All language subtitles for PBS.Genius.By.Stephen.Hawking.1of6.Can.We.Time.Travel.720p.HDTV.x264.AAC.MVGroup.org.eng

STEPHEN HAWKING:
WE ALL HAVE QUESTIONS...

BIG QUESTIONS.

NORMAN: CAN I JOURNEY
INTO THE PAST?

HAWKING: IT'S PART OF
WHAT IT MEANS TO BE HUMAN.

PAUL: IS TIME TRAVEL
JUST SCIENCE FICTION?

HAWKING:
MY NAME IS STEPHEN HAWKING.

AND I BELIEVE THAT ANYONE

CAN ANSWER BIG QUESTIONS
FOR THEMSELVES.

SO WITH THE HELP
OF SOME ORDINARY PEOPLE...

PAUL: WOW!

MARISOL: THIS IS AWESOME!

HAWKING:
AND A TEAM OF EXPERTS...

ALEX FILIPPENKO: YOU CAN'T
GET A PLACE IN THE UNIVERSE

WHERE GRAVITY IS STRONGER.

HAWKING: WE ARE GOING
ON THE ULTIMATE VOYAGE...

NORMAN: PULLING
A LOT OF Gs!

HAWKING: A QUEST TO ANSWER

THE GREATEST
MYSTERIES OF THE UNIVERSE...

USING THE POWER
OF THE HUMAN MIND.

[PARTICIPANTS CHEERING]

HAWKING: BECAUSE ANYONE

CAN THINK LIKE A GENIUS.

ANNOUNCER: "GENIUS BY
STEPHEN HAWKING"

WAS MADE POSSIBLE IN PART BY

CONTRIBUTIONS TO YOUR PBS
STATION FROM VIEWERS LIKE YOU.

THANK YOU.

PARTICIPANTS:
CAN WE TIME TRAVEL?

HAWKING: TIME TRAVEL IS ONE OF
MY FAVORITE IDEAS.

MOST OF US HAVE DREAMT OF
VISITING A DIFFERENT AGE...

PERHAPS A PEEK INTO OUR OWN
FUTURE...

[CHEERING]

OR TO SEE A MONUMENTAL EVENT
IN HISTORY.

FOR DECADES, TIME TRAVEL
HAS PROVED IRRESISTIBLE

TO SCIENCE FICTION WRITERS

AND HOLLYWOOD DIRECTORS.

BUT CAN WE WORK OUT IF IT IS
REALLY POSSIBLE

TO TRAVEL THROUGH TIME?

I HAVE ASKED 3 ORDINARY PEOPLE
TO COME ON A JOURNEY

OF DISCOVERY...

A SERIES OF PUZZLES
AND CHALLENGES AWAIT THEM.

THEY'LL BE GIVEN EQUIPMENT
AND INSTRUCTIONS TO HELP.

PAUL: WOW!

MARISOL: HA HA! NICE.

HAWKING: CAN THEY SOLVE
THE MYSTERIES

AND FIND THE TRUTH ABOUT
TIME TRAVEL?

CAN I TRAVEL IN TIME?

MARISOL: I DON'T KNOW. I DON'T--
I DON'T KNOW WHERE TO START.

I FEEL EXCITED TO CONTEMPLATE
THE ISSUE OF TIME TRAVEL.

I'M GOING TO SAY NO.

BUT--TECHNOLOGY NOW--
POSSIBLY IN THE FUTURE.

I DON'T KNOW HOW OR WHAT
THE ACTUAL MECHANICS OF IT ARE,

BUT I--I THINK IT'S POSSIBLE.

YES, I BELIEVE IT IS POSSIBLE.

HAWKING: I HAVE BROUGHT
MY VOLUNTEERS TO NEW YORK CITY.

WHAT BETTER PLACE TO BEGIN
THEIR QUEST THAN TIMES SQUARE?

HAWKING: I WANT TO SEE IF
MY TEAM CAN GRASP HOW SCIENCE

BEGAN TO EXPLORE THIS ELUSIVE
THING WE CALL TIME.

I HAVE LINED UP A SURPRISE.

NORMAN: OH! LOOK,
LOOK, LOOK.

[PAUL LAUGHS]

HAWKING: HELLO, MY BUDDING
GENIUSES.

PAUL: WOW!

THIS IS AWESOME!

HAWKING: WELCOME TO NEW YORK.

I HOPE YOU ARE READY FOR
SOME FUN.

H--HEY!
HA HA!

I DID NOT EXPECT
STEPHEN HAWKING. IT WAS AWESOME.

IT WAS A COMPLETE SURPRISE
AND COMPLETE SHOCK.

PAUL: OH, I WAS FLABBERGASTED
TO SEE HIS FACE THERE.

HAWKING: I'D LIKE YOU TO COME
TO A PARTY.

USING THESE 3 NUMBERS, CAN YOU

WORK OUT HOW TO GET THERE?

GOOD LUCK.

NORMAN: 48, 16...

ALL: 11.

PAUL: CAN WE MAKE IT
TO A PARTY

USING THOSE 3 DIGITS?

11?
48...

48, 16...
48, 16...

11.
11.

HAWKING: TIME TO GET THINKING.

MARISOL: WHAT DO
THOSE NUMBERS HAVE...

PAUL: IN COMMON?
YEAH.

WHAT COMES
IN 3 NUMBERS?

A TRIANGLE.

PAUL: 48, 16, 11.

DISTANCE AND WIDTH.

I CAN'T THINK OF
A MATHEMATICAL RELATION.

NORMAN: I CAN'T
PICTURE IT, NO.

COULD BE, UM...

LIKE LONGITUDE
AND LATITUDE.

MARISOL: OR IS IT STREETS?

IN TIME--
GOOD THINKING.

YEAH.

IS THERE A 48th STREET?

THERE IS
A 48th STREET.

16th AVENUE WOULD PUT
YOU INTO THE HUDSON.

WELL! THEY STOP
THERE, DO THEY?

THE NUMBERS STOP THERE.

NORMAN: YEAH. 'CAUSE
THERE'S A RIVER.

ALSO, 48th STREET,
11th AVENUE.

AND MAYBE
ONCE WE GET

TO 48th AND 11th,

THE 16 WILL
PRESENT ITSELF.

PAUL: YES.

WE CAN PONDER IT
ON THE WAY.

MARISOL: LET'S GO.

HAWKING: I HAVE ASKED
THE VOLUNTEERS TO MAKE

A VIDEO DIARY OF THEIR JOURNEY.

THEY WILL NEED THIS LATER.

PAUL: OK, MARISOL,

WHAT ARE WE UP TO?

HA HA! WE'RE GONNA
GO TO A PARTY. HA HA!

NORMAN.
A PARTY, BRO.

WE'RE ON A MISSION.

WE MIGHT BE WRONG,
BUT WE TOOK THAT ADDRESS

TO BE THE ONE THING WE COULD
TAKE ACTION ON.

MARISOL: ALL RIGHT.
WHAT STREET ARE WE ON?

NORMAN: THIS IS, UH--
WHAT IS THAT?

PAUL: 46th.

MARISOL: AND THIS IS 7th.

7th.

MARISOL, VOICE-OVER: IT MADE
SENSE TO FOLLOW THE GRID.

LIKE, TO FOLLOW THE STREETS.

MARISOL: WE ARE, 48th--
THE FIRST NUMBER.

THE FIRST DIGIT.
EXCELLENT!

SHOW WHAT WE GOT HERE?

MARISOL: SELFIE. SELFIE.
SELFIE.

PAUL: WHERE ARE WE?
48th.

48th.
48th.

IT'S US.
AND THERE'S A SIGN.

NOW OFF TO 11th.

NORMAN: SO, YEAH.
11th IS THAT WAY.

NORMAN: HOPEFULLY,
48th AND 11th WAS GONNA PAN OUT.

OR WERE WE GONNA HAVE
TO START ALL OVER?

NORMAN: HERE WE GO.

48th STREET
AND 10th AVENUE.

PAUL: ONE MORE AVENUE
TO GO.

PAUL, VOICE-OVER: WE WERE
REALLY HOPING THAT

WE WOULD BE--WE WOULD
COME ACROSS SOME KIND OF

[CHUCKLING]
DIVINE INSPIRATION.

NORMAN: HERE WE GO.
11th AND 48th.

48th AND 11th.

PAUL, IN HIGH-PITCHED VOICE:
¶ AH! ¶

HAWKING: THEY'RE RIGHT ABOUT

THE INTERSECTION
OF 48th AND 11th.

BUT CAN THEY USE THE THIRD
NUMBER TO GET THEM TO THE PARTY?

I DON'T SEE ANYTHING
IN PARTICULAR.

WE GOT THE 48.
WE GOT THE 11.

THAT JUST LEAVES 16.

MARISOL: FIRST
JUST SAW THE BUILDING.

NOTHING WAS SCREAMING "16."

BUT IT WAS JUST, LIKE,
A REALLY TALL BUILDING.

1, 2, 3, 4, 5, 6, 7...

16th FLOOR?

MARISOL, VOICE-OVER: 16 FLOORS.
IT HAD TO BE A LEVEL.

SO LET'S CHECK IT OUT, YEAH?

YEAH.
LET'S DO IT.

ALL RIGHT.
LET'S DO IT.

HAWKING: TRAVELING
THROUGH ANYTHING,

BE IT SPACE OR NEW YORK CITY,

MEANS GOING
FROM ONE PLACE TO ANOTHER.

THANKS TO A GENIUS WHO LOVED
TO LIE IN BED,

SCIENCE HAS A WAY TO DESCRIBE
WHAT THIS MEANS.

GREG RADICK: IN EUROPE

IN THE FIRST HALF
OF THE 17th CENTURY,

WHAT BECAME THE SCIENTIFIC
REVOLUTION BEGAN TO GATHER PACE

AS A NEW GENERATION CAME ALONG.

AMONG THEIR NUMBER
WAS A FRENCHMAN, RENE DESCARTES.

HE WAS ESTEEMED, IN PARTICULAR,
FOR HIS WORK

IN THE STUDY OF NATURE,

ABOVE ALL THE MATHEMATICAL
STUDY OF NATURE.

THE STORY GOES LIKE THIS--

THAT DESCARTES WAS
A SICKLY CHILD,

AND SO HE WAS ALLOWED BY
AN ENLIGHTENED TEACHER

TO SPEND HIS MORNINGS IN BED.

AND, INDEED, DESCARTES FOUND
THIS SO USEFUL, UH,

THAT HE KEPT IT UP FOR
THE REST OF HIS LIFE.

HE FOUND OFTEN HIS BEST THOUGHTS
CAME WHILE HE WAS IN BED.

HAWKING: DESCARTES FOUND
INSPIRATION IN ORDINARY THINGS.

ON ONE OCCASION, IT WAS THOUGHT
TO BE A COMMON HOUSEFLY.

RADICK: ONE DAY, DESCARTES WAS
IN BED,

AND HE WAS IDLY WATCHING A FLY
UP ON THE CEILING.

AND AS THE FLY WANDERS AROUND,
IT OCCURS TO DESCARTES

THAT WITH JUST 2 NUMBERS...

ONE TO DESCRIBE ITS POSITION
ALONG A HORIZONTAL AXIS,

ANOTHER TO DESCRIBE ITS POSITION

ALONG A VERTICAL AXIS.

HE CAN CAPTURE MATHEMATICALLY
THE POSITION OF THE FLY

AT ANY GIVEN MOMENT.

SO THERE'S DESCARTES WATCHING
THE FLY UP ON THE CEILING.

AND AT A CERTAIN MOMENT,
IT DROPS DOWN.

NOW, ON THE CEILING, THE FLY
NEEDED JUST 2 NUMBERS

FOR ITS POSITION TO BE
UNIQUELY DESCRIBED.

WHEN IT DROPS DOWN, IT LEAVES
2 DIMENSIONS

AND ENTERS INTO 3 DIMENSIONS.

NOW WE NEED 3 NUMBERS.

[FLY BUZZING]

AND IT TURNS OUT THAT ANYTHING
CAN BE POSITIONED

USING JUST 3 NUMBERS.

[FLY BUZZING]

HAWKING:
IN THIS SIMPLE

STROKE OF GENIUS,
DESCARTES LAID

THE FOUNDATION FOR

MODERN
MATHEMATICAL SCIENCE.

RADICK:
AND THIS INSIGHT

BECOMES
THE GERM OF

WHAT WE NOW CALL
THE CARTESIAN COORDINATE SYSTEM.

HAWKING: THE CARTESIAN
COORDINATE SYSTEM IS

STILL IN USE TODAY, ESPECIALLY
IN NEW YORK CITY.

MARISOL:
ALL RIGHT. 16th FLOOR?

YUP. GO FOR IT.

NORMAN: THAT'S THE LAST
OF OUR COORDINATES.

HAWKING: IT ALLOWS US TO
PRECISELY PINPOINT A LOCATION,

WHICH IS WHAT YOU NEED FOR
A PARTY.

PAUL: STEPHEN HAWKING--HE'S
UP THERE WAITING FOR US.

PROBABLY. THAT WOULD
BE A SURPRISE.

THAT WOULD BE GOOD.
THAT WOULD BE GOOD.

YEAH!
THAT WOULD BE A PARTY.

IT WOULD BE
A PARTY!

[LAUGHTER]

PAUL: OK, GUYS,
WE'RE HERE.

ALL RIGHT. WHAT?

NORMAN, VOICE-OVER:
WE WALK OUT ONTO THE 16th FLOOR,

AND THERE'S A PARTY...

PAUL: OH, HO! WOW!

NORMAN: HEY! IT LOOKS LIKE WE
GOT THE RIGHT SPOT.

NORMAN, VOICE-OVER: THAT HAD
FINISHED UP SOME TIME AGO.

THERE WAS A PARTY.

THERE WAS!
IT'S OVER.

THERE WAS A PARTY, YEAH.

WE MISSED IT.

NORMAN: IT LOOKS LIKE
THEY HAD A GOOD TIME.

PAUL, VOICE-OVER:
MY INITIAL FEELING WAS

ONE OF MASSIVE DISAPPOINTMENT TO
HAVE MISSED WHAT LOOKED LIKE

IT HAD BEEN A GREAT TEAR-UP.

PAUL: SIGH.

MARISOL: SHUCKS.

WELL, AT LEAST WE'RE
ON THE RIGHT PATH.

HAWKING: MY INVITATION
WASN'T COMPLETE.

SO MY VOLUNTEERS HAD MISSED
THE PARTY.

CAN THEY FIGURE OUT WHY?

"I'M SORRY I HAD TO GO.

"HOW MANY PIECES OF
INFORMATION DO YOU NEED

TO MAKE IT TO A PARTY?"

PAUL: "HOW MANY PIECES OF
INFORMATION DO YOU NEED

TO MAKE IT TO A PARTY?"

48, 16, AND 11.

SO A POINT.

SO, LIKE,
AN INTERSECTION.

WE GOT 48...

SO 2 NUMBERS FOR
THE POINT.

THAT'S IT. TWO DIMENSIONS.

THEN YOUR THIRD DIMENSION
IS IN HEIGHT.

SO WE WENT--WENT THAT WAY,
THAT WAY, THAT WAY.

SO THAT'S 3 POINTS
OF INFORMATION.

AND THE FOURTH PIECE OF
INFORMATION WOULD BE TIME.

SO YOU'D NEED 4 PIECES
OF INFORMATION.

AND WE ONLY HAD 3.

THE ADDITIONAL ONE
BEING

THE FOURTH
DIMENSION--TIME.

PAUL: YES.

SO TIME IS A DIMENSION

THAT WE'RE
TRAVELING THROUGH,

BUT WE DON'T REALLY REALIZE IT
BECAUSE IT'S ALWAYS PRESENT.

PAUL: SO THAT'S WHY
WE MISSED IT.

THAT'S WHY WE
MISSED IT. WE MISSED--

WE DIDN'T HAVE ALL
THE INFORMATION WE NEEDED.

HAWKING: THIS WAS
A MEAN TRICK TO PLAY

BUT THEY'RE RIGHT.

YOU NEED 3 NUMBERS
TO DESCRIBE A PLACE,

BUT YOU NEED
A FOURTH TO DESCRIBE AN EVENT,

AND THAT FOURTH IS TIME.

[CHEERING]

SO WE MADE IT. HA HA!

NORMAN: IT WAS MORE OF
A REVELATION

THAN A DISAPPOINTMENT.

HEY!

AWESOME!

NORMAN, VOICE-OVER: WE'RE
USED TO WHAT WE CAN SEE.

AND YOU GIVE ME A HEIGHT,
DISTANCE, PLACE,

I CAN WORK WITH THOSE
BECAUSE I CAN SEE IT.

TIME IS THERE WORKING,
BUT YOU'RE NOT AWARE OF IT.

THINGS ARE ALWAYS HAPPENING

IN THAT FOURTH DIMENSION,
AS WELL.

I GUESS THIS GOES BEYOND
BEING FASHIONABLY LATE.

[CHUCKLES]

CHEERS, GUYS.
CHEERS.

CHEERS. CONGRATULATIONS.

HAWKING: TO TRAVEL IN TIME,

WE NEED TO FIND A MEANS
OF TRAVELING

THROUGH THE FOURTH DIMENSION.

BUT WHAT DOES THIS REALLY MEAN?

TO HELP UNDERSTAND,

I AM GIVING MY VOLUNTEERS
A TOUGH NEW CHALLENGE.

IN THE NEXT PHASE OF
THEIR QUEST,

TO DISCOVER IF TIME TRAVEL
IS POSSIBLE,

I HOPE THE VOLUNTEERS WILL GRASP
A CONCEPT

THAT REVOLUTIONIZED OUR
UNDERSTANDING OF THE UNIVERSE.

MARISOL: HMM?

PAUL: SERIOUS?

HAWKING:
IF THEY CAN UNDERSTAND IT,

THEN THEY REALLY WILL BE
THINKING LIKE A GENIUS.

MARISOL: THANK YOU.
PAUL: THANK YOU.

NORMAN: MY PLEASURE.

NORMAN, VOICE-OVER:
WE'RE WALKING IN.

AND AT FIRST, REALLY,

I WASN'T SURE
WHAT I'M LOOKING AT.

MARISOL: IT'S WHERE WE WERE.

PAUL: TIMES SQUARE.

NORMAN, VOICE-OVER:
AND THEN WE ALL SEE

THE MAPS OF NEW YORK.

PAUL: THEY'RE ALL
THE SAME MAP, AREN'T THEY?

LOOK, BROADWAY, BROADWAY,
BROADWAY...

MARISOL: AT DIFFERENT TIMES.

AT DIFFERENT
TIMES.

PAUL, VOICE-OVER:
THE MAPS WERE IDENTICAL,

SAVE FOR THE TIME.

MARISOL: THIS ONE SAYS
50 MINUTES, 10 MINUTES,

+20,

+30, +40 MINUTES.

HAWKING: EACH MAP COVERS
THE AREA OF NEW YORK

THEY TRAVELED THROUGH TO GET
TO THE PARTY.

AND EACH REPRESENTS
A MOMENT IN TIME.

THE MAP ON THE LIGHT BOX HAS
THEIR START TIME

IN TIMES SQUARE.

NORMAN, LOOK, IT'S
YOU WITH HAIR.

MARISOL: HA HA! LOOK! HA HA!

PAUL: AND MINE'S
FAR TOO PRETTY.

[MARISOL LAUGHING]

HAWKING: I HAVE ASKED THEM TO
VISUALIZE THEIR JOURNEY

FROM TIMES SQUARE TO THE PARTY
IN BOTH SPACE AND TIME.

LET'S SEE IF THEY CAN GET
THE PURPOSE OF THIS.

PAUL: OH! I'VE GOT IT.

EACH OF THESE MAPS IS
A POINT IN TIME, ISN'T IT?

MM-HMM.
RIGHT.

AND WE CAN PUT OUR
POSITIONS ON THE MAPS

WHERE WE WERE AT THAT POINT
IN TIME.

NORMAN, VOICE-OVER:
SEVEN MAPS,

7 FIGURES FOR EACH OF US.

SO IT WAS PRETTY CLEAR THAT
EACH OF US WILL REPRESENT

A CERTAIN SPOT
DURING THE JOURNEY

AT A CERTAIN TIME.

WH--WHERE DO
WE START, GUYS?

RIGHT HERE.
TIMES SQUARE, 43rd.

WE'RE GOING THIS WAY.

HERE ON THE...

PAUL: SHOULD WE SEE
WHERE WE WERE

10 MINUTES LATER?

HAWKING: THE CAMERA WAS
NOT JUST FOR SELFIES.

MARISOL ON VIDEO: WE'RE
GONNA GO TO A PARTY!

[LAUGHTER]

HAWKING: HOPEFULLY,
IT WILL COME IN HANDY.

NORMAN, VOICE-OVER: WE WERE ABLE
TO PLOT WHERE WE WERE

BECAUSE WE HAD
THE TIME SIGNATURE

ON THE VIDEO.

DO YOU SEE THE STREET SIGN?

PAUL ON VIDEO: 46th.

MARISOL: SO AT
10 MINUTES,

WE GOT
TO 46th STREET.

LET'S DO IT.

YOU--YOU TAKE
YOUR TIME, NORM.

HA HA!

MARISOL, VOICE-OVER:
IT JUST KIND OF SEEMED NATURAL

TO STACK THE GLASS GRIDS
OF MANHATTAN INTO LAYERS

AND TO PLACE US
IN EACH TIME LABEL

THAT WAS ON EACH TABLE.

ALL RIGHT.

THEN THE NEXT ONE, I THINK
IT'S +20.

SO IF YOU GUYS WANT
TO GRAB IT.

YUP, SURE.

TO ME TO YOU,
TO ME TO YOU.

PAUL ON VIDEO:
WHERE ARE WE?

48th.
48th.

48th. IT'S US...

THIS IS THE END OF
OUR FIRST BLOCK.

NORMAN: 48th STREET.

MARISOL: THAT'S
WHEN WE TURNED LEFT.

NORMAN: AND THEN WE GO
TO 30, +30.

MARISOL: 30.
GOOD JOB, GUYS.

PRECISION ENGINEERING,
NORMAN.

NORMAN: WE'LL HAVE TO
UPDATE OUR RESUMES.

MARISOL: SO 40 MINUTES.
THERE WE GO.

NORMAN: 45.

ALL RIGHT. SO WE ARE ON...

PAUL: DESTINATION!

MARISOL: 11th AND 48th...

NORMAN: AND HERE'S
48th. YUP.

AT THE PARTY. THERE WE GO.

THAT'S US!

MARISOL: WE DID IT, GUYS.

AWESOME.

PAUL: WE'VE BUILT
A PATH OF WHERE WE STARTED

AND WHERE WE FINISHED

IN SPACE AND TIME.

SO YOU CAN THINK
OF EACH LAYER

AS THE SPATIAL DIMENSION,
COULDN'T YOU,

AND EACH LEVEL, IF YOU LIKE,
AS THE TIME DIMENSION.

WHICH IS
THE FOURTH DIMENSION.

PAUL AND MARISOL:
THE FOURTH DIMENSION.

YEAH. SO WE'VE
KIND OF PLOTTED

THE FOURTH DIMENSION.

SO WHERE DOES THAT GET US?

[CHUCKLING]

HAWKING: THE CONCLUSION I HOPE
THEY WILL REACH IS ONE

THAT WAS DREAMT UP BY
A CLERK IN SWITZERLAND.

HE WOULD BECOME THE MOST
INFLUENTIAL PHYSICIST

IN THE 20th CENTURY.

RADICK: IF YOU WERE PLACING BETS

ON WHO WAS ABOUT TO
REVOLUTIONIZE PHYSICS,

YOU WOULDN'T HAVE BET ON
ALBERT EINSTEIN.

26 YEARS OLD, A VIOLIN PLAYING
BOHEMIAN

WORKING NOT IN ONE OF
THE GREAT LABS,

BUT IN THE SWISS PATENT OFFICE
IN BERN,

WHERE HE WAS A LOWLY PATENT
EXAMINER.

BUT EINSTEIN TOILED AWAY

ON SOME OF THE MOST FUNDAMENTAL
PROBLEMS OF THE DAY...

BECAUSE IN EUROPE AT THAT TIME,

ONE OF THE MOST PRESSING
PRACTICAL PROBLEMS WAS

ABOUT HOW TO COORDINATE
THE CLOCKS

SO THAT THE TRAINS RAN ON TIME.

[CLOCK TICKING]

AND EINSTEIN WAS EXAMINING
SYSTEMS

WHICH PURPORTED TO DO THAT.

[WHISTLE BLOWS]

HAWKING: PERHAPS
THIS WORK INSPIRED HIM

TO START THINKING ABOUT TIME.

IN 1905,
EINSTEIN PUBLISHED A PAPER

WHICH CHANGED THE WAY
WE SEE SPACE AND TIME.

[CLOCK TICKING]

RADICK: BEFORE EINSTEIN,
THE CONVENTIONAL VIEW WAS THAT

SPACE AND TIME WERE
TWO COMPLETELY DIFFERENT THINGS.

SPACE WAS A KIND OF
GRAND CONTAINER

HOLDING OBJECTS AND EVENTS...

WHEREAS TIME WAS A UNIVERSAL
FLOW CARRYING EVERYTHING

FROM THE PRESENT
INTO THE FUTURE.

EINSTEIN CAME TO
A COMPLETELY DIFFERENT VIEW

ON SPACE AND TIME.

THEY WERE NOT
INDEPENDENT OF ONE ANOTHER.

THEY WERE ASPECTS OF
A SINGLE THING--

A SINGLE FABRIC OF SPACE-TIME...

[CLOCK TICKING]

EVERYTHING UNFOLDING WITHIN
THOSE 4 DIMENSIONS ALWAYS.

HAWKING: BEFORE THE VOLUNTEERS
CAN REALLY UNDERSTAND

HOW WE MIGHT TRAVEL
THROUGH TIME,

THEY'LL NEED TO MAKE THE SAME
INTELLECTUAL LEAP

THAT EINSTEIN MADE.

PAUL: WE REALIZED IT WAS
A MODEL OF OUR JOURNEY.

I THINK THE REALIZATION
OF WHAT IT MEANT

CAME QUITE A BIT LATER ON,
THOUGH. HA HA!

MARISOL: TRAVELING THROUGH
TIME WITH THIS VISUAL,

IT SEEMS LIKE MOVING UP,
MOVING FORWARD.

I MEAN, ULTIMATELY,
I THINK WE WANT TO--

TO BE ABLE TO MANIPULATE
WHERE WE ARE

AND WHEN WE ARE

AND THAT THE TWO ARE
INTER--INTERTWINED.

NOW WITH THIS YOU CAN SEE

YOU CAN'T SEPARATE
SPACE FROM TIME,

EVEN THOUGH WE

DON'T TYPICALLY
LOOK AT IT THAT WAY.

ARE YOU SAYING IT'S NOT
SPACE AND TIME? IT'S...

NORMAN AND MARISOL:
SPACE-TIME.

PAUL: WOW!
SPACE-TIME.

IT'S NO LONGER
A SEPARATION,

FOR NOW WE HAVE
A SPACE-TIME MAP.

SO BOTH ARE ALL IN
THE SAME...

NORMAN, WE'VE BROUGHT
TOGETHER THE 4 DIMENSIONS!

[LAUGHTER]

ALL RIGHT!

WHAT A STUNNING ACHIEVEMENT!

HAWKING: THEY'VE GOT IT.

THEY HAVE SEEN THAT THEIR
JOURNEY THROUGH SPACE...

AND THEIR PASSAGE
THROUGH TIME...

ARE INEXTRICABLY LINKED...

TIME AND SPACE DO NOT
EXIST SEPARATELY.

THEY ARE UNIFIED.

HAWKING: SPACE-TIME FILLS
EVERY CORNER OF THE UNIVERSE

AND ALWAYS HAS.

EVERY EVENT IN OUR LIVES HAS
A UNIQUE REFERENCE POINT

WITHIN IT,

BOTH A PHYSICAL LOCATION
AND A SPECIFIC MOMENT IN TIME.

THE SAME IS TRUE FOR
EVERY PARTICLE IN THE COSMOS

AND EVERY MOMENT IN HISTORY.

I WON'T LOOK AT IT
THE SAME WAY ANYMORE

BECAUSE I AM WHERE I AM

AND I'M ALSO WHEN I AM.

MARISOL: SPACE-TIME,
IT'S THE SAME THING.

AND YOU CAN'T SEPARATE THEM.

SO WE'D HAVE TO MANIPULATE
BOTH TO TRAVEL THROUGH TIME.

HAWKING: MOST PEOPLE THINK
OF TIME TRAVEL

AS A SUDDEN DISAPPEARANCE
FROM ONE MOMENT IN TIME...

AND AN INSTANTANEOUS ARRIVAL
IN ANOTHER...

USUALLY INVOLVING

A CLEVERLY ENGINEERED
TIME MACHINE.

I HATE TO BE A KILLJOY, BUT
I DOUBT IT WILL EVER BE POSSIBLE

TO JUMP THROUGH SPACE-TIME
IN THIS WAY.

TO UNDERSTAND TIME TRAVEL,

WE NEED TO THINK OF IT
AS A JOURNEY--

AN EXPEDITION EITHER
FORWARDS OR BACKWARDS

ALONG THE FOURTH DIMENSION.

HAVING GRASPED THE CONCEPT OF
SPACE-TIME, THE VOLUNTEERS ARE

READY TO COME TO GRIPS
WITH TIME TRAVEL.

FOR THEIR NEXT
TIME TRAVEL CHALLENGE,

MY TEAM WILL NEED PLENTY
OF ROOM,

SO WE'VE LEFT NEW YORK AND COME

TO THE BEAUTIFUL DESERT
OF ARIZONA.

I WANT THEM TO IMAGINE TRAVELING
BACKWARDS IN TIME.

PAUL: YEAH. LOOK.
LINES.

HAWKING: AND THERE'S
ANOTHER SURPRISE IN STORE.

MARISOL: SO I'M WALKING IN.

AND THERE'S
A DIRT AREA.

AND THERE'S 3 TRACKS.

NORMAN:
LOOK AT THIS.

ARROWS.

NORMAN: WE GOT 2
"FORWARDS."

WHAT'S THAT ONE
SAY DOWN THERE?

MARISOL: YEAH.
LET'S CHECK IT OUT.

NORMAN, VOICE-OVER:
THERE'S A LANE

WITH AN ARROW POINTING AWAY
FROM US THAT SAYS "FORWARD."

PAUL: THE SECOND LANE
SAYS "BACK"

AND WAS LABELED BACK.

MARISOL: AND THEN THE NEXT ONE

IS A THIRD TRACK
WITH "FORWARD" AGAIN.

PAUL: TWO "FORWARD,"
ONE "BACK."

HAWKING: IMAGINE THIS IS
A MAGICAL PARKING LOT

THAT WILL ALLOW THEM TO TRAVEL
THROUGH THE DIMENSION OF TIME.

BUT TO DO THAT, THEY'LL NEED
A TIME MACHINE.

[PAUL LAUGHING]

NORMAN: OH,
LOOK AT THAT!

HEY! HA HA!
WELL...

ALL RIGHT!

MARISOL:
A DeLOREAN.

PAUL, VOICE-OVER:
TO OUR ABSOLUTE AMAZEMENT,

A DeLOREAN CAME SPINNING
ROUND THE CORNER.

[EXCITED CHATTER, LAUGHTER]

PAUL, VOICE-OVER: AND THEN
THE DRIVER JUMPS OUT,

WANGLED KEYS IN FRONT OF US.

AND NO RIGHT-MINDED PERSON
CONFRONTED WITH DeLOREAN KEYS

WOULD NOT GRAB THEM.

HEY!

HA HA!
MARISOL: AWESOME.

INSTRUCTIONS.

"IMAGINE THIS IS
A MAGICAL PARKING LOT."

HAWKING:
IMAGINE EACH LANE REPRESENTS

THE SAME PASSAGE THROUGH
SPACE-TIME.

IN THE FIRST LANE, THEY WILL
BE TRAVELING FORWARDS WITH TIME

IN THE USUAL WAY JUST LIKE
THE REST OF US.

IN THE SECOND, THEY BECOME
TIME TRAVELERS

AS THEY RETRACE
THEIR ROUTE BACKWARDS

THROUGH SPACE-TIME
TO THE MOMENT THEY BEGAN.

[CLOCK TICKING]

IN THE THIRD LANE, THEY WILL BE
TRAVELING FORWARDS WITH TIME

IN THE USUAL WAY ONCE AGAIN.

[CLOCK TICKING]

MARISOL: "YOU MUST COMPLETE
ALL 3 LANES OF THE COURSE.

"BUT BEFORE YOU SET OFF DOWN
EACH LANE,

THINK ABOUT WHAT YOU WILL SEE."

HAWKING: THEIR CHALLENGE
IS TO PREDICT...

ALL 3 LANES.

WHAT IT WOULD LOOK LIKE
TO TRAVEL BACKWARDS IN TIME.

THE FIRST TIME WE GO DOWN,

WE'LL SEE NOTHING OUT OF
THE ORDINARY,

EXCEPT US IN THE DeLOREAN.

WE GET TO THE END.

WE COME BACK IN TIME.

AND AT SOME STAGE,

WE WILL PASS OURSELVES GOING
FORWARD IN TIME, WON'T WE?

YEAH.

NORMAN: ARE YOU SURE?

HAWKING: NORMAN IS RIGHT
TO QUESTION THIS PLAN.

IT HAS A FLAW.

PAUL: HERE'S A RADIO!

WE'LL CALL YOU
FROM THE FUTURE.

ALL RIGHT.

HAWKING: BUT PERHAPS
ONCE THEY'RE UNDERWAY,

THEY'LL SPOT THEIR MISTAKE.

PAUL: TIME TO FIRE UP
THE DeLOREAN.

[ENGINE REVS]

MARISOL: FIRE IT UP! HA HA!

BYE!
HA HA!

WE'RE IN A DeLOREAN.
INTO THE FUTURE.

AWESOME.

PAUL, VOICE-OVER: OUR INITIAL
THOUGHT WAS,

WHEN WE CAME BACK, WE THOUGHT
THAT WE WOULD PASS OURSELVES

OR--OR WE'D PASS OURSELVES
AT ABOUT THE HALFWAY POINT.

WE HADN'T CONSIDERED AT
THAT POINT WHAT WE HAD MISSED.

PAUL: LET'S SLIDE OUT,

READY TO GO BACK
TO THE PAST.

ALL RIGHT.
OK.

PAUL: ALL RIGHT. LET'S
GIVE NORMAN A CALL.

MARISOL: HEY, NORM,

WHAT WE SHOULD EXPECT TO
SEE WHEN WE GO BACKWARDS

THROUGH THE SPACE-TIME
IS OURSELVES.

THERE'S GOING TO BE
ANOTHER DeLOREAN

JUST PASSING BY.

WHAT DO YOU THINK?

NORMAN: I--I DON'T KNOW.

HAWKING: THEY'RE RIGHT
ABOUT ONE THING.

IF THEY JOURNEY BACK
THROUGH SPACE-TIME,

THEY WOULD SEE THEMSELVES.

SO FOR THAT, THEY'RE GOING
TO NEED ANOTHER CAR.

[PAUL LAUGHING]

PAUL, VOICE-OVER:
ALL OF A SUDDEN,

ANOTHER DeLOREAN APPEARS
WHERE WE WERE.

AND TO OUR UTTER AMAZEMENT,
NOW, THERE'S NOT ONLY--

NOW THERE'S NOT ONE DeLOREAN.

NOW THERE'S
TWO DeLOREANS!

NORM, WHO IS THAT?
IS THAT US?

NORMAN: YEAH. YUP,
THAT IS YOU.

[BOTH LAUGHING]

LET'S GO BACK IN TIME.
LET'S GO BACK IN TIME.

HAWKING: LET'S SEE IF COMING
FACE-TO-FACE WITH THEMSELVES

HELPS THEM REALIZE THEIR
MISTAKE.

[MARISOL AND PAUL LAUGHING]

IT'S US!
IT'S US!

[LAUGHTER]

MARISOL, VOICE-OVER:
IT WAS ACTUALLY US.

LIKE, OUR FACES WERE
THERE--HA HA!--

JUST STARING AT US.

PAUL, VOICE-OVER: WE STARTED
TO SEE FLAWS IN OUR LOGIC

AT THAT POINT.

HAWKING: I THINK THIS CROSSING
OF PATHS IS

WHAT MOST PEOPLE WOULD PREDICT.

BUT I DON'T SEE BACKWARD
TIME TRAVEL THIS WAY.

THEY MUST THINK AGAIN.

PAUL: NOW, WHAT WOULD
YOU EXPECT TO SEE

IF YOU RETRACED
YOUR STEPS

BACK THROUGH SPACE-TIME?
WELL, THINK ABOUT IT.

YOU WOULD SEE--NO.
YOU WOULD--

BOTH: SEE YOURSELF...

GO.
GOING WHAT?

YOU'D SEE YOURSELF
GOING BACKWARDS,
WOULDN'T YOU?

IMAGINE--AT THE TOP OF
THAT SPACE-TIME MODEL
AND COMING DOWN IT.

YOU'D SEE YOURSELF
GOING BACKWARDS,
WOULDN'T YOU?

MARISOL: YEAH.

HAWKING: PAUL HAS SPOTTED
THEIR ERROR.

IF YOU IMAGINE GOING FORWARDS

THROUGH THE TIME DIMENSION
ONE WAY,

THEN RETURNING BACK
THE OTHER,

YOU WOULD NOT CROSS PATHS
WITH YOURSELF.

INSTEAD, YOU WOULD SEE YOURSELF
GOING BACKWARDS.

ONCE YOU RETURNED,

YOU WOULD CONTINUE TO TRAVEL
FORWARDS WITH TIME ONCE AGAIN...

ONLY NOW THERE WOULD BE
THREE OF YOU...

WHICH CALLS FOR ANOTHER CAR.

MARISOL: AWESOME!

[MARISOL AND PAUL LAUGHING]

MARISOL: LOOK AT US!
OH, MY GOD!

[LAUGHTER]

NORMAN, VOICE-OVER:
WHEN WE LEFT,

WE CREATED A NEW FUTURE.

AND THAT'S WHEN THE THIRD CAR
POPS UP.

[LAUGHTER]

HAWKING: TO MAKE THIS CLEAR,

LET'S TRY IT ONCE MORE
FROM THE BEGINNING.

ALL RIGHT.

WE'RE GONNA DRIVE
INTO THE FUTURE.

FROM FORWARDS TO BACK
TO FORWARDS.

MARISOL: AND HERE WE
GO AGAIN.

OH, THIS IS TRIPPY.

[LAUGHTER]

HAWKING: IN A LINEAR JOURNEY
THROUGH SPACE-TIME,

PAUL AND MARISOL WOULD SEE
THEIR FUTURE SELVES

TRAVELING BACK IN TIME
AND MOVING FORWARDS WITH TIME

AFTER THEIR BACKWARD JOURNEY.

PAUL: THREE DeLOREANS!
1, 2, 3.

[LAUGHTER]

PAUL, VOICE-OVER: WHEN YOU
MOVE FORWARD IN TIME,

LANES ONE AND 3 ARE GOING
IN THE SAME DIRECTION,

RELATIVE TO LANE 2.

IT'S GOING BACKWARDS.

HAWKING: AS THEY JOURNEY BACK
THROUGH TIME,

THEY WOULD BE FLANKED BY

THEIR FORWARD-TRAVELING
PAST SELVES

AND THEIR FORWARD-TRAVELING
FUTURE SELVES.

NORMAN: EVERYTHING IS
HAPPENING IN SYNC.

IT ALL HAS TO HAPPEN TOGETHER.
IT ALL...

YOU'RE MOVING FORWARD
AND BACKWARDS TOGETHER.

HAWKING: ONCE THEY'D STOP
TIME TRAVELING

AND TIME PASSED NORMALLY FOR
THEM ONCE MORE,

THEY'D SEE BOTH SETS OF THEIR
PAST SELVES

STILL TRAVELING THROUGH TIME.

MARISOL: IT'S SO WEIRD
LOOKING AT--AT MYSELF.

YOU LOOK SO SERIOUS.

PAUL: AND TO THEM, IT'S
GONNA LOOK LIKE

WE'VE GONE BACKWARDS
IN TIME.

[LAUGHING]

HAWKING: THERE'S A FUNDAMENTAL
ISSUE WITH BACKWARD TIME TRAVEL.

LET'S SEE IF MY VOLUNTEERS
HAVE SPOTTED IT.

PAUL: COMING BACK
STARTS TO GET

A BIT PROBLEMATIC

BECAUSE WE
WITNESSED OURSELVES

GOING FORWARD
IN TIME, DIDN'T WE?

SO AT THAT POINT,
THERE'S NOW TWO OF US.

SOMETHING HAS
TO POP INTO EXISTENCE

AND POP OUT AND...

AT THE MOMENT, WELL,
IF YOU JUST THINK,
IT'S NOT POSSIBLE,

BECAUSE I DON'T SEE HOW
WE CAN HAVE TWO OF US

IN EXISTENCE
AT THE SAME TIME.

MARISOL: THAT--
THAT'S WHAT I'M SAYING.
IT ALWAYS SEEMS LIKE...

NORMAN, VOICE-OVER:
YOU CAN'T BE MAKING THINGS

OUT OF THIN AIR,

THAT THERE'S LIVING,
BREATHING CREATURES

AND MASS AND ENERGY SHOWING UP
ESSENTIALLY OUT OF NOTHING.

THAT'S NOT GONNA HAPPEN.

NORMAN: IF YOU GO BACK,

THERE'S--YOU'VE CREATED
SOMETHING THAT WAS

NEVER THERE
IN THE FIRST PLACE.

YOU CAN'T GO BACK.

MARISOL, VOICE-OVER:
WE CAME TO THE CONCLUSION

THAT MOST LIKELY

TRAVELING BACK IN TIME
WAS IMPOSSIBLE.

SO IT WAS NICE TO ACTUALLY
HAVE IT CHECKED OFF THE LIST.

HAWKING: THEY'RE RIGHT.

THE LAWS OF NATURE
DO NOT SUPPORT

THE SUDDEN APPEARANCE

OF SUCH LARGE QUANTITIES
OF NEW MATTER.

IN OTHER WORDS, DUPLICATES
OF TIME MACHINES AND PEOPLE

COULD NOT
FLASH INTO EXISTENCE.

SO BACKWARD TIME TRAVEL
IS UNLIKELY TO WORK.

IT'S DISAPPOINTING, BUT I PREFER
TO LOOK ON THE BRIGHT SIDE.

AT LEAST HISTORY IS SAFE

FROM MEDDLING
TIME-TRAVELING TOURISTS.

[CROWD CHEERING]

NOW THAT THEY'VE RULED OUT
TRAVELING BACKWARDS IN TIME,

MY VOLUNTEERS NEED TO THINK
ABOUT TRAVELING TO THE FUTURE.

WE'VE COME
TO THE UNIVERSITY OF ARIZONA.

THE VOLUNTEERS
WILL BE SURROUNDED

BY INQUISITIVE MINDS,

AS THEY ENDEAVOR TO FIND OUT
IF IT'S POSSIBLE TO TRAVEL

FORWARDS THROUGH TIME.

MARISOL: I SEE A LINE OF CLOCKS

WITH NO NUMBERS AND A CHEST.

IT ALMOST LOOKS LIKE
A TREASURE CHEST, A BOX.

PAUL: DARE WE?
MARISOL: DO WE?

1...

2...

WHAT THE HECK?

NORMAN: TIMERS.
HA HA!

PAUL, VOICE-OVER:
THERE WERE SEVERAL COUNTERS.

THEY WERE COUNTING DEVICES.

IT'S A PARACHUTE.

LET'S GET IT OUT.

NORMAN, VOICE-OVER: IN
THE BEGINNING, WE JUST FIGURED

IT WAS PACKING
TO HOLD THE COUNTERS,

AND THEN SOME
INSPIRATION CAME TO US.

MARISOL: THERE'S
A PLUG OVER HERE.

DO YOU WANT TO
GIVE IT A WHIRL, THEN?

DEFINITELY!
GOSH.

THERE WE GO. READY?

YUP.
COMING ON.

ALL RIGHT.

IT INFLATES.

PAUL: SHALL I GET
UNDERNEATH IT?

NORMAN: YES!

[MARISOL LAUGHING]

MARISOL: HAVE YOU GOT IT?

YEAH, B--BECAUSE IT'S
GONNA COME UP.

HAWKING: ONCE INFLATED,
THEY WILL HAVE

EVERYTHING THEY NEED TO WORK OUT

HOW TO TRAVEL TO THE FUTURE.

HAWKING: SWITCHING
THE CLOCKS ON MAY HELP.

PAUL: AH!

NORMAN: THEY'RE MOVING
AT DIFFERENT SPEEDS.

MARISOL: THEY'RE ALL
GOING DIFFERENT SPEEDS.

NORMAN: YEAH, THEY ARE.

PAUL, VOICE-OVER:
AT FIRST IT LOOKED LIKE

THEY WERE RUNNING
IN SOME KIND OF RANDOM ORDER.

BUT IT BECAME APPARENT
WHEN YOU STOOD BACK

THEY WERE ACTUALLY RUNNING
SLOWER AND SLOWER AND SLOWER

THE FURTHER AWAY
YOU GOT FROM THE FIRST ONE.

MARISOL: WHAT DO
YOU GUYS THINK?

PAUL: THERE SEEMS
TO BE A PATTERN,

DOESN'T THERE,
IN THE...

THIS ONE'S
WHIZZING ROUND...
YEAH.

THIS ONE'S GOING
A LITTLE BIT SLOWER

THAN THAT ONE.
RIGHT.

HAWKING:
TIME IS BEHAVING STRANGELY

NEAR THEIR INFLATABLE.

BUT WILL THIS HELP THEM
WORK OUT WHAT IT REPRESENTS?

PAUL, VOICE-OVER:
WE WASN'T TOO SURE

WHAT THE SIGNIFICANCE OF IT WAS.

IT LOOKED LIKE
A PLANET AT FIRST,

AND THEN REALIZED
IT WAS--IT WAS A BLACK HOLE.

BLACK HOLE?

BLACK HOLE.

HAWKING: BLACK HOLES
ARE STRANGER

THAN ANYTHING DREAMT UP
BY SCIENCE FICTION WRITERS,

BUT THEY ARE FIRMLY
SCIENCE FACT.

A BLACK HOLE IS A STAR
WITH AN EXTREME AMOUNT OF MASS

COMPACTED INTO A RELATIVELY
SMALL AMOUNT OF SPACE.

THIS MASS CREATES THE STRONGEST
GRAVITATIONAL FIELD

IN THE UNIVERSE...

A FIELD SO STRONG THAT
THE STAR'S OWN LIGHT

CANNOT ESCAPE,

WHICH IS WHY THEY
ARE CALLED BLACK HOLES.

ALBERT EINSTEIN DISCOVERED
HOW THEY FUNCTION

WHEN HE TURNED HIS ATTENTION

TO SOMETHING
THAT HAD BEEN PUZZLING HIM--

GRAVITY.

[MOTOR RUNNING]

FILIPPENKO:
SO EINSTEIN SAID, YOU KNOW,

"NONE OF YOU GUYS...

"NONE OF YOU
PHYSICISTS REALLY HAS

"AN ADEQUATE THEORY OF GRAVITY.
AND I DON'T EITHER,

BUT I'M GONNA COME UP WITH ONE."

WHAT EINSTEIN CAME UP WITH
IS THAT THE PRESENCE OF MASS

ACTUALLY BENDS OR WARPS
THE SHAPE

OF BOTH SPACE AND TIME
IN ITS SURROUNDINGS.

AND OTHER OBJECTS THEN FOLLOW

THEIR NATURAL PATHS THROUGH
THIS INTRINSICALLY CURVED SPACE.

THAT'S WHAT THE SUN DOES,
SO EARTH ORBITS IT.

THAT'S WHAT EARTH DOES,

SO THE MOON ORBITS IT.

THAT'S WHAT THE MOON DOES,

SO ROCKETS THAT WE
SEND UP THERE ORBIT IT.

HAWKING: EINSTEIN SAID
THIS WARPING OF SPACE-TIME IS

WHAT CREATES GRAVITY

AND THAT IT ALSO
ALTERS TIME ITSELF.

[CLOCK TICKING]

AND THAT TIME PASSES
AT DIFFERENT SPEEDS

DEPENDING ON HOW STRONG
THE GRAVITY IS.

THE STRONGER THE GRAVITY,
THE MORE PRONOUNCED THE EFFECT.

[CLOCK TICKING SPEED SLOWS DOWN]

HE CALLED HIS THEORY
GENERAL RELATIVITY.

WELL, MOST PEOPLE REACTED

IN A VERY PUZZLED
AND INCREDULOUS WAY

WHEN EINSTEIN FIRST SAID
THAT THIS IS

WHAT GRAVITY IS, YOU KNOW.

"WHAT THE HECK?" YOU KNOW,
"WHAT ARE YOU TALKING ABOUT?"

HAWKING: BUT WHEN WE
APPLY GENERAL RELATIVITY

TO BLACK HOLES,
THINGS GET TRULY STRANGE.

FILIPPENKO: A BLACK HOLE'S
A PLACE WHERE GRAVITY IS

AT ITS STRONGEST.

YOU CAN'T GET A PLACE
IN THE UNIVERSE WHERE GRAVITY

IS STRONGER THAN WHAT'S
IN A BLACK HOLE.

IN EINSTEIN'S
GENERAL RELATIVITY,

THE PASSAGE OF TIME
SLOWS DOWN TO A HALT

AT THE BOUNDARY OF A BLACK HOLE.

REGIONS NEAR THE MASS
ARE BENT OR CURVED MORE.

AND IN A SIMILAR WAY,
TIME IS SLOWED DOWN MORE.

HAWKING: THIS IS
A HARD CONCEPT TO GRASP.

LET'S TRY AN EXPERIMENT
TO MAKE IT CLEAR.

CAN THE VOLUNTEERS WORK OUT HOW
WARPED TIME NEAR A BLACK HOLE

CAN BE USED TO TRAVEL
TO THE FUTURE?

CAN YOU USE A BLACK HOLE
TO TRAVEL TO THE FUTURE?

NORMAN: TRAVEL
TO THE FUTURE? YEAH.

PAUL: SO IF YOU WERE
STANDING AT THE FIRST CLOCK,

TIME WOULD APPEAR TO BE
GOING VERY SLOWLY TO YOU,

WOULDN'T IT,
COMPARED TO SOMEBODY HERE.

MM-HMM. YES.

IF YOU CAME BACK FROM
THAT POINT TO HERE...

TIME WOULD ALREADY HAVE
BEEN GOING AHEAD,

SO YOU'RE
IN THE FUTURE.

PAUL: EXACTLY.
NORMAN: RIGHT.

MARISOL: OK.

NORMAN: WE STAGED OURSELVES

ONE AT THE NEAREST CLOCK
AND ONE AT THE FURTHEST

AND ONE IN THE MIDDLE.

AND WE DID COUNTS OF HOW MANY
TIMES WE WENT PAST M--MIDNIGHT.

NORMAN:
WE'LL SYNCH ON 12.

AND GO.

1...

2...

3...

[LAUGHING]
4...

5...

6...

HAWKING:
THEY ARE GETTING THE IDEA.

THE SPEED
AT WHICH TIME IS PASSING

IS RELATIVE TO THEIR PROXIMITY
TO THE BLACK HOLE.

3.

MARISOL, VOICE-OVER: I WAS
COUNTING ON THE FASTEST CLOCK.

AND WHEN I GOT TO 20,
WE ALL STOPPED.

19, 20.

STOP!
PAUL: STOP!

PAUL: WE'RE COMING BACK
TO THE PRESENT. HA HA!

ALL RIGHT,
GUYS. HA HA!

ALL RIGHT, GUYS.
WHAT DID YOU GET?

PAUL: THIS IS
HOW MANY

UNITS OF TIME
HAVE PASSED.

LET'S CALL IT DAYS.
DAYS.

OK, AFTER 3.
NORMAN: ALL RIGHT.

1, 2, 3.
...2, 3.

HOW MANY
HAVE YOU GOT?

1.
20.

PAUL:
WELL I'M ON 5.

SO LET ME GET
IN THE MIDDLE.
ALL RIGHT.

SO I SAW ONE DAY;
YOU SAW 5; AND YOU SAW 20.

I SAW 20.

SO WE CAN USE A BLACK HOLE
TO TRAVEL TO THE FUTURE.

AWESOME.

HAWKING:
IT SEEMS COUNTERINTUITIVE,

BUT HANGING OUT IN A PLACE
WHERE TIME PASSES SLOWLY

ALLOWS US TO TRAVEL
TO THE FUTURE.

WHEN WE RETURN TO WHERE
OUR JOURNEY BEGAN,

WE WILL HAVE EXPERIENCED
LESS TIME

RELATIVE TO THOSE
WE LEFT BEHIND.

BUT TO DO THIS IN REALITY,
WE WOULD REQUIRE A SPACECRAFT.

[PARTICIPANTS LAUGHING]

PAUL: I'LL GIVE
YOU A COUNTDOWN.

NORMAN: COUNTDOWN!

5, 4, 3, 2, 1.

ENGINES GO!
[NORMAN YELLS]

TAKE OFF.
[MARISOL LAUGHING]

NORMAN, VOICE-OVER:
WE WERE OUTFITTED

WITH THE LATEST
AND GREATEST EQUIPMENT

FOR MAKING THE TRIP
TO THE BLACK HOLE.

MARISOL: GOOD TIMING,
CAPTAIN.

[BOTH MOCK YELLING]

NORMAN: PULLING A LOT OF Gs,
PULLING A LOT OF Gs!

NORMAN, VOICE-OVER:
YOU COULD LOOK AT IT

AS JUST DRIVING AROUND IN
CIRCLES ON A GOLF CART,

OR, YOU KNOW,
YOU'RE REALLY FOCUSED.

YOU'RE IN A SPACESHIP
GOING AROUND A BLACK HOLE.

MARISOL: WE'RE AT 2.

HAWKING:
IMAGINE NORMAN AND MARISOL

HAVE TRAVELED
26,000 LIGHT YEARS

TO THE SUPER MASSIVE BLACK HOLE
AT THE CENTER OF OUR GALAXY.

IF THEY MANAGED TO GO INTO
ORBIT WITHOUT GETTING SUCKED IN,

TIME WOULD PASS
NORMALLY FOR THEM.

BUT THEY MIGHT
COME BACK MILLIONS,

EVEN BILLIONS OF YEARS LATER.

[IMITATES GRAVELLY VOICE]
OH! WELCOME BACK

TO EARTH, GUYS.

YOU'VE BEEN GONE
70 YEARS!

NORMAN: WOW.

MARISOL: REALLY. YEAH!
WE GOT 3.

PAUL: OH, SO, YOU GUYS
HAVE COME INTO THE FUTURE.

WELCOME TO THE FUTURE.

THANK YOU.
THANK YOU.

ONLY 3 YEARS HAVE GONE BY.

WOW.

NORMAN: OK. WELL,
THERE YOU GO.

WE CAN USE A BLACK HOLE

TO TRAVEL
FORWARD IN TIME.

HAWKING: THOUGH IT IS NOT
THE JUMP THROUGH TIME

THAT POPULAR CULTURE PREFERS,

THIS IS A METHOD OF TIME TRAVEL

THAT IS
THEORETICALLY ACHIEVABLE.

BUT CAN MY VOLUNTEERS WORK OUT

WHY TIME BEHAVES
THIS WAY AROUND A BLACK HOLE?

PAUL, VOICE-OVER:
AS I THINK ABOUT IT,

AS THE GRAVITATIONAL STRENGTH
GETS STRONGER AND STRONGER,

I WOULD EXPECT TIME TO
ACTUALLY SPEED UP,

NOT SLOW DOWN.

T--OH! OF COURSE, OF COURSE.

YOU'VE GOT TIME,
AND IT'S BEING STRETCHED.

SO, OF COURSE, IF I TAKE
ONE UNIT AND STRETCH IT,

IT'S WORTH MORE
OF THE OTHER UNITS

THE FURTHER YOU GO.

AND, OF COURSE,
THE CLOSER AND CLOSER YOU GET

TO THE BLACK HOLE, THE MORE
AND MORE TIME GETS STRETCHED.

THAT'S THE EXPLANATION,
ISN'T IT?

HAWKING: PAUL'S GOT IT.

NORMAN:
IT'S AMAZING TO SEE IT

PLAY OUT LIKE THIS...

MARISOL: YEAH. TO ACTUALLY
BE IN IT PHYSICALLY.

NORMAN: YEAH.

AWESOME. GOOD JOB, GUYS.

THANK YOU. WHOO!

MARISOL, VOICE-OVER:
SO IT'S NOT SO MUCH

AS LEARNING HOW TO
MANIPULATE SPACE-TIME.

IT IS JUST FINDING
THE LOCATION

WHERE SPACE-TIME IS
ALREADY DISTORTED AND ALTERED

AND THEN USING IT
TO OUR ADVANTAGE

IN ORDER TO GO INTO THE FUTURE.

PAUL: IF YOU CAN IMAGINE
A THEORETICAL SPACE JOURNEY

FOR A LENGTH OF TIME,

COME BACK YOUNGER
THAN YOUR CHILDREN--

SO, YEAH, IT'S A--IT IS
A CRAZY IDEA

TO THINK THAT, YOU KNOW,

YOU WILL LITERALLY
BE TRAVELING IN TIME.

[CLOCK WINDING DOWN]

HAWKING: NOW THEY'VE
WORKED OUT THAT WE CAN USE

THE WARPING OF SPACE-TIME
TO TRAVEL INTO THE FUTURE,

THEY ARE READY
TO ATTEMPT THIS FOR REAL...

HERE ON EARTH.

AS MY VOLUNTEERS
TRY TO DISCOVER

WHETHER WE CAN TRAVEL
THROUGH TIME,

I'VE ARRANGED FOR THEM
TO ATTEMPT

A HIGHLY UNUSUAL EXPERIMENT.

OVER THE NEXT 24 HOURS,

THEIR CHALLENGE IS TO SEND
ONE OF THEM INTO THE FUTURE

RIGHT HERE IN ARIZONA.

AND YESTERDAY'S CHALLENGE
WAS USING A BLACK HOLE

TO TRAVEL
TO THE FUTURE.

THE USE OF THE BLACK HOLE
FOR TRAVELING THROUGH TIME

WAS BECAUSE OF
THE INTENSE GRAVITY THERE.

PAUL: SURE.

SO WE DO HAVE
GRAVITY HERE.

HAWKING: THIS IS THE PERFECT
PLACE TO TRY TIME TRAVEL.

LET'S SEE
IF THEY CAN WORK OUT WHY.

PAUL: I WOULD GUESS
WE CAN USE

OUR PHYSICAL LOCATIONS TO
GIVE US 2 REFERENCE POINTS.

WE JUST NEED TO GO HIGHER.

AND I CAN SEE SOMETHING
RIGHT IN FRONT OF US

THAT WILL LET US DO THAT.

LIKE WHAT, PAUL?

PAUL: LIKE THAT MOUNTAIN
OVER THERE, NORMAN!

[LAUGHTER]

PAUL: YOU COULD HAVE ONE
AT THE TOP OF THE MOUNTAIN,

ONE AT THE BOTTOM OF
THE MOUNTAIN.

THAT GIVES US THE SAME
THING WE HAD YESTERDAY.

WE NEED CLICKERS BASICALLY.
YEAH, WE NEED SOME...

WE NEED CLICKERS
AT EACH LOCATION.

REALLY GOOD CLICKERS.
YEAH. THAT'S WHAT WE NEED.

HAWKING: THEY ARE
ON THE RIGHT TRACK.

JUST LIKE WITH A BLACK HOLE,

GRAVITY IS STRONGER
NEARER EARTH'S MASS,

MAKING TIME PASS MORE SLOWLY.

HIGH ON A MOUNTAIN,
FURTHER AWAY FROM EARTH'S MASS,

GRAVITY IS WEAKER,
AND TIME THERE PASSES FASTER.

TO SEE THE TIME DIFFERENCE,

I'VE ARRANGED
FOR A WORLD EXPERT ON CLOCKS

TO LOAN THEM
SOME IMPRESSIVE EQUIPMENT.

SO TOM OPENS
THE BACK OF HIS TRUNK.

NORMAN: H--HEY!
ALL RIGHT. WOW!

MARISOL, VOICE-OVER:
AND IT LOOKS LIKE OLD--

LIKE 1980s COMPUTER SERVERS,
ALL WITH A CLOCK,

SIX OF THEM GOING
AT THE SAME TIME.

LIKE, EXACTLY AT THE SAME TIME.

THESE ARE
CESIUM ATOMIC CLOCKS.

ATOMIC CLOCKS!
THEY ARE.

THEY ARE SO ACCURATE

THAT IT TAKES MILLIONS OF
YEARS FOR THERE TO BE

ONE SECOND OF ERROR.

PERFECT.

SO WE'VE GOT A CHALLENGE

THAT'S GOING TO REQUIRE US
TO HAVE A CLOCK

WITH A HIGHER ELEVATION.

SO IF YOU COULD LEND US
A COUPLE OF CLOCKS...

SURE! YOU NEED AT LEAST
TWO CLOCKS. NO PROBLEM.

AT LEAST TWO. YEAH.

HAWKING:
THE CLOCKS HAVE BEEN SET

TO COORDINATED UNIVERSAL TIME.

RIGHT NOW, THEY ARE
ALL PERFECTLY SYNCHRONIZED

TO EACH OTHER.

MARISOL: PERFECT FIT.
OH, YEAH. GOOD TO GO.

HAWKING: THOUGH THEY
ARE STUNNINGLY PRECISE,

CESIUM CLOCKS ARE FRAGILE.

AND IT'S GOING TO BE COLD
WHERE THIS ONE'S GOING.

[NORMAN LAUGHS]

NORMAN: OK, WATCH OUT,
MARISOL.

[INDISTINCT CHATTER]

OK.
ALL RIGHT. WELL,

WE'RE GONNA GO UP.
YOU STAY DOWN.

AND, UH, WE'LL
SEE YOU AT THE END.

HAWKING: BY CLIMBING
TO A HIGH ELEVATION,

NORMAN AND MARISOL
SHOULD EXPERIENCE

A DIFFERENT AMOUNT
OF TIME TO PAUL,

WHO WILL REMAIN CLOSER
TO THE MASS OF THE EARTH.

IT'S GONNA BE FUN.

MARISOL: OH, MY GOD.
HA HA!

HAWKING: TOMORROW PAUL CAN
JOIN THEM ON THE MOUNTAIN

TO COMPARE THEIR CLOCKS

AND SEE HOW GRAVITY
HAS WARPED SPACE-TIME.

MARISOL, VOICE-OVER:
THE LANDSCAPE IS BEAUTIFUL

AND KEEPS ON CHANGING.

WE GET HIGHER AND HIGHER.

AND THEN SUDDENLY
THE CACTUS AROUND US

DISAPPEARED, AND THEN TURN
INTO, LIKE, ALPINES AND SNOW.

NORMAN: IT'S A, UH,
WORLD OF DIFFERENCE,

BEING UP AND OUT
OF THE DESERT.

MARISOL: A COMPLETELY
DIFFERENT WORLD.

HAWKING: THE HIGHER THEY CLIMB,

THE WEAKER THE EARTH'S
GRAVITATIONAL PULL BECOMES.

IT'S NOT BY MUCH, BUT TIME
IS PASSING FASTER AS THEY GO.

I DON'T KNOW HOW
MUCH HIGHER WE CAN GET.

BUT I THINK WE ARE DOING
A GOOD JOB ABOUT

REACHING THE HIGHEST
ELEVATION WE CAN.

YEAH, LOOKS LIKE WE'RE
ALMOST AT THE TOP.

NORMAN: OH!
LOOK AT THE DOME!

MARISOL: NICE. HA HA!

NORMAN, VOICE-OVER: WE SAW
THE TOWER WAS THE--

THE HIGHEST POINT.

MARISOL: ALL RIGHT. LET'S
GET THIS SHOW ON THE ROAD.

NORMAN, VOICE-OVER: AND
IT'S LIKE WE'VE ALREADY COME UP,

YOU KNOW, 6,000 FEET OR SO.

DO WE REALLY NEED TO BRING
IT UP THAT LAST LITTLE BIT

TO GET IT UP THE TOWER?

BUT, YOU KNOW, IF YOU'RE
GOING TO DO IT, THEN DO IT.

ALL RIGHT. GOD.

MARISOL: OH, MY GOSH.
THAT IS HEAVY.

THIS BETTER WORK, 'CAUSE
I'M NOT DOING THAT AGAIN.

ALL RIGHT.
LET'S SEE.

SO WE GOT IT UP HERE.

AND WE ARE AT...

WHAT HAVE WE GOT?
9,091 FEET.

NICE!

HAWKING:
AT THE PEAK OF MOUNT LEMMON,

THEY'VE REACHED 9,091 FEET.

BELOW, PAUL IS AT 2,357.

THE DIFFERING STRENGTHS
OF GRAVITY OVER THIS RANGE

SHOULD BE ENOUGH TO ALLOW
THEM TO TIME TRAVEL ON EARTH.

HAWKING: THEIR TASK FOR
THE NEXT 24 HOURS IS SIMPLE--

SIT BACK AND WAIT,

PERHAPS WITH SOME LIGHT READING,

WHILE THE WARPING OF
SPACE-TIME TAKES EFFECT.

[RING]

NORMAN: PAUL!

NORMAN, NORMAN, HOW ARE YOU?

I'M FINE, PAUL. I
COULD NOT BE BETTER.

HA HA!

PAUL: I'M GLAD TO HEAR

YOU'VE NOT BEEN EATEN
BY A MOUNTAIN LION.

THAT'S RIGHT. SO FAR.
IT'S STILL EARLY.

HA HA!

MARISOL: DO YOU HAVE
AN IDEA OF WHAT POSSIBLY

IS GONNA HAPPEN TOMORROW?

PAUL: UH, WELL,
I'D EXPECT MY CLOCK

TO RUN A LITTLE SLOWER
THAN YOURS. YOU KNOW,

I'M CLOSER TO THE CENTER
OF THE EARTH THAN YOU ARE.

I DON'T REALLY KNOW WHAT
THE DIFFERENCE IS GONNA BE.

UM, SO, YEAH, I'M
CURIOUS TO SEE--

I'M INTERESTED TO SEE
WHAT THE DIFFERENCE IS...

HAWKING:
IN THEIR ATTEMPT TO TRAVEL

INTO THE FUTURE HERE ON EARTH,

MY VOLUNTEERS' 24-HOUR WAIT
IS OVER.

BY COMPARING THEIR CLOCKS,

WE CAN SEE IF
THEY'VE ACCOMPLISHED THEIR GOAL.

PAUL: GOOD MORNING!
GUYS, HOW ARE YOU?

GOOD.
HOW WAS IT?

NORMAN: GOOD.

PAUL: THIS IS GOING
TO BE VERY TRICKY.

MARISOL: WE CAN DO IT!

SO 24 HOURS LATER, WE TRANSFER

PAUL'S ATOMIC CLOCK UP
TO THE TOWER.

NORMAN: THEN IT WAS
JUST KIND OF WAITING

TO OPEN OUR CHRISTMAS PRESENT
TO SEE WHAT WAS IN THERE.

ARE YOU READY
FOR YOUR RESULTS?

MARISOL: YES!

NORMAN: AM I EVER!

HERE'S THE CLOCK THAT WE
BROUGHT UP YESTERDAY.

YUP.
YUP.

IT'S BEEN UP HERE

PROBABLY RUNNING FASTER,
GAINING TIME.

HERE'S THE CLOCK WE LEFT
DOWN AT THE HOTEL

FOR THE WHOLE DAY.

WE THINK THIS CLOCK SHOULD
BE AHEAD OF THIS CLOCK.

AND THE ANSWER IS...

20.485 NANOSECONDS.

MARISOL AND NORMAN:
NANOSECONDS!

TOM: 20 BILLIONTHS
OF A SECOND.

PAUL: WOW.
NORMAN: ALL RIGHT.

JUST SEEING THE NUMBER
WAS AMAZING

BECAUSE IT ACTUALLY DID HAPPEN.

MARISOL: OH, MY GOSH!

THAT'S THE DIFFERENCE
BETWEEN THESE TWO CLOCKS.

AND THAT WAS TIME TRAVEL.

THAT WAS TIME TRAVEL.

MARISOL, VOICE-OVER:
UM, IT'S KIND OF UNBELIEVABLE

AND, UM, AMAZING THAT IT
CAN ACTUALLY BE CALCULATED

AND IT CAN ACTUALLY
BE DONE WITHIN 24 HOURS.

HAWKING: HAVING JOINED THEM
AT THE MOUNTAINTOP,

PAUL HAS TRAVELED
INTO THEIR FUTURE

BY 20 NANOSECONDS.

PAUL, VOICE-OVER:
IT'S INCREDIBLE.

I WAS 20 BILLIONTHS OF
A SECOND BEHIND THE OTHER CLOCK.

SO REALLY I AM 20 BILLIONTHS
OF A SECOND YOUNGER

THAN THE OTHER TWO GUYS.

HAWKING:
JUST LIKE WITH A BLACK HOLE,

BY BEING NEARER
THE MASS OF THE EARTH,

PAUL HAS EXPERIENCED
A SLOWER PASSING OF TIME

THAN MARISOL AND NORMAN.

WOW! LOOK AT THE VIEW!

MARISOL: OH! AH, OOH.
THANK YOU...

HAWKING: THEY ARE
TRULY TIME TRAVELERS.

NORMAN: WOW.
LOOK AT THAT. THANK YOU.

MARISOL:
IT'S PRETTY UNBELIEVABLE

THAT YOU WERE JUST
DOWN THERE,

AND WE JUST TOOK A QUICK
TRIP UP THE MOUNTAIN.

AND TIME SPED UP, OUR
CLOCK WAS FASTER UP HERE.

SO IT'S JUST COOL THAT
WE CAN HAVE, LIKE,

BINOCULARS AND...JUST
LOOK AT PEOPLE DOWN THERE.

AND TECHNICALLY
THEY'RE IN THE PAST.

NORMAN: THE IDEA OF TIME
TRAVEL WHERE IT'S ALWAYS SEEMED

AS THIS FAR-FETCHED THING,

IT'S HAPPENING ALL
THE TIME, ALBEIT

IN LITTLE, TINY INCREMENTS.

THE WORLD IS WORKING IN A--
IN A WAY

THAT YOU HADN'T
REALLY PAID ATTENTION TO.

MARISOL: LOWER.

NORMAN: YOU, SIR, HAVE
TRAVELED INTO THE FUTURE.

SO YOU'VE ALLOWED ME
TO JOIN YOU.

I'VE TIME TRAVELED TO
JOIN YOU IN YOUR PRESENT.

[LAUGHTER]

TIME TRAVELER.

PAUL: TIME TRAVELER.

UH, IS THAT WORTH
A HIGH FIVE?

MARISOL: YEAH! HA HA!

WHOO!

PAUL, VOICE-OVER:
IT'S AN INCREDIBLE DEMONSTRATION

OF HOW GRAVITY AFFECTS TIME,

HOW YOU CAN BY DEFINITION
MOVE FORWARDS THROUGH TIME.

STEPHEN: HELLO,
MY BUDDING GENIUSES.

MARISOL, VOICE-OVER:
IN THE BEGINNING I WAS THINKING,

TIME TRAVEL

IS JUST LIKE A RIDICULOUS IDEA,

SO IT WAS PRETTY AMAZING
TO ACTUALLY GET AN ANSWER.

TOM: 20 BILLIONTHS
OF A SECOND.

PAUL: WOW.

YES, WE CAN TRAVEL
THROUGH TIME.

WE DID IT. WE ACTUALLY DID IT.

HAWKING: THE VOLUNTEERS
HAVE COME

A LONG WAY ON THEIR JOURNEY.

THEY'VE UNDERSTOOD THAT
THE FOURTH DIMENSION OF TIME

IS UNIFIED WITH SPACE

INTO THE SINGLE ENTITY
OF SPACE-TIME.

TRAVELING TO THE PAST
HAS BEEN RULED OUT.

BUT THEY'VE LEARNED HOW TO USE
GRAVITY'S WARPING OF SPACE-TIME

TO TRAVEL TO THE FUTURE.

NORMAN: EACH CHALLENGE
HAS HELPED BUILD

A BETTER UNDERSTANDING
OF HOW TIME WORKS,

NOT JUST WHAT IT TAKES
FOR TIME TRAVEL,

BUT HOW IT ACTUALLY WORKS.

AND IT'S GOOD TO HAVE.

YOU'VE BEEN GONE
70 YEARS!

NORMAN: WOW.

SO WE'VE COME TO THE CONCLUSION
AT THE END OF THE WEEK

THAT IT IS POSSIBLE
TO TRAVEL FORWARD THROUGH TIME.

WOW!

PAUL, VOICE-OVER: AND, UH, YEAH.

IT'S A LOVELY FEELING
TO DRAW THAT CONCLUSION--

TO HAVE THOSE EUREKA MOMENTS.

IT'S GOT TO BE
WORTH ONE, THEN! COME ON!

[LAUGHTER]

HAWKING: WE ALL TRAVEL IN TIME
ALL THE TIME.

WHEN YOU FLY IN AN AIRPLANE,
CLIMB A MOUNTAIN,

OR EVEN USE AN ELEVATOR,

YOU ARE ALTERING THE SPEED
AT WHICH YOU GET TO THE FUTURE.

AS FOR ME, IT'S TIME TO GO.

Hawking: Are we alone
in the universe?

¶

My name is Stephen Hawking.

I believe that anyone can answer
big questions for themselves.

Sian: Listen to that.

Hawking: Have you ever wondered
if there is anyone out there?

Scientist: It blew my mind--
this was exactly the signal

that I was hoping to see.

Hawking: Think like a genius.

¶