HEY EVERYBODY WELCOME BACK TO
THE SHOW.
LADIES AND GENTLEMEN, OUR NEXT
GUEST TONIGHT IS THE FOUNDER OF
THE WORLD SCIENCE FESTIVAL
( BAND PLAYING )
( CHEERS AND APPLAUSE )
PLEASE WELCOME MY ACTUAL
FAVORITE THEORETICAL PHYSICIST,
BRIAN GREENE.
COME ON UP.
♪ ♪ ♪
( APPLAUSE )
>> Stephen: WELL, WE ALWAYS
LOVE HAVING YOU ON TO TALK ABOUT
SCIENCE BECAUSE WE LOVE IT.
BUT THE LAST TIME YOU WERE HERE,
OUR GOVERNMENT WAS SLIGHTLY MORE
SCIENCE FRIENDLY THAN IT IS NOW.
HAVE YOU OR YOUR COLLEAGUES BEEN
AFFECTED IN ANY WAY BY THIS?
>> YEAH, IT'S UTTERLY AWFUL.
I MEAN FOR MORE THAN 50 YEARS,
SCIENCE HAS DRIVEN INNOVATION,
PROSPERITY.
AND, "LOOK, IF YOU WANT TO MAKE
AMERICA GREAT AGAIN, YOU MAKE
AMERICA SMART.
YOU MAKE AMERICA THINK.
AND YOU KEEP AMERICA AT THE
FRONTIER OF SCIENCE.
( CHEERS AND APPLAUSE ).
>> Stephen: OKAY.
ONE OF THE WAYS-- ONE OF THE
THINGS WE LIKE HAVING YOU ON FOR
IS OFTEN YOU'RE HERE WHEN WE'RE
TALKING ABOUT AN ANNIVERSARY OF
A MAJOR BREAKTHROUGH IN MODERN
SCIENCE.
WHAT ARE WE CELEBRATING RIGHT
NOW?
>> WELL, THIS IS THE 90th
ANNIVERSARY OF ONE OF THE MOST
FAMOUS EXPERIMENTS IN ALL OF
SCIENCE.
IT'S CALLED THE DOUBLE-SLIT
EXPERIMENT AND IT ESTABLISHED
THE QUANTUM LAWS OF PHYSIC S.
>> Stephen: AND THE DOUBLE
SLIT IS-- IS THAT THE BAKING
SODA VOLCANO WITH THE TWO HOLES
ON THE TOP?
WHAT IS THE DOUBLE SLIT.
>> IT IS AN EXPERIMENT THAT IS
PRETTY STRAIGHTFORWARD TO
DESCRIBE.
I HAVE AN ANIMATION TO GIVE YOU
A FEEL FOR IT.
>> Stephen: JIM, CAN WE PUT IT
ON THE SCREEN.
>> IMAGINE YOU HAVE A GUN FIRING
BULLETS OR PELLETS AT A SCREEN
WITH TWO SLITS, TWO OPENINGS.
THOSE ARE THE DOUBLE SLITS.
AND YOUR INTUITION TELLS YOU THE
PELLETS THAT GET THROUGH THE
LEFT OPENING WILL LAND IN A BAND
ALIGNED ON THE RIGHT, AND THOSE
ON THE RIGHT WILL LAND ALIGNED
ON THE RIGHT.
AND THAT'S WHAT HAPPENS WITH
BULLETS.
LET'S RUN THAT EXPERIMENT WITH
ONE CHANGE.
WE'RE SIMPLY GOING TO DIAL DOWN
THE SIZE OF THE BULLETS MAKING
THEM SMALLER.
SMALL LITTLE PARTICLES, LIKE
ELECTRONS.
YOUR INTUITION TELLS YOU PRETTY
MUCH THE SAME THING SHOULD LAP.
THOSE ELECTRONS THAT WILL GO
THROUGH THE LEFT WILL LAND IN A
BAND ON THE LEFT.
AND THOSE THAT GO THROUGH THE
RIGHT WILL LAND IN A WAND BAND
ON THE RIGHT.
BUT THE AMAZING THING DISCOVERED
IN 1927 IS THAT IS NOT WHAT
HAPPENS.
THIS IS AN EXPERIMENT THAT
ACTUALLY HAPPENED, IN SOME
SENSE, BY ACCIDENT.
THERE WERE TWO PHYSICISTS OUT AT
BILLION LABS, DAVIDSON AND GERM
ATHEY'RE DOING AN EXPERIMENT, IT
EXPLODES.
THEY FIX IT BY THE NICKEL
CRYSTAL THEY WERE FIRING
ELECTRONS ON GOT TARNISHED.
THEY HEATED IT UP, AND WHEN THEY
HEATED IT, THEY UNWITTINGLY
CHANGEDLY THE EXPERIMENT INTO
WHAT WE'RE GOING TO LOOK AT
RIGHT HERE.
AND WHAT THEY FOUND IS WHEN YOU
FIRE WANT ELECTRONS AND THE
BARRIER WITH THE TWO SLITS, YOU
DON'T JUST GET TWO BANDS.
YOU GET MORE BANDS.
AND THAT SIMPLE CHANGE, GOING
FROM OU EXPECTATION OF TWO BANDS
IN THIS CASE FIVE BANDS, THAT
REPRESENTS THE SINGLE GREATEST
UPHEAVAL IN OUR UNDERSTANDING OF
REALITY THAT THE SPECIES HAS
EVER ENCOUNTERED.
>> Stephen: WHY DOES THAT
HAPPEN.
( CHEERS AND APPLAUSE )
OKAY.
OKAY.
WHY DOES-- WHY DOES THAT HAPPEN?
THAT IS THE QUESTION.
WHY DOES THIS HAPPEN.
>> Stephen: THAT'S MY
QUESTION.
>> AN & AMAZINGLY, WE HAVE THE
MATHEMATICS, THE MATH OF QUANTUM
PHYSICS THAT DESCRIBES THAT
PERFECTLY, RIGHT.
BUT 90 YEARS LATER, WE ARE STILL
ARGUING ABOUT WHAT THAT MATH
TELLS US ABOUT THE NATURE OF
REALITY.
>> Stephen: BECAUSE AT A-- IF
THE BULLETS GET SMALL ENOUGH
THINGS GET UNCERTAIN.
>> THINGS GET UNCERTAIN.
AND MOREOVER BECAUSE THE BANDS
ARE SPREAD OUT, IT MUST MEAN
THAT THE PARTICLES THEMSELVES IN
SOME SENSE ARE SPREAD OUT.
WHICH LEADS US TO THE IDEA THAT
PARTICLES ARE ACTUALLY WAVES.
A WAVE GOES --
>> Stephen: BUT PARTICLES AT
THE SAME TIME.
>> THAT'S RIGHT.
SO THEY'RE BOTH PARTICLES AND
WAVES AT THE SAME TIME.
THAT'S THE CRAZY THING.
>> Stephen: OKAY, THAT
UNCERTAINTY AT THAT SMALL SCALE
HOW COME I DON'T FEEL THAT
UNCERTAINTY AS A BIG SCALE.
I'M HERE, I'M NOT PARTICLE AND
WAVE.
I'M PARTICLE, AREN'T YOU?
>> YOU THINK SO.
>> Stephen: I DO.
>> THE MATH SHOWS QUITE CLEARLY
THE BIGGER YOU GET THE WEIRDNESS
OF THE QUANTUM WORLD GETS
SUPPRESSED.
>> Stephen: OKAY.
>> BUT IT'S STILL THERE.
SO YOU ACTUALLY ARE SUBJECT TO
THE LAWS OF QUANTUM PHYSICS --
>> Stephen: CAN WE DEMONSTRATE
SOME QUANTUM WEIRDNESS AT A
SCALE PEOPLE CAN UNDERSTAND?
>> YES.
>> Stephen: WHAT IS THIS OVER
HERE.
>> THIS IS CALLED QUANTUM
LEVITATION.
AND WHEN WE LEARN THE QUANTUM
LAWS, WE WERE ABLE TO UNDERSTAND
A WHOLE CLASS OF STRANGE
MATERIALS CALLED SUPER
CONDUCTORS.
A SUPER CONDUCTOR IS A PIECE OF
MATERIAL THAT'S EMBEDDED IN THIS
PLASTIC CASING WHEN YOU MAKE IT
VERY COLD, LIKE 300 DEGREES
BELOW ZERO, IT CONDUCTS TRFT
WITHOUT ANY RESISTANCE.
TO MAKE IT COLD, WE NEED LIQUID
NITROGENS.
I'M GLAD YOU HAVE YOUR GLOVES
ON.
>>
>> Stephen: WE KEEP A TANK OF
THAT AROUND ALL THE TIME.
>> IT'S VERY GOOD STUFF.
>> Stephen: THAT GOES IN
THERE?
>> WE CAN POUR THIS IN HERE.
WE DON'T REALLY NEED THE REST.
PUT THAT OVER THERE.
>> Stephen: I'M GOING TO BILL
YOU FOR THAT.
>> YEAH, THERE YOU GO.
HERE'S THE THING, SO A SUPER
CONDUCTOR DETESTS MAGNETIC
FIELDS.
>> Stephen: OKAY.
>> WHICH MEANS IF I BRING IT
NEAR A STRONG MAGNET-- THIS IS A
VERY STRONG MAGNET RIGHT OVER
HERE.
I'M GOING TO PICK IT UP AND LET
YOU MANIPULATE IT.
SO I'M GOING TO PUT THIS OVER
HERE ON THE TOP.
IF YOU HOLD IT STILL, I CAN PUT
IT-- LOOK AT THAT.
STRANGE ANGLE.
IT STILL HOLDS IN.
WHAT'S HAPPENING HERE, THE SUPER
CONDUCTOR IS EXPELG MAGNETIC
FIELD, BUT QUANTUM MECHANICS
ALLOWS QUANTUM SPIKES TO GRAB
HOLD OF IT.
IN FACT, LET ME HOLD IT FOR ONE
SECOND.
I WANT YOU TO FEEL IT.
PUSH STRAIGHT DOWN ON THAT.
WHAT ARE YOU FEELING?
>> Stephen: WHOA.
A LOT OF RESISTANCE.
>> ARE YOU PUTTING THIS IN THE
QUANTUM SPIKE SO MUCH SO YOU CAN
TURN THIS UPSIDE DOWN LIKE THAT.
IT'S NOT JUST TWO MAGNETS
REPELLING EACH OTHER.
IT'S QUANTUM TENTACLES.
THIS IS A CIRCULAR MAGNET.
I CAN PUT THIS ON.
GIVE THIS A GENTLE SPIN.
>> Stephen: IS THAT HOW FIGIT
SPINNERS WERE INVENTED.
>> Stephen: WHAT HAPPENS OVER
HERE.
>> LET'S TAKE THIS GUY OVER HERE
THIS IS A CIRCULAR TRACK.
SO THE FIELD IS UNIFORM ALONG.
SO IF I TAKE --
>> Stephen: DON'T PUT YOUR
FINGERS-- MR. SCIENTIST.
EVEN I KNOW NOT TO PUT MY FINGS,
OR LIQUID NITROGEN.
>> NOWIMENT TO YOU TAKE THIS GUY
AND GIVE THIS GUY A GENTLE
LITTLE PUSH.
SEE THAT?
LOOK AT THAT.
NOW WE CAN ALSO-- PLAWZ --
>> Stephen: HOW SOON UNTIL I
GO TO WORK ON ONE OF THESE
THINGS.
>> THAT'S GOING TO BE A WHILE.
CHECK THIS OUT.
WE CAN DO THAT UPSIDE DOWN.
THIS DOESN'T ALWAYS WORK.
LET'S GIVE THIS A WHIRL.
HERE WE GO.
COME TO THE OTHER SIDE HERE.
PUT THIS HERE.
AND I DOLL THIS BARE HANDED.
ANYTHING FOR SCIENCE.
AND THERE IT GOES.
LOOK AT THAT.
>> Stephen: WOW.
( APPLAUSE ).
>> IT'S HOLDING ON TO IT.
>> Stephen: PROFESSOR BRIAN
GREENE, EVERYBODY.
QUANTUM LEVITATION.
WE'LL BE RIGHT BACK.
