WHEN I THINK ABOUT TIME,
I'M ELATED AND I'M DEPRESSED. ELATED IN THAT TO TRY
TO APPRECIATE TIME IS TO TOUCH THE FABRIC OF REALITY. DEPRESSED IN THAT TO TRY TO
UNDERSTAND TIME, IS TO WANDER IN RAW SPECULATION. WHAT IS IT ABOUT TIME THAT
PROVOKES SUCH BIPOLAR EMOTIONS? IS THE REALITY OF TIME
SOMEHOW DIFFERENT FROM OUR COMMON PERCEPTIONS? WHAT IS TIME? I'M ROBERT LAWRENCE KUHN, AND
CLOSER TO TRUTH IS MY JOURNEY TO FIND OUT. PURUSING TIME, I ATTEND A
CONFERENCE ON THE NATURE OF TIME SPONSORED BY THE FOUNDATIONAL
QUESTIONS INSTITUTE - FQXI PHYSICISTS AND COSMOLOGISTS WHO
PUSH FRONTIERS OF KNOWLEGE, AND VENTURE BEYOND. THE CONFERENCE
BEGINS ABOARD SHIP, CRUISING FROM NORWAY TO DENMARK. SAILING IS NOT SMOOTH AND
I BECOME DIZZY, BUT WHETHER FROM THE TOSS OF THE
WAVES OR THE TALK ABOUT TIME, I CANNOT TELL. I MEET THE BERTRAND-RUSSELL
PROFESSOR OF PHILOSOPHY AT CAIMBRIDGE, AN EXPERT AT
FOLLOWING TIME'S ARROW - HUGH PRICE. HUGH, THE MOST FUNDAMENTAL THING
SEEMS TO BE TIME, AND YET, MANY OF MY PHYSICIST FRIENDS
TELL ME TIME IS NOT FUNDAMENTAL. IT SEEMS TO ME IMPOSSIBLE FOR
SOMETHING TEMPORAL TO EMERGE OUT OF SOMETHING ATEMPORAL. THE FIRST THING WE NEED TO DO IS
TO THINK A LITTLE BIT ABOUT WHAT WE MEAN BY TIME, AND IT'S
HELPFUL TO MAKE THE DISTINCTION BETWEEN THREE PROPERTIES
OF TIME, WHICH SEEM TO BE GOOD REASONS FOR THINKING
ARE REALLY NOT PART OF THE PHYSICAL WORLD, BUT COMING FROM
US, AND WHAT I HAVE IN MIND THERE IS THE IDEA THAT THERE'S A
SPECIAL PRESENT MOMENT; THE IDEA THAT THERE'S SOME KIND
OF FLOW OR PASSAGE OF TIME, AND THE IDEA THAT TIME HAS
A FUNDAMENTAL DIRECTION. WHAT PHYSICS GIVES US IS
A PICTURE OF, SO-CALLED, "BLOCK UNIVERSE", WHERE TIME IS
JUST PART OF A 4-DIMENSIONAL SPACE-TIME. WHEN SOME PEOPLE SAY THAT TIME
IS NOT FUNDAMENTAL, THEY'RE TALKING ABOUT THE FIRST HALF. SO, THEY'RE JUST EXPRESSING THE
VIEW THAT THINGS LIKE THE SPECIALNESS OF THE PRESENT
AND THE FLOW OF TIME TURN OUT NOT TO BE
PART OF PHYSICS. I THINK THEY'RE PROBABLY RIGHT
ABOUT THAT, AND SO, IF THAT'S WHAT YOU MEAN BY TIME, THAT'S
ONE WAY OF GIVING SENSE TO THE CLAIM THAT TIME IS
NOT FUNDAMENTAL. NOW, THERE'S ANOTHER THING THAT
CAN BE MEANT BY THE CLAIM THAT IT'S NOT FUNDAMENTAL, WHICH
TAKES FOR GRANTED THE BLOCK UNIVERSE PICTURE OF SPACE-TIME,
BUT LOOKS AT THEORIES ACCORDING TO WHICH, SPACE-TIME
ITSELF IS NOT FUNDAMENTAL. IT'S EMERGING OUT OF SOME
LOWER STRUCTURE. SO, YOU WOULD SEE NO FUNDAMENTAL
PROBLEM WITH TIME NOT BEING FUNDAMENTAL, AND WITH SOMETHING
THAT GIVES THE FEELING OF FLOW OF TIME EMERGING FROM
SOMETHING ELSE WHICH HAD NO TIME COMPONENT AT ALL;
NO SENSE OF TIME. I CERTAINLY SEE NO PROBLEM WITH
THE IDEA THAT ASPECTS OF ORDINARY TIME, LIKE FLOW AND THE
SPECIALNESS OF THE PRESENT, ARE SOMEHOW SUBJECTIVE. SEEMS TO ME, THAT NOT ONLY DON'T
I SEE ANY PROBLEM WITH THAT, I THINK THE ARGUMENTS IN FAVOR
OF IT ARE VERY STRONG. WELL, WOULDN'T THAT AFFECT
THINGS LIKE CAUSATION? WE ALWAYS THINK OF CAUSE AND
EFFECT AS SOMETHING THAT HAS TO BE A RAID IN TIME. I THINK YOU'RE ABSOLUTELY RIGHT,
BUT THE IMPLICATION OF IT IS THAT OUR NOTIONS OF
CAUSATION ARE, THEMSELVES, TO SOME EXENT, SUBJECTIVE. SO, OUR SENSE THAT CAUSATION
RUNS FROM THE PAST TO THE FUTURE IS, AT LEAST IN SOME DEGREE,
A RESULT OF OUR OWN TEMPORAL PERSPECTIVES, AS AGENTS; AS
CREATURES, MANIPULATING THINGS IN THE WORLD TO ACHIEVE ENDS,
WHICH ARE MORE SATISFACTORY THAN OTHER OUTCOMES. I THINK THE RIGHT APPROACH, AS A
PHILOSOPHER, IS TO LOOK AT THE KIND OF PICTURE THAT PHYSICS
HAS GIVEN US ABOUT TIME - THAT'S THE 4-DIMENSIONAL,
BLOCK UNIVERSE KIND OF PICTURE, AND THEN ASK, HOW DO WE FIT
OUR ORDINARY NOTIONS OF CAUSATION INTO THAT? IN PARTICULAR, HOW DO WE FIT
IN THE SO-CALLED ARROW OF CAUSATION, THE DIFFERENCE
BETWEEN CAUSE AND EFFECT, AND ITS ALIGNMENT WITH THE
PAST-FUTURE ARROW? AND I THINK THE BEST ANSWER TO
THOSE QUESTIONS IS TO ACCEPT THAT THERE'S A SUBJECTIVE
INGREDIENT IN OUR NOTION OF CAUSATION TOO, SO IN A SENSE,
WE'RE PROJECTING ONTO THE WORLD THE TEMPORAL PERSPECTIVE
WE HAVE AS AGENTS. I CANNOT OVERSTATE THE
SIGNIFICANCE OF HUGH'S RADICAL CLAIM: BECAUSE WE ARE WITHIN
TIME, WE ARE MISLEAD BY OUR HUMAN PERSPECIVE, WHICH GIVES
FALSE IMPORTANCE TO THE PRESENT MOMENT, FALSE FEELING TO THE
FLOW OR PASSAGE OF TIME, AND FALSE SENSE TO A NECESSARY
DIRECTION OF TIME. WHAT ABOUT OUR ORDINARY
NOTIONS OF CAUSATION? HUGH WAS RIGHT TO ASK. SUBJECTIVE, HE SAYS, TO OUR
SENSE OF TIME, WHICH IS CONSISTENT, BUT CONVINCING? PERHAPS I SHOULD TRY TO BE
PURSUADED THAT MY SENSE OF TIME IS AN ILLUSION. CAUSE AS SUBJECTIVE DOES
NOT WIN MY CONFIDENCE. PERHAPS I SHOULD TRY
TO BE CONVINCED. THE CONFERENCE CONTINUES IN
COPENHAGEN, THE CITY THAT GAVE ITS NAME TO A PROBABLISTIC
INTERPRETATION OF QUANTUM PHYSICS. I PURSUE THIS TIME-AS-ILLUSION
VISION; A TIMELSS PHYSICS WITH ONE OF ITS CHIEF
PROPONENTS: AUTHOR OF "THE END OF TIME",
JULIAN BARBER. TIME, AS WE EXPERIENCE, IS
DEFINITELY RELATED TO CHANGES THAT WE EXPERIENCE. THE WAY I LIKE TO PUT IT IS, WE
SEE, AS IT WERE, A SUCCESSION OF SNAPSHOTS OF SEEMINGLY
PASSING CONTINUOUSLY, ONE INTO EACH OTHER. IF ONE JUST TOOK PHOTOGRAPHS, AS
I SAY, AND THERE'S NOTHING CHANGED IN THE PHOTOGRAPH,
YOU CAN'T SAY WHETHER TIME HAS PASSED. NOW, AS PEOPLE STUDIED
THINGS MORE, BIT BY BIT, NOTIONS OF TIME - PEOPLE
STARTED TO MEASURE TIME, AND TO ACTUALLY SUCCESSFULLY
MAKE CLOCKS AND THINGS LIKE THAT, AND THE REALLY MAJOR
CHANGE CAME WITH ISAAC NEWTON, WHO FORMULATED LAWS OF MOTION,
WHICH STILL WORK EXTRAORDINARILY WELL TO THIS DAY, AND THAT
EXPLAINS, ACTUALLY, WHY WE'RE ABLE TO KEEP APPOINTMENTS. BECAUSE IT DOES ULTIMATELY
EXPLAIN WHY WATCHMAKERS CAN MAKE WATCHES
WHICH MARCH IN STEP. BUT, WHAT IS REALLY HAPPENING -
THEY'RE NOT MARCHING IN STEP WITH TIME, THEY'RE MARCHING
IN STEP WITH EACH OTHER. THAT'S THE KEY THING, AND THIS
WAS THE FANTASTIC DISCOVERY THAT NEWTON MADE. UTTERLY SIMPLE LAWS HE WAS
ABLE TO FORMULATE, WHICH CAPTURE THAT PERFECTLY. HE CONFUSED THE ISSUE, I
BELIEVE, BY SAYING THAT IN ADDITION TO THESE CORRELATIONS
BETWEEN THE WATCHES, THERE IS THIS MYSTERIOUS
INVISIBLE TIME, BUT THIS IS ALSO VERY DEEP ROOTED IN PSYCHOLOGY. OKAY, TAKE IT FORWARD FROM
NEWTON - THEN WHAT? THERE WERE TWO REALLY GREAT
THEORIES IN THE 20TH CENTURY. THE FIRST WAS EINSTEINS GENERAL
THEORY OF RELATIVITY, WHERE HE MADE TIME DEPENDENT ON
WHAT MATTER IS DOING. IF MATTER DOES
SOMETHING DIFFERENT, TIME FLOWS DIFFERENTLY. AND THEN, TEN YEARS LATER
ABOUT, QUANTUM MECHANICS WAS DISCOVERED. NOW, IN QUANTUM MECHANICS,
THAT HAS A GOOD OLD-FASHIONED NEWTONIAN ABSOLUTE TIME, AND
IT'S VERY MYSTERIOUS BECAUSE IT'S QUITE EXTERNAL TO
EVERYTHING ELSE WHICH IS GOING ON IN QUANTUM MECHANICS, SO THIS
HAS ALWAYS DISTURBED PEOPLE. JOHN WHEELER IS THE MAN
WHO COINED THE EXPRESSION "BLACK HOLE", BUT HE WAS
DESPERATELY KEEN TO UNDERSTAND HOW THESE TWO THEORIES
WOULD BE PUT TOGETHER, SO, HE KEPT ON PUSHING BRYCE
DEWITT TO FIND THE EQUATION WHICH WOULD DESCRIBE IT, AND
WHEN DEWITT FOUND THIS EQUATION, HE WAS VERY DISCONCERTED TO
LEARN THAT TIME HAD DISAPPEARED FROM IT ALTOGETHER, AND ON THE
FACE OF IT, IT SEEMED THAT THERE WAS NO TIME AT ALL; IT WAS JUST
A COMPLETELY STATIC UNIVERSE. IT WAS AS IF THERE WERE LOTS OF
POSSIBLE CONFIGURATIONS OF THE UNIVERSE, WHICH
DON'T CHANGE. IN FACT, ALL POSSIBLE
CONFIGURATIONS THAT UNIVERSE COULD HAVE ARE, SO TO SPEAK,
THERE, AND ATTACHED TO THEM IS A NUMBER WHICH
GIVES A PROBABILITY. NOW, THIS IS ALL
VERY MYSTERIOUS, BECAUSE THE WAY I
TRY AND EXPLAIN IT IS IF THERE WAS A HUGE
BAG WITH ALL THESE SNAPSHOTS IN THERE, BUT SOME OF
THEM ARE MUCH MORE COMMON THAN OTHER ONES, AND IF YOU PUT YOUR
HAND IN, YOU'LL DRAW OUT ONE MORE PROBABLY THAN OTHERS. THEN, IN A FLASH, AN IDEA
CAME TO ME: IT MUST BE IN THE STRUCTURE OF THE CONFIGURATIONS
THAT GET A HIGH PROBABILITY. NOW, WE KNOW WE LIVE IN A VERY
HIGHLY STRUCTURED UNIVERSE, AND THEN I THOUGHT OF THIS WONDERFUL
THING THAT HAPPENED IN GEOLOGY - THAT'S WHAT I CALL A TIME
CAPSULE; THAT RECORD IN ROCKS. NOW, THERE'S ANOTHER MARVELOUS
TIME CAPSULE HERE, IN MY HEAD. I'VE GOT ALL MY MEMORIES THERE,
SO FIRST OF ALL, MY KNOWLEDGE OF THE PAST RELIES ON TWO THINGS. FIRST OF ALL, IF I MOVE MY HAND
LIKE THAT, I SEE MY HAND BOTH HERE AND HERE AT THE SAME
TIME, AND THE MOTION, AND THAT SUGGESTS TO ME THAT MOTION IS
REAL, AND THEN, THE ONLY OTHER EVIDENCE I HAVE IS THE COHERENCE
OF MY MEMORIES AND SEEING YOU NOD WHEN I SAY SOMETHING, AND
YOU'RE OBVIOUSLY RECALLING WHAT I SAID BEFORE. THIS IS ALL IN STANDARD TERMS,
BUT THAT MUST MEAN THAT THERE'S A FANTASTIC TIME CAPSULE SITTING
INSIDE MY HEAD, AND IN FACT, THE WHOLE OF SCIENCE IS
TELLING THE SAME STORY. THAT THERE WAS A BIG BANG WHICH
STARTED IN A VERY SPECIAL WAY -- IT DEVOLVED IN ACCORDANCE
WITH LAWS AND CREATED ALL THESE RECORDS AROUND US. SO, THAT, I THINK, IS WHY WE
BELIEVE IN TIME AND HISTORY. BUT IS THIS GOOD
PHYSICS, OR GROUP FAD? DOES JULIAN'S TIME CAPSULE
UNMASK A MENTAL MODULE THAT CONSTRUCTS A FEELING OF TIME? I'M STILL A SKEPTIC. COULD WHAT SEEMS SO
OBVIOUS BE SO WRONG? MY PHYSICIST FRIENDS TELL
ME TO CONSIDER TIME AS I CONSIDER SPACE. SINCE SPACE-TIME,
ACCORDING TO EINSTEIN, IS, IN DEEP REALITY, UNIFIED. I AM GAME TO GET WHAT STILL
SEEMS - WELL, A BIT ABSURD, SO I GO AFTER THE
DIMENSIONALITY OF TIME. STILL AT THE TIME CONFERENCE,
I ASK AN EXPERT IN THE PHILOSOPHICAL FOUNDATIONS OF
PHYSICS: COLOMBIA PROFESSOR, DAVID ALBERT. DAVID, IN TRYING TO UNDERSTAND
THE NATURE OF TIME, I'M TOLD THAT WE SHOULD CONSIDER TIME IN
A SPATIAL SENSE; THE SO-CALLED SPATIALIZATION OF TIME. SO, WHAT DOES IT MEAN? THAT IS, THE WAY TIME APPEARS IN
PHYSICS IS AS ANOTHER COMPONENT IN THE ADDRESS OF AN EVENT. WHAT PHYSICS ASPIRES TO TELL YOU
IS HOW EVENTS ARE DISTRIBUTED OVER DIFFERENT VALUES OF
THESE SPATIAL AND TEMPORAL AXES. WHAT IS MISSING FROM THIS
METAPHYSICAL FRAMEWORK FROM WHICH PHYSICS STARTS OUT ARE
THESE NOTIONS OF FLOW, THESE NOTIONS OF PASSAGE, THESE
NOTIONS OF BECOMING SO ON AND SO FORTH. WHICH, TO NORMAL
PEOPLE, IS TIME. WHICH, TO NORMAL
PEOPLE, CERTAINLY IS TIME. THE TROUBLE IS THAT IF YOU TRY
TO FORMALIZE THESE NOTIONS SO THAT THEY'RE FIT TO DO JOBS IN
A DISCOURSE THAT YOU WANT TO BE EXTREMELY CLEAR AND EXTREMELY
EXPLICIT AND EXTREMELY LOGICAL, IT'S HARD TO KNOW
HOW TO DO THAT. PEOPLE TALK ABOUT TIME FLOWING;
A COMMON QUESTION THAT GETS ASKED OF SUCH PEOPLE IS,
HOW FAST IS IT FLOWING? AND, YOU KNOW, MAYBE THE NORMAL
ANSWER IS, I DON'T KNOW, ONE SECOND PER SECOND, AND THE
NEXT QUESTION IS, GEE - AND WHAT WOULD IT BE LIKE IF IT WERE
FLOWING 2 SECONDS PER SECOND INSTEAD OF 1 SECOND PER SECOND. IT'S NOT EVEN CLEAR
WHAT THAT MEANS, OKAY? THE CLAIM THAT TIME IS FLOWING 1
SECOND PER SECOND DOESN'T HAVE THE FEEL OF A CLAIM ABOUT HOW
THE WORLD IS, IT HAS THE FEEL OF SOMETHING THAT'S
TRUE BY DEFINITION. IT'S LIKE SAYING A BACHELOR IS
AN UNMARRIED MALE, OR SOMETHING LIKE THAT, AND PHYSICS HAS
ALWAYS BEEN ABOUT, SINCE ITS BEGINNINGS, WAS TO GIVE AN
ACCOUNT OF THE TRACKS THAT MATERIAL BODIES MAKE THROUGH
THIS 4-DIMENSIONAL ARENA, OKAY? THROUGH THIS
SPATIO-TEMPORAL ARENA. THERE ARE ALL SORTS OF SENSES
IN WHICH EINSTEINIAN RELATIVITY MADE THAT SPATIALIZATION
MORE VIVID, MORE EXPLICITLY GEOMETRICAL, SO ON AND SO FORTH,
BUT SINCE THE BEGINNINGS OF THE SCIENTIFIC REVOLUTION, SINCE
GALILEO, SINCE NEWTON, WE'VE BEEN DEALING WITH TIME AS A
PARAMETER, OKAY, AND WE HAVEN'T BEEN ABLE TO MAKE FUNDAMENTAL
METAPHYSICAL SENSE OF TALK OF TIME'S FLOW, OF TIME'S PASSAGE. THIS IS TALK THAT PHYSICS NEEDS
TO ACCOUNT FOR IN THE WAY THAT PHYSICS ACCOUNTS FOR THE FACT
THAT, SAY, IF YOU PUT A PENCIL IN A GLASS OF WATER, THE
PENCIL APPEARS TO BENT, OKAY, EVEN THOUGH IT ISN'T. SCIENCE, WHENEVER IT ENCOUNTERS
SOMETHING PUZZLING, ALWAYS HAS 2 OPTIONS, OKAY? IT HAS THE OPTION OF EXPLAINING
IT, AND IT HAS THE OPTION OF EXPLAINING IT AWAY, OKAY? IT'S THE SECOND STRATEGY OF
EXPLAINING IT AWAY THAT WE APPLY TO THE BENT APPEARANCE OF A
PENCIL IN A GLASS OF WATER, AND IT'S THE SECOND STRATEGY OF
EXPLAINING IT AWAY THAT WE APPLY TO OUR SENSATION, OR TO OUR
TEMPTATION TO USE WORDS LIKE PASSAGE AND FLOW TO
DESCRIBE OUR EXPERIENCE OF TIME. I ADMIT THAT IF I STICK WITH
MY COMMON PERCEPTION OF TIME, I MAKE NO PROGRESS. TIME IS TIME, AND IT
FLOWS AS IT FEELS. THE ONLY ALTERNATIVE IS TO DIVE
DEEPLY INTO TIME, WHICH REQUIRES EINSTEIN'S RELATIVITY,
UNIFYING TIME WITH SPACE, GIVING TIME A SPATIALIZATION. IT ALSO REQUIRES
QUANTUM PHYSICS. THE FUNDAMENTAL LAWS OF
HOW THE MICRO-WORLD WORKS. TO CHECK OUT THE LATTER, I GO
LOS ANGELES TO MEET AN EXPERT IN QUANTUM REALITY AND
NON-LOCAL ASPECTS OF TIME - PHYSICIST JEFF TOLLEFSON. SO, IN CLASSICAL PHYSICS, WE
KNOW THAT IF YOU KNOW THE STATE OF THE UNIVERSE AT ONE TIME,
EVERY OTHER LATER TIME IS NOT INDEPENDENT OF THAT STATE. THEY'RE ALL COMPLETELY SLAVED,
IN A SENSE, BECAUSE THE THEORY IS DETERMINISTIC. IT'S REALLY JUST LIKE A BIG
MACHINE; IT'S JUST A CLOCKWORK THAT THERE'S NO, YOU
KNOW, THERE'S NO FREEDOM. HOWEVER, IN QUANTUM MECHANICS,
IN PRINCIPLE, WE CANNOT KNOW MORE THAN WHAT IS THE BASIC
DESCRIPTION, WHICH IS GIVEN BY THE WAVE FUNCTION, EVEN
FOR A SINGLE PARTICLE. EVEN IF YOU KNOW EVERYTHING
THAT CAN BE KNOWN ABOUT A SINGLE PARTICLE, OR THE UNIVERSE FOR
THAT MATTER, YOU CANNOT PREDICT THE FUTURE LIKE WE COULD
DO IN CLASSICAL PHYSICS. SO, THIS ALLOWS ONE TO SAY THAT
THE MOST BASIC DESCRIPTION OF A PARTICLE, OF A QUANTUM PARTICLE,
ALLOWS YOU TO SAY THAT YOU HAVE 2 BOUNDARY CONDITIONS -- THE
PAST OF THAT PARTICLE, AND ITS FUTURE. SO, IF YOU'RE ASKING WHAT IS THE
NATURE OF THE PROPERTIES OF THE PARTICLE, DURING THE TIME
BETWEEN ITS PAST AND ITS FUTURE, IT TURNS OUT THAT THE PAST AND
THE FUTURE PLAY AN EQUAL ROLE ON AN EQUAL FOOTING. AND SO NOW, WHEN YOU'RE ASKING
ABOUT THE NATURE OF TIME, AS YOU CAN KIND OF SEE, THIS IS TOTALLY
DIFFERENT FROM WHAT HAPPENS IN CLASSICAL PHYSICS. YOU'RE ASKING ABOUT THE NATURE
OF TIME ON A QUANTUM MECHANICAL LEVEL, YOU HAVE TIME GOING IN
BOTH DIRECTIONS, AND IN A SENSE, THE WAY THE PROPERTIES OF THE
QUANTUM WORLD SHOW UP, YOU HAVE TO- THEY SORT OF KISS IN
THE PRESENT, SO TO SPEAK. SO, YOU'RE CLAIMING THAT THE
MOVEMENT FROM THE PAST TO THE PRESENT IS EQUAL TO THE MOVEMENT
FROM THE FUTURE TO THE PRESENT? THAT'S RIGHT. OUR VIEW OF THE NATURE OF TIME
CAME OUT FROM ANCIENT TIMES - PARMENIDES, IN PARTICULAR, I
BELIEVE -- WHICH, HE SAID THAT THE WAY WE SHOULD THINK
ABOUT THE UNIVERSE IS THAT THE UNIVERSE EXISTS WITH UNIQUE
OBJECTS WHICH SIMPLY CHANGE THEIR STATE AND TIME, BUT IT'S
THE SAME OBJECT FROM ONE MOMENT TO THE NEXT, RIGHT? I MEAN, WE'VE JUST SORT OF,
WE'VE ACCEPTED THIS WAY OF THINKING ABOUT THE UNIVERSE. HOWEVER, AROUND THE SAME TIME,
IN THE ANCIENT GREEKS, THERE WAS A VERY DIFFERENT WAY OF THINKING
ABOUT THE NATURE OF TIME, WHICH JUST DIDN'T CATCH ON, AND THIS
IS FROM HERACLIDES -- HE SAID, YOU NEVER BATHE
TWICE IN THE SAME RIVER. AND, ONE WAY OF INTERPRETING
THAT IS THAT, IN FACT, EACH MOMENT OF TIME, IT'S
NOT THE SAME UNIVERSE. IT'S NOT THE SAME OBJECT AS IT
WAS A SECOND AGO OR 100 YEARS AGO, BUT LITERALLY, EACH MOMENT
IN TIME IS LIKE A NEW UNIVERSE, BECAUSE IT'S SOMETHING
COMPLETELY NEW. IT GETS REBORN AGAIN AND AGAIN,
AND SO, ONE MIGHT ASK, IS IT POSSIBLE TO REFORMULATE OUR
BASIC PHYSICS IN A WAY THAT'S CONSISTENT WITH THAT IDEA? THE ONLY WAY YOU COULD DO IT
-- IF YOU WANT TO HAVE SUCH A PICTURE -- IS TO USE THE TIME IS
SYMMETRIC APPROACH, WHERE THE FUTURE PLAYS AS MUCH A ROLE IN
THE PRESENT AS THE PAST, AND SO, USING THAT, LITERALLY
EVERY MOMENT IS LIKE RECREATING THE UNIVERSE. AGAIN AND AGAIN AND AGAIN. JEFF MAKES THE EXTRAORDINARY
CLAIM THAT, IN THE QUANTUM WORLD OF FEELS AND FORCES, PAST AND
FUTURE MAKE EQUAL CLAIMS ON CAUSING OR
AFFECTING THE PRESENT. FOR PAST AND FUTURE TO KISS IN
THE PRESENT IS A NICE METAPHOR, BUT WHAT COULD THIS MEAN? WOULD THE UNIVERSE THEN
HAVE SOME SORT OF TELEOLOGICAL FOUNDATIONS? WHERE WHAT HAPPENS LATER SOMEHOW
GENERATES WHAT HAPPENS BEFORE? WHERE AFFECTS CAN
INFLUENCE CAUSES? WHAT COULD BE MORE BIZARRE? EVEN IF QUANTUM THEORY SUGGESTS
UNCANNY PATHS OF CAUSATION, NOT EVERY PHYSICIST AGREES
THAT TIME IS NOT FUNDAMENTAL. I GO TO CAMBRIDGE TO MEET JOHN
POKINGHORN, A QUANTUM PHYSICIST WHO BECAME AN ANGLICAN PRIEST. JOHN BELIEVES THAT THE UNIVERSE
IS TRULY ONE OF BECOMING; THAT THE FLOW AND DIRECTION OF TIME
ARE REAL AND RELENTLESS, BUT IS THIS IS PHYSICS OR HIS THEOLOGY? AS A PHYSICIST, I THINK, THERE'S
NO REASON TO GENERALIZE THE REALITY OF TIME. SOME PEOPLE THINK THE SPECIAL
RELATIVITY, FOR EXAMPLE, HAS PUT THAT IN DOUBT; DIFFERENT
OBSERVERS JUDGE SIMULTANEITY IN DIFFERENT WAYS. IF OBSERVER NUMBER 1 THINKS
THAT EVENTS A AND B ARE THE SAME TIME, OBSERVER NUMBER 2 - THE B
IS BEFORE A; OBSERVER NUMBER 3 - A IS BEFORE B. YOU SAY, WELL, GOSH -- TIME
MUST BE THERE FOR AN ILLUSION. I THINK THAT'S A
MISTAKEN ARGUMENT. IT'S A MISTAKEN ARGUMENT BECAUSE
NO OBSERVER HAS KNOWLEDGE OF A DISTANT EVENT, OR THE
SIMULTANEITY OF DIFFERENT EVENTS, UNTIL THEY ARE
UNAMBIGUOUSLY IN THAT OBSERVER'S PAST. AND, THEREFORE, THAT ARGUMENT
CAN JUST ENTIRELY FOCUS ON THE WAY OBSERVERS DESCRIBE THE PAST
-- ORGANIZE THEIR DESCRIPTION OF THE PAST -- CANNOT ESTABLISH THE
REALITY OF THE AWAITING FUTURE, SO I DON'T THINK THE BLOCK
UNIVERSE, THIS TOTAL PACKAGE DEAL OF SPACE AND TIME
TOGETHER, IS CORRECT. I THINK WE LIVE IN A WORLD OF
UNFOLDING BECOMING, BUT I THINK THAT IT'S PERFECTLY CONSISTENT
LAW OF SCIENCE CAN TELL US ABOUT IT. IF SPACE AND TIME EMERGED FROM
SOMETHING MORE FUNDAMENTAL, WHAT WOULD THAT DO TO THE
FUNDAMENTAL NATURE OF TIME? WELL, I DON'T THINK IT WOULD
REMOVE THE FUNDAMENTAL NATURE OF TIME. I MEAN, AFTER ALL, MATTER AND
ENERGY EMERGE IN THE SAME SORT OF THING, WE DON'T THINK
THAT THEY'RE ILLUSIONS. WE'RE NOT MADE OF
ILLUSIONS OURSELVES. IN TRYING TO UNDERSTAND TIME,
ANOTHER WAY TO LOOK AT THIS WOULD BE FROM A THEOLOGICAL
POINT OF VIEW, PARTICULARLY FROM THE CONCEPT OF GOD, AND IF
THERE IS A GOD, HOW DOES GOD EXPERIENCE TIME, IF AT ALL? THE CLASSICAL VIEW WAS THAT
GOD SAW A WHOLE OF CREATION, ALL AT ONCE. IN OTHER WORDS, ACTUALLY, IN
SCIENTIFIC TERMS, GOD SAW A BLOCK UNIVERSE - THE SPACE-TIME
CONTINUUM - IN THAT SENSE, BUT I DON'T THINK THAT'S RIGHT. I THINK WE LIVE IN A WORLD OF
TRUE BECOMING -- THAT IS TO SAY THAT THE FUTURE IS NOT THERE
ALREADY WAITING FOR US, WE MAKE IT OR HELP TO MAKE IT AS WE GO
ALONG, AND IF THAT'S CORRECT ABOUT THE NATURE OF THE WORLD,
I THINK IT'S ALSO, OBVIOUSLY, THEOLOGICALLY CORRECT
THAT GOD KNOWS THINGS TRULY. THAT'S TO SAY, KNOWS THEM AS
THEY ACTUALLY ARE, AND THAT MEANS, I THINK, THAT GOD WILL
NOT ONLY KNOW, IN OUR FOLDING UNIVERSE, NOT ONLY KNOW THE
EVENTS OF SUCCESSION, BUT WILL KNOW THEM ACCORDING TO THEIR
NATURES, WHICH MEANS THAT GOD WILL KNOW THEM IN
THEIR SUCCESSION. IF THAT'S THE CASE, THEN THERE
MUST BE A GENUINE ENGAGEMENT OF GOD WITH TIME. OF COURSE, GOD IS NOT ENTHRALLED
TO TIME; THERE MUST BE A TIMELESS, ETERNAL, UNCHANGING
ASPECT OF GOD -- OR STEADFAST FAITH WAS THE SORT, BUT I
BELIEVE THAT WHEN GOD BROUGHT INTO BEING A UNIVERSE
ENDOWED WITH TIME, ENDOWED WITH BECOMING, GOD, AS AN ACT OF
DIVING SELF-LIMITATION, IN A WAY, CHOSE TO KNOW THAT WORLD
ACCORDING TO ITS NATURE, AND ITS BECOMINGNESS. THEREFORE, I THINK THAT GOD --
EVEN GOD DOES NOT YET KNOW THE FUTURE, AND THAT'S NOT AN
IMPERFECTION IN GOD; GOD KNOWS EVERYTHING THAT CAN BE KNOWN,
BUT THE FUTURE IS NOT YET THERE TO BE KNOWN. SO, INTEGRATING THE TWO FROM
A PHYSICS POINT OF VIEW AND A THEOLOGICAL POINT OF VIEW,
WHAT IS THE NATURE OF TIME? YOU COULD EITHER, FROM THE
PHYSICS POINT OF VIEW, BELIEVE IN THE BLOCK UNIVERSE, AS
EINSTEIN DID, OR IN A WORLD OF BECOMING THAT I'VE BEEN TRYING
TO DESCRIBE, AND THAT TELLS US THAT PHYSICS BY ITSELF, THAT
MAYBE CONSTRAINS HOW WE THINK ABOUT TIME, DOES NOT
TOTALLY DETERMINE HOW WE THINK ABOUT TIME. NOW, WITH YOU AND I, THEY CAN
BE THEOLOGICAL REASONS INDEED, WHICH SETTLE WHETHER WE GO FOR
THE BLOCK UNIVERSE, OR WHETHER WE GO FOR AN UNFOLDING WORLD. SO, TIME IS NOT WHAT IT SEEMS. TIME IS NOT A SIMPLE UNITY
WITHOUT PARTS; THE EVER-EXISTING STAGE ON WHICH
EVENTS ARE PLAYED. TIME HAS VARIOUS PARTS OR
FEATURES, OR ELEMENTS THAT MAY WORK TOGETHER AND APPEAR
SEAMLESS, BUT ARE NOT REQUIRED TO DO SO. WHAT ARE THESE PARTS OF TIME? TIME HAS FLOW;
MOVEMENT LIKE A RIVER. TIME HAS DIRECTION, ALWAYS
PROCEEDING FORWARD INTO THE FUTURE. TIME HAS ORDER -- ONE
THING AFTER ANOTHER. TIME HAS DURATION - A MEASURABLE
PERIOD BETWEEN EVENTS. TIME HAS A PRIVILEGED
PRESENT; ONLY NOW IS REAL. TIME HAS A DIMENSION,
SOMETHING LIKE SPACE. THE QUESTION IS WHETHER THESE
PARTS ARE MORE CONSTRUCTS OF HUMAN BRAINS THAN ACTUAL
REALITIES OF THE PHYSICAL WORLD. THE CHALLENGE IS THAT PHYSICS
SUPPORTS A BLOCK UNIVERSE - A 4-DIMENSION STRUCTURE
WHERE TIME IS LIKE SPACE. WHERE EVERY EVENT HAS ITS
OWN COORDINATE OR ADDRESS IN SPACE-TIME, SO THAT FUTURE
AND PAST ARE NO LESS REAL THAN THE PRESENT. THE ALTERNATIVE IS THAT
THE PRESENT IS, INDEED, SUPER-SPECIAL, AND THE
DEEP NATURE OF REALITY IS ONE OF BECOMING. I CANNOT DECIDE. BUT IF I IGNORE TIME,
I AM NOT CLOSER TO TRUTH.
