHAT THOSE NUMBERS

MEAN.

BUT 14 BILLION YEARS AGO, NONE

OF IT EXISTED...UNTIL THE BIG

BANG.

>> THE BIG BANG IS THE ORIGIN OF

SPACE AND THE ORIGIN OF TIME

ITSELF.

>> Narrator: WE TAKE A JOURNEY

THROUGH SPACE AND TIME, FROM

THE BEGINNING TO THE END OF THE

UNIVERSE ITSELF.

-- Captions by VITAC --
www.vitac.com

THIS IS OUR WORLD.

CITIES...FORESTS...

OCEANS...PEOPLE -- EVERYTHING IN

THE UNIVERSE IS MADE FROM MATTER

CREATED IN THE FIRST SECONDS OF

THE BIG BANG...

...EVERY STAR, EVERY PLANET,

EVERY ATOM, EVERY BLADE OF

GRASS, EVERY DROP OF WATER.

>> WATER IS ANCIENT.

THE HYDROGEN ATOMS IN HERE WERE

BORN MOMENTS AFTER THE BIG BANG.

THEN CAME EVERYTHING ELSE.

>> Narrator: THE BIG BANG IS THE

DEFINING EVENT OF OUR

UNIVERSE...AND EVERYTHING IN IT.

THE SECRETS OF OUR PAST, OUR

PRESENT, AND OUR FUTURE ARE

LOCKED INSIDE THIS ONE MOMENT IN

TIME.

TO UNLOCK THE SECRETS OF THE BIG

BANG, WE HAVE TO TRAVEL OUTSIDE

OF OUR OWN SOLAR SYSTEM...

AND JOURNEY BEYOND EVEN OUR OWN

GALAXY.

AS WE TRAVEL INTO DEEP SPACE,

WE'RE ACTUALLY SEEING INTO THE

PAST...AND GETTING CLOSER TO

BEING ABLE TO WITNESS THE DAWN

OF TIME ITSELF.

PASSING THE FIRST INFANT

GALAXIES AND THE FIRST STARS...

WE ARRIVE BACK AT THE MOMENT THE

UNIVERSE BEGAN AND FACE THE

BIGGEST QUESTIONS IN ALL OF

SCIENCE.

>> THIS IS THE HOLY GRAIL OF

PHYSICS.

WE WANT TO KNOW WHY IT BANGED.

WE WANT TO KNOW WHAT BANGED.

WE WANT TO KNOW WHAT WAS THERE

BEFORE THE BANG.

>> Narrator: TO GET THE ANSWERS,

WE'VE BUILT MACHINES THE SIZE OF

CITIES TO SIMULATE CONDITIONS

WHEN THE UNIVERSE WAS CREATED...

AND SPACE TELESCOPES TO PEER

DEEP INTO OUR PAST.

>> WE ARE GETTING CLOSE TO

ANSWERING THE OLD-AGE QUESTIONS.

WHY ARE WE HERE?

WHERE DID WE COME FROM?

DOES THE UNIVERSE IN FACT HAVE A

BEGINNING OR AN END?

AND, IF SO, WHAT ARE THEY LIKE?

IF WE FIND THE ANSWER TO THAT,

IT WOULD BE THE ULTIMATE TRIUMPH

OF HUMAN REASON.

WE WOULD KNOW THE MIND OF GOD.

>> Narrator: THE ORIGIN OF THE

BIG BANG IS THE GREATEST MYSTERY

OF ALL TIME.

AND THE MORE WE LEARN, THE

DEEPER THE MYSTERY BECOMES.

>> WE LIKE TO THINK THAT OUR

UNIVERSE IS UNIQUE.

HOWEVER, NOW WE'RE NOT SO SURE.

PERHAPS THERE IS A MULTIVERSE OF

UNIVERSES.

>> ANOTHER POSSIBILITY IS THAT

OUR BIG BANG IS JUST ONE OF MANY

BIG BANGS, BUT IT MAY BE ONE OF

JUST AN INFINITE NUMBER OF

UNIVERSES.

AND THERE MAY BE OTHER REGIONS

IN THAT INFINITE NUMBER OF

UNIVERSES WHERE A BIG BANG IS

JUST HAPPENING TODAY.

>> Narrator: BUT THERE'S ONLY

ONE UNIVERSE WE'RE SURE OF, AND

UNDERSTANDING THIS ONE IS HARD

ENOUGH.

SINCE THE LATE 1920s, EVERYTHING

WE KNOW ABOUT HOW OUR UNIVERSE

WORKS HAS BEEN TURNED UPSIDE

DOWN.

>> IT'S IMPORTANT TO REALIZE HOW

MUCH OUR PICTURE OF THE UNIVERSE

HAS CHANGED IN THE LAST CENTURY.

AT THE BEGINNING OF THE

20th CENTURY, THE CONVENTIONAL

WISDOM IN SCIENCE WAS THAT THE

UNIVERSE WAS STATIC AND ETERNAL.

>> Narrator: IN 1929, THAT ALL

CHANGED.

AT THE MOUNT WILSON OBSERVATORY

ABOVE LOS ANGELES, ASTRONOMER

EDWIN HUBBLE DISCOVERED GALAXIES

AREN'T STUCK IN ONE PLACE.

NOT ONLY ARE THEY MOVING, BUT

THEY'RE FLYING AWAY FROM EARTH

AT INCREDIBLE SPEEDS.

THIS WAS THE FIRST REAL EVIDENCE

OF THE BIG BANG.

>> ALL GALAXIES ON AVERAGE ARE

MOVING AWAY FROM US, AND,

STRANGER STILL, THOSE THAT WERE

TWICE AS FAR AWAY WERE MOVING

TWICE AS FAST.

AND THOSE THAT WERE THREE TIMES

AS FAR AWAY WERE MOVING THREE

TIMES AS FAST, AND SO ON.

EVERYTHING WAS MOVING AWAY FROM

US.

>> Narrator: IT BECAME KNOWN AS

HUBBLE'S LAW.

HIS DISCOVERY IS STILL THE

STARTING POINT FOR EXPLORATION

OF THE BIG BANG.

>> WHAT HUBBLE CONVINCINGLY

DEMONSTRATED, BY SEEING THE

MOTION OF THOSE GALAXIES, IS

THAT THE UNIVERSE IS EXPANDING.

>> Narrator: THEORETICALLY, AN

EXPANDING UNIVERSE MUST HAVE

STARTED FROM A SINGLE POINT.

BY MEASURING HOW FAST THE

UNIVERSE IS EXPANDING,

ASTRONOMERS CALCULATED

BACKWARDS AND FIGURED OUT WHEN

IT BURST INTO LIFE.

>> PEOPLE ASK THE QUESTION,

"HOW DO YOU KNOW THAT THE

UNIVERSE IS 13.7 BILLION YEARS

OLD?

I MEAN, SMARTY-PANTS, YOU

WEREN'T THERE 13.7 BILLION YEARS

AGO."

WELL, WHEN YOU WATCH TELEVISION

ON VIDEOTAPE, YOU HIT THE STOP

BUTTON WHEN YOU SEE AN

EXPLOSION, AND YOU CAN RUN IT

BACKWARDS AND SEE WHEN IT

ACTUALLY TOOK PLACE.

THE SAME THING TAKES PLACE WITH

COSMOLOGY.

WE CAN RUN THE VIDEOTAPE

BACKWARDS AND THEN CALCULATE

WHEN IT ALL CAME FROM A COSMIC

EXPLOSION.

>> Narrator: YOU DON'T HAVE TO

BE AN ASTRONOMER TO LOOK BACK IN

TIME.

IF YOU GAZE UP AT THE NIGHT SKY,

YOU'RE SEEING STARS THAT ARE

MILLIONS OF LIGHT-YEARS AWAY,

MEANING IT TOOK THE LIGHT FROM

THOSE STARS MILLIONS OF YEARS TO

GET HERE.

SO IF YOU LOOK FAR ENOUGH, YOU

SHOULD BE ABLE TO SEE THE

BEGINNING OF THE UNIVERSE.

NAMED FOR THE GROUNDBREAKING

ASTRONOMER, THE HUBBLE SPACE

TELESCOPE ALLOWS US TO LOOK DEEP

INTO THE UNIVERSE, BACK IN TIME,

AND CLOSER TO THE MOMENT OF THE

BIG BANG.

BUT FOR SCIENTISTS, WINDING BACK

THE CLOCK TO THE BIG BANG WAS

ONLY THE FIRST STEP.

>> WHEN PEOPLE FIRST HEAR ABOUT

THE BIG BANG THEORY, THEY SAY,

WELL, WHERE DID IT TAKE PLACE?

IT TOOK PLACE OVER THERE.

IT TOOK PLACE OVER THERE.

WHERE DID IT TAKE PLACE?

ACTUALLY, IT TOOK PLACE

EVERYWHERE, BECAUSE THE UNIVERSE

ITSELF WAS EXTREMELY SMALL AT

THAT TIME.

>> Narrator: THESE ARE ONLY SOME

OF THE MOST ABSTRACT AND

DIFFICULT CONCEPTS THERE ARE.

SO HERE'S A MIND-BENDER.

WHAT CAME BEFORE THE BIG BANG?

>> THE PHILOSOPHERS IN ANCIENT

TIMES USED TO SAY HOW COULD

SOMETHING ARISE FROM NOTHING?

AND WHAT'S AMAZING TO ME IS THAT

THE LAWS OF PHYSICS ALLOW THAT

TO HAPPEN.

AND IT MEANS THAT OUR WHOLE

UNIVERSE, EVERYTHING WE SEE,

EVERYTHING THAT MATTERS TO US

TODAY, COULD HAVE ARISEN OUT OF

PRECISELY NOTHING.

>> Narrator: IT'S ONE OF THE

BIGGEST HURDLES TO UNDERSTANDING

THE BIG BANG.

FIRST YOU HAVE TO BUY INTO THE

PREMISE THAT SOMETHING WAS

CREATED OUT OF NOTHING.

>> IT'S IMPOSSIBLE TO DESCRIBE

THE MOMENT OF CREATION IN HUMAN

LANGUAGE.

ALL WE KNOW IS THAT FROM WHAT

MAY HAVE BEEN NOTHING, WE GO TO

A STATE OF...ALMOST INFINITE

DENSITY AND INFINITE TEMPERATURE

AND INFINITE VIOLENCE.

>> Narrator: UNDERSTANDING HOW

NOTHING TURNED INTO SOMETHING

MAY BE THE GREATEST MYSTERY OF

OUR UNIVERSE.

BUT IF YOU UNDERSTAND THAT, YOU

START TO UNDERSTAND THE BIG

BANG, WHEN TIME AND SPACE BEGAN,

AND THE GREAT BIG EXPLOSION

CREATED EVERYTHING.

>> Narrator: AT THE DAWN OF

TIME, THE UNIVERSE EXPLODES INTO

EXISTENCE FROM ABSOLUTELY

NOTHING INTO EVERYTHING.

BUT EVERYTHING IS ACTUALLY A

SINGLE POINT, INFINITELY SMALL,

UNIMAGINABLY HOT, A SUPER-DENSE

SPECK OF PURE ENERGY.

>> THE BIG BANG WAS SO IMMENSE

THAT IT BROUGHT INTO EXISTENCE

ALL OF THE MASS AND ALL OF THE

ENERGY CONTAINED IN ALL OF THE

400 BILLION GALAXIES WE SEE IN

OUR UNIVERSE IN A REGION SMALLER

THAN THE SIZE OF A SINGLE ATOM.

THE ENTIRE OBSERVABLE UNIVERSE

WAS A MILLIONTH OF A BILLIONTH

OF A CENTIMETER ACROSS AT THAT

TIME.

EVERYTHING WAS COMPRESSED INTO

AN INCREDIBLY HOT, DENSE REGION.

>> Narrator: IT'S NOT EVEN

MATTER YET, JUST A POINT OF

RAGING ENERGY.

IT WAS THE BEGINNING OF THE

UNIVERSE AND EVERYTHING IN IT.

>> EVERYTHING WAS SIMPLE.

ALL THE FORCES THAT WE KNOW

ABOUT TODAY WERE ONE AND THE

SAME.

THE UNIVERSE WAS AMORPHOUS.

IT HAD NO STRUCTURE.

>> Narrator: IN THAT INSTANT OF

CREATION, ALL THE LAWS OF

PHYSICS, THE VERY FORCES THAT

ENGINEER OUR UNIVERSE, BEGAN TO

TAKE SHAPE.

THE FIRST FORCE TO EMERGE WAS

GRAVITY.

THE FATE OF THE UNIVERSE -- ITS

SIZE, STRUCTURE, AND EVERYTHING

IN IT -- WAS DECIDED IN THAT

MOMENT.

CARLOS FRENK STUDIES HOW GRAVITY

SHAPED THE UNIVERSE BY CREATING

ARTIFICIAL UNIVERSES IN THIS

SUPERCOMPUTER.

HE GIVES EACH ONE A DIFFERENT

AMOUNT OF GRAVITY.

THE FIRST ONE HE TRIED HAD TOO

LITTLE, RESULTING IN, WELL,

NOTHING.

>> GRAVITY HAS SAVED OUR

UNIVERSE, FOR IF GRAVITY WAS

WEAKER THAN IT IS, WE WOULD HAVE

A VERY BORING UNIVERSE IN WHICH

EVERYTHING WOULD BE FLYING APART

SO FAST THAT THERE WOULD BE NO

GALAXIES FORMING.

>> Narrator: NEXT, HE PROGRAMMED

A UNIVERSE WITH TOO MUCH

GRAVITY.

>> IF GRAVITY WAS STRONGER THAN

WE THINK IT IS, AGAIN, WE'LL END

UP WITH A FAILED UNIVERSE.

EVERYTHING WILL END UP IN BLACK

HOLES.

IT HAS TO BE JUST SO.

IT HAS TO BE JUST RIGHT.

>> Narrator: LUCKY FOR US, THE

BIG BANG GOT IT JUST RIGHT --

THE PERFECT AMOUNT OF GRAVITY.

IN THE TURMOIL OF FORCES AFTER

GRAVITY EMERGED, STILL A

FRACTION OF A SECOND AFTER THE

BIG BANG, A SHOCK WAVE OF ENERGY

ERUPTED AND EXPANDED THE

UNIVERSE IN ALL DIRECTIONS AT

INCREDIBLE SPEED.

>> ALL OF SPACE EXPANDED BY AN

UNBELIEVABLY LARGE FACTOR IN A

FRACTION OF A SECOND.

WE THINK THAT IN LESS THAN A

MILLIONTH OF A MILLIONTH OF A

MILLIONTH OF A MILLIONTH OF

A SECOND, SPACE EXPANDED BY A

FACTOR BIGGER THAN A MILLION,

MILLION, MILLION, MILLION TIMES.

>> Narrator: AND FOR THE RECORD,

THAT'S FASTER THAN THE SPEED OF

LIGHT.

BUT, WAIT, DOESN'T THAT BREAK

ONE OF THE LAWS OF PHYSICS?

>> EVEN SCHOOLCHILDREN KNOW

THAT, "YOU CAN'T GO FASTER THAN

THE SPEED OF LIGHT."

BUT I SAY THERE'S A LOOPHOLE

THERE.

YOU SEE, NOTHING CAN GO FASTER

THAN LIGHT, NOTHING BEING EMPTY

SPACE.

>> Narrator: DON'T WORRY.

THIS IDEA GIVES EVEN THE BEST

MINDS IN SCIENCE A HEADACHE.

BUT IT'S CRITICAL TO

UNDERSTANDING THE EARLY

UNIVERSE.

SCIENTISTS THINK IT TOOK LESS

THAN A MILLIONTH OF A MILLIONTH

OF A MILLIONTH OF A MILLIONTH OF

A SECOND FOR THE UNIVERSE TO

EXPAND FROM THE SIZE OF AN ATOM

TO A BASEBALL.

THAT MAY NOT SOUND LIKE MUCH,

BUT IT'S LIKE A GOLF BALL

EXPANDING TO THE SIZE OF THE

EARTH IN THE SAME AMOUNT OF

TIME.

THAT MEANS IT WAS EXPANDING

FASTER THAN THE SPEED OF LIGHT.

THAT'S FAST.

>> SO MANY THINGS WERE HAPPENING

SO FAST IN THE EARLY UNIVERSE,

BECAUSE EVERYTHING WAS SO CLOSE

TOGETHER, THAT WE NEEDED A NEW

UNIT OF TIME TO DESCRIBE THINGS.

>> Narrator: IT'S CALLED PLANCK

TIME.

TO UNDERSTAND JUST HOW SHORT A

PLANCK TIME IS, CONSIDER THIS.

THERE ARE MORE UNITS OF PLANCK

TIME IN ONE SECOND THAN ALL THE

SECONDS SINCE THE BIG BANG.

THE MATH IS MIND-BLOWING.

THERE ARE MORE THAN 31 MILLION

SECONDS IN A YEAR, AND IT'S BEEN

14 BILLION YEARS SINCE THE BIG

BANG.

SO MULTIPLY 31,556,926 BY

14 BILLION, AND WHAT YOU GET IS

A REALLY BIG NUMBER.

>> IT'S A TIME SCALE THAT'S SO

SMALL THAT ALL HUMAN INTUITION

GOES OUT THE WINDOW.

IF WE LOOK AT OUR WATCHES AND

MEASURE ONE SECOND, WE CAN ASK,

HOW MANY PLANCK TIMES IS THAT?

WELL, IT IS A BILLION, BILLION,

BILLION, BILLION, BILLION

PLANCK TIMES.

>> Narrator: SO, NOW THE BIG

BANG IS ONLY A FEW PLANCK TIMES

OLD, AN EXPLODING MASS OF PURE

ENERGY EXPANDING FASTER THAN THE

SPEED OF LIGHT.

IN THE NEXT FEW PLANCK TIMES,

THE UNIVERSE AS WE KNOW IT WILL

BE BORN.

>> Narrator: A FRACTION OF A

SECOND AFTER THE BIG BANG, THE

UNIVERSE IS SO SMALL IT CAN FIT

IN THE PALM OF YOUR HAND.

BUT IN ANOTHER TINY FRACTION OF

A SECOND, IT EXPANDS TO THE SIZE

OF THE EARTH.

THEN, MOVING FASTER THAN THE

SPEED OF LIGHT, IT GROWS LARGER

THAN OUR SOLAR SYSTEM.

AND IT'S STILL JUST A RAGING

STORM OF SUPERHEATED ENERGY.

>> IT WOULD BE HOTTER AND DENSER

AND MORE VIOLENT THAN ANYTHING

THAT WE CAN EXPERIENCE IN THE

UNIVERSE TODAY.

EVEN THE INTERIOR OF A STAR IS

CALM AND SERENE BY COMPARISON TO

THE VIOLENCE OF THE EARLIEST

MOMENTS OF THE BIG BANG.

>> TEMPERATURES WERE SO HOT THAT

EVEN THE ATOMS OF YOUR BODY

WOULD DISINTEGRATE -- SO HOT, IN

FACT, THAT THE ATOMS WOULD BE

RIPPED APART.

>> Narrator: HOW HOT?

TRILLIONS OF DEGREES HOT.

BUT AS THE UNIVERSE CONTINUES TO

EXPAND, IT ALSO BEGINS TO COOL.

DROPPING TEMPERATURES TRIGGER

THE NEXT STAGE IN THE UNIVERSE'S

EVOLUTION.

THE RAW ENERGY OF THE EXPLOSION

TRANSFORMS INTO TINY SUBATOMIC

PARTICLES.

IT'S THE FIRST MATTER IN THE

UNIVERSE.

THIS CONVERSION OF ENERGY INTO

MATTER WAS PREDICTED BY

ALBERT EINSTEIN YEARS BEFORE

ANYONE STARTED TALKING ABOUT THE

BIG BANG.

IT'S THE ONE SCIENTIFIC EQUATION

EVERY SCHOOLKID KNOWS.

>> THERE IS ONE VERY FAMILIAR

FORMULA.

AND THAT IS E EQUALS MC SQUARED.

IT SAYS SOMETHING ABOUT THE

CREATION OF THE UNIVERSE.

IT SAYS EVEN IF THE UNIVERSE IS

CREATED JUST OUT OF PURE ENERGY,

THAT BECAUSE ENERGY CAN BE

CONVERTED TO MATTER AND MATTER

TO ENERGY, THAT YOU CAN GET ALL

OF THE STUFF THAT WE SEE IN THE

UNIVERSE FROM THIS PURE

ENERGETIC EVENT.

>> Narrator: EINSTEIN'S LITTLE

EQUATION HAD A BIG IMPACT.

IT LED TO THE FIRST NUCLEAR

BOMBS.

IN A NUCLEAR EXPLOSION, A SMALL

AMOUNT OF MATTER IS CONVERTED

INTO AN ENORMOUS AMOUNT OF

ENERGY.

AS THE UNIVERSE WAS FORMING, THE

EXACT OPPOSITE HAPPENED.

PURE ENERGY TRANSFORMED INTO

PARTICLES OF MATTER.

>> YOU DON'T NEED TO CREATE

MATTER IN THE BEGINNING.

YOU JUST NEED ENERGY.

AND ENERGY ALONE CAN LEAD TO THE

CREATION OF AN ENTIRE UNIVERSE.

>> Narrator: IN JUST A FRACTION

OF A SECOND AFTER THE BIG BANG,

THE BUILDING BLOCKS OF OUR

UNIVERSE BEGIN TO TAKE SHAPE.

BUT THIS FIRST MATTER IS LIKE

NOTHING WE SEE TODAY.

>> THE STUFF OF MATTER HAS BEEN

VERY DIFFERENT OVER THE AGE OF

THE UNIVERSE.

WHAT WE NOW THINK IS NORMAL

MATTER WAS NOT AT ALL NORMAL IN

THE EARLIEST MOMENTS OF THE BIG

BANG.

>> Narrator: THAT'S BECAUSE

CONDITION WERE SO EXTREME.

THERE WERE NO ATOMS YET.

BUT THERE WERE TINY SUBATOMIC

PARTICLES.

>> IN THE EARLIEST MOMENTS OF

THE BIG BANG, THE UNIVERSE WAS

SO HOT AND DENSE, THERE WERE

GREAT AMOUNTS OF ENERGY.

AND SO PARTICLES WERE BEING

CREATED ALL THE TIME, AND ENERGY

AND MATTER WERE TRANSFERRING

BACK AND FORTH IN THIS HOT,

DENSE SOUP.

>> Narrator: THAT EARLIEST

MATTER WAS TOO UNSTABLE TO START

FORMING THE UNIVERSE AS WE KNOW

IT.

THINK OF IT LIKE THIS.

IMAGINE RUSH HOUR AT

GRAND CENTRAL IN NEW YORK CITY

AS THAT SUPERHEATED EARLY

UNIVERSE.

THE COMMUTERS RACING THROUGH THE

MAIN CONCOURSE ARE SUBATOMIC

PARTICLES.

>> IF YOU LOOK AT A CROWD OF

PEOPLE -- A LARGE CROWD OF

PEOPLE -- THEY MAY APPEAR

RANDOM.

THAT RANDOM, QUIRKY MOTION IS

VERY SIMILAR THAN WHAT WAS

HAPPENING IN THE PARTICLES IN

THE UNIVERSE IN THE EARLIEST

MOMENTS OF THE BIG BANG.

>> Narrator: THE EXTREME

TEMPERATURE OF THE EARLY

UNIVERSE ENERGIZES THE SUBATOMIC

PARTICLES.

THEY APPEAR.

THEY DISAPPEAR.

THEY RACE AROUND AT INCREDIBLE

SPEEDS.

IT'S PURE CHAOS.

>> IT'S LIKE PEOPLE.

IF THEY'RE EXCITED AND RUNNING

AROUND FAST TO CATCH TRAINS AT A

TRAIN STATION, THEY'LL BE MOVING

AROUND QUICKLY.

BUT EVENTUALLY, THEY CALM DOWN

AND GET SLOWER.

THAT'S WHAT'S BEEN HAPPENING TO

OUR UNIVERSE, IN A SENSE.

THE PARTICLES ARE MOVING AROUND

VERY FAST.

AND AS THE UNIVERSE COOLS DOWN,

THE PARTICLES MOVE MORE SLOWLY

AND, IN SOME SENSE, LESS RANDOM.

>> Narrator: AS THE UNIVERSE

COOLS, THE PARTICLES STOP

CHANGING BACK INTO ENERGY.

NOW THERE ARE MORE AND MORE

SUBATOMIC PARTICLES, BUT IT'S

STILL A HOT, VIOLENT PLACE.

ALL THIS IS HAPPENING IN

FRACTIONS OF A SECOND TOO SMALL

TO DETECT.

BUT THE BIG BANG IS MOVING INTO

A CRITICAL STAGE NOW, A TITANIC

BATTLE BETWEEN MATTER AND THE

ONE THING THAT CAN DESTROY THE

UNIVERSE BEFORE IT EVEN GETS

STARTED...ANTIMATTER.

>> Narrator: EVERYTHING IN THE

UNIVERSE IS MADE FROM MATTER,

FROM THE SMALLEST ROCK TO THE

LARGEST STAR.

AND ALL THE MATTER THERE WILL

EVER BE WAS CREATED FROM THE

PURE ENERGY OF THE BIG BANG.

EINSTEIN'S EQUATION,

E EQUALS MC SQUARED,

SAYS THAT ENERGY TRANSFORMS INTO

MATTER.

BUT IT WAS JUST A THEORY.

TODAY SCIENCE IS ABLE TO TEST

THAT THEORY.

THIS IS CERN IN SWITZERLAND,

HOME TO THE WORLD'S LARGEST

MACHINE.

IT'S THE SIZE OF A CITY AND

ENGINEERED TO RE-CREATE THE

CONDITIONS MILLIONTHS OF A

SECOND AFTER THE BIG BANG.

>> IF WE WANT TO PROBE

EVER-SMALLER SCALES,

PARADOXICALLY WE NEED AN

EVER-BIGGER MACHINE.

THERE'S JUST NO OTHER WAY OF

DOING IT, SO BIG MACHINES MEAN

SMALL PHYSICS, MEANS EARLY TIMES

AND, THEREFORE, GETTING CLOSER

AND CLOSER TO THE ORIGIN OF THE

UNIVERSE ITSELF.

>> Narrator: THIS MONSTER

MACHINE IS CALLED A COLLIDER.

IT'S DESIGNED TO TAKE US BACK TO

THOSE FIRST FRACTIONS OF A

SECOND AFTER THE BIG BANG.

IT'S A 12-FOOT-WIDE

CONCRETE-LINE CIRCULAR TUNNEL

17 MILES AROUND.

THE COLLIDER MAKES TINY

PARTICLES OF MATTER SMASH INTO

EACH OTHER AT ALMOST THE SPEED

OF LIGHT.

FOR A SPLIT SECOND, THOSE

COLLISIONS GENERATE TURBOCHARGED

ENERGY SIMILAR TO THE EXPLOSIVE

FORCE OF THE BIG BANG.

AND THEN THAT PURE ENERGY

BRIEFLY TRANSFORMS INTO MATTER,

JUST LIKE IT DID NEARLY

14 BILLION YEARS AGO.

BUT A MONSTER MACHINE NEEDS A

MONSTER DETECTOR TO SEE THESE

COLLISIONS.

>> THIS DETECTOR IS FIVE STORIES

TALL AND WEIGHS OVER 7,000 TONS.

AND 7,000 TONS -- TO GIVE YOU A

SENSE OF PERSPECTIVE -- IS THE

WEIGHT OF THE EIFFEL TOWER.

>> Narrator: BUT AS BIG AS IT

IS, IT CAN'T SEE THE ACTUAL

PARTICLES OF NEW MATTER.

THEY HANG AROUND FOR JUST A

SPLIT SECOND AND MOVE SO FAST IT

CAN ONLY RECORD THEIR TRAILS.

>> THERE'S A LOT OF ENERGY IN

THESE PARTICLES.

THEY MOVE VERY, VERY QUICKLY,

AND SO YOU NEED A VERY LARGE

AMOUNT OF DETECTOR IN ORDER TO

BE ABLE TO MAP THE PATH OF THESE

PARTICLES VERY PRECISELY.

SO, THE DETECTOR IS SO BIG

BECAUSE YOU NEED BETTER

RESOLUTION.

IT WORKS EXACTLY THE SAME AS A

CAMERA.

THE MORE PIXELS YOU HAVE, THE

BETTER THE PICTURE.

IT'S EXACTLY THE SAME HERE.

WE JUST HAVE A FIVE-STORY

CAMERA.

>> Narrator: SCIENTISTS HOPE

THAT IT'LL REVEAL JUST HOW

ENERGY TRANSFORMS INTO MATTER...

BUT NOT JUST ANY MATTER -- THE

KIND OF MATTER THAT EMERGED

14 BILLION YEARS AGO AT THE DAWN

OF TIME ITSELF.

BUT THE DAWN OF TIME WAS A

CRITICAL MOMENT IN THE BIRTH OF

THE UNIVERSE, BECAUSE PURE

ENERGY ALSO PRODUCED ONE OF THE

MOST DANGEROUS THINGS IN THE

UNIVERSE -- ANTIMATTER.

THAT'S RIGHT, ANTIMATTER --

IT'S REAL.

>> ANTIMATTER IS THE MIRROR

IMAGE OF ORDINARY MATTER.

HOWEVER, MATTER HAS ONE CHARGE,

AND ANTIMATTER HAS THE OPPOSITE

CHARGE.

IF THERE WAS AN ANTI-ME MADE OUT

OF ANTIMATTER, THAT PERSON, IN

PRINCIPLE, COULD LOOK EXACTLY

LIKE ME -- SAME PERSONALITY

QUIRKS, SAME EVERYTHING, EXCEPT,

OF COURSE, WHEN I DECIDE TO

SHAKE HIS HAND.

AT THAT POINT, WE BOTH WOULD

BLOW OURSELVES TO SMITHEREENS IN

A GIGANTIC NUCLEAR EXPLOSION.

>> Narrator: MATTER WITH A

POSITIVE CHARGE LOCKS HORNS WITH

ITS ARCHENEMY, ANTIMATTER,

WITH A NEGATIVE CHARGE.

THE FATE OF THE UNIVERSE HANGS

IN THE BALANCE OF THIS EPIC

BATTLE.

EQUAL AMOUNTS OF MATTER AND

ANTIMATTER WILL CANCEL EACH

OTHER OUT -- NOT GOOD.

>> A UNIVERSE WITH EQUAL AMOUNTS

OF MATTER AND ANTIMATTER IS

EQUIVALENT TO A UNIVERSE WITH

NO MATTER AT ALL, BECAUSE THE

MATTER AND ANTIMATTER WILL

ANNIHILATE BACK INTO PURE

RADIATION.

AND THERE'LL BE NOTHING

INTERESTING -- NO STARS AND

GALAXIES AND PEOPLE IN BETWEEN.

>> Narrator: LIKE A COSMIC GAME

OF RISK, THE SIDE WITH THE MOST

SOLDIERS WINS.

THE SCORE WAS VERY CLOSE, BUT

THERE WAS A WINNER.

>> FOR EVERY BILLION PARTICLES

OF ANTIMATTER, THERE WERE A

BILLION AND ONE PARTICLES OF

MATTER.

THAT WAS THE MOMENT OF CREATION.

THE ONE EXTRA PARTICLE OF MATTER

IN EACH LITTLE VOLUME SURVIVES,

SURVIVES ENOUGH TO FORM ALL THE

MATTER WE SEE IN THE STARS AND

GALAXIES TODAY.

>> Narrator: ONE IN A BILLION

MIGHT NOT SOUND LIKE MUCH, BUT

IT'S ENOUGH TO BUILD A UNIVERSE.

>> WE'RE THE LEFTOVERS.

SO, BELIEVE IT OR NOT,

EVERYTHING YOU SEE AROUND YOU,

THE ATOMS OF YOUR BODY, THE

ATOMS OF THE STARS, ARE NOTHING

BUT LEFTOVERS -- LEFTOVERS FROM

THIS ANCIENT COLLISION BETWEEN

MATTER AND ANTIMATTER.

>> Narrator: LUCKY FOR US, THERE

WAS ENOUGH LEFT OVER TO MAKE ALL

THE STARS AND PLANETS.

AND THE UNIVERSE IS STILL LESS

THAN ONE SECOND OLD.

BUT NOW IT'S SWARMING WITH TINY,

PRIMITIVE PARTICLES.

THE NEXT STAGE IS ASSEMBLING

THOSE TINY PARTICLES INTO THE

FIRST ATOMS.

>> Narrator: GIVE OR TAKE A

COUPLE OF PLANCK TIMES, THE

UNIVERSE IS NEARLY A SECOND OLD

AND STILL A VERY STRANGE PLACE.

BUT MATTER HAS WON THE BATTLE

WITH ANTIMATTER.

AND NOW IT'S TIME TO BUILD THE

UNIVERSE.

IT'S STILL EXTREMELY HOT AND

EXPANDING INCREDIBLY FAST.

>> WHEN THE UNIVERSE WAS A

SECOND OLD, THE PARTICLES IN IT

WERE VERY DIFFERENT THAN THE

PARTICLES WE SEE TODAY.

THERE WERE NO ATOMS.

NOTHING THAT WE RECOGNIZE IN THE

ROOM AROUND US TODAY YET

EXISTED.

>> Narrator: NOW ALL THAT BEGINS

TO CHANGE.

TEMPERATURES CONTINUE TO COOL.

AND AS THE PRIMITIVE PARTICLES

KEEP SLOWING DOWN, THEY START

BONDING TOGETHER TO FORM THE

ATOMS OF THE FIRST ELEMENTS.

THE FIRST ONE TO FORM IS

HYDROGEN.

THEN OVER THE NEXT THREE

MINUTES, THE UNIVERSE BEGINS TO

CREATE TWO MORE ELEMENTS --

HELIUM AND LITHIUM.

>> WE WENT FROM A UNIVERSE THAT

WAS INFINITELY SMALL TO A

UNIVERSE THAT WAS LIGHT-YEARS IN

SIZE.

IN THE FIRST THREE MINUTES,

ESSENTIALLY EVERYTHING

INTERESTING THAT WAS GOING TO

HAPPEN IN THE UNIVERSE HAPPENED.

>> Narrator: WELL, NOT QUITE.

IF YOU WERE THERE, YOU COULDN'T

SEE IT.

>> WHEN WE LOOK AT THE NIGHT

SKY, WE CAN SEE LITERALLY

BILLIONS OF YEARS INTO THE PAST,

AND WE THINK IT'S ALWAYS BEEN

THAT WAY.

NOPE, NOT TRUE.

380,000 YEARS AFTER THE BIG

BANG -- THAT'S WHEN THE UNIVERSE

BEGAN TO BECOME TRANSPARENT.

BUT BEFORE THEN, IT WAS MILKY.

>> Narrator: THERE IS A MILKY

SOUP OF LOOSE ELECTRONS.

THE YOUNG UNIVERSE HAS TO COOL

DOWN ENOUGH FOR THE ELECTRONS

TO SLOW DOWN AND STICK TO NEW

ATOMS.

IT TOOK A LONG TIME FOR ALL OF

THE HYDROGEN, HELIUM, AND

LITHIUM ATOMS IN THE UNIVERSE TO

FORM.

SCIENTISTS CALCULATE IT TOOK

380,000 YEARS FOR THE ELECTRONS

TO SLOW DOWN ENOUGH SO THAT THE

UNIVERSE COULD START

MASS-PRODUCING ATOMS.

WHEN THAT HAPPENS, THE MILKY FOG

CLEARS.

THE FIRST LIGHT ESCAPES AND

RACES ACROSS THE UNIVERSE.

NEARLY 14 BILLION YEARS LATER,

TWO YOUNG SCIENTISTS IN

NEW JERSEY PICK IT UP BY

ACCIDENT.

IN 1964, ARNO PENZIAS AND

ROBERT WILSON WERE MAPPING

RADIO SIGNALS ACROSS OUR GALAXY.

EVERYWHERE THEY LOOKED, THEY

PICKED UP A STRANGE BACKGROUND

HUM.

THEY FIRST SUSPECTED THEIR

EQUIPMENT.

MAYBE PIGEON DROPPINGS ON THE

ANTENNA WERE CAUSING THE STRANGE

SIGNAL.

BUT AFTER CLEANING THE ANTENNA,

THE MYSTERIOUS HUM REMAINED.

SO MUCH FOR PIGEON DROPPINGS.

>> PENZIAS DELIVERED A TALK AT

PRINCETON UNIVERSITY.

AND ACCORDING TO LORE, ONE

PERSON IN THE BACK SAID, "EITHER

YOU HAVE DISCOVERED THE EFFECTS

OF BIRD DROPPINGS OR THE

CREATION OF THE UNIVERSE."

>> Narrator: IT WAS IN FACT THE

MOMENT OF CREATION, NEARLY

14 BILLION YEARS AGO, WHEN THOSE

FIRST ATOMS GOT THEIR ELECTRONS.

THAT'S THE MOMENT WHEN THE MILKY

CLOUD CLEARS AND THE NEW

UNIVERSE COMES INTO VIEW FOR THE

FIRST TIME.

TO CAPTURE BETTER IMAGES OF THIS

CRITICAL EVENT, NASA LAUNCHED

THE COSMIC BACKGROUND EXPLORER

SATELLITE, OR COBE.

THEY POINTED IT OUT INTO SPACE,

WHERE IT TOOK THE TEMPERATURE OF

THE UNIVERSE.

BY MEASURING DIFFERENCES IN

TEMPERATURE ACROSS SPACE,

THEY CREATED THE FIRST MAP OF

OUR EARLY UNIVERSE.

THE IMAGES WERE CALLED THE FACE

OF GOD.

>> WE GOT GORGEOUS PICTURES --

BABY PICTURES OF THE INFANT

UNIVERSE WHEN IT WAS 380,000

YEARS OF AGE.

BUT THERE WERE PROBLEMS WITH IT.

THE PICTURE WAS VERY FUZZY.

THE COBE RESULTS WERE SIMPLY NOT

GOOD ENOUGH.

>> MISSION LOOKING GOOD.

>> LIFTOFF.

>> Narrator: SO NASA LAUNCHED AN

EVEN MORE ADVANCED SATELLITE,

WMAP, THE WILKINSON MICROWAVE

ANISOTROPY PROBE.

IN 2001, DAVID SPERGEL WAS PART

OF THE TEAM LOOKING FOR A

CLEARER IMAGE OF THE EARLY

UNIVERSE.

>> IT WAS EXCITING TO GO TO THE

CAPE.

IT WAS ONE OF THESE MOMENTS WE

WERE SITTING THERE, WATCHING

THIS -- I WAS THERE WITH MY

FAMILY -- WATCHING THE ROCKET GO

OFF.

IT WAS VERY EXCITING WHEN,

WITHIN ABOUT A DAY, WE WERE ABLE

TO GET OUR FIRST SIGNAL FROM THE

SATELLITE AND KNOW IT WAS

WORKING AND WORKING PROPERLY.

>> Narrator: THIS IS THE MOST

DETAILED PICTURE OF THE EARLY

UNIVERSE EVER TAKEN, JUST

380,000 YEARS AFTER THE BIG

BANG.

THE RED AND YELLOW AREAS ARE

WARMER, THE BLUE AND GREEN

REGIONS COOLER.

AND THOSE TEMPERATURE

DIFFERENCES ARE CLUES TO THE

FUTURE STRUCTURE OF THE

UNIVERSE.

>> YOU SEE TINY VARIATIONS IN

TEMPERATURE.

THOSE TINY VARIATIONS IN

TEMPERATURE REFLECT SMALL

VARIATIONS IN DENSITY.

THIS REGION HAS MORE MATTER.

THIS REGION HAS LESS MATTER.

>> Narrator: LIKE A BLUEPRINT

FOR THE CONSTRUCTION OF OUR

UNIVERSE, THIS IMAGE SHOWS US

WHERE THERE'S MORE MATTER AND

WHERE THERE'S LESS.

REGIONS WITH NO MATTER WILL

BECOME EMPTY SPACE.

AREAS WITH DENSER MATTER WILL

BECOME THE CONSTRUCTION SITES OF

GALAXIES, STARS, AND PLANETS.

>> THESE ARE THE FLUCTUATIONS

THAT WILL GROW TO FORM GALAXIES.

SO IF IT WASN'T FOR THOSE LITTLE

DENSITY FLUCTUATIONS, YOU AND I

WOULD NOT BE HERE TODAY.

>> Narrator: OUR UNIVERSE IS NOW

380,000 YEARS OLD AND TRILLIONS

AND TRILLIONS OF MILES ACROSS.

CLOUDS OF HYDROGEN AND HELIUM

GAS FLOAT THROUGH SPACE.

IT WILL TAKE ANOTHER

200 MILLION YEARS BEFORE THOSE

GASES CREATE THE FIRST STARS.

>> THESE FIRST STARS IGNITED THE

UNIVERSE INTO WHAT MUST HAVE

BEEN THE MOST AMAZING FIREWORKS.

THE UNIVERSE WENT FROM THE DARK

AGES TO AN AGE OF SPLENDOR WHEN

THE FIRST STARS ILLUMINATED THE

GAS AND THE UNIVERSE BEGAN TO

GLOW IN MAJESTIC FASHION.

I WISH I'D BEEN THERE.

>> IT WAS LIKE CHRISTMAS-TREE

LIGHTS TURNING ON.

THE UNIVERSE BEGAN TO LIGHT UP

IN ALL DIRECTIONS, UNTIL YOU

FORM THE BEAUTIFUL MOSAIC WE NOW

SEE TODAY.

>> Narrator: MORE AND MORE STARS

TURN ON.

1 BILLION YEARS AFTER THE BIG

BANG, THE FIRST GALAXY FORMS.

OVER THE NEXT 8 BILLION YEARS,

COUNTLESS MORE TAKE SHAPE.

THEN ABOUT 5 BILLION YEARS AGO,

IN A QUIET CORNER OF ONE OF

THOSE GALAXIES, GRAVITY BEGINS

TO DRAW IN DUST AND GAS.

GRADUALLY THEY CLUMP TOGETHER

AND GIVE BIRTH TO A STAR, OUR

SUN.

9 BILLION YEARS AFTER THE BIG

BANG, OUR TINY SOLAR SYSTEM

SPRINGS TO LIFE, AND WITH IT,

PLANET EARTH.

EVERYTHING THERE IS EXISTS

BECAUSE OF THE BIG BANG, AND

IT'S STILL GOING ON.

OUR UNIVERSE IS STILL EXPANDING.

BUT IT WON'T JUST KEEP GOING

FOREVER.

OUR UNIVERSE HAD A BEGINNING,

AND IT WILL ALSO HAVE AN END.

>> Narrator: IN THE 14 BILLION

YEARS SINCE THE BIG BANG,

GALAXIES HAVE BEEN CREATED...

FILLED WITH STARS, PLANETS, AND

MOONS.

AND THE UNIVERSE HAS BEEN

EXPANDING THE WHOLE TIME.

>> WE'VE LEARNED SPACE IS QUITE

BIG -- AT LEAST 150 BILLION

LIGHT-YEARS ACROSS.

>> Narrator: THE UNIVERSE MAY BE

INFINITE.

IT MIGHT LITERALLY GO ON

FOREVER.

>> THE ANSWER IS THERE DOESN'T

HAVE TO BE ANYTHING, IN

PRINCIPLE.

THE UNIVERSE COULD BE INFINITE,

AND THERE'S NO OUTSIDE, OR IT

COULD BE CLOSED ON ITSELF.

IT COULD BE SUCH THAT IF I

LOOKED FAR ENOUGH IN THAT

DIRECTION I'D SEE THE BACK OF MY

HEAD.

>> Narrator: WE MAY NEVER KNOW

IF THE BIG BANG PRODUCED A

UNIVERSE THAT GOES ON FOREVER.

BUT WE DO KNOW THAT THE BIG BANG

HASN'T STOPPED YET.

>> THE BIG BANG IS REALLY

CONTINUING NOW.

WE'RE CONTINUING TO BANG, IF YOU

WANT, IN THE SENSE THAT THE

EXPANSION OF THE UNIVERSE IS

CONTINUING.

>> ONE OF THE MOST ASTOUNDING

DISCOVERIES IN THE LAST FEW

YEARS HAS BEEN THE REALIZATION

THAT OUR UNIVERSE IS NOT SLOWING

DOWN, LIKE WE ONCE THOUGHT, BUT

IT'S ACTUALLY SPEEDING UP.

IT'S ACCELERATING.

IT'S IN A RUNAWAY MODE.

WE NOW BELIEVE THERE'S SOMETHING

CALLED DARK ENERGY, THE ENERGY

OF NOTHING, THAT IS PUSHING THE

GALAXIES APART AND IS KILLING

THE UNIVERSE.

>> Narrator: WE CAN'T SEE THIS

DESTRUCTIVE FORCE, AND WE HAVE

NO IDEA WHY IT EXISTS.

BUT IT COULD MEAN THE END OF

EVERYTHING CREATED IN THE BIG

BANG.

IF DARK ENERGY CONTINUES PUSHING

THE UNIVERSE APART, OUR

MILKY WAY GALAXY COULD BECOME A

LONELY OUTPOST.

100 BILLION YEARS FROM NOW, MOST

OF OUR GALACTIC NEIGHBORS WILL

BE OUT OF SIGHT.

STARS WILL BURN OUT.

GALAXIES WILL GROW DARK.

EVEN ATOMS WILL TEAR APART.

THE BIRTH OF THE UNIVERSE, THE

BIG BANG, WAS OVER IN A FLASH.

BUT THE DEATH OF OUR UNIVERSE

WILL TAKE ALMOST FOREVER.

>> THAT GREAT PHILOSOPHER OF THE

WESTERN WORLD, WOODY ALLEN, ONCE

SAID ETERNITY IS AN AWFUL LONG

TIME, ESPECIALLY TOWARD THE END.

>> Narrator: FIGURING OUT HOW

OUR UNIVERSE WILL END IS AS DARK

A MYSTERY AS THE BIG BANG.

IT COULD COLLAPSE BACK IN ON

ITSELF, LIKE A BALLOON WHEN THE

AIR IS LET OUT.

>> SO, WOULD THE UNIVERSE END

WITH A BIG CRUNCH, A REVERSE OF

THE BIG BANG, OR WOULD IT END BY

EXPANDING OUT AND BECOMING COLD

AND DARK?

IF YOU WISHED, WOULD IT END IN

FIRE OR ICE, OR WITH A BANG OR A

WHIMPER?

>> Narrator: IF THE UNIVERSE

COLLAPSES, IT MIGHT TRIGGER

ANOTHER BIG BANG.

MAYBE THAT'S ALREADY HAPPENED,

AND WE'RE JUST ONE IN A LONG

LINE OF UNIVERSES.

>> PERSONALLY, I BELIEVE IN

CONTINUAL GENESIS -- THAT IS,

THERE'S A NEVER-ENDING PROCESS

WHEREBY UNIVERSES COLLIDE, SPLIT

APART, GIVE BIRTH TO NEW

UNIVERSES, PERHAPS WITH

DIFFERENT LAWS OF PHYSICS WITHIN

EACH UNIVERSE.

>> MAYBE THIS ISN'T THE FIRST

TIME IT'S HAPPENED.

MAYBE IT'S CYCLIC, AND IT GOES

AROUND AND AROUND AGAIN,

EVENTUALLY WILL COLLAPSE, AND

THE WHOLE THING WILL START OVER

AGAIN.

>> Narrator: ONE UNIVERSE OR

MANY, THEY ALL START WITH A BIG

BANG.

>> EVERYTHING THAT MAKES US

HUMAN -- THE ATOMS IN OUR

BODIES, THE JEWELRY WE WEAR, ALL

THE THINGS THAT LEAD TO THE

TRAGEDY OF LIFE AND THE BEAUTY

AND THE EXCITEMENT, LOVE,

EVERYTHING ELSE -- AROSE BECAUSE

OF PROCESSES THAT HAPPENED

14 BILLION YEARS AGO.

AND IF WE REALLY WANT TO

UNDERSTAND OURSELVES AT SOME

FUNDAMENTAL LEVEL, WE REALLY

HAVE TO UNDERSTAND THE BIG BANG.

>> Narrator: 14 BILLION YEARS

AGO, THE BIG BANG CREATED TIME

AND SPACE, OUR WHOLE VAST

UNIVERSE, AND EVERYTHING IN IT,

INCLUDING US.

>> SOME PEOPLE ASK THE QUESTION,

"WHAT'S IN IT FOR ME?"

THE BIG BANG GAVE US EVERYTHING

WE SEE AROUND US -- THE

DISTRIBUTION OF GALAXIES AND

STARS.

IT SET INTO MOTION THE CREATION

OF ELEMENTS THAT WE SEE IN THE

UNIVERSE.

AND EVEN THE LAWS OF PHYSICS

THEMSELVES, WE THINK, WERE BORN

AT THE INSTANT OF CREATION.

>> Narrator: EVERYTHING STARTED

WITH THE BIG BANG, ONE BRIEF

MOMENT IN TIME 14 BILLION YEARS

AGO, THAT CONTAINS THE ANSWERS

TO OUR GREATEST QUESTIONS ABOUT

OUR PAST, OUR PRESENT, AND OUR

FUTURE.

EACH DISCOVERY BRINGS US ONE

STEP CLOSER TO UNDERSTANDING HOW

THE UNIVERSE WORKS.