>I WANT TO KNOW REALITY, SO I MUST CONFRONT THE QUANTUM. QUANTUM LEAP, QUANTUM JUMP, QUANTUM THEORY, QUANTUM MECHANICS - WHAT'S THE QUANTUM? I HEAR THE WORD ALL THE TIME. WHAT DOES IT MEAN? SOMETHING SCIENTIFIC, ADVANCED, MYSTERIOUS. THAT'S THE POPULAR SENSE. BUT THE POPULAR SENSE IS WRONG. QUANTUM'S ACTUALLY MEANING IS A SPECIFIC AMOUNT OR QUANTITY OF SOMETHING. BUT THE STORY OF THE QUANTUM IS BIZARRE, DEFYING ALL COMMON SENSE. WHY IS THE QUANTUM SO STRANGE? I'M ROBERT LAWRENCE KUHN AND CLOSER TO TRUTH IS MY JOURNEY TO FIND OUT. I'LL TRY TO UNDERSTAND THE QUANTUM. SO, I ASK SOME OF MY FRIENDS AT THE FOUNDATIONAL QUESTIONS INSTITUTE. VISIONARY SCIENTISTS UNAFRAID TO CHALLENGE CURRENT BELIEF. THEY ARE MEETING IN ICELAND, THEY SAY. SO, TO ICELAND I GO. I MEET WOJCIECH ZUREK, A LEADING AUTHORITY ON QUANTUM THEORY. ORIGINALLY FROM POLAND, NOW AT LAS ALAMOS, WOJCIECH EXPLORES THE DEEP MEANING OF THE QUANTUM. I HEAR HE IS A CHARACTER. >>THE REASON WE NEED TO UNDERSTAND QUANTUM THEORY BEFORE WE UNDERSTAND REALITY IS THAT QUANTUM THEORY IS THE ONLY THEORY WHICH IS ENCOMPASSING EVERYTHING. IT HAS NO LIMITS. QUANTUM THEORY IS WEIRD. IT IS WEIRD BECAUSE IT'S SO EGALITARIAN. IN QUANTUM THEORY, ANY SUPER-POSITION OF STATES IS A LEGAL STATE. NOW, I KNOW IT SOUNDS MYSTERIOUS. >TELL ME WHAT THAT - TELL ME WHAT THAT MEANS. >>THIS MEANS THAT IF THIS GLASS CAN BE HERE AND IT CAN BE THERE, IT CAN BE ALSO IN HERE AND THERE AT THE SAME TIME. WE DON'T SEE THINGS WHICH ARE HERE AND THERE. WE SEE THINGS WHICH ARE LOCALIZED, WHICH ARE IN DEFINITE PLACES. >AND WE SEE THAT NO MATTER HOW SMALL WE LOOK AT THINGS, IN MICROSCOPES, WE NEVER SEE THINGS IN TWO PLACES. >>IN MICROSCOPES YOU HAVE EVIDENCE OF THINGS BEING IN TWO PLACES, RIGHT? >UH-HUH. >>SO, IN SOME SENSE, FOR EXAMPLE, ELECTRO MICROSCOPY WORKS BECAUSE THINGS ARE IN MANY PLACES AT THE SAME TIME, AND THEN GET RECOMBINED, OKAY. SO, MICROSCOPY, ELECTRO MICROSCOPY IS THERE BECAUSE TUM MECHANICS IS THERE. IN FACT, YOU KNOW, IF YOU LOOK AT APPLICATIONS - A LOT OF THAT IS BECAUSE OF QUANTUM MECHANICS. TRANSISTORS, COMPUTERS RUN BECAUSE OF QUANTUM MECHANICS. >LET'S UNDERSTAND THE WEIRDNESS - THE WEIRDNESS IS THE SUPER POSITION? >>THE PLACE WHERE THE WEIRDNESS STARTS - >OKAY. >>IS THE SUPER POSITION. >AND IT GETS WEIRDER? >>IT GETS WEIRDER. >TELL ME. >>THE WEIRDER PART HAS TO DO WITH THE FACT THAT IN CLASSICAL PHYSICS, IF YOU HAVE A WELL-DEFINED STATE OF AN OBJECT WHICH CONSISTS OF SEVERAL PIECES, THIS MEANS THAT YOU HAVE A WELL-DEFINED STATE OF EACH OF THE PIECES. IN QUANTUM MECHANICS, THIS IS NOT THE CASE. IN QUANTUM MECHANICS, YOU CAN KNOW EVERYTHING THAT IS TO BE KNOWN ABOUT A COLLECTION OF OBJECTS AND YET YOU CAN BE LEFT IN A SITUATION WHERE YOU KNOW NOTHING ABOUT ANY OF THE PARTS, SO THESE ARE THE ENTANGLED STATES. SO, ENTANGLEMENT IS AN INTIMATE KNOWLEDGE OF TWO PARTICLES ABOUT EACH OTHER, AND THE KNOWLEDGE IS SO INTIMATE THAT IT PRECLUDES ANY COMMUNICATION WITH ANYTHING ELSE. SO, THESE TWO PARTICLES KNOW ABOUT EACH OTHER SO WELL THAT INDEED IF YOU ASK A QUESTION OF ONE OF THEM AND IT GIVES YOU THE ANSWER, THE OTHER ONE WILL GIVE YOU A CORRELATED ANSWER. >NO MATTER HOW FAR AWAY. >>NO MATTER HOW FAR AWAY. SO, THE INTERACTION DOESN'T MATTER. THE STATE IS A SHARED PROPERTY. >AND THE PARTICLES CAN BE SO FAR APART THAT EVEN LIGHT WOULD NOT HAVE A CHANCE TO COMMUNICATE BETWEEN THEM. >>AND THIS HAS BEEN CONFIRMED EXPERIMENTALLY. >I'M MORE MYSTIFIED NOW. HOW DO WE MAKE PROGRESS IN UNDERSTANDING THIS? IS IT POSSIBLE? >>IT IS POSSIBLE. AND I THINK ONE OF THE LINKS WE WERE MISSING UNTIL RECENTLY HAD TO DO WITH OUR PREJUDICES OF HOW WE UNDERSTOOD CLASSICAL THEORIES. IN CLASSICAL PHYSICS, WE ALWAYS THOUGHT THAT A SYSTEM BY ITSELF IS SOMETHING TO BE UNDERSTOOD REALLY IN SEPARATION FROM THE REST OF THE UNIVERSE. >OKAY. >>NOW, IN QUANTUM MECHANICS IN TURNS OUT THAT BECAUSE OF ENTANGLEMENT, THE NATURE OF THESE INTERACTIONS, THE CONSEQUENCES OF THESE INTERACTIONS ARE SO SUBTLE THAT THE FACT THAT EVEN VERY WEAK INTERACTIONS EXIST CAN CHANGE THE BEHAVIOR OF THE SYSTEM IN A VERY DRAMATIC WAY. >OH. >>SO, IN FACT, THE MOST QUANTUM ASPECT OF QUANTUM MECHANICS, WHICH IS ENTANGLEMENT, CAN HELP ONE UNDERSTAND HOW QUANTUM MECHANICS ENDS UP EXPLAINING WHAT WE SEE CLASSICALLY. >SO, HELP ME UNDERSTAND HOW SUPER POSITION, HOW ENTANGLEMENT, CAN HELP US UNDERSTAND HOW THE MICRO WORLD EXPLAINS THE MACRO WORLD. >>THE KEY POINT IS THAT QUANTUM SYSTEMS ARE NOT ISOLATED. THEY INTERACT WITH OUR ENVIRONMENTS. WHEN THEY INTERACT WITH OUR ENVIRONMENTS, THEY LEAVE RECORDS, THEY LEAVE MEMORY IN THEIR ENVIRONMENTS. SO, THERE'S A TRANSFER OF INFORMATION. SO, THE INTERACTION WITH THE ENVIRONMENT ALLOWS THE ENVIRONMENT TO KNOW WHERE AN OBJECT OF INTEREST IS. >RIGHT. AND BEFORE THAT, IT WAS JUST A PROBABILITY OF WHERE IT MAY BE. >>IT'S WORSE THAN THAT. SO, BEFORE THE INTERACTION WITH THE ENVIRONMENT HAPPENED, YOU HAD OODLES OF POSSIBILITIES, ESSENTIALLY ALL OF THEM INCOMPATIBLE WITH WHAT WE SEE IN THE REAL WORLD. AFTER THAT INTERACTION HAPPENS, YOU END UP BEING OFFERED A MENU, BUT THE MENU HAS ONLY ON IT POSITIONS WHICH ARE "CLASSICAL". IT DOESN'T TELL YOU WHICH ONE OF THEM HAPPENS, BUT IT TELLS YOU THE SET OF POSSIBILITIES. AND THE SET IN MODELS THAT WE CAN CALCULATE IS CLASSICAL. >AND THAT'S THE PROBABILITY. >>AND THEN YOU CAN SAY, I ASSIGN PROBABILITY TO THIS SET OF POSSIBILITIES. >OKAY. SO, HOW THEN CAN WE GO BACK AND SAY, WELL, WHAT IS REALLY HAPPENING IN QUANTUM THEORY? IS THIS JUST A MATHEMATICAL FORMULATION THAT IS A KIND OF A WAY TO UNDERSTAND SOMETHING REALITY? OR IS THIS REALLY WHAT'S HAPPENING? >> NOW, WE KNOW THAT COMPONENTS THAT MAKE OBJECTS THAT WE DEAL WITH ARE DEFINITELY QUANTUM, SO THE QUESTION THAT CAN ARISE IS, DOES ANYTHING STRANGE HAPPEN WHEN THESE OBJECTS GET BIGGER AND BIGGER? >RIGHT. >>NOTHING SEEMS TO. EVERYTHING SEEMS TO BE STILL QUANTUM. SO, IF YOU'RE IN A CONTROLLED SITUATION, WHEN THE SYSTEM IS ISOLATED, IT BEHAVES AS IF QUANTUM LAWS WERE SACROSANCT. WE HAVE NO CHOICE. >THE ISOLATION OF THE ENVIRONMENT IS THE KEY, IT'S NOT JUST THE SIZE? >>ABSOLUTELY. >BECAUSE THE SIZE GETS BIGGER AND THIS QUANTUM WEIRDNESS IS MAINTAINED? >>SO, YOU PUT YOUR FINGER ON THE KEY THING. IF THE SYSTEM GETS BIGGER, IT'S HARDER TO ISOLATE FROM THE ENVIRONMENT. >YEAH. YEAH, YEAH. SO - >>SO IF SOMETHING AS SMALL AS AN ATOM OR AN ELECTRON - >IT'S EASY. >>WELL, YOU CAN MAKE IT SEPARATE AND KEEP IT CAREFULLY AWAY FROM EVERYTHING ELSE. BUT IF SOMETHING IS AS BIG AS A GLASS OR AS YOU OR ME, THAT'S IMPOSSIBLE. >LET'S DRINK TO QUANTUM MECHANICS. >>LET'S DRINK TO QUANTUM MECHANICS. >I UNDERSTAND IT A LITTLE BIT BETTER. >>LET'S DRINK TO IT. >OKAY. SOME QUANTUM BASICS - ENERGY IS NOT SMOOTH, IT OCCURS IN STEPS - THINK CLIMBING UP STAIRS, NOT WALKING UP A RAMP. QUANTUM DESCRIBES THE SMALLEST UNIT OR DISCREET PACKET OF ENERGY, BUT THEN THE QUANTUM GOES WEIRD. SUPER POSITION - THINGS IN MORE THAN ONE STATE OR PLACE AT THE SAME TIME. ENTANGLEMENT - OBJECTS RELATED TO EACH OTHER IRRESPECTIVE OF DISTANCE. THIS, I SAY, MAKES NO SENSE. AH, MY PHYSICS FRIENDS REPLY, NOW YOU'RE STARTING TO GET IT. FIND OUT ABOUT THE UNCERTAINTY PRINCIPLE, THEY SUGGEST. IT'S FUNDAMENTAL AND IT'S WILD. OKAY, THE UNCERTAINTY PRINCIPLE. I GO TO HARVARD TO MEET NIMA ARKANI-HAMED, AN INNOVATIVE PHYSICIST LINKING THEORY AND EXPERIMENT. I HEAR NIMA EMBODIES THE EXCITEMENT OF THIS GRAND QUEST TO DIG INTO DEEP REALITY. HE'LL HAVE TO DEAL WITH THE UNCERTAINLY PRINCIPLE, PERHAPS AS PART OF THE HISTORY OF THE QUANTUM. NIMA, HOW CAN WE UNDERSTAND QUANTUM THEORY? >>IN THE LATE 1800S, WE HAD TWO BASIC KINDS OF PHENOMENON THAT WE'D SEE IN NATURE - THINGS LIKE LIGHT AND SOUND WAVES AND OTHER EXERTATIONS OF DIFFERENT MEDIA WERE DESCRIBED BY WAVES, BUT THINGS LIKE BILLIARD BALLS AND, WELL, THEY DIDN'T HAVE CARS, BUT IF THEY HAD CARS, CARS AND OTHER THINGS WERE DESCRIBED AS PARTICLES. HAVING THESE TWO DIFFERENT KINDS OF DESCRIPTIONS FOR PHENOMENON IN, IN NATURE, STARTED LEADING TO SOME CONFUSION. WHAT PEOPLE REALIZED IN THE EARLY PART OF THE 20TH CENTURY WAS THAT THESE TWO DIFFERENT THINGS THAT WERE BEING DESCRIBED BY CLASSICAL PHYSICS, WAVE-LIKE PROPERTIES ON ONE HAND AND PARTICLE-LIKE PROPERTIES ON THE OTHER WERE, AT THE END OF THE DAY, ALL ACTUALLY DESCRIBING PARTICLES, BUT PARTICLES THAT DON'T MOVE ACCORDING TO THE LAWS OF CLASSICAL MECHANICS, BUT MOVE INSTEAD ACCORDING TO THE LAWS OF QUANTUM MECHANICS, WHICH ARE VERY, VERY, DIFFERENT THAN THE CLASSICAL LAWS THAT GOVERN PARTICLES. FOR EXAMPLE, THERE WAS THE FAMOUS UNCERTAINTY PRINCIPLE THAT SAID THAT WHILE IN THE WORLD OF CLASSICAL PHYSICS, WE ASSOCIATED THE MOVEMENT OF A PARTICLE THROUGH SPACE AND TIME BY SPECIFYING IT'S POSITION AND IT'S VELOCITY AT ANY GIVEN POINT, THAT WE CAN'T, IN FACT, SPECIFY THE POSITION AND THE VELOCITY TO INFINITE ACCURACY. AND THAT IF WE KNOW THE POSITION VERY WELL, AH, WE DON'T KNOW THE VELOCITY VERY WELL, AND VICE VERSE. AND ALL OF THIS HAPPENED IN CONJUNCTION WITH THE REALIZATION THAT THERE'S A NEW FUNDAMENTAL CONCEPT OF NATURE, PLANK'S CONSTANT, WHICH DETERMINED WHEN CLASSICAL APPROXIMATIONS TO THE REAL UNDERLYING QUANTUM PHYSICS WAS GOOD AND WHEN THAT CLASSICAL APPROXIMATION BROKE DOWN. >NOW, TODAY WE KNOW THAT FROM THIS, THERE'S A LARGE NUMBER OF OBSERVATIONS WHICH WE KNOW TO BE TRUE, BUT WHICH WOULD SEEM COUNTERINTUITIVE TO OUR NORMAL MACROSCOPIC LIVES. PARTICLES ENTANGLED, TUNNELING EFFECTS WHERE THINGS SEEM TO JUMP FROM ONE PLACE TO THE OTHER. AND THIS SEEMS TO BE IMPOSSIBLE, BUT IT IS REAL. >>IT IS ABSOLUTELY REAL. AND ONE OF THE UNFORTUNATE THINGS ABOUT THE WAY SOMETIMES QUANTUM MECHANICS IS DESCRIBED, IS THAT THERE'S AN AWFUL LOT OF MYSTICISM ASSOCIATED WITH IT AND UNCERTAINTY MEANS THAT WE CAN'T BE SURE OF ANYTHING, AND MAYBE CONSCIOUSNESS HAS SOMETHING TO DO WITH THE WAY THE WORLD IS. AND THERE'S AN AWFUL LOT OF NONSENSE SAID ABOUT QUANTUM MECHANICS WHEREAS, IN FACT, QUANTUM MECHANICS IS RESPONSIBLE FOR THE ABSOLUTELY STABILITY OF EVERYTHING WE'RE MADE OF - ATOMS, FOR EXAMPLE. >BECAUSE THE ELECTRONS CAN'T OCCUPY THE SAME POSITION. >>RIGHT. I MEAN, THERE WAS THIS OLD CLASSICAL PICTURE THAT AN ATOM WAS LIKE A LITTLE SOLAR SYSTEM WITH AN ELECTRON ORBITING AROUND A NUCLEUS, AND THERE WERE A VARIETY OF PROBLEMS WITH THAT PICTURE. ONE OF THEM WAS THAT THE ELECTRONS WOULD QUICKLY LOSE ENERGY AND SPIRAL INTO THE NUCLEUS AND ATOMS WOULD BE COMPLETELY UNSTABLE. AND ANOTHER ONE, A RELATED ONE, IS THAT EVEN IF YOU IGNORED THAT PROBLEM, YOU COULD IMAGINE LOTS OF DIFFERENT SOLAR SYSTEMS WITH LOTS OF DIFFERENT DISTANCES AND WHY WERE ALL THE ATOMS IDENTICAL? WHY IS EVERYTHING MADE OUT OF THE SAME, THE SAME STUFF? AND BOTH OF THESE MYSTERIES WERE SOLVED BY QUANTUM MECHANICS, WITH THE REALIZATION THAT IT WAS IMPOSSIBLE FOR THE ELECTRON TO FALL INTO THE NUCLEUS, BECAUSE IF IT DID YOU WOULD KNOW BOTH WHERE IT WAS AND HOW QUICKLY IT WAS MOVING AT THE SAME TIME. AND THE UNCERTAINTY PRINCIPLE TELLS YOU THAT THAT'S NOT POSSIBLE. >SO, THE UNCERTAINTY PRINCIPLE ACTUALLY CREATES STABILITY AND ABSOLUTE CONFIDENCE IN THE MODERN WORLD. >>EXACTLY. THE UNCERTAINTY PRINCIPLE, FAR FROM INTRODUCING ALL KINDS OF FUZZY GARBAGE, ACTUALLY ALLOWS THINGS TO BE STABLE AND IS RESPONSIBLE FOR ALL THE GROSS PROPERTIES OF MATTER. >ATOMS ARE NOT LITTLE SOLAR SYSTEMS. LITTLE SOLAR SYSTEMS WOULD BE UNSTABLE. ONLY THE UNCERTAINTY PRINCIPLE CAN CREATE STABILITY. ONLY BECAUSE IT'S IMPOSSIBLE TO KNOW THE PRECISE LOCATION AND VELOCITY OF A PARTICLE. THAT'S WHY ATOMS DO NOT COLLAPSE. WOW. YET, IT SOUNDS, WELL, TOO PERFECT, TOO PAT? DARE I SAY, TOO SIMPLE? THERE MUST BE PROBLEMS LURKING SOMEWHERE. AND I KNOW JUST WHO IS READY TO REVEAL THEM. LEE SMOLIN, WHO HAS VERY CONTROVERSIAL IDEAS ABOUT FUNDAMENTAL PHYSICS, WHICH MANY OF HIS COLLEAGUES DON'T LIKE, WHICH IS WHY I SHOULD GET TO HIM. LEE'S AT THE PERIMETER INSTITUTE IN CANADA, BUT I FIND HIM IN SAN FRANCISCO, AND ARRANGE TO MEET. LEE, EVERYBODY TALKS ABOUT QUANTUM MECHANICS, PARTICULAR WHAT YOU CALL THE FOUNDATIONS OF QUANTUM MECHANICS, THE RELATIONSHIP BETWEEN QUANTUM MECHANICS AND GENERAL RELATIVITY. HOW CAN WE BEGIN TO UNDERSTAND THESE FUNDAMENTAL PROBLEMS? >>ONE WAY TO SAY IT IS THAT IF YOU THINK THAT PHYSICS IS SUPPOSED TO GIVE YOU A PICTURE OF REALITY INDEPENDENT OF US, THAT TELLS YOU IN EVERY EXPERIMENT EXACTLY WHAT'S HAPPENING AND WHY, WHICH IS WHAT EINSTEIN AND EVERYBODY BEFORE EINSTEIN THOUGHT PHYSICS WAS ABOUT, QUANTUM MECHANICS DOESN'T DO THAT. QUANTUM MECHANICS TALKS IN TERMS OF PROBABILITIES, AND NOT EVEN PROBABILITIES, SOME THINGS PRIOR TO PROBABILITIES. IF YOU SCATTER TWO PARTICLES OFF OF EACH OTHER, QUANTUM MECHANICS DOESN'T TELL YOU WHAT'S HAPPENING IN AN INDIVIDUAL EVENT, IT TELLS YOU IN THE CLASS OF EVENTS WHAT ARE THE PROBABILITIES FOR DIFFERENT OUTCOMES. EINSTEIN - >NEVER LIKED THAT. >>NEVER LIKED THAT. SCHRöDINGER, DE BROGLIE - THESE WERE SORT OF HALF THE FOUNDERS OF THE SUBJECT - THOUGHT THAT CERTAINLY IT WORKS. IT GIVES CORRECT PREDICTIONS, AS FAR AS IT'S BEEN TESTED. IT IS THE BASIS OF MORE AND MORE TECHNOLOGY, IT'S EXTRAORDINARILY SUCCESSFUL, BUT THEY DIDN'T BELIEVE IT, AND MANY OF US STILL DON'T BELIEVE IT. IT WAS CONTROVERSIAL IN THE 1930S, AND IT'S BEEN CONTROVERSIAL SINCE. IF YOU TALK TO DIFFERENT OF US, THERE ARE SOME PEOPLE WHO HAVE BOUGHT THE WHOLE THING, WHICH MEANS THAT THEY HAVE FOUND A WAY OF THINKING AND A WAY OF TALKING THAT ACCOMMODATES THE WEIRDNESS OF QUANTUM MECHANICS. >YEAH, BUT NO EXPERIMENTAL EVIDENCE HAS CONTRADICTED IT. >>SURE, BUT THE CONTROVERSY REMAINS. SOME OF US CONTINUE TO THINK THAT IT'S A GOOD TOOL, IT'S A GOOD BOOKKEEPING ADVICE, IT'S A GOOD PREDICTIVE DEVICE, BUT IT'S NOT A FUNDAMENTAL THEORY, BECAUSE A FUNDAMENTAL THEORY SHOULD DESCRIBE WHAT'S HAPPENING IN DETAIL IN EACH EXPERIMENT. EINSTEIN NEVER BOUGHT IT AS A FUNDAMENTAL THEORY, SCHRöDINGER NEVER BOUGHT IT, DE BROGLIE, MANY OTHERS, AND I'VE NEVER BEEN ABLE TO BUY IT, THOUGH MAYBE I'M DUMB, BUT - L, IT ISN'T DUMB, I THINK IT'S A PREJUDICE BECAUSE A PROBABLISTIC WAY OF LOOKING AT A WORLD, THE WORLD BEING SMEARED IN SOME WAY, IS UNCOMFORTABLE IN OUR MODERN WAY OF THINKING. BUT IF NO EXPERIMENTAL DATA CONTRADICTS IT, IT'S AH, IT LOOKS PRETTY IMPRESSIVE. >>IT IS PRETTY IMPRESSIVE. AND THE KEY THING THAT WE'VE LEARNED IS THAT ANY THEORY THAT GOES BEYOND QUANTUM MECHANICS, THAT GIVES A DEEPER EXPLANATION, A DEEPER DESCRIPTION, HAS TO BE FUNDAMENTALLY NON LOCAL. THIS IS THE - DISTANCE THAT EINSTEIN TALKED ABOUT. >WHAT DOES THAT MEAN, SPECIFICALLY? >>IT MEANS THAT IF YOU HAVE AN ATOM IN AN EXCITED STATE AND IT DECAYS AND SPLITS OUT TWO PHOTONS - >RIGHT. >>THAT THE STATE OF THOSE TWO PHOTONS REMAINS WHAT WE CALL ENTANGLED, AND THAT MEANS THAT IF I MAKE A MEASUREMENT ON THIS ONE, AND I MAKE A MEASUREMENT ON THIS ONE, THE PROBABILITIES FOR THE OUTCOME OF THIS MEASUREMENT DEPEND ON WHICH MEASUREMENT I CHOOSE TO MAKE OVER HERE. >EVEN THOUGH THE DISTANCE BETWEEN THEM COULD BE VASTLY GREATER THAN THE SPEED OF LIGHT COULD TRAVEL AND EVERYTHING? >>YES. YES, AND THAT'S REALLY - THAT EXPERIMENT HAS BEEN DONE. NEWTONIAN PHYSICS WORKED, AND WORKS AND IT, YOU KNOW, IS OUR UNDERSTANDING OF WHY THESE BRIDGES STAY UP AND WHY THE WATER IS DIFFERENT FROM THE AIR, AND SO FORTH. BUT IT'S FUNDAMENTALLY MISCONSTRUED, IT'S FUNDAMENTALLY WRONG, TOTALLY WRONG, WHEN IT COMES TO THE DESCRIPTION OF NATURE. SO, THERE'S NO PROBLEM, IN MY MIND, WITH QUANTUM MECHANICS WORKING VERY WELL BUT BEING TOTALLY WRONG. >AND WORKING AT A CERTAIN LEVEL? >>YES. YEAH, NOW, WHERE YOU HAVE TO BELIEVE THAT - IF YOU BELIEVE IT'S WRONG, YOU HAVE TO BELIEVE THERE'S A CRUNCH SOMEWHERE. ONE PLACE I BELIEVE THE CRUNCH IS LIKELY TO BE IS IN COSMOLOGY. THAT IS, WE USE QUANTUM THEORY TO STUDY SYSTEMS WHICH ARE TINY COMPARED TO THE UNIVERSE AS A WHOLE, OKAY? SOME OF US, AND I CERTAINLY AM GUILTY OF THIS, HAVE THE PRETENSION TO STUDY THIS SUBJECT OF QUANTUM COSMOLOGY, WHERE WE TRY TO PUT THE DESCRIPTION OF COSMOLOGY IN THE LANGUAGE OF QUANTUM MECHANICS. SO, WE TALK ABOUT THE QUANTUM STATE OF THE UNIVERSE, OKAY? THIS - MY BET IS THAT THAT'S COMPLETELY WRONG, THAT AT SOME POINT BETWEEN OUR LABORATORY AND THE UNIVERSE AS A WHOLE, QUANTUM MECHANICS BREAKS DOWN. >WHAT'S THE ALTERNATIVE? >>AN OLD HYPOTHESIS, ONE OF THE OLDEST HYPOTHESES IN THE SUBJECT, IS THAT WHEN YOU INCLUDE QUANTUM MECHANICS TOGETHER WITH GENERAL RELATIVITY, THE SINGULARITY GOES AWAY. AND THERE IS A TIME BEFORE THE BIG BANG SINGULARITY. THAT THERE WAS A UNIVERSE BEFORE THE BIG BANG, AND THAT RATHER THAN HAVING TO TALK ABOUT THE INITIAL CONDITIONS OF THE UNIVERSE AS THE EXPLANATION FOR WHY EVERYTHING IS THE WAY IT IS, ONE HAS TO TALK ABOUT HOW THE UNIVERSE PASSED THROUGH THIS EVENT. WHAT WAS BEFORE THE BIG BANG? BECAUSE WHAT WAS BEFORE THE BIG BANG EVOLVED TO BECOME THIS VERY, VERY DENSE STATE, WHICH THEN BEGAN TO EXPAND, WHICH MADE EVERYTHING. SO, IF YOU LIKE, YOU PUSHED THE EXPLANATION BACK, AND MAYBE THAT'S A GOOD THING, MAYBE THAT'S A BAD THING, BUT IT'S A SCIENTIFIC QUESTION. >QUANTUM MECHANICS WORKING VERY WELL, BUT BEING TOTALLY WRONG? QUANTUM COSMOLOGY, THE QUANTUM STATE OF THE ENTIRE UNIVERSE? MY HEAD IS SPINNING. TALK ABOUT AN UNCERTAINTY PRINCIPLE, THAT DESCRIBES ME. HOW TO MAKE SENSE OF ALL THIS? I GO TO MIT TO SEE A PIONEER IN QUANTUM COMPUTING, SETH LLOYD, WHO USES THE WEIRDNESS OF THE QUANTUM TO MAKE RADICALLY POWERFUL COMPUTERS. I KNOW SETH - CAN HE HELP? WE MEET IN HIS LAB. SETH, HOW CAN I BEGIN TO UNDERSTAND THIS WEIRDNESS OF QUANTUM THEORY? >>WELL, MAYBE YOU SHOULDN'T EVEN TRY. NOBODY UNDERSTANDS IT, THAT'S THE WAY I FEEL ABOUT IT, YOU KNOW, I'VE STUDIED THIS FOR YEARS. I DID MY MASTER'S DEGREE AT CAMBRIDGE IN PHILOSOPHY OF SCIENCE, STUDYING QUANTUM MECHANICS, TRYING TO UNDERSTAND WHY IT WAS THAT, YOU KNOW, THAT I COULD HAVE AN ELECTRON THAT'S BOTH HERE AND THERE AT THE SAME TIME. FORGET ABOUT IT. I NEVER UNDERSTOOD IT. BUT HOWEVER, YOU CAN, IF YOU TRY, YOU CAN BECOME MORE COMFORTABLE WITH IT OVER TIME. SO, YOU KNOW, ONE WAY TO BECOME MORE COMFORTABLE, UNFORTUNATELY, IS TO LEARN THE MATH BEHIND QUANTUM THEORY, BECAUSE THERE'S A VERY NICE, STRAIGHT-FORWARD MATHEMATICAL BACKGROUND BEHIND QUANTUM THEORY, AND THE MATH SAYS, HEY, AN ELECTRON HERE, ELECTRON THERE AT THE SAME TIME, NO PROBLEM, OKAY? BUT UNFORTUNATELY, YOU KNOW, IF WE WANT TO DO THIS INTUITIVELY, THEN IT'S TOUGH. OUR INTUITIONS, OUR POOR, CLASSICAL INTUITIONS ARE NEVER GOING TO UNDERSTAND THIS. IN FACT, I THINK THAT OUR INTUITION FOR QUANTUM THEORY GETS RUINED AT A VERY EARLY AGE, AROUND 3 MONTHS, BECAUSE IT'S AT 3 MONTHS, WHEN THEY DO STUDIES ON INFANT COGNITION, IT'S AROUND 3 MONTHS THAT BABIES START TO BELIEVE IN THE PERMANENCE OF OBJECTS, RIGHT? YOU KNOW, PEEK A BOO, RIGHT? >RIGHT. >>YOU PLAY PEEK A BOO WITH A KID WHO IS YOUNGER THAN 3 MONTHS OLD, IT'S NO FUN, BECAUSE YOU GO LIKE THIS AND THEY'RE LIKE, OH, DADDY'S GONE, RIGHT? AFTER 3 MONTHS, THEY'RE LIKE, THEY KNOW YOU'RE THERE. >RIGHT. >>BUT THEIR INTUITION FOR QUANTUM MECHANICS HAS NOW BEEN RUINED. SO, I THINK YOU SHOULD JUST FORGET ABOUT GETTING A GOOD INTUITION ABOUT IT. >OKAY. ALL RIGHT. >>IN FACT, YOU KNOW, EVEN MANY FAMOUS NOBEL PRIZE WINNERS HAVE, YOU KNOW, HAVE - PEOPLE WHO GOT THEIR NOBEL PRIZES IN QUANTUM MECHANICS, LIKE EINSTEIN - EINSTEIN, HE DIDN'T REALLY EVEN BELIEVE IN QUANTUM MECHANICS AT SOME LEVEL. >RIGHT. >>AND I THINK THAT'S BECAUSE, YOU KNOW, IF YOU - QUANTUM MECHANICS IS JUST INTRINSICALLY COUNTER-INTUITIVE, AND IF YOU'RE EINSTEIN, YOU BELIEVE YOU'RE INTUITION, RIGHT? HIS INTUITION SAID, HEY, THIS QUANTUM MECHANIC STUFF IS WEIRD, I DON'T BELIEVE IT, RIGHT? SO, HE DIDN'T BELIEVE IT. EVEN THOUGH HE GOT HIS NOBEL PRIZE FOR THE PHOTO-ELECTRIC EFFECT. >I THINK FEYNMAN SAID SOMETHING LIKE AH IF YOU THINK YOU UNDERSTAND QUANTUM THEORY, THAT PROVES THAT YOU DON'T. >>YEAH, YEAH, NIEILS BOHR SAID - I CAN'T SAY IT IN DANISH, THAT WOULD BE MORE IMPRESSIVE - SO, HE SAID, ANYBODY WHO THINKS THEY CAN CONTEMPLATE QUANTUM MECHANICS WITHOUT GETTING DIZZY, HASN'T PROPERLY UNDERSTOOD IT. >THIS STUFF'S HARD, I'VE STRUGGLED. BUT TO KNOW REALITY, I MUST DEAL WITH THE QUANTUM. SO, HERE'S WHAT I KNOW. QUANTUM MECHANICS IS HOW THE WORLD WORKS AT IT'S MOST FUNDAMENTAL LEVEL. UNCERTAINTIES - ALL IS PROBABILITY. SUPER POSITION - PARTICLES HAVING TWO STATES AT ONCE. ENTANGLEMENT - PARTICLES INSTANTLY LINKED NON-LOCALLY. NONE OF THIS HAPPENS IN THE ORDINARY WORLD, BUT EVERYTHING IN THE ORDINARY WORLD IS CONSTRUCTED FROM THE QUANTUM WORLD. HOW IS THIS POSSIBLE? HOW DOES QUANTUM WEIRDNESS TRANSFORM INTO NORMAL STUFF? IS DECOHERENCE THE ANSWER - THE COLLAPSE OF THE QUANTUM WAVE FUNCTION WHEN IT HITS THE LARGER ENVIRONMENT? OR DO WE NEED SO-CALLED HIDDEN VARIABLES TO SOLVE THE PUZZLE? OR IS QUANTUM THEORY NOT FUNDAMENTAL? ARE DEEPER TRUTHS YET TO BE FOUND? LIKE IT OR NOT, THE QUANTUM GETS US CLOSER TO TRUTH.
