THE MORE REMARKABLE ARE THE DISCOVERIES WE MAKE.

MUCH OF MY WORK HAS BEEN CONCERNED

WITH THE MYSTERIES OF BLACK HOLES.

MANY PEOPLE DISMISS BLACK HOLES

AS JUST AN ARTIFACT OF THE THEORY,

WHICH WOULDN'T EXIST IN THE REAL WORLD.

BUT THEN OBSERVERS BEGAN TO FIND THINGS IN THE SKY

WHICH WERE JUST AS PECULIAR.

Narrator: IN THE END, SCIENTISTS WOULD FIND

SOME VERY PECULIAR THINGS --

IMPOSSIBLY BRIGHT OBJECTS BLAZING FROM THE DISTANT PAST,

AND FORCES OF IMPENETRABLE DARKNESS.

THE FIRST THING THEY FOUND WAS SIGNALS,

RADIO WAVES FROM SPACE.

ASTRONOMERS TUNED IN IN SEARCH OF ALIENS.

Man: WELL, MY NAME IS SETH SHOSTAK,

AND I'M A AN ASTRONOMER AT THE SETI INSTITUTE

HERE IN LOVELY MOUNTAIN VIEW, CALIFORNIA.

THE ACRONYM "SETI" STANDS FOR

SEARCH FOR EXTRA-TERRESTRIAL INTELLIGENCE.

NOW, THAT "I" ON THE END

MEANS WE'RE NOT LOOKING FOR EXTRATERRESTRIAL LIFE,

BUT WE'RE LOOKING FOR INTELLIGENT LIFE.

THAT MEANS THEY CAN HOLD UP THEIR SIDE OF THE CONVERSATION,

IF YOU WILL.

AFTER THE SECOND WORLD WAR,

RADIO ASTRONOMY REALLY GOT GOING.

AND IN THE LATE '50s,

THEY STARTED BUILDING LARGE RADIO TELESCOPES,

LIKE THE ONE WE'RE SITTING UNDERNEATH.

COULD THIS TECHNOLOGY

ACTUALLY BE USED TO SEND MESSAGES, AS IT WERE,

BETWEEN THE STARS?

IN 1959, 1960, THE FIRST EXPERIMENTS WERE MADE

USING THIS KIND OF TECHNOLOGY -- A BIG RADIO TELESCOPE --

TO TRY AND EAVESDROP ON ANY CIVILIZATIONS

THAT MIGHT BE NEARBY.

Narrator: NO ALIENS FOUND, GRANTED,

BUT THERE WAS NO MISTAKING THE SIGNALS.

Shostak: SUDDENLY, YOU WERE GETTING

THESE CLEAR RADIO VIEWS, SO YOU KNEW THAT

IN THAT DIRECTION

THERE'S A VERY STRONG SOURCE OF RADIO WAVES.

YOU WOULD TELL YOUR FRIEND THE OPTICAL ASTRONOMER,

AND THEY WOULD GO USE A BIG TELESCOPE,

LIKE THE PALOMAR 200-INCH TELESCOPE,

OR SOMETHING SIMILAR,

AND THEY WOULD POINT IT IN THAT DIRECTION.

Narrator: WHERE THE UNIVERSE EMITTED A RADIO SIGNAL,

OPTICAL ASTRONOMERS NOW TRAINED THEIR GAZE.

WHAT THEY SAW DEFIED EXPLANATION.

BUT AT FIRST, ITS SIGNIFICANCE ELUDED THEM.

Man: PEOPLE SAW THAT THEY WERE UNUSUAL OBJECTS.

FOR EXAMPLE, A GALAXY THAT HAD A PECULIAR BLOB WITHIN IT

IN SOME CASES WAS FOUND TO EMIT RADIO WAVES.

WHEREAS A NORMAL-LOOKING, BORING-LOOKING GALAXY DID NOT.

OR, FOR EXAMPLE,

A CLOUD OF GAS THAT HAD

ALL SORTS OF LITTLE STRIATIONS IN IT,

AND LOOKED AS THOUGH IT MIGHT BE EXPLODING --

THOSE WERE PRECISELY THE OBJECTS

THAT SEEMED TO EMIT RADIO WAVES.

WHEREAS MORE NORMAL, QUIESCENT CLOUDS OF GAS DID NOT.

Narrator: GRADUALLY, THE STRANGE EVIDENCE MOUNTED.

WHEN OBSERVERS TURNED THEIR TELESCOPES

ON THE SOURCE OF PARTICULARLY STRONG RADIO SIGNALS,

THEY EXPECTED TO SEE COSMOLOGICAL CATASTROPHES.

INSTEAD, THEY WERE LEFT WITH COSMIC QUESTIONS.

Filippenko: IN THE EARLY 1960s,

OPTICAL ASTRONOMERS TOOK PHOTOGRAPHS

OF CTAIN POSITIONS IN THE SKY

FROM WHICH RADIO WAVES SEEMED TO BE COMING,

AND THEY JUST SAW NOTHING UNUSUAL.

THERE WAS JUST THE USUAL SMATTERING OF STARS,

AND THERE WAS NO OBVIOUSLY EXPLODING STAR,

NO TURBULENT CLOUD OF GAS, NOTHING SEEMINGLY UNUSUAL --

JUST NORMAL STARS.

AND THIS PERPLEXED THE ASTRONOMERS.

Narrator: TAKE THE CASE OF 3C273,

A STAR OF NO PARTICULAR DISTINCTION.

IT HARDLY SEEMED WORTH NOTICE,

THAT IS, UNTIL OBSERVERS BEGAN TO LOOK A LITTLE CLOSER.

Filippenko: 3C273 IN THE CONSTELLATION VIRGO

LOOKED JUST LIKE A STAR,

YET WE KNOW THAT ORDINARY STARS DON'T EMIT RADIO WAVES,

AND SO THIS WAS HIGHLY, HIGHLY UNUSUAL.

Narrator: USING A TECHNIQUE CALLED SPECTROSCOPY,

ASTRONOMERS STUDIED THE LIGHT

EMITTED BY 3C273.

WHEN YOU TAKE A SPECTRUM OF AN ORDINARY STAR,

THAT IS WHEN YOU PASS THE LIGHT THROUGH A PRISM

AND BREAK IT UP INTO A RAINBOW,

YOU CAN SEE SMALL DIPS, SMALL WIGGLES IN THE SPECTRUM.

AND THOSE ARE THE WIGGLES THAT ARE PRODUCED BY ATOMS,

BY GASES IN THE ATMOSPHERE OF THOSE STARS

THAT ARE ABSORBING SOME OF THE LIGHT.

AND BY IDENTIFYING THE PATTERN OF THESE LINES,

THESE LITTLE WIGGLES THAT APPEAR IN A STAR,

YOU CAN DEDUCE WHETHER THE ATMOSPHERE OF THE STAR

HAS HYDROGEN OR HELIUM AND OXYGEN --

THINGS LIKE THAT.

BUT IF THAT PATTERN IS SHIFTED TOWARD REDDER COLORS,

THEN YOU DEDUCE NOT ONLY THAT THE STAR HAS HYDROGEN

OR OTHER COMMON ELEMENTS,

BUT ALSO THAT THE STAR IS MOVING AWAY FROM YOU.

Hawking: 34 YEARS EARLIER,

THE AMERICAN ASTRONOMER, EDWIN HUBBLE,

HAD USED SPECTROSCOPY TO DISCOVER THAT

THE UNIVERSE IS EXPANDING.

DISTANT GALAXIES ARE MOVING AWAY FROM US.

THE SPECTRUM OF 3C273 WAS ABOUT TO TELL US EVEN MORE.

Filippenko: THE SPECTRUM OF 3C273

DIDN'T FIT ANY PATTERNS OF NORMAL GASES

THAT HAVE BEEN OBSERVED IN NORMAL STARS.

AND SO THIS REALLY BEFUDDLED ASTRONOMERS.

NOT ONLY WAS THE OBJECT EMITTING RADIO WAVES PROFUSELY,

BUT IT HAD THIS REALLY STRANGE SPECTRUM

THAT COULDN'T BE MATCHED WITH ANY KNOWN TYPE OF GAS.

Narrator: A STAR'S SPECTRUM IS ITS SIGNATURE,

AND THIS ONE WAS AN ABERRATION.

IT WAS ENOUGH TO LEAVE MANY ASTRONOMERS CONFOUNDED.

BUT FOR ONE, 3C273 WAS A REVELATION.

HE WAS CONVINCED SPECTROSCOPY COULDN'T LIE.

Filippenko: MARTIN SCHMIDT AT CALTECH.

NOTICED THAT TWO OF THE WIGGLES

HAD THE SAME SPACING BETWEEN THE COLORS

AS HYDROGEN DOES, BUT BOTH OF THE LINES

WERE SHIFTED WAY OVER TOWARD REDDER PARTS OF THE SPECTRUM

THAN NORMAL HYDROGEN GAS IS.

AND IF HE BELIEVED THAT THAT IDENTIFICATION WAS CORRECT,

THEN THE CONCLUSION WAS THAT THE SHIFT IS A FULL 16%.

YET A SHIFT OF 16% MEANT THAT THIS OBJECT

WAS MOVING AWAY FROM US ENORMOUSLY FAST, AND HAD TO BE

ONE OR TWO BILLION LIGHT YEARS AWAY.

SO, NO WAY COULD IT BE A NORMAL STAR

OR EVEN A PECULIAR MAGNETIC STAR IN OUR OWN GALAXY.

IT HAD TO BE SOME SORT OF A STRANGE OBJECT

THAT LOOKS STELLAR OR QUASI-STELLAR

SIMPLY BECAUSE IT'S SO, SO FAR AWAY,

AND YET IT'S ENORMOUSLY BRIGHT.

SO THIS REALLY CAUGHT PEOPLE BY SURPRISE,

AND A FEW PEOPLE, I THINK, HAD A HARD TIME BELIEVING

THAT ANYTHING SO RELATIVELY BRIGHT

COULD BE SO FAR AWAY.

ASTRONOMERS DECIDED TO CALL THESE OBJECTS,

THESE RADIO-STARS,

QUASI-STELLAR RADIO SOURCES.

THEY WERE CLEARLY RADIO SOURCES --

THEY WERE DISCOVERED WITH RADIO TELESCOPES --

AND THEY LOOKED STAR-LIKE,

AND HENCE THE STELLAR ASPECT OF THE TERM.

SO "QUASI-STELLAR RADIO SOURCES" GOT CONTRACTED TO "QUASARS."

MARTIN SCHMIDT CONCLUDED THAT IT MUST BE, INTRINSICALLY,

AN EXTREMELY POWERFUL SOURCE --

AN EXCEEDINGLY BRIGHT OBJECT INTRINSICALLY --

BECAUSE TO APPEAR AS BRIGHT AS IT DOES IN THE SKY,

YET BE SO FAR AWAY,

IT HAS TO PUT OUT A TREMENDOUS AMOUNT OF ENERGY PER SECOND --

MUCH, MUCH MORE THAN OUR SUN --

IN FACT, 100 TO 1,000 TIMES MORE

THAN OUR ENTIRE MILKY WAY GALAXY OF STARS.

AND THIS WAS THE REAL KICKER.

Hawking: WHEN THE MYSTERIOUS QUASARS WERE DISCOVERED,

I WAS JUST BEGINNING MY POST-GRADUATE RESEARCH.

MY WORK WAS TO LEAD ME TO STUDY THINGS

EVEN MORE MYSTERIOUS --

BLACK HOLES.

I WAS DEALING WITH EINSTEIN'S GENERAL THEORY OF RELATIVITY,

AND THIS SEEMED, TO SOME PHYSICISTS,

A PROMISING PLACE TO LOOK

FOR AN EXPLANATION OF THE QUASARS.

ASTRONOMERS AND ASTROPHYSICISTS WANTED AN EXPLANATION

FOR HOW THESE STRANGE OBJECTS

COULD BEHAVE IN THIS EXTRAORDINARY WAY --

HOW THEY COULD PRODUCE SO MUCH ENERGY,

AND YET BE SO SMALL.

AND SO THEY TURNED TO THE GENERAL RELATIVISTS,

AND ASKED THEM,

"WELL, DO YOU HAVE ANY MODELS FOR OBJECTS

"THAT COULD LOOK LIKE THIS,

THAT COULD BEHAVE IN THIS WAY AT ALL?"

AND THE RELATIVISTS SAID,

"WELL, THERE IS THIS ISSUE OF GRAVITATIONAL COLLAPSE,

AND MAYBE THIS IS WHAT YOU'RE LOOKING FOR."

Narrator: GRAVITY IS THE DOMINANT FORCE

IN THE UNIVERSE.

THIS TENET OF EINSTEIN'S WAS IRREFUTABLE.

BUT THERE WAS NO SUCH CONSENSUS ABOUT WHAT WOULD HAPPEN

UNDER VIOLENT CONDITIONS, LIKE THE DEATH OF A LARGE STAR.

EINSTEIN WONDERED, COULD ITS GRAVITATIONAL COLLAPSE

CRUSH ITS VAST QUANTITIES OF MATTER

INTO THE TINIEST OF POINTS?

Dowker: IN 1939, TWO PAPERS APPEARED.

ONE WAS BY EINSTEIN HIMSELF,

AND ONE WAS BY THE AMERICAN PHYSICIST,

ROBERT OPPENHEIMER, AND HIS CO-WORKER, SNYDER.

THEY DISCUSSED WHAT WOULD HAPPEN

WHEN A LARGE AMOUNT OF MATTER

WAS CONCENTRATED IN A SMALL REGION.

Narrator: EINSTEIN REJECTED

THE PROSPECT OF INFINITE COLLAPSE.

BUT OPPENHEIMER AND SNYDER'S CALCULATIONS

MADE THE CONCEPTUAL LEAP.

Dowker: USING THE RULES OF GENERAL RELATIVITY,

THEY PREDICTED THAT THAT MASSIVE OBJECT

WOULD UNDERGO CATASTROPHIC GRAVITATIONAL COLLAPSE

AND WOULD REACH A CRITICAL RADIUS

AT WHICH IT SEEMINGLY CUTS ITSELF OFF

FROM THE REST OF THE UNIVERSE.

Narrator: FOR MANY, THE IDEA OF A STAR

DESCENDING INTO SUCH AN ABYSS WAS UNTHINKABLE --

ALL THE MORE SO WHEN THE VIEW WAS SHARED

BY THE GREATEST LIVING SCIENTIST.

Dowker: EINSTEIN WAS CONVINCED

THAT YOU COULD NEVER GET TO THIS CRITICAL RADIUS,

THAT THIS CRITICAL RADIUS WAS AN IMPOSSIBILITY IN NATURE.

Narrator: THE CONTROVERSY WAS SHORT-LIVED FOR NOW.

WITH THE SECOND WORLD WAR,

OPPENHEIMER'S TALENTS WERE NEEDED ELSEWHERE,

DEVELOPING THE ATOMIC BOMB.

HIS EARLIER WORK LANGUISHED, DISMISSED BY PEERS

AS A RADICAL DEPARTURE FROM EINSTEIN.

BUT OPPENHEIMER HAD CONVINCED ONE COLLEAGUE,

JOHN WHEELER.

STICK UP FOR SOMETHING.

AND I THINK THAT'S A WONDERFUL WAY OF SAYING

WHAT SCIENCE IS ALL ABOUT.

STICK UP FOR SOMETHING.

Man: I'M DANIEL HOLZ, I'M A GRADUATE STUDENT

AT THE UNIVERSITY OF CHICAGO,

AND I'M GOING TO SEE JOHN WHEELER,

WHO WAS MY UNDERGRADUATE ADVISER HERE AT PRINCETON.

Narrator: FOR HOLZ,

THESE PERIODIC VISITS WITH HIS MENTOR ARE A PRIVILEGE.

AT AGE 85, JOHN WHEELER IS STILL A LUMINARY

OF 20th CENTURY SCIENCE.

Holz: HE'S CERTAINLY ONE OF THE GREATEST PHYSICISTS ALIVE,

AND HE'S CONTRIBUTED IN IMPORTANT WAYS

IN MANY DIFFERENT ASPECTS OF PHYSICS.

HE'S HAD FRESH IDEAS

THAT HAVE PUSHED THE VERY EDGES OF OUR KNOWLEDGE.

HE LOVES TO JUST SINK HIS TEETH INTO PROBLEMS.

PART OF HIS APPROACH IN PHYSICS IS,

FIND THE BIGGEST, MOST CONFUSING THING HE CAN,

AND THEN GO AT IT FULL STEAM AND TRY TO MAKE SENSE OF IT.

Narrator: WHEELER WAS WITNESS TO A REMARKABLE CHAPTER

IN THE ANNALS OF PHYSICS.

HE WORKED WITH OPPENHEIMER ON THE ATOMIC BOMB.

BUT BEFORE THAT,

WHEN WHEELER ARRIVED AT PRINCETON

IN THE 1940s,

EINSTEIN WAS THE MOST EMINENT MEMBER OF THE FACULTY.

IN 1963, THE CONTROVERSY ABOUT COLLAPSING STARS

WAS REKINDLED BY THE DISCOVERY OF QUASARS.

WHEELER HAD A DIFFICULT CHOICE BETWEEN TWO CONVICTIONS

AND TWO CHERISHED COLLEAGUES.

THOUGH HE DIFFERED WITH EINSTEIN,

HE RECALLS HIM FONDLY.

Wheeler: HE WAS KIND ENOUGH TO INVITE ME

TO BRING MY GRADUATE STUDENTS AROUND TO HIS HOUSE