>> IN THE BEGINNING, THERE WAS DARKNESS, AND THEN-- BANG-- GIVING BIRTH TO AN ENDLESS, EXPANDING EXISTENCE OF TIME, SPACE, AND MATTER. NOW, SEE FURTHER THAN WE'VE EVER IMAGINED, BEYOND THE LIMITS OF OUR EXISTENCE, IN A PLACE WE CALL THE UNIVERSE. >> THERE MAY BE OTHER WORLDS OUT THERE-- >> --UNIVERSES BUDDING OFF OTHER UNIVERSES-- >> --WHERE THERE COULD BE AN EXACT COPY OF OUR SOLAR SYSTEM, OUR EARTH, AND EACH ONE OF US. >> --WHERE EVERYTHING'S PRETTY MUCH THE SAME OR MAYBE ONLY SLIGHTLY DIFFERENT. >> BUT WHERE ARE THESE OTHER UNIVERSES? WHY CAN'T WE SEE THEM? >> BECAUSE WE'RE IN DIFFERENT DIMENSIONS. >> CAN THIS BE TRUE? >> IF THERE ARE ACTUAL DIMENSIONS OF A CERTAIN SIZE AND SHAPE, THIS EXPERIMENT WILL FIND THEM. >> THE QUESTION ISN'T WHETHER THEY EXIST, BUT WHETHER THERE'S ONE, TWO-- >> --THREE, OR FOUR DIFFERENT KINDS OF THEM. >> THIS SENSATIONALLY MEANS THE UNIVERSE SITS IN A SEA OF PARALLEL UNIVERSES. [MUSIC] [MUSIC] IMAGINE ANOTHER WORLD, A WHOLE OTHER UNIVERSE WITH A SOLAR SYSTEM AND A PLANET EXACTLY LIKE OURS. ON THIS PARALLEL EARTH, THERE LIVES AN EXACT COPY OF YOU. YOU COULD BE LEADING EXACTLY THE SAME LIFE, BUT IN ANOTHER UNIVERSE. NOW, IMAGINE AN ENTIRELY SEPARATE UNIVERSE WHERE YOU COULD BE LIVING A SLIGHTLY DIFFERENT LIFE AT THE SAME TIME AS YOU LIVE THIS LIFE. IT MAY SEEM FANTASTIC, INCREDIBLE, AND IMPOSSIBLE, BUT THERE COULD BE MANY OTHER UNIVERSES OUT THERE. AND NOW, SOME OF THE WORLD'S LEADING PHYSICISTS BELIEVE THAT THEY HAVE EVIDENCE TO PROVE IT. >> WE ARE EXPERIENCING AN EXISTENTIAL SHOCK. OUR WORLDVIEW HAS BEEN SHATTERED WITH THE REALIZATION THAT, YES, THERE COULD BE PARALLEL UNIVERSES. >> I MEAN, IT'S JUST A MIND-BOGGLING IDEA THAT THERE MAY BE, ESSENTIALLY, EXACT REPLICAS OF US OUT THERE IN THE VASTNESS OF SPACE. >> THE IDEA OF A PARALLEL UNIVERSE IS PART OF OUR POPULAR CULTURE. PEOPLE ALL AROUND US THINK OF IT EVERY DAY BUT USUALLY IN TERMS OF FICTION. ONE OF THE REALLY EXCITING THINGS IS THAT SCIENTISTS TODAY ARE TRYING TO SEE WHETHER PARALLEL UNIVERSES ARE A PHYSICAL REALITY. >> AMAZING NEW DISCOVERIES ABOUT THE TRUE SIZE OF THE UNIVERSE SEEM TO INDICATE THAT ALL THAT WE SEE IS NOT ALL THAT THERE IS. >> WE HUMANS HAVE ASSUMED, LIKE OSTRICHES WITH OUR HEADS IN THE SAND, THAT IF WE CAN'T SEE SOMETHING, IT AIN'T THERE. WHEN MY GRANDMA WAS A LITTLE GIRL, FOR INSTANCE, THEY STILL DIDN'T KNOW THAT THERE WERE OTHER GALAXIES. NOW, WE KNOW THAT THERE ARE BILLIONS AND BILLIONS OF OTHER GALAXIES OUT THERE. >> REMARKABLY, THERE MAY BE FOUR TYPES OF PARALLEL UNIVERSE OUT THERE. ONE KIND COULD EXIST IN THE SAME EXACT SPACE WE ARE IN, BUT IT IS SO FAR AWAY WE CANNOT SEE IT OR REACH IT. IN ANOTHER SCENARIO, MULTIPLE OTHER UNIVERSES COULD BE IN GIANT, COSMIC SOAP BUBBLES ADRIFT IN A COSMIC SEA OF GIANT BUBBLES. >> REVOLUTIONARY DEVELOPMENTS HAVE CHANGED THE ENTIRE LANDSCAPE. DATA FROM OUTER SPACE HAVE GIVEN US A NEW LOOK AT COSMOLOGY AND SATELLITE DATA INDICATES THERE COULD BE PARALLEL UNIVERSES. >> IN YET ANOTHER SCENARIO, MANY PARALLEL UNIVERSES OCCUPY THE SAME SPACE AND TIME AS OUR UNIVERSE, BUT BECAUSE THEY'RE IN DIFFERENT DIMENSIONS, THEY ARE INVISIBLE. IN YET ANOTHER, ALL THE LAWS OF PHYSICS ARE DIFFERENT, SO EVERYTHING LOOKS COMPLETELY DIFFERENT. >> NEW THEORIES CALLED STRING THEORIES ARE GIVING US WORLDS OF HIGHER DIMENSIONS. QUANTUM PHYSICS AT THE MICROSCOPIC SCALE IS ALSO REVEALING TO US THE FACT THERE COULD BE PARALLEL UNIVERSES. >> TO KEEP THINGS SIMPLE, PHYSICISTS HAVE DIVIDED PARALLEL UNIVERSES INTO DIFFERENT LEVELS. MEET THE LEVEL ONE PARALLEL UNIVERSE. ACCORDING TO PHYSICISTS, THE LEVEL ONE PARALLEL UNIVERSE IS JUST AN EXTENSION OF OUR OWN UNIVERSE. >> NOW THAT'S THE KIND OF UNIVERSE WHICH IS REALLY SORT OF PART OF OUR SPACE, OF OUR GIANT SPACE, BUT IT'S SO FAR AWAY THAT WE CAN'T SEE IT. >> THE LEVEL ONE PARALLEL UNIVERSE IS BASED ON THE IDEA THAT THE UNIVERSE IS INFINITE IN SIZE. IF TRUE, JUST BY THE SHEER MATHEMATICAL ODDS, THERE MUST BE OUT THERE IN ENDLESS SPACE, AN EXACT COPY OF THE SOLAR SYSTEM, THE EARTH, AND ALL THE PEOPLE ON IT. IF YOU ARE PLANNING A TRIP, THE CLOSEST LEVEL ONE PARALLEL UNIVERSE IS REALLY INCREDIBLY FAR AWAY. >> CRUDELY SPEAKING, WE HAVE TO GO GOOGOLPLEX YARDS, WHERE A GOOGOL IS ONE WITH A HUNDRED ZEROES AFTER IT, AND A GOOGOLPLEX IS ONE WITH A GOOGOL ZEROES. SO IT'S AN AWFULLY LONG WAY, FARTHER THAN WE CAN SEE. >> THOSE UNIVERSES ARE SO FAR AWAY THAT LIGHT HASN'T REACHED US. >> BUT IS OUR UNIVERSE REALLY INFINITE? A NEW THEORY CALLED COSMIC INFLATION SUGGEST THAT IT IS. >> WE THINK THAT IT WAS BORN IN A VERY, VERY SMALL STATE, AND THEN THERE WAS A KIND OF A WEIRD ENERGY THAT PUSHED IT APART BY A TREMENDOUS AMOUNT. IT JUST WENT, "WHOOSH." >> INFLATION ACCOUNTS FOR HOW OUR UNIVERSE SUDDENLY AND MASSIVELY GREW AFTER ITS INCEPTION. >> THE BEST THEORY WE HAVE RIGHT NOW FOR WHAT MADE SPACE SO BIG-- THE THEORY OF INFLATION SAYS THAT, IN FACT, THAT SPACE ISN'T JUST BIG OR HUGE, BUT IT'S REALLY INFINITE. IT GOES ON FOREVER, WHICH MEANS THAT THERE AREN'T JUST ONE, TWO, THREE, BUT INFINITELY MANY OTHER REGIONS OF SPACE JUST AS BIG AS OUR UNIVERSE. >> EVEN THE UNIVERSE THAT WE KNOW IS MIND-BLOWINGLY BIG. WHEN WE FLY AROUND IN INTERGALACTIC SPACE LIKE THIS, EVERY LITTLE BLOB YOU SEE HERE CAN CONTAIN A GALAXY, WHICH, IN TURN, MIGHT CONTAIN HUNDREDS OF BILLIONS OF STARS WITH SOLAR SYSTEMS AROUND THEM AND SO ON. >> SO THERE IS JUST THIS ENORMOUS NUMBER OF OTHER SPACES OUT THERE THAT WE CAN'T SEE. >> AND THERE IS MORE. >> WE ACTUALLY THINK THAT THERE IS A GIGANTIC NUMBER, PERHAPS EVEN AN INFINITE NUMBER OF LEVEL ONE UNIVERSES. >> THIS RADICAL IDEA IS LEADING TO A COMPLETELY NEW DEFINITION OF THE COSMOS. >> WE USED TO SAY "UNIVERSE"-- "UNI" MEANING "ONE"-- A ONE-WORLD THEORY. EVERYTHING THERE IS, EVERYTHING WE CAN SEE IS THE UNIVERSE. NOW, WE HAVE A MULTI-VERSE IDEA WHERE THERE ARE UNSEEN WORLDS-- WORLDS THAT WE CANNOT SEE, WORLDS THAT WE CANNOT TOUCH. >> IF THIS WILD THEORY IS CORRECT, THE CONSEQUENCES ARE SENSATIONAL. >> WITHIN THIS INFINITE UNIVERSE, WE MIGHT HAVE OTHER COPIES OF THE SOLAR SYSTEM, OF PLANET EARTH. >> AND THIS IS THE REAL SHOCKER. >> THEN THERE'S A COPY OF ME AND YOU AND EVERYONE ELSE OUT THERE SOMEWHERE. >> AND THAT'S NOT ALL. THERE ARE AN INFINITE NUMBER OF OTHER UNIVERSES AND OTHER EARTHS AND INFINITE COPIES OF EACH ONE OF US. IF TRUE, THEN EVERY POSSIBLE OUTCOME FOR EVERY LIFE HAS TO HAPPEN. IN SOME UNIVERSES, IN WHAT SOME NOW CALL THE MULTI-VERSE, ONE LEADS EXACTLY THE SAME LIFE, BUT IN OTHERS, THINGS CAN BE SLIGHTLY DIFFERENT. >> YOU DIDN'T GET THAT PARKING TICKET THAT IRKED YOU SO MUCH OR YOU, UNFORTUNATELY, NEVER MET YOUR WIFE. >> ANYTHING THAT IS PHYSICALLY POSSIBLE ACTUALLY DOES OCCUR IN SOME OTHER PARALLEL UNIVERSE. >> IT MEANS THAT IN ONE UNIVERSE, ELVIS PRESLEY IS STILL ALIVE. >> IN A DIFFERENT LEVEL ONE UNIVERSE, GEORGE W. BUSH IS THE BASEBALL COMMISSIONER. >> OR PERHAPS WE DON'T EXIST AT ALL IN SOME OF THESE UNIVERSES. THE IMPLICATIONS ARE STAGGERING. >> AND IF THE UNIVERSE IS INFINITE AND THERE REALLY ARE ALL THESE LEVEL ONE UNIVERSES IN THE INFINITE MULTI-VERSE, ALL THOSE OTHER POSSIBILITIES DID SOMEWHERE HAPPEN. >> TECHNICALLY, THERE ARE A COUPLE OF WAYS MATHEMATICALLY FOR THE UNIVERSE TO BE TRULY INFINITE BUT, ESSENTIALLY, IT MUST BE SHOWN TO BE FLAT. >> THE UNIVERSE SEEMS TO BE PERFECTLY FLAT, WHICH MEANS EITHER THE UNIVERSE IS FLAT OR IS CURVED SO SLIGHTLY THAT WE CAN'T SEE IT. >> IN THIS CASE, THE UNIVERSE WOULD EVENTUALLY CURVE BACK IN ON ITSELF AND FORM A HYPERSPHERE. IT WOULD THEN BE FINITE IN SIZE AND VOLUME AND NOT FLAT AND INFINITE. ANOTHER WAY TO LOOK AT THIS IS THAT THE UNIVERSE MAY HAVE INFLATED SO QUICKLY AND SO ENORMOUSLY THAT IT ONLY LOOKS FLAT. >> THINK OF A BUG WALKING ON A GIGANTIC BALLOON. THE LARGER THE BALLOON, THE FLATTER THINGS GET. THE BUG WALKS IN ANY DIRECTION, AND THE BUG SAYS, "WELL, THE UNIVERSE SEEMS PERFECTLY FLAT TO ME." BUT FROM A DISTANCE, WE SEE THAT THE BUG IS WALKING ON A GIGANTIC BALLOON. >> BUT NOW, AN AMAZING NEW TOOL, THE WILKINSON MICROWAVE ANISOTROPY PROBE OR WMAP, IS CHANGING EVERYTHING. SOME SAY THE REMARKABLE IMAGES REVEAL THE TRUE SHAPE OF THE UNIVERSE. >> WHAT WE HAVE HERE ARE BABY PICTURES OF THE UNIVERSE, WHAT IT LOOKED LIKE WHEN IT WAS ONLY 400,000 YEARS OLD. WE'RE LOOKING SO FAR BACK IN TIME THAT THE GALAXIES HADN'T EVEN FORMED YET. WE JUST HAD THIS DEAD, DIFFUSED GAS WHICH, GRADUALLY, OVER TIME, CLUMPED INTO GALAXIES, STARS, PLANETS. >> THE WMAP IS CATCHING THE VERY EARLIEST SIGNS OF CREATION. OFFICIALLY, IT IS TASKED WITH MEASURING RADIATION LEFT OVER FROM THE BIG BANG. BUT NOW, SOME SCIENTISTS HAVE DEVISED AN EXPERIMENT TO CALCULATE THE OVERALL SHAPE OF THE UNIVERSE. >> IF I SEND LIGHT WAVES THROUGH SPACE AND MAKE A GIGANTIC TRIANGLE GOING FROM US HERE OUT TO THE FARTHEST EDGES THAT WE CAN SEE AND THEN BACK, THE ANGLES OF THOSE-- THAT TRIANGLE SHOULD ADD UP TO EXACTLY 180 DEGREES. >> IF THE UNIVERSE IS CURVED LIKE A BALLOON, THE ANGLES OF THE GIANT TRIANGLE WOULD ADD UP TO MORE THAN 180 DEGREES. TO FIND OUT IF THE UNIVERSE IS FLAT OR CURVED, THEY SHOT LASER BEAMS DEEP INTO SPACE AND MADE A GIANT LIGHT TRIANGLE. >> NOW WE CAN TELL AND THE MEASUREMENT IS IN, AND THE ANSWER IS, IT WORKS BEAUTIFULLY. THE ANGLES ADD UP TO EXACTLY 180 DEGREES. THE UNIVERSE IS FLAT. >> THE WMAP SEEMS TO SHOW THAT THE UNIVERSE IS FLAT. FOR SOME, HOWEVER, THE JURY IS STILL OUT ON THE FLAT UNIVERSE QUESTION. >> I TEND TO THINK THAT THE UNIVERSE IS, IN FACT, A SOAP BUBBLE OF SOME SORT, BUT IT IS BENT SO SLIGHTLY THAT WE CAN'T SEE IT. >> SOME EXPERTS SAY THAT THERE ARE OTHER, EVEN MORE MIND-BOGGLING KINDS OF PARALLEL UNIVERSES OUT THERE, A LEVEL-TWO TYPE PARALLEL UNIVERSE MADE UP OF GIANT, COSMIC SOAP BUBBLES THAT FLOAT IN HYPERSPACE. EACH INDEPENDENT BUBBLE HAS WITHIN IT AN ENTIRE UNIVERSE. THE QUESTION IS, "DO WE ALL REALLY LIVE IN A GIANT, COSMIC BUBBLE?" [MUSIC] COULD OUR UNIVERSE BE JUST ONE MEGA BUBBLE IN A COSMIC CROWD OF MEGA BUBBLES? IF THE SENSATIONAL, LEVEL-TWO TYPE PARALLEL UNIVERSE IDEA IS RIGHT, THEN THE TRUE NATURE OF THE COSMOS COULD BE EVEN MORE ASTONISHING THAN EVER IMAGINED. THE AMAZING CONCEPT IS THAT IN THE INSTANCE OF CREATION, OUR UNIVERSE RAPIDLY, SUDDENLY, AND MASSIVELY INFLATED, CREATING A GIANT, COSMIC SOAP BUBBLE. OUR UNIQUE UNIVERSE FLOATS IN A SEETHING SEA OF OTHER SUPER BUBBLES, WHERE BUBBLES CAN CLASH, AND SPAWN BABY BROTHER AND SISTER UNIVERSES. >> IT'S HAPPENING ALL THE TIME. UNIVERSES ARE INFLATING, POPPING OUT, AND THEN BLOWING UP TO THESE HUGE SIZES OF UNIVERSES. >> THE MEDIUM THESE LEVEL TWO BUBBLES ARE FLOATING IN IS WHAT SOME CALL THE BULK AND OTHERS CALL HYPERSPACE. >> IN THIS NEW PARADIGM, SOAP BUBBLES CAN FORM, REFORM, THEY CAN SPLIT, IT'S DYNAMIC; UNIVERSES BEING CREATED OUT OF NOTHING, UNIVERSES BUDDING OFF OTHER UNIVERSES. >> ALTOGETHER, THESE BUBBLES FORM THE LEVEL TWO TYPE PARALLEL UNIVERSE. AND WITHIN IT, THERE ARE AN INFINITE NUMBER OF LEVEL ONE TYPE PARALLEL UNIVERSES. >> THE LEVEL ONE AND LEVEL TWO UNIVERSES ARE ALL IN THE SAME ONE SPACE. THERE'S ONLY ONE SPACE. THEN THERE ARE THESE DIFFERENT REGIONS WHICH WE CALL LEVEL ONE AND LEVEL TWO PARALLEL UNIVERSES. >> A FLY-BY THROUGH THE LEVEL TWO PARALLEL UNIVERSE, OR WHAT SOME ALSO CALL THE MULTI-VERSE, WOULD BE A TERRIFYING AND SPECTACULAR EXPERIENCE. >> A MULTI-VERSE OF UNIVERSES, EACH ONE POPPING INTO EXISTENCE, POPPING OUT OF EXISTENCE, PERHAPS COLLIDING WITH EACH OTHER. >> OUT OF CALAMITY COMES EXISTENCE. >> WHAT WE CALL THE LEVEL TWO MULTI-VERSE IS REALLY BEST THOUGHT OF AS A TREE OR FRACTAL STRUCTURE WHERE YOU HAVE A REGION OF SPACE EXPANDING REALLY CRAZY AND SPIRALING OFF OTHER REGIONS WHICH THEN EXPAND, SPIRALING OFF OTHER REGIONS. >> AND OTHER ONES CAN BUD OFF OF THAT. SO YOU CAN GET THIS CHAOTIC, ETERNALLY BRANCHING SET OF UNIVERSES, BUDDING OFF FROM THEIR PREDECESSORS. AN INFINITE SET OF UNIVERSES IN THIS MULTI-VERSE. >> THE BIG TERM FOR THIS MONUMENTAL PROCESS IS BUBBLE NUCLEATION. >> THE BUBBLE NUCLEATION IS THE GEEK-SPEAK PHRASE FOR THE PROCESS WHERE YOU HAVE THIS INFLATING STRANGE MATERIAL, AND THEN A LITTLE PIECE OF IT STOPS INFLATING AND CAUSES A BUBBLE SHAPE REGION EXPANDING AROUND IT TO ALSO STOP INFLATING AND THEN YOU CREATE IN THIS BUBBLE A NICE, CALM REGION OF SPACE, WHERE YOU WILL EVENTUALLY FORM GALAXIES, STARS, PLANETS, AND EVEN PEOPLE LIKE US. SO WE ARE THE CHILDREN OF THE BUBBLE. >> FOR THE FIRST TIME IN HUMAN HISTORY, CHILDREN OF BUBBLE ARE PEERING OUT AND SEEING ON THE HORIZON PARALLEL UNIVERSES. DETERMINED PHYSICISTS BELIEVE THEY ARE NOW ON THE BRINK OF UNCOVERING THE ULTIMATE MYSTERIES OF THE UNIVERSE. >> WHY LOOK FOR THESE PARALLEL UNIVERSES THAT WE CAN'T TOUCH? BECAUSE THEY HOLD THE SECRET OF SECRETS. THEY HOLD THE SECRET OF THE ORIGIN OF EVERYTHING THERE IS. FOR THE FIRST TIME, WE CAN IMAGINE WHERE OUR UNIVERSE ITSELF CAME FROM. >> PERHAPS, WHEN OUR UNIVERSE POPPED INTO EXISTENCE, COLLIDING WITH ANOTHER PARALLEL UNIVERSE, PERHAPS BUDDING FROM ANOTHER UNIVERSE, THESE ARE THE STUFF OF MODERN RESEARCH TODAY: PRE-BIG BANG PHYSICS. PHYSICS BEFORE GENESIS-- >> BUT THERE IS A PROBLEM. FOR DECADES, SCIENTISTS HAVE BEEN SEARCHING FOR ONE COHESIVE THEORY OF EVERYTHING; ONE TO UNITE EINSTEIN'S THEORY OF GENERAL RELATIVITY, WHICH EXPLAINS HOW GRAVITY WORKS OVER LARGE SCALES, WITH QUANTUM PHYSICS, THE SCIENCE OF THE TINIEST MATTER. TOGETHER, THESE TWO GREAT THEORIES EXPLAIN EVERYTHING HUMANITY KNOWS SO FAR ABOUT THE COSMOS. BUT LIKE A CARTOON CAT AND MOUSE-- >> THEY ARE AT WAR WITH ONE ANOTHER. >> THESE TWO THEORIES HATE EACH OTHER. >> THEY'RE COMPLETELY INCONSISTENT, INCOMPATIBLE. NO WAY TO UNDERSTAND IN TODAY'S WORLD A QUANTUM VERSION OF GENERAL RELATIVITY. >> HOW CAN WE GET A SHOTGUN MARRIAGE BETWEEN THESE TWO THEORIES THAT DON'T LIKE EACH OTHER? [EXPLOSION] >> BRINGING THOSE TOGETHER WOULD GIVE YOU A THEORY OF EVERYTHING IN THE SENSE THAT THOSE ARE THE INGREDIENTS YOU WOULD NEED, I THINK, TO UNDERSTAND THE BIG BANG, TO UNDERSTAND THE ORIGIN OF THE UNIVERSE. >> WHEN, IN THE 1980s, SCIENTISTS CAME UP WITH A LYRICAL-SOUNDING IDEA, STRING THEORY, IT PROMISED TO SOLVE ALL THE MYSTERIES OF THE UNIVERSE, INCLUDING WHETHER OR NOT PARALLEL UNIVERSES ARE REAL. THE IDEA IS THAT ALL PARTICLES ARE NOT SOLID POINTS OR DOTS AS SCIENCE SAID THEY WERE. INSTEAD, IF YOU COULD SEE UP-CLOSE, PARTICLES ARE IN FACT TINY STRING-LIKE OBJECTS THAT INDIVIDUALLY VIBRATE IN VARIOUS WAYS. >> STRING THEORY STARTS OUT BY TAKING THE IDEA OF A STRING WHICH VIBRATES, GIVING RISE TO DIFFERENT PARTICLES. AND DOING PHYSICS WITH THAT, THAT'S RATHER MUSICAL, IN A WAY. IT'S LIKE USING GUITAR AND BASS IN A BAND TO GENERATE DIFFERENT NOTES FROM VIBRATIONS OF STRINGS. >> AS SCIENTISTS EXPLORED STRING THEORY MORE CLOSELY, THEY MADE A REMARKABLE DISCOVERY. >> WE FOUND THAT IT WASN'T JUST STRINGS THAT WERE INVOLVED IN THE PHYSICS BUT ALSO MEMBRANES, AND OTHER EXTENDED OBJECTS WHICH COULD VIBRATE. AND THAT'S RATHER LIKE ENLARGING THE BAND TO HAVE DRUMS AND OTHER INSTRUMENTS, WHICH ENRICH THE SOUND AND REALLY BROADEN THE REPERTOIRE OR THINGS THAT COULD BE PLAYED. >> STRING THEORY HAS NOW EVOLVED INTO WHAT IS CALLED "M" OR MEMBRANE THEORY. >> SO NOW, WE REALIZE THAT THE PARTICLES WE SEE IN NATURE, THE UNIVERSE ITSELF, CONSISTS OF VIBRATING MEMBRANES AND VIBRATING STRINGS. >> THE CROWNING ACHIEVEMENT OF M-THEORY CAME WHEN SCIENTISTS REALIZED THAT, TO MAKE SENSE OF EVERYTHING, YOU NEED TO THINK OF THE UNIVERSE AS EXISTING IN 11 DIMENSIONS. >> IF YOU'RE SITTING ON A MOUNTAINTOP AND YOU LOOK DOWN, YOU CAN SEE ALL THE SEPARATE LITTLE VILLAGES THAT ARE NOT UNIFIED AT ALL. BUT FROM A MOUNTAINTOP, YOU LOOK AT A COHERENT WHOLE BEAUTIFUL PICTURE. AND THAT'S M-THEORY. >> M-THEORY EXPLAINS HOW THE TINIEST AS WELL AS THE BIGGEST THINGS IN THE COSMOS WORK. IT ALSO PROPOSES THAT WE ALL LIVE ON A GIANT, AND ENERGETIC MEMBRANE. OUR UNIVERSE IS TETHERED TO THIS WALL BY INVISIBLE, EXTRA DIMENSIONS. TO MAKE MATTERS CRAZIER, M-THEORY PROPOSES THAT SIX OR SEVEN OF THESE DIMENSIONS, THE EXTRA ONES WE DON'T SENSE EVERY DAY, ARE TINY AND RIGHT IN FRONT OF YOUR NOSE. >> AT EVERY POINT OF ANY ONE OF THESE PEOPLE WALKING BY, YOU PICK A POINT, AT THAT POINT, THERE WILL BE AN INCREDIBLY TINY CURLED UP EITHER SIX OR SEVEN DIMENSIONS THAT YOU JUST DON'T PERCEIVE. >> THESE MEMBRANES ARE ALSO VERY CLOSE TO EACH OTHER. >> YOU COULD HAVE ONE OF THESE MEMBRANES BEING A UNIVERSE. AND THEN MOVING SIDEWAYS, YOU HAVE ANOTHER MEMBRANE BEING A SEPARATE UNIVERSE, AND THEY MAY BE JUST A MILLIMETER OR TWO AWAY. >> THE GIANT WALLS OF ENERGETIC MATTER FLOAT SIDE-BY-SIDE LIKE HUMONGOUS SHEETS IN THE BULK OR IN HYPERSPACE. AN ENTIRE UNIVERSE MAY BE ATTACHED TO A BRANE OR A UNIVERSE CAN OCCUPY THE WHOLE OF ANOTHER ONE. OUR OWN UNIVERSE SITS ON THE SKIN AMONG THESE GIANT BRANES, THAT IN TURN, IS ADRIFT IN THE COSMIC SEA OF SPACE. >> AND IT'S FLOATING AROUND IN A BIGGER STRUCTURE CALLED THE BULK. OUR THREE-DIMENSIONAL UNIVERSE IS LIKE A MEMBRANE FLOATING AROUND WITHIN THIS LARGER STRUCTURE. >> BELIEVING THAT INVISIBLE EXTRA DIMENSIONS, THAT LIKE AN UMBILICAL CORD, CONNECT US TO A HYPER OR BULK SPACE, WHERE GIANT MEMBRANES LIVE DEMANDS A HUGE LEAP OF FAITH. WHERE ARE THESE MEMBRANES THAT WE ARE STUCK TO? AND WHY CAN'T WE SEE THESE EXTRA DIMENSIONS THAT CONNECT US? >> I'M FLOATING AROUND HERE ON THIS KAYAK ON THE SURFACE OF THE OCEAN, AND YOU CAN THINK OF THIS AS A TWO-DIMENSIONAL SURFACE. BUT BELOW ME, THERE'S A WHOLE OTHER DIMENSION. THERE'S THE DOWN DIMENSION WHERE ALL THE FISH LIVE. YOU CAN THINK OF THAT AS THE BULK. I'M ON A MEMBRANE FLOATING AROUND AND THE BULK IS THE OTHER DIMENSION. THE FISH DOWN BELOW THE SURFACE OF THE WATER ARE IN A DIFFERENT DIMENSION THAN I AM. THEY DON'T EVEN KNOW THAT I'M HERE UNLESS I HAPPEN TO SPLASH AROUND AND HIT ONE ON THE HEAD OR SOMETHING LIKE THAT. SO THEY MIGHT BE COMPLETELY OBLIVIOUS TO MY EXISTENCE AND I CAN BE OBLIVIOUS TO THEIR EXISTENCE BECAUSE WE'RE IN DIFFERENT DIMENSIONS. >> BUT, CAN A FLEETING THOUGHT SEND YOU INTO AN EXTRA DIMENSION AND ONTO A PARALLEL UNIVERSE? [MUSIC] ACCORDING TO THE LATEST M-THEORY, IN LESS THAN AN INSTANT IN A FIRST TRILLIONTH OF A TRILLIONTH OF A SECOND, MEMBRANES IN A PRE-UNIVERSE COSMOS LIKE GIGANTIC COSMIC SYMBOLS, SMASH TOGETHER AND PRODUCED THE BIG BANG. OVER ALMOST 13.7 BILLION YEARS, A HUGE EXPANDING BUBBLE OF PRIMORDIAL MATTER EVOLVED INTO THE UNIVERSE WE NOW KNOW AND LOVE. CAN CRASHING MEMBRANES CREATE PARALLEL UNIVERSES TOO? >> IF IT HAPPENED ONCE, IT CAN HAPPEN AGAIN AND AGAIN AND AGAIN. >> SO IT'S POSSIBLE THAT THERE IS A CONTINUOUS CYCLE OF BRANES SMASHING TOGETHER TO PRODUCE UNIVERSES, AND THAT IT NEVER STOPS. >> IF THIS IS TRUE, LEVEL TWO PARALLEL UNIVERSES MUST EXIST. >> TIME GOES ON FOREVER AND THERE'S A CONTINUAL PROCESS OF BIRTH OF UNIVERSES THROUGH COSMIC CATASTROPHES. >> IN THE LEVEL THREE TYPE, THERE IS AN EVEN MORE FANTASTIC WAY PARALLEL UNIVERSES CAN FORM. HERE'S HOW IT WORKS: IN BOTH THE LEVEL ONE AND LEVEL TWO KINDS, THERE ARE REPLICA UNIVERSES SEPARATED FROM US IN THE HERE AND NOW BY TIME AND SPACE, BUT IN THE LEVEL THREE PARALLEL UNIVERSE, THESE COPIES OF US ARE RIGHT HERE, RIGHT NOW LIVING IN THE EXACT SAME SPACE AND TIME. THEY'RE SEPARATED FROM US BECAUSE THEY ARE IN A DIFFERENT DIMENSION OF THIS SAME SPACE. AND TO BEND OUR MINDS MORE, THERE ARE AN INFINITE NUMBER OF THEM. IF TRUE, THIS CONTROVERSIAL, MANY WORLDS CONCEPT HAS MONUMENTAL CONSEQUENCES. >> PARALLEL UNIVERSES DON'T EXIST. RIGHT. THEY'RE NONSENSE. THEY'RE SOMETHING OUT OF A "TWILIGHT ZONE" EPISODE, A BAD "STAR TREK" RERUN. BUT YOU FORGET ONE THING. ONE SMALL QUANTUM DIFFERENCE COULD SEPARATE ME FROM AN ENTIRELY DIFFERENT UNIVERSE WHERE I HAVE MULTIPLE COPIES OF MYSELF LEADING MULTIPLE DIFFERENT LIVES. THIS IS SHOCKING. THIS EVEN AFFECTS MORALS, I MEAN, WHY SHOULD I OBEY THE LAW KNOWING THAT IN SOME UNIVERSE, IF I COMMIT A CRIME, I'M GONNA GET AWAY WITH IT? >> THE OUTRAGEOUS IDEA COMES FROM THE STRANGE WORLD OF QUANTUM MECHANICS, THE SCIENCE OF THE ATOM. >> IN THE BIZARRE ATOMIC WORLD, WE HAVE ELECTRONS THAT LITERALLY DISAPPEAR, REAPPEAR SOMEPLACE ELSE. ELECTRONS THAT CAN BE IN MULTIPLE PLACES AT THE SAME TIME. >> THIS STAGGERING QUANTUM MECHANICAL PHENOMENON IS ENSHRINED IN THE HEISENBERG UNCERTAINTY PRINCIPLE. >> AS CRAZY AS IT SOUNDS, NOT ONLY DOES QUANTUM PHYSICS TELL YOU THAT A LITTLE PARTICLE CAN BE IN TWO PLACES AT ONCE, BUT THE SO-CALLED HEISENBERG UNCERTAINTY PRINCIPLE TELLS YOU THAT SOMETIME THE PARTICLE EVEN MUST BE IN TWO PLACES AT ONCE. >> WITH A LASER LIGHT AND A GLASS APPLE, IT CAN BE SEEN HOW LIGHT PARTICLES, OR PHOTONS, DO THIS. >> THIS SHOWS THAT PHOTONS, THE LITTLE PARTICLES OF LIGHT COMING OUT OF MY LASER, CAN END UP IN SEVERAL PLACES AT ONCE. AND SINCE WE ARE MADE OF LITTLE PARTICLES, THAT MEANS IF THEY CAN BE IN SEVERAL PLACES AT ONCE, SO CAN WE. >> IN OTHER WORDS, IN THE INSTANT THAT YOU HAVE A FLEETING THOUGHT, YOUR WHOLE BODY MAKES A QUANTUM LEAP INTO ANOTHER DIMENSION AND INTO A PARALLEL UNIVERSE. >> AND WHAT IT MEANS IS THAT IF I AM WALKING DOWN THE PAVEMENT AND JUST MAKE A SNAP DECISION AS TO WHETHER I'M GONNA GO LEFT OR RIGHT, IF MY DECISION DEPENDS ON WHAT SOME LITTLE PARTICLE OF MY BRAIN WAS DOING, THEN I WILL ACTUALLY END UP DOING BOTH, AND THE LIFE OF MINE EFFECTIVELY SPLITS INTO TWO PARALLEL REALITIES. IN A LEVEL THREE TYPE PARALLEL UNIVERSE, EVEN A CAT HAS MANY MORE THAN NINE LIVES; THE TROUBLE IS, IN SOME OF THESE WORLDS, THE CAT COULD BE DEAD. AND AT THE SAME TIME, IN OTHER PARALLEL UNIVERSES, THE SAME CAT CAN BE ALIVE AND KICKING. >> BUT HOW? HOW CAN YOU HAVE A DEAD CAT AND A LIVE CAT SIMULTANEOUSLY-- BECAUSE THE UNIVERSE SPLITS IN HALF. IN ONE UNIVERSE, WE HAVE A DEAD CAT, IN THE OTHER UNIVERSE, WE HAVE A LIVE CAT. GET USED TO IT. [MUSIC] >> WHAT IS EVEN MORE SHOCKING IS THAT IN SOME OF THESE MANY WORLDS, A TINY QUANTUM DIFFERENCE IN THOUGHT CAN CHANGE THE WHOLE WORLD. >> IT'S LIKE THE BUTTERFLY THAT FLAPS ITS WING AND MAKES A HURRICANE-- TINY MICROSCOPIC EVENTS WOULD CHANGE THE COURSE OF HISTORY. SO EVERY HISTORICAL EVENT ACTUALLY HAPPENED IN EVERY POSSIBLE WAY IN SOME BRANCH OF THIS EVER-SPLITTING MANY WORLDS UNIVERSE. >> IN ONE, THE NAZIS WON WORLD WAR II. >> IN WHICH CASE, I'M NOW SPEAKING GERMAN, AND THERE'S A SWASTIKA BEHIND ME. >> IN ANOTHER WORLD, NONE OF THE HORROR EVER HAPPENED. >> IN ONE UNIVERSE, THERE'S NO WORLD WAR II, AND 50 OR SO MILLION PEOPLE DIDN'T HAVE TO DIE. >> LIKE THE ENDLESS ROLLS OF THE DICE, ALL POSSIBLE NUMBERS AND ALL POSSIBLE KINDS OF UNIVERSES AND OUTCOMES WILL EVENTUALLY TURN UP AND OCCUR IN ONE OF THESE MANY WORLDS. IN FACT, ALL OUR WISHES, TOO, CAN COME TRUE IN A PARALLEL UNIVERSE. >> IF THE MANY WORLDS IDEA IS RIGHT, THEN THERE'S A BRANCH OF THE UNIVERSE IN WHICH THE CHICAGO CUBS WON THE WORLD SERIES LAST YEAR. >> YOU CAN IMAGINE THAT THE USA WAS STILL A COLONY OF THE BRITISH FOR EXAMPLE. >> EVEN THE IMPOSSIBLE IS PROBABLE IN SOME PARALLEL UNIVERSE. THERE CAN EVEN BE CREATURES COMING INTO OUR WORLD FROM THESE MYSTERIOUS EXTRA DIMENSIONS. [MUSIC] AS MIND-BOGGLING AS IT SOUNDS, WHEN IT COMES TO THE AMAZING WORLD OF PARALLEL UNIVERSES, ANYTHING THAT CAN HAPPEN HAS HAPPENED OR WILL HAPPEN IN SOME OTHER UNIVERSE IN SOME OTHER DIMENSION, SPACE, AND TIME. QUANTUM DIFFERENCES CAN REWRITE HISTORY, CREATING MULTIPLE UNIVERSES, EACH WITH WILDLY DIFFERENT OUTCOMES WHERE ANYTHING AND EVERYTHING IS POSSIBLE. SOME WARS NEVER HAPPENED; OTHERS WE NEVER IMAGINED, DID. A SLIGHT CHANGE MEANS A COMET MISSED AND EVEN DINOSAURS STILL ROAM SOME EARTH SOMEWHERE. ALL AND EVERYONE OF THESE FANTASTIC PARALLEL UNIVERSES OCCUPY THE SAME SPACE, BUT ARE IN A DIFFERENT DIMENSION AND SO INVISIBLE TO US. EVEN AS YOU PEACEFULLY WATCH TV, WHOLE OTHER INVISIBLE WORLDS COULD BE RAGING ALL AROUND YOU. >> THESE PARALLEL UNIVERSES ARE IN YOUR LIVING ROOM. THIS MEANS THAT IN YOUR LIVING ROOM, THERE ARE DINOSAURS. YOU CAN'T HEAR THEM. YOU CAN'T SEE THE DINOSAURS THAT ARE RAMPAGING THROUGHOUT YOUR LIVING ROOM, BUT THEY'RE THERE. >> THE QUANTUM PRINCIPLE THAT CREATES MANY VERSIONS OF EACH PERSON CAN ALSO CREATE ENTIRE UNIVERSES. >> THE UNIVERSE, AT ONE POINT, WAS ACTUALLY SMALLER THAN AN ELECTRON. IF THAT'S TRUE AND ELECTRONS ARE DESCRIBED BY BEING MANY PLACES AT THE SAME TIME IN PARALLEL STATES, THIS MEANS THAT THE UNIVERSE ALSO EXISTS IN PARALLEL STATES, YOU INEVITABLY GET PARALLEL UNIVERSES. THERE'S NO CHOICE. >> BUT THAT'S NOT ALL. SCIENTISTS RECENTLY HAVE SHOCKED THE WORLD AGAIN AND CLAIMED THAT THERE COULD BE ONE MORE KIND OF PARALLEL UNIVERSE. THESE LEVEL FOUR TYPE ARE CREATED EITHER BY QUANTUM FLUCTUATIONS OR BY BRANES CLASHING. WHAT IS CREATED IS RADICALLY DIFFERENT. IN THIS TYPE OF PARALLEL UNIVERSE, ALL THE RULES ARE OUT OF THE WINDOW. >> THERE COULD BE, IN FACT, THAT THE MATHEMATICS AND PHYSICS DESCRIBING REALITY DIFFERS FROM WHAT WE'RE USED TO IN OUR UNIVERSE. >> IF THE LAWS OF PHYSICS ARE DIFFERENT IN A LEVEL FOUR PARALLEL UNIVERSE, SPACE COULD JUST CONSIST OF GAS AND PARTICLES. GALAXIES, STARS AND PLANETS WOULD NOT HAVE FORMED AND LIFE, AS WE KNOW IT, WOULD NOT EXIST. TO SHOW THAT ANY TYPE OF PARALLEL UNIVERSE, LEVEL ONE, TWO, THREE OR FOUR, TRULY EXISTS, EXPERTS MUST FIND THE EVIDENCE. BE THEY BIG, TINY OR INVISIBLE, SCIENTISTS MUST FIND PHYSICAL INDICATIONS OF THE EXTRA DIMENSIONS THAT SUPPOSEDLY CONNECT US TO THESE OTHER WORLDS. TO DO IT, TODAY, PHYSICISTS AT FERMILAB IN ILLINOIS, ARE CONDUCING EXTRAORDINARY EXPERIMENTS, HOPING TO PROVE THAT ANY KIND, EVEN THE WILDEST TYPE OF PARALLEL UNIVERSE IS REALLY OUT THERE. FOR THE FIRST TIME EVER, REAL AND REMARKABLE EXPERIMENTS ARE TAKING PLACE AT PARTICLE COLLIDERS LIKE THE TEVATRON AT FERMILAB. >> RIGHT NOW, THIS DETECTOR IS LOOKING FOR EVIDENCE OF EXTRA DIMENSIONS. IF THERE ARE EXTRA DIMENSIONS OF A CERTAIN SIZE AND SHAPE, THIS EXPERIMENT WILL FIND THEM. >> THEIR BEST CHANCE OF EXPOSING EXTRA DIMENSIONS COMES FROM SMASHING MICROSCOPIC PARTICLES TOGETHER AT SUPER SPEEDS. THE SMOKING GUN IN THE HUNT IS GRAVITY. IT HAS BEEN FOUND TO BE A UNIQUELY WEAK FORCE. SO THE FERMI LAB PHYSICISTS ARE LOOKING FOR THE PARTICLE THAT CARRIES GRAVITY. IT IS CALLED A GRAVITON. >> IT'S THE PARTICLE THAT CARRIES GRAVITY WHICH WE THINK KNOWS ABOUT ALL OF THE EXTRA DIMENSIONS OF SPACE. SO, WE THINK, THE GRAVITONS, IF YOU CAN PRODUCE THEM IN HIGH ENERGIES, SHOULD ACTUALLY MOVE OFF INTO THE EXTRA DIMENSIONS. >> BUT FINDING A GRAVITON OR AT LEAST A SIGN OF ONE IS A HUGE CHALLENGE. >> IT'S TRICKY AND COMPLICATED BECAUSE YOU'RE LOOKING FOR NOTHING. YOU'RE LOOKING FOR SOMETHING THAT HAS DISAPPEARED. >> WHAT'S THE RATE NOW? >> IT'S VERY, VERY RARE THAT YOU MAKE A REALLY EXOTIC PARTICLE. SO WE, LITERALLY, HAVE TO COLLIDE THEM BILLIONS OF TIMES IN ORDER TO FIND THE VERY RARE EVENT WHERE YOU MAKE SOMETHING LIKE A PARTICLE THAT DISAPPEARS INTO EXTRA DIMENSIONS. >> THE TEVATRON COLLIDER SHOOTS MINISCULE PROTONS AND ANTIPROTONS AT TERRIFIC SPEEDS JUST SHORT OF THE SPEED OF LIGHT AROUND A FOUR-MILE LONG, SUPER-ENFORCED, STEEL ENCASED RING. TO PROTECT THE SENSITIVE EXPERIMENTS FROM SURFACE NOISE, AND, FOR SAFETY REASONS, THE COLLISION RING LIES DEEP UNDERGROUND. >> WE TAKE BEAMS OF HIGH ENERGY PROTONS GOING ONE WAY AROUND A BIG RING AND A BEAM OF HIGH ENERGY ANTI-PROTONS GOING THE OTHER WAY AND AROUND THE RING. AND THEN, AT TWO PLACES IN THE RING, WE SMASH THEM TOGETHER. >> THE MIGHTY COLLISION ANNIHILATES THE PARTICLES AND PRODUCES AN INTENSE BALL OF PURE ENERGY. >> THE IDEA BEING THAT, PERHAPS, YOU CAN MAKE NEW PARTICLES THAT DISAPPEAR INTO THE EXTRA DIMENSIONS. >> IF NOTHING HAPPENS, HOW WILL THE SCIENTISTS KNOW THAT A GRAVITON HAS MOVED OFF INTO AN EXTRA DIMENSION? >> THE WAY THAT YOU TELL IS BY RECONSTRUCTING EVERYTHING ELSE THAT HAPPENED IN THIS MESSY COLLISION AND THEN SAYING, "OOPS, THERE'S SOME ENERGY "AND MOMENTUM THAT'S MISSING HERE." SO, WE CALL THIS A MISSING ENERGY SURGE. >> IT COULD TAKE YEARS AND BILLIONS OF COLLISIONS BEFORE HISTORY HAPPENS AND HIGHER DIMENSIONS ARE FOUND. >> IF EXTRA DIMENSIONS ARE THERE, IT MEANS THE UNIVERSE IS A MUCH BIGGER AND MUCH STRANGER PLACE THAN WE HAVE EVER IMAGINED. >> BUT IF IT DOES HAPPEN, IT WOULD BE PROOF POSITIVE THAT PARALLEL WORLDS EXIST. THE QUESTION THEN WILL BE, HOW DO WE GET THERE? FACED WITH EXTINCTION IN THE FAR FLUNG FUTURE, CAN HUMANKIND OPEN A PORTAL TO A PARALLEL UNIVERSE? [MUSIC] PARALLEL UNIVERSES ARE NOT JUST A CRAZY IDEA DREAMED UP BY PHYSICISTS TO MARRY SCIENCE WITH FICTION. IF FINALLY PROVEN TO EXIST, THEY COULD HAVE AN IMPORTANT PRACTICAL PURPOSE IN THE FAR OFF FUTURE. FINDING A TUNNEL TO ANOTHER WORLD COULD ONE DAY SAVE HUMANITY. BILLIONS OF YEARS FROM NOW, OUR EARTH WILL MEET ITS INEVITABLE DEMISE. EXPERTS SAY, IT WILL ALL END, EITHER IN A BIG CRUNCH, OR BIG FREEZE. IF OTHER UNIVERSES ARE SHOWN TO EXIST, SOME SAY, THEY CAN SERVE AS A KIND OF COSMIC LIFEBOAT. FOR A FUTURE GENERATION, A PASSAGE OR GATEWAY TO ANOTHER WORLD COULD BE THEIR ONLY HOPE FOR SURVIVAL. THE QUESTION IS, CAN WE FIND A WAY TO GET THERE? >> ONE COOL WAY OF THEORETICALLY GOING FROM OUR UNIVERSE TO ANOTHER ONE IS TO GO THROUGH, WHAT'S CALLED A WORMHOLE, A BRIDGE CONNECTING TWO UNIVERSES, KIND OF, LIKE, GETTING ON A TRAIN OR A SUBWAY. >> LIKE A SUBWAY SYSTEM IN THE CITY, GOING THROUGH THIS TUNNEL TO A DIFFERENT PLACE. >> THINK OF TWO SHEETS OF PAPER THAT ARE STACKED PARALLEL TO EACH OTHER, BUT THEN, THINK OF A GATEWAY, A SHORTCUT, A PORTAL CONNECTING THESE TWO UNIVERSES. >> THIS EXTREME IDEA WAS FIRST PROPOSED BACK IN 1935 BY THE INIMITABLE, ALBERT EINSTEIN AND HIS STUDENT, NATHAN ROSEN. A "THROAT" WITH TWO CONJOINED BLACK HOLES, THEORETICALLY, ALLOW SOMEONE, LIKE A PASSENGER ON A SUBWAY TRAIN, TO QUICKLY TRAVEL TO ANOTHER SPACE AND TIME. THIS COULD WORK IF THE UNIVERSE IS REALLY AN INFINITE MULTI-VERSE. >> CERTAINLY, IT'S A THEORETICAL POSSIBILITY, A SORT OF SHORTCUT, IF YOU LIKE. AND IT ALLOWS THE POSSIBILITY OF TRAVELING BETWEEN DISTANT PARTS OF THE UNIVERSE OR PERHAPS BETWEEN DIFFERENT UNIVERSES. >> THERE ARE ALL SORTS OF PROBLEMS WITH TRYING TO TRAVERSE A WORMHOLE. BUT ONE CHALLENGE ABOVE ALL SEEMS INSURMOUNTABLE. >> WHEN EINSTEIN INTRODUCED THE WORMHOLE INTO HIS EQUATIONS, HE DIDN'T THINK THAT ANYONE COULD EVER WALK THROUGH ONE OF THESE THINGS BECAUSE AFTER ALL, YOU DIE IN THE PROCESS. >> IMPOSSIBLE AS IT MAY SOUND, EXPERTS THINK THERE MAY BE A WAY TO TRAVEL THROUGH A WORMHOLE AND LIVE TO TELL ABOUT IT. >> IN PRINCIPLE, YOU CAN GO RIGHT THROUGH TO ANOTHER PARALLEL UNIVERSE. IF YOU GO THROUGH AGAIN, YOU WIND UP ON YET, ANOTHER PARALLEL UNIVERSE. AND IF YOU GO AGAIN AND AGAIN AND AGAIN, YOU WIND UP ON REPEATED PARALLEL UNIVERSES. IT'S LIKE GOING INTO AN ELEVATOR, AND HITTING THE "UP" BUTTON. EACH FLOOR LOOKS LIKE A UNIVERSE. >> ONCE AGAIN, HOWEVER, THERE IS A MAJOR DRAWBACK. >> ONE PROBLEM IS YOU DON'T KNOW WHERE YOU'RE GONNA WIND UP. YOU DON'T WIND UP IN A MIDDLE OF A STAR, WIND UP IN THE MIDDLE OF A PLANET. >> IT MAY ULTIMATELY PROVE IMPOSSIBLE FOR INDIVIDUALS TO PASS THROUGH A PORTAL TO A PARALLEL UNIVERSE, BUT, THERE MAY BE ANOTHER WAY TO SAVE HUMANKIND. >> IF THE GATEWAY IS VERY SMALL, LIKE FOR EXAMPLE ATOMIC IN SIZE, PERHAPS, WHAT WE SHOULD DO IS SEND A SEA, A NANOBOT, A MICROSCOPIC ROBOT THROUGH THE GATEWAY CONTAINING THE DNA, CONTAINING ALL THE INFORMATION NECESSARY TO CREATE A NEW CIVILIZATION ON THE OTHER SIDE OF THE UNIVERSE. WHERE DO WE SEE THAT IN NATURE? THINK OF A TREE. A TREE CREATES A SEED. THE SEED CONTAINS THE DNA THAT IT SHOOTS OUT IN ALL DIRECTIONS, CAPABLE OF CREATING A NEW TREE. >> THE IDEA IS THAT IF AN ADVANCED CIVILIZATION IN THE FUTURE COULD ASSEMBLE ENOUGH HIGH ENERGY LASER BEAMS, THEY COULD IN THEORY, BURN A HOLE IN THE FABRIC OF SPACE TIME. >> IT'S VERY DIFFICULT. WE PHYSICISTS HAVE CALCULATED THAT IF YOU CONCENTRATE ENORMOUS ENERGY AT A SINGLE POINT TO ATTAIN SOMETHING CALLED THE PLANK ENERGY, THE ULTIMATE ENERGY, SPACE AND TIME ITSELF BECOME UNSTABLE. LITTLE BUBBLES BEGIN TO FORM, LITTLE BUBBLES THAT ARE, PERHAPS, PORTALS, GATEWAYS TO ANOTHER UNIVERSE. >> IN THIS WAY, A MICROSCOPIC POD OR NANOBOT CONTAINING HUMANITY'S DNA AND THE COSMIC CODE OF OUR WORLD CAN BE TRANSPORTED TO A PARALLEL UNIVERSE. FACED WITH EXTINCTION, THIS COULD BE HUMANITY'S LAST GREAT HOPE. >> IF WE CAN'T DO IT, IT MEANS THE DEATH OF THE UNIVERSE. >> BUT IF THIS INCREDIBLE FEAT IS ACHIEVED, OUR ENTIRE UNIVERSE WOULD BE RESURRECTED AND, LIKE A PHOENIX, RISE FROM THE ASHES. >> IN OTHER WORDS, YOU ARE PLAYING GOD. >> THIS FANTASTIC IDEA, LIKE THE REPLAY BUTTON ON THE UNIVERSAL IPOD, COULD RESET THE COSMIC CONCERTO OF HUMAN HISTORY BACK TO THE BEGINNING. >> AT LEAST, SOME KINDS ALMOST CERTAINLY EXIST. MAYBE THE OTHER KINDS EXIST AS WELL. WE JUST DON'T KNOW. >> ONLY THEN, PERHAPS, WILL WE BE CERTAIN THAT THERE ARE PARALLEL UNIVERSES. CAPTIONING PERFORMED BY
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