♪ ♪
[ APPLAUSE ]
-THANK YOU VERY MUCH.
AND THIS IS KIND OF A NEAT SLIDE.
THAT ACTUALLY IS A PICTURE OF ME TAKEN BY DREW FEUSTEL
AS I WAS REPAIRING THE HUBBLE SPACE TELESCOPE.
AND AS CHRIS SCOLESE SAID, I STARTED OUT LIFE --
UH, WELL, I'M NOT GONNA TELL YOU THE LONG STORY --
BUT AS A HIGH-ENERGY ASTROPHYSICIST,
AND I WAS JUST FASCINATED BY BLACK HOLES AND NEUTRON STARS.
MY FIRST SCIENTIFIC PAPER
WAS AN OBSERVATION OF A NEUTRON STAR --
A STAR THE SIZE
OF WASHINGTON, D.C., ROTATING RAPIDLY
WITH THE DENSITY OF NUCLEAR OF MATTER --
AND WENT ON TO BUILD BALLOON PAYLOADS
AND DO EXPERIMENTS AND WORK WITH SPACE EXPERIMENTS,
INCLUDING THE COMPTON OBSERVATORY,
THAT I WAS CONVINCED WAS GONNA BE MY CAREER.
AND I LOOKED VERY JEALOUSLY AT THE HUBBLE SPACE TELESCOPE,
THINKING, "OH, IT'S JUST AN OPTICAL TELESCOPE.
IT'S TAKING ALL THE MONEY.
THE REAL ACTION IS IN HIGH-ENERGY ASTROPHYSICS."
YOU KNOW, BUT I THINK WE SHOULD ALL BE CONTINUOUS LEARNERS,
AND I LEARNED HOW IMPORTANT HUBBLE IS.
AND THE NEXT SPEAKER WILL REFER TO THAT.
AND, IN FACT, I BECAME,
ACTUALLY, QUITE TRANSFORMED BY THE HUBBLE SPACE TELESCOPE.
BUT I ALSO BECAME TRANSFORMED BY THE FACT THAT WHEN
THE COMPTON OBSERVATORY WAS ON THE END OF THE ROBOTIC ARM,
THE HIGH-GAIN ANTENNA DIDN'T DEPLOY.
AND IT WAS JERRY ROSS AND JAY APT WHO WENT OUT
AND DID A SPACE WALK AND DEPLOYED IT,
ENABLING MY RESEARCH AND MANY OF THE FOLKS
THAT ARE IN THIS ROOM
TO BE ABLE TO UNRAVEL THE MYSTERIES OF THE UNIVERSE --
THE HIGH-ENERGY UNIVERSE --
WITH COMPTON.
AND WE'RE GONNA HEAR MORE ABOUT, YOU KNOW,
SOME OF THE FOLLOW-ON GREAT SPACE CRAFT AND EXPERIMENTS
AND THE SCIENCE.
BUT IT REALLY COMES DOWN TO WHAT NASA's ALL ABOUT.
YOU KNOW, WE INNOVATE,
WE EXPLORE,
WE DISCOVER,
AND WE INSPIRE.
AND WE INNOVATE TO BUILD THE KIND OF TECHNOLOGIES
THAT ALLOW US TO BUILD SPACE CRAFT LIKE NuSTAR,
WHICH YOU'LL HEAR ABOUT.
WE USE THOSE INNOVATIONS TO EXPLORE THE UNIVERSE.
AND WHEN WE EXPLORE, WE DISCOVER THINGS.
AND THAT'S WHERE THE HUMAN ELEMENT IS AT ITS STRONGEST.
WE'RE DRIVEN.
I THINK WE'RE GENETICALLY PROGRAMMED
TO BE ENERGIZED BY THOSE DISCOVERIES.
AND WHEN WE'RE ENERGIZED AS SCIENTISTS,
WE'RE ABLE TO INSPIRE A COUNTRY, A WORLD, STUDENTS,
EVERYONE.
AND I THINK THAT'S THE IMPORTANCE OF THE SCIENCE
THAT WE DO.
WE'RE ALSO ASKING HUMAN QUESTIONS, IN ESSENCE.
WE'RE ASKING FUNDAMENTAL PHYSICS QUESTIONS, SCIENCE QUESTIONS,
BUT WE'RE TRYING TO FIND OUT, YOU KNOW,
WHERE DID WE COME FROM, WHERE DID THE UNIVERSE
THAT WE LIVE IN COME FROM,
AND WHY DOES IT LOOK THE WAY THAT IT DOES.
WHERE DO THE CHEMICAL ELEMENTS
THAT WE'RE MADE OUT OF COME FROM?
AND IT TURNS OUT THEY CAME FROM A VERY VIOLENT UNIVERSE.
AND WE'LL HEAR, HOPEFULLY, A LITTLE BIT ABOUT THAT.
YOU KNOW, WE'RE MADE OUT OF STAR STUFF
THAT HAD TO GET FROM THE INSIDE OF STARS, OUT OF STARS,
TO FORM NEW STARS, PLANETS, AND US.
WHERE ARE WE GOING?
WHAT'S THE FUTURE OF THE UNIVERSE?
THAT'S ALSO DOMINATED BY HIGH-ENERGY PROCESSES.
BUT ALSO, WHERE ARE WE GOING ON PLANET EARTH?
THAT'S ONE OF THE THINGS THAT WE DO IN EARTH SCIENCE.
AND THEN THE BIG QUESTION,
WHICH I DON'T THINK HIGH-ENERGY ASTROPHYSICS IS GONNA ANSWER,
BUT ONE I'M FASCINATED BY IS "ARE WE ALONE?"
AND THAT'S WHY SOME OF OUR PLANETARY MISSIONS
AND OUR EXOPLANET MISSIONS, I THINK, ARE SO INTERESTING NOW.
BECAUSE WE ARE ONE STEP
AWAY FROM HAVING THE TECHNOLOGICAL CAPABILITY
TO ANSWER THE QUESTION THROUGH TELESCOPIC OBSERVATION
OF NEARBY EXOPLANETS,
INTERROGATING THEIR ATMOSPHERES,
TO FIND OUT IF WE'RE ALONE IN THE UNIVERSE.
OR A FUTURE PLANETARY SCIENTIST --
AND THERE'S SOME YOUNG PEOPLE IN THE AUDIENCE
THAT ARE THOSE FUTURE PLANETARY SCIENTISTS --
WHO ARE GONNA WALK ON THE SURFACE
OF MARS WITH ANALYTIC TOOLS
THAT MAY BE ABLE TO TELL US WHETHER THERE'S LIFE
ON MARS OR A PLANETARY MISSION EXPLORING EUROPA.
SO, THIS IS ONE OF MY FAVORITE EVENTS, BECAUSE EVERY YEAR,
WE GET TO HEAR ABOUT THE GREAT SCIENCE
THAT'S GOING ON AT THE GODDARD SPACE FLIGHT CENTER
AND THROUGH ITS PARTICIPATING SCIENTISTS
AND REALLY LEARN SOMETHING IMPORTANT.
AND SO, WHAT I'D LIKE TO DO IN MY FINAL COMMENT TONIGHT
IS ADDRESS THE "INSPIRE" PART
OF OUR MISSION,
WHICH IS TO ASK ALL OF YOU TONIGHT,
AFTER YOU LEAVE, YOU KNOW,
DRIVE SAFELY GOING HOME,
BUT TOMORROW AND THE NEXT DAY AND, YOU KNOW,
FOR REALLY, HOPEFULLY,
THE REST OF YOUR LIVES,
AS YOU LEARN ABOUT OUR GREAT SCIENTIFIC ACHIEVEMENTS,
AS YOU YOURSELVES,
YOU KNOW, DISCOVER THINGS,
SHARE IT WITH YOUR NEIGHBORS.
CERTAINLY SHARE IT WITH YOUR FAMILY MEMBERS.
YOU KNOW, MANY OF US GO TO WORK IN THE SCIENCE COMMUNITY.
WE WORK REALLY HARD, WE COME HOME,
WE'RE TIRED, YOU KNOW, WE HAVE A MEAL, WE GO TO SLEEP,
AND WE DON'T TELL OUR FAMILIES ABOUT THE GREAT WORK
AND INCREDIBLE WORK WE'RE DOING STUDYING THE ENVIRONMENT
AROUND A BLACK HOLE OR A ROTATING NEUTRON STAR
OR AN ACTIVE GALACTIC NUCLEI,
AND IT REALLY IS AMAZING.
PEOPLE ARE AMAZED BY WHAT WE DO.
SHARE IT WITH YOUR COMMUNITY GROUPS.
SHARE IT WITH LOCAL SCHOOLS,
BECAUSE IT'S THROUGH THAT COMMUNICATION
THAT WE INSPIRE THE WORLD.
SO, I HOPE YOU'RE ALL INSPIRED TONIGHT.
AND I WAS INSPIRED WHEN I WAS A HIGH SCHOOL STUDENT --
I LIKE TO SAY EVERYTHING I LEARNED ABOUT ASTRONOMY,
I LEARNED AS A HIGH SCHOOL STUDENT --
IN A PROGRAM AT A SMALL PLANETARIUM IN CHICAGO
CALLED THE ADLER PLANETARIUM.
AND ONE OF THE GRADUATE ASSISTANTS THAT WAS TEACHING US
WAS SOMEBODY WHO HAS, THROUGHOUT MY CAREER,
BECOME A MENTOR
AND WAS MY PREDECESSOR.
AND SO, I'D LIKE TO BRING UP DR. ED WEILER
TO GIVE US AN INTRODUCTION.
[ APPLAUSE ]
-THANKS, JOHN.
I'M REALLY NOT THAT OLD.
[ LAUGHTER ]
BUT I AM RETIRED, IF YOU WONDER WHERE I'VE BEEN
THE LAST FOUR YEARS.
UH, BUT WHEN YOU'RE RETIRED,
YOU HAVE LOTS OF TIME,
FINALLY, ESPECIALLY BETWEEN TENNIS MATCHES,
TO GAIN PERSPECTIVE
ON WHAT'S HAPPENED IN YOUR FIELD OF ASTROPHYSICS
OVER THE PAST 40 YEARS.
THAT'S HOW LONG MY CAREER HAS BEEN.
BACK IN THE '70s AND '80s,
WHEN MANY OF US WERE IN GRAD SCHOOL OR JUST STARTING COLLEGE,
WE THOUGHT WE KNEW A LOT ABOUT THE UNIVERSE.
WE WERE PRETTY ARROGANT.
WE KIND OF KNEW HOW STARS WERE FORMED
AND HOW THEIR ATMOSPHERES WORKED, ET CETERA.
BUT THERE WERE SOME AWFULLY BIG PROBLEMS LEFT UNSOLVED,
WHICH WERE NAGGING AT US.
AND THOSE ARE THE ONES WE'LL BE ADDRESSING,
SOME OF THEM, TONIGHT.
FOR INSTANCE, DO SUPERMASSIVE BLACK HOLES REALLY EXIST?
OR ARE THEY JUST MERE SCIENCE FICTION
AND FODDER FOR SHOWS LIKE "STAR TREK"?
WHAT ARE QUASI-STELLAR OBJECTS, QUASARS?
THEY APPEAR AS PINPOINTS OF LIGHT IN THE SKY,
BUT EXTREMELY DISTANT AND THUS VERY ENERGETIC.
SOME ARE RELATIVELY QUIET WHILE OTHERS SEEM HIGHLY VARIABLE.
DO THEY HAVE HOMES IN THE UNIVERSE,
OR ARE THEY SOLITARY OBJECTS IN THE VAST DARKNESS?
IN THE EARLY '80s, DIFFUSE X-RAY BACKGROUND
WAS DISCOVERED TO FILL THE NIGHTTIME SKY.
WHAT WAS IT?
GAMMA-RAY BURSTS WERE SEEN ALMOST ONCE A DAY.
THEY LAST VERY SHORT PERIODS OF TIME -- SECONDS,
OR UP TO A DAY.
ARE THEY NEARBY OR EXTREMELY DISTANT AND THUS VERY ENERGETIC?
AND FINALLY, WE THINK SUPERNOVA -- BACK IN THE '80s,
WE KNEW SUPERNOVA WERE PROBABLY VIOLENT EXPLOSIONS,
BUT WHAT WAS THEIR EXACT NATURE?
WE KNOW THAT THEY CREATED ELEMENTS IN OUR BODIES --
CALCIUM, IRON, ET CETERA.
AND THUS, IT WAS IMPORTANT TO BETTER UNDERSTAND
THESE VIOLENT PHENOMENA.
IT WAS RECOGNIZED BY MANY BACK THEN TO TACKLE
AS BROAD A RAY OF MYSTERIES,
IT WOULD TAKE LARGE SPACE OBSERVATORIES OPERATED
IN MULTIPLE WAVELENGTH BANDS FROM GAMMA RAY TO INFRARED.
AND SOON, WE'LL SEE --
YOU CAN THINK YOU'LL HEAR THE TERM WAVELENGTH
TONIGHT, PERHAPS.
THINK OF WAVELENGTH AS COLORS.
OUR EYES CAN ONLY SEE IN THIS LITTLE AREA
OF VISIBLE LIGHT HERE.
IF YOU WANT TO LOOK IN THE ULTRAVIOLET, X-RAY,
GAMMA RAY, MUCH OF THE INFRARED,
YOU HAVE TO GO INTO SPACE TO GET -- TO SEE, BASICALLY,
THE REST OF THE UNIVERSE.
I REMEMBER AFTER WE SOLD HUBBLE,
WE WERE TRYING TO SELL A GAMMA-RAY OBSERVATORY
AND SIRTF AND AXAF.
AND ONE CONGRESSIONAL STAFFER,
WHO SHALL REMAIN UNNAMED,
CAME UP TO ME AND SAID, "HEY, YOU GUYS ARE GETTING HUBBLE.
WE'RE PAYING A LOT FOR HUBBLE.
WHY IN THE WORLD DO YOU NEED ALL THESE OTHER OBSERVATORIES?"
AND I'LL USE THE ANALOGY I USED THAT DAY WITH HIM,
AND I SAID, "WELL, IF YOU HAD A REALLY BAD DISEASE
AND YOU WENT TO THE DOCTOR TO GET DIAGNOSED,
WOULD YOU GO TO A DOCTOR WHO BASICALLY USES
THEIR EYES AND THEIR HANDS TO DIAGNOSE YOU?
OR WOULD YOU PREFER A DOCTOR
THAT MIGHT USE STATE-OF-THE-ART TECHNOLOGY
LIKE MRIs, CAT SCANNERS,
STETHOSCOPES, EVEN,
ULTRASOUNDS?"
AND ASTRONOMERS ARE IN THE SAME BOAT.
IF YOU REALLY WANT TO UNDERSTAND
A LOT OF OBJECTS IN THE UNIVERSE,
YOU'VE GOT TO LOOK AT ALL WAVELENGTH AREAS.
BECAUSE THESE WAVELENGTH AREAS REALLY TELL YOU
ABOUT THE TEMPERATURE OF THE MATTER IN THE OBJECT.
GAMMA RAYS AND X-RAYS --
TENS OF MILLIONS, HUNDREDS OF MILLIONS OF DEGREES.
ULTRAVIOLENT -- HUNDREDS OF THOUSANDS OF DEGREES.
VISIBLE LIGHT -- TENS OF THOUSANDS OF DEGREES.
INFRARED -- HUNDREDS OF DEGREES.
SO, IF YOU WANT TO UNDERSTAND AN OBJECT,
YOU REALLY HAVE TO LOOK AT IT IN MANY, MANY DIFFERENT WAYS.
AN EXAMPLE OF MULTISPECTRAL IMAGINING IS
DISPLAYED IN THE NEXT TWO IMAGES THAT WILL BE COMING UP.
ON THE LEFT HERE IS A HUBBLE IMAGE OF CASSIOPEIA A.
IT'S THE RESULT OF A SUPERNOVA THAT HAPPENED A LONG TIME AGO.
SUPERNOVA OCCURRED HERE.
AND WHAT YOU'RE SEEING NOW IS THE LEFTOVERS OF THE SUPERNOVA
GLOWING AT ABOUT 10,000, 20,000 DEGREES.
AND UNTIL WE LAUNCHED X-RAY TELESCOPES,
THAT'S AS MUCH AS WE SAW.
THIS IS A CHANDRA IMAGE HERE ON THE RIGHT.
LET'S SEE -- YOUR RIGHT.
AND AS YOU CAN SEE,
THIS IS NOW SHOWING US MILLION-DEGREE GAS,
TENS-OF-MILLIONS-DEGREE GAS.
AND YOU CAN SEE THE VERY BIG DIFFERENCE IN STRUCTURE.
YOU LEARN UNIQUE THINGS BY LOOKING AT DIFFERENT WAVELENGTHS
AND A DIFFERENT TEMPERATURE OF OBJECTS.
IN THE EARLY 1980s,
THE GREAT OBSERVATORY PROGRAM WAS CREATED
BY DR. CHARLIE PELLERIN.
HE WAS A VISIONARY AT HEADQUARTERS WHO REALIZED IT
WOULD BE DIFFICULT TO SELL INDIVIDUAL FLAGSHIP MISSIONS
THAT COVERED THE WHOLE SPECTRUM FROM GAMMA RAY TO INFRARED,
SO HE CREATED A SCIENTIFICALLY DRIVEN PROGRAM
THAT INCLUDED THE ALREADY-FUNDED HUBBLE AND COMPTON MISSIONS
AND THE AXAF AND SIRTF MISSIONS THAT WERE UNDER STUDY.
HE WAS OBVIOUSLY SUCCESSFUL,
AND THE EARLY DISCOVERIES FROM THESE OBSERVATORIES
ALLOWED US TO LAUNCH FOLLOW-ON MISSIONS
THAT YOU'LL HEAR ABOUT TONIGHT,
SUCH AS FERMI, SWIFT,
AND NuSTAR,
TO NAME A FEW.
NOW, FOR THE REST OF THE EVENING,
WE'LL BE DESCRIBING THE PROGRESS
WE HAVE MADE OVER THE PAST 30 YEARS
IN TACKLING SOME OF THE QUESTIONS
I JUST DISCUSSED IN OUR VIOLENT UNIVERSE.
I HOPE THAT WE WILL CONVINCE YOU THAT THE LAST 30 YEARS --
THREE DECADES -- HAVE TRULY BEEN
AN AGE OF DISCOVERY AND AN ASTROPHYSICAL RENAISSANCE.
I WILL DISCUSS BRIEFLY THREE MAJOR BREAKTHROUGHS,
INCLUDING THE EXISTENCE OF SUPERMASSIVE BLACK HOLES,
THE NATURES OF QUASARS AND THEIR POWER SOURCE,
AND THE NATURE OF DIFFUSE X-RAY BACKGROUND.
JEREMY WILL FOLLOW ME WITH A MORE DETAILED LOOK
INTO THE NATURE OF BLACK HOLES.
FIONA WILL DISCUSS SUPERNOVA EXPLOSIONS AND THEIR AFTERMATH.
AND NEIL WILL CONCLUDE BY TELLING US HOW FAR
WE'VE COME IN UNDERSTANDING MYSTERIOUS GAMMA-RAY BURSTS.
FIRST, ONE OF THE MOST INTRIGUING MYSTERIES
OF ASTROPHYSICS,
ESPECIALLY BACK IN THE '70s AND '80s.
DO SUPERMASSIVE BLACK HOLES EXIST?
AND, UH, ACTUALLY, THAT QUESTION
CAME TO AN ABRUPT END IN 1994 WHEN SOME OF THE FIRST IMAGES
FROM THE REPAIRED HUBBLE TELESCOPE CAME BACK.
THIS IS THE GALAXY M87 HERE.
YOU SEE THE RADIO JET.
AND FOR THE FIRST TIME,
WE WERE ABLE TO IMAGE THE GAS --
HOT GAS GOING AROUND THE CENTRAL OBJECT.
AND WE WERE ABLE TO MEASURE THE VELOCITIES
WITH THE FAINT OBJECT SPECTROGRAPH.
AND LITERALLY USING HIGH-SCHOOL MATH,
YOU COULD DETERMINE -- KNOWING THE DISTANCE OF M87,
KNOWING THE VELOCITY OF THE GAS,
KNOWING THE SCALE OF THIS PICTURE --
YOU WERE ABLE TO VERY QUICKLY DISCOVER THAT,
WITHIN A VOLUME OF LESS THAN A SOLAR SYSTEM,
THERE WERE THREE BILLION TIMES THE MASS OF THE SUN.
EINSTEIN WAS RIGHT, BECAUSE NOTHING THAT DENSE
CAN BE ANYTHING BUT A BLACK HOLE.
THIS ONE OBSERVATION BASICALLY PUT TO AN END
THE DISCUSSION OF WHETHER BLACK HOLES EXISTED OR NOT.
OKAY.
OVER THE FOLLOWING YEARS, MORE DISCOVERIES WERE MADE
BY VARIOUS SPACE OBSERVATORIES THAT DEMONSTRATED
THAT NOT ONLY DID SUPERMASSIVE BLACK HOLES EXIST
BUT THEY MAY BE AT THE CORE OF EVERY GALAXY,
EVEN OUR OWN MILKY WAY.
HERE WE HAVE A BLACK HOLE GOING THROUGH SPACE.
AND AN UNSUSPECTING STAR.
BY THE WAY, THIS IS AN ARTIST'S RENDITION.
[ CHUCKLES ]
AN UNSUSPECTING STAR GETS A LITTLE TOO CLOSE,
GETS CAUGHT UP IN THE WEB OF GRAVITY,
STARTS GETTING TORN APART,
CREATES AN ACCRETION DISK OF HOT GAS AND DUST
ROTATING RAPIDLY AROUND THE BLACK HOLE.
BLACK HOLES -- CONTRARY TO POPULAR BELIEF,
THEY'RE NOT THE ULTIMATE ROACH MOTEL.
THEY DON'T EAT EVERYTHING.
THEY'RE VERY MESSY EATERS.
THEY EAT, AND THEY'RE VERY, VERY MESSY.
YOU'VE GOT TREMENDOUS MAGNETIC FIELDS
CREATED BY THE RAPIDLY ROTATING CHARGED PARTICLES HERE,
WHICH CREATE MAGNETIC FIELDS.
AND SOME OF THE MATTER THAT DOESN'T GET TRAPPED IN
GETS SHOT OUT IN JETS.
THIS IS -- THE CLOSER YOU GET TO A BLACK HOLE,
THE TEMPERATURES GET HOTTER AND HOTTER.
IF YOU REALLY WANT TO STUDY THE INNER PARTS
OF THE ACCRETION DISK, YOU HAVE TO LOOK IN THE GAMMA RAYS,
X-RAYS, 'CAUSE WE'RE TALKING ABOUT GAS
THAT'S 10 MILLION OR MORE DEGREES.
AND THE OUTER PORTIONS OF THE RING --
OF THE ACCRETION DISK ARE A LITTLE COOLER.
BUT WHAT WE DISCOVERED HERE
WAS THE ACTUAL POWER SOURCE OF QUASARS.
THIS IS WHAT POWERS QUASARS -- ACTIVELY EATING BLACK HOLES.
THE QUIESCENT QUASARS ARE QUIET EATERS,
NOT EATING TOO MUCH AT A TIME,
AND THE ACTIVE QUASARS THAT ARE HIGHLY VARIABLE
ARE PROBABLY CONSUMING AT A HIGH RATE.
NOW THE STAGE IS SET FOR THE NEXT MYSTERY.
ARE QUASARS THE HOMELESS CITIZENS OF OUR UNIVERSE
OR ARE THEY AN INTEGRAL PART OF SOME LARGER STRUCTURES?
MY FRIEND AND COLLEAGUE FROM PRINCETON,
WHEN I WAS AT PRINCETON, WAS JOHN BAHCALL,
AND HE WAS LOOKING FORWARD TO USING HUBBLE
BECAUSE HIS THEORY WAS THAT QUASARS WERE REALLY IN GALAXIES,
THAT QUASARS WEREN'T HOMELESS, SO TO SPEAK,
THAT THEY LIVED IN GALAXIES.
AND INDEED, WITH HUBBLE IMAGING CAPABILITY --
THIS IS A HUBBLE IMAGE.
THIS IS A RADIO JET COMING OUT OF THIS GALAXY.
AND ZOOMING IN ON THE CENTER OF THE GALAXY WITH HUBBLE,
WE SEE THE ACCRETION DISK
AND WE SEE WHAT LOOKS LIKE A BLACK HOLE.
SO, JOHN WAS RIGHT.
AND SUBSEQUENT OBSERVATIONS HAVE SHOWN THAT ALL QUASARS
SEEM TO HAVE A HOME IN SOME GALAXY, AT THEIR CENTER,
AND THAT THE POWER SOURCE IS PROBABLY
A SUPERMASSIVE BLACK HOLE.
THE LAST MYSTERY THAT I'LL BE ADDRESSING
IS THAT OF THE COSMIC SOFT X-RAY BACKGROUND.
BACK IN THE '80s -- THIS IS LOW RESOLUTION --
THE FIRST X-RAY SATELLITES SAW THIS FUZZ IN THE UNIVERSE --
LOW-ENERGY X-RAYS.
MY ANALOGY HERE IS IF YOU --
IF I GAVE ALL OF YOU A CANDLE
AND YOU HELD IT UP, RIGHT NOW,
I WOULDN'T SEE INDIVIDUAL LIGHTS.
I'D JUST SEE A FUZZ 'CAUSE MY GLASSES ARE OFF.
RIGHT?
IF I PUT MY GLASSES ON, 20/20 VISION,
SUDDENLY I'D SEE IT'S NOT A FUZZ.
IT'S ALL INDIVIDUAL CANDLES.
AND THAT'S EXACTLY WHAT HAPPENED HERE.
THE EARLY SATELLITES DIDN'T HAVE THE RESOLUTION.
THIS IS A CHANDRA IMAGE
THAT SHOWED THIS FUZZ WAS ACTUALLY CREATED BY THOUSANDS,
IF NOT HUNDREDS OF THOUSANDS OF POINT SOURCES.
IN FACT, THIS LITTLE AREA --
THESE FIVE OBJECTS HERE IN THE CHANDRA IMAGE
MATCH UP BEAUTIFULLY
WITH GALAXIES IN THE HUBBLE DEEP FIELD.
AS IT TURNS OUT, ABOUT 80% OF THIS BACKGROUND --
THESE INDIVIDUAL SOURCES -- TURN OUT TO BE QUASARS.
ANOTHER MYSTERY SOLVED.
NOW I'D LIKE TO WRAP UP BY GETTING A BIT PHILOSOPHICAL,
IF I COULD.
I'VE TALKED ABOUT SEVERAL LONG-STANDING MYSTERIES
THAT HAVE BEEN SOLVED OVER THE PAST 30 YEARS,
BUT THE UNIVERSE IS A VERY, VERY BIG PLACE.
THIS IS THE DEEPEST IMAGE OF THE SKY EVER OBTAINED --
THE HUBBLE ULTRA-DEEP FIELD.
THERE ARE OVER 10,000 GALAXIES IN THIS ONE IMAGE.
SOME OF THE GALAXIES ARE SO FAR AWAY THEY'RE ONLY BABIES
AS THEY APPEARED 13 BILLIONS YEARS AGO,
700 MILLION YEARS AFTER THE UNIVERSE WAS BORN.
YET THE IMAGE IS ONLY ONE-FORTY-MILLIONTH OF THE SKY.
IN OTHER WORDS, IT WOULD TAKE
40 MILLION HUBBLE ULTRA-DEEP FIELDS TO COVER
THE ENTIRE SKY.
IF YOU WANTED A HUMAN ANALOGY,
GO OUT ON A CLEAR NIGHT, GET A STANDARD SEWING NEEDLE,
HOLD IT UP AT ARM'S LENGTH
AND LOOK AT A HOLE IN THE SEWING NEEDLE.
THAT'S THE SIZE OF THE SKY YOU'RE SEEING PORTRAYED HERE.
SO, DESPITE ALL THE MYSTERIES WE HAVE SOLVED,
LET'S NOT GET TOO ARROGANT.
AS I SAID, THE HUBBLE IS --
I MEAN, THE UNIVERSE IS A VERY, VERY BIG PLACE,
AND THERE'S A WEE BIT OF WORK TO BE DONE.
IF THIS MAKES YOU FEEL SMALL, IT SHOULD.
WE HUMANS, AFTER ALL,
HAVE ONLY BEEN AROUND FOR ABOUT 100,000 YEARS
ON A PLANET THAT'S BEEN HERE FOR FOUR BILLION YEARS OR SO.
WE LIVE ON A SMALL ROCK CALLED THE EARTH,
WHICH ORBITS A ROUTINE STAR CALLED THE SUN.
AND THE SUN IS ONE OF HUNDREDS OF BILLIONS OF STARS
IN OUR GALAXY.
AND, SORRY, OUR GALAXY ISN'T REALLY SPECIAL.
IT'S JUST ONE OF HUNDREDS OF BILLIONS OF GALAXIES.
BUT BEFORE YOU GET TOO DEPRESSED,
ON THE POSITIVE SIDE,
WE MERE HUMANS, JUST IN THE PAST 30 YEARS,
HAVE BUILT SPACE OBSERVATORIES WHICH AN ENABLED OUR MINDS
AND OUR SPIRITS TO TRAVEL ANY PLACE IN THIS VAST UNIVERSE
AND EXPERIENCE SOME OF THE MOST VIOLENT PHENOMENA IMAGINABLE,
PLACES OUR PHYSICAL BODIES CAN NEVER GO.
AND NOW, SPEAKING ABOUT PLACES YOUR BODY SHOULD AVOID,
OUR NEXT SPEAKER, JEREMY, WILL TAKE US
ON A MUCH MORE DETAILED JOURNEY
THROUGH THE WORLD OF BLACK HOLES.
[ APPLAUSE ]
-THANK YOU, ED, FOR THAT WONDERFUL INTRODUCTION.
I'D LIKE TO JUST START WITH A PERSONAL REQUEST
TO ALL THE STUDENTS IN THE ROOM THAT WERE MENTIONED EARLIER.
IF YOU SEE ANYTHING OR HEAR ANYTHING
THAT PIQUES YOUR CURIOSITY IN MY TALK TONIGHT,
PLEASE, PLEASE, DON'T HESITATE -- LOOK UP MY E-MAIL.
I'M THE ONLY JEREMY SCHNITTMAN IN THE WORLD.
[ LAUGHTER ]
SEND ME AN E-MAIL AND ASK ME YOUR QUESTION.
I'D BE HAPPY TO TALK TO YOU MORE.
OR EVEN BETTER, NEXT TIME YOU'RE AT GODDARD,
JUST STOP BY MY OFFICE.
SO, AS ED MENTIONED,
I'M GOING TO TALK ABOUT BLACK HOLES TONIGHT.
SO, UH, LET'S START WITH THE BASICS.
WHAT EXACTLY IS A BLACK HOLE?
JUST LIKE SAURON IN HIS DARK TOWER...
[ LAUGHTER ]
BLACK HOLES ARE KNOWN FOR BEING TERRIFYING,
INVISIBLE SOURCES OF DEATH AND DESTRUCTION,
MUCH FEARED BUT LITTLE UNDERSTOOD,
FAR OFF IN THE LAND OF SHADOWS,
VEILED IN AN IMPENETRABLE CLOAK OF MYSTERY.
WELL, I'M AFRAID I'VE GOT SOME DISAPPOINTING NEWS FOR YOU.
BLACK HOLES ARE ACTUALLY BORING.
THERE IS LITERALLY NOTHING TO THEM.
NOW, THE COSMIC WEB OF GALAXIES IS INTRICATE AND BEAUTIFUL.
STARS ARE SOURCES OF TWINKLING WONDER.
PLANETS ARE GRACEFUL AND MAJESTIC.
BUT BLACK HOLES...
ARE BLACK.
LET'S ZOOM IN FOR A CLOSER LOOK, PLEASE.
[ LAUGHTER ]
YEP, STILL BORING.
IT'S REALLY ONLY WHEN WE ZOOM OUT
AND SEE THE BLACK HOLE IN THE CONTEXT
OF ITS SURROUNDING ENVIRONMENT DO WE BEGIN TO APPRECIATE
HOW THEY MIGHT NOT BE SO BORING AFTER ALL.
TRULY, IT'S THE STUFF
AROUND BLACK HOLES THAT MAKES THEM SO INTERESTING.
AND WHEN THIS STUFF IS GAS,
IT USUALLY FORMS SOMETHING CALLED AN ACCRETION DISK,
LIKE ED MENTIONED.
WHAT WE'RE WATCHING HERE IS AN ARTIST'S IMPRESSION
OF WHAT AN ACCRETION DISK WOULD LOOK LIKE CLOSE UP.
NOW, THAT IS BEAUTIFUL.
AND WHILE I ADMIT I AM CERTAINLY BIASED ON THE SUBJECT,
I CAN'T HELP BUT THINK THAT THE ASTROPHYSICIST'S IMPRESSION
OF AN ACCRETION DISK IS EVEN MORE BEAUTIFUL.
BLACK HOLES ARE SUCH POWERFUL GRAVITATIONAL MONSTERS
THAT THEY WARP AND TWIST
THE VERY FABRIC OF SPACE-TIME ITSELF AROUND THEM.
THEY CAN ACTUALLY BEND LIGHT,
LEADING TO IMAGES LIKE THIS OF AN ACCRETION DISK
SIMULTANEOUSLY VIEWED FROM ABOVE AND BELOW.
WE CAN EVEN SEE AN INNER RING CAUSED BY LIGHT
THAT GOES ALL THE WAY AROUND THE BLACK HOLE
BEFORE ESCAPING AND EVENTUALLY MAKING IT TO US.
I COULD WATCH THIS MOVIE FOR HOURS.
IT'S REALLY MORE -- IT'S MORE PEACEFUL THAN TERRIFYING.
AND THE TRUTH IS, JUST LIKE A VORTEX IN A POOL OF WATER,
BLACK HOLES REALLY AREN'T THAT DANGEROUS
UNLESS YOU GET EXTREMELY CLOSE TO THEM.
AND IN PRACTICE,
IT'S REALLY VERY DIFFICULT TO GET CLOSE TO A BLACK HOLE.
WHY? BECAUSE -- FOR THE SAME REASON
THAT PLANETS JUST GO 'ROUND AND 'ROUND THE SUN
WITHOUT EVER GETTING SUCKED IN --
BECAUSE OF ANGULAR MOMENTUM.
SO, GAS ORBITING AROUND A BLACK HOLE
CAN NEVER ACTUALLY REACH THE EVENT HORIZON
UNLESS IT FIRST SHEDS ITS ANGULAR MOMENTUM.
AND IT TURNS OUT THIS IS QUITE DIFFICULT TO DO
IF IT DOESN'T HAVE ANYTHING TO PUSH OFF OF.
IF YOU WERE A BLOB OF GAS ORBITING
AROUND A BLACK HOLE AT HALF THE SPEED OF LIGHT,
I MEAN, WHAT -- WHAT WOULD YOU PUSH OFF OF?
I SUGGEST WE COULD ACTUALLY LEARN FROM ROLLER DERBY.
THERE'S A MANEUVER CALLED THE WHIP.
AND THE SKATER ON THE INSIDE TRACK STARTS OFF
BY GOING FASTER, AND THEN SHE WHIPS HER PARTNER AROUND,
TRANSFERRING ANGULAR MOMENTUM OUTWARDS.
AFTERWARDS, THE INNER SKATER IS GOING SLOWER
AND, IF SHE WERE ORBITING A BLACK HOLE,
IS ONE STEP CLOSER TO GETTING SUCKED IN.
AROUND REAL BLACK HOLES,
MAGNETIC FIELDS TAKE THE ROLE OF THE WHIPPERS,
PULLING SOME GAS IN AND THROWING THE REST OUT INTO SPACE.
AGAIN, LIKE ED MENTIONED, THEY'RE MESSY EATERS.
IN THE ACCRETION DISK, THE GAS IS THREADED
WITH THIS COMPLEX, TURBULENT NETWORK OF MAGNETIC FIELDS
CONSTANTLY GETTING TWISTED AND WRAPPED AROUND
LIKE RUBBER BANDS.
AND JUST LIKE RUBBER BANDS, THESE MAGNETIC FIELDS
CAN STRETCH UNTIL THE POINT WHERE THEY SNAP,
RELEASING MASSIVE AMOUNTS OF ENERGY,
HEATING THE GAS TO MILLIONS OR EVEN BILLIONS OF DEGREES,
JUST LIKE IN THE CORONA OF OUR SUN.
NOW, THIS SUPER-HEATED GAS SHINES VERY BRIGHTLY IN X-RAYS,
WHICH IS EXACTLY WHY WE LIKE TO USE TELESCOPES
LIKE CHANDRA AND NuSTAR TO STUDY BLACK HOLES.
NOW, ACCRETION DISKS AREN'T THE ONLY WAY
THAT YOU CAN STUDY THE CURVED SPACE AROUND BLACK HOLES.
ONE OF THE REMARKABLE PREDICTIONS
OF EINSTEIN'S THEORY OF RELATIVITY IS
THAT SPACE-TIME IS NOT ONLY CURVED BUT IT'S ALSO TWISTED.
IN THIS COMPUTER SIMULATION
OF PARTICLES PLUNGING INTO A BLACK HOLE,
WE CAN SEE THIS EFFECT OF THE TWISTING OF SPACE TIME
MOST PROMINENTLY RIGHT
OUTSIDE OF THE EVENT HORIZON,
WHERE PARTICLES
ARE BEING SWEPT AROUND IN A COUNTERCLOCKWISE SWIRL
AT NEARLY THE SPEED OF LIGHT.
WE'RE WATCHING NATURE'S OWN PARTICLE COLLIDER
IN ACTION HERE --
A FURIOUS MAELSTROM GENERATING
HIGHER ENERGY PHOTONS CALLED GAMMA RAYS.
NOW, ALTOGETHER, THE PULLING, THE TWISTING, THE SLINGING,
THE WHIPPING OF GAS BY THE BLACK HOLE
LEADS TO TREMENDOUS HIGH-ENERGY PARTICLES AND RELATIVISTIC JETS,
BOTH OF WHICH CAN BE SEEN
WITH TELESCOPES THAT LOOK IN THE X-RAYS AND GAMMA RAYS.
AND TO CONCLUDE, I WOULD LIKE TO OBSERVE THAT THIS YEAR
DOES MARK THE 100th ANNIVERSARY OF EINSTEIN'S THEORY
OF GENERAL RELATIVITY.
AND WE'RE JUST BEGINNING TO START TO SCRATCH THE SURFACE
OF WHAT THIS REMARKABLE THEORY PREDICTS.
WE LOOK FORWARD TO THE NEXT 100 YEARS OF FINDING
AND CONQUERING THE BEASTS OF THE COSMOS.
AND NOW, TO TELL US EXACTLY HOW YOU FIND THESE BEASTS
AND TAME THEM WITH THE NuSTAR TELESCOPE IS
DR. FIONA HARRISON.
THANK YOU.
[ APPLAUSE ]
-OKAY. THANKS, JEREMY.
SO, I'M GONNA TELL YOU ABOUT DISCOVERIES
FROM THE NuSTAR MISSION,
WHICH IS THE FIRST REAL TELESCOPE
TO LOOK AT THE UNIVERSE IN HIGH-ENERGY,
OR BLUE, X-RAYS.
SO, VISIBLE LIGHT IS MADE UP OF A RAINBOW OF COLORS,
AND SO IS X-RAY LIGHT.
THIS IS A HUBBLE SPACE TELESCOPE IMAGE
OF THE NEARBY GALAXY MESSIER 82, SEEN IN BLACK AND WHITE.
WE GET MUCH MORE INFORMATION
WHEN WE LOOK AT ASTRONOMICAL OBJECTS IN DIFFERENT COLORS.
WE GET INFORMATION ABOUT HOW HOT, DUSTY,
AND ENERGETIC DIFFERENT REGIONS
ARE.
MAKING AN ANALOGY WITH THE VISIBLE PORTION
OF THE ELECTROMAGNETIC SPECTRUM,
BEFORE NuSTAR,
WE COULD ONLY MAKE CRISP PICTURES OF THE UNIVERSE
IN RED, ORANGE, AND YELLOW X-RAY LIGHT.
THIS IS WHAT M82 WOULD LOOK LIKE IF YOU COULD ONLY SEE IT
IN RED, ORANGE, AND YELLOW IN VISIBLE.
MOSTLY WHAT YOU'RE SEEING HERE IS DUSTY, WARM REGIONS.
WHEN YOU ADD THE BLUE TO M82,
THE BLUE HIGHLIGHTS HOT REGIONS
WHERE STARS ARE ACTIVELY FORMING.
SO, NuSTAR HAS ADDED BLUE,
INDIGO, AND VIOLET TO THE X-RAY PALETTE.
THIS IS BRINGING A RICHNESS TO OUR VIEW
OF THE ENERGETIC UNIVERSE THAT WE'VE NEVER HAD.
IT'S LIKE BEING AN ARTIST THAT HAS A FULL SET OF PAINTS
TO WORK WITH.
SO, HOW DID WE ADD THESE COLORS TO THE X-RAY BAND?
WELL, IT WAS BY MAKING A NEW KIND OF TELESCOPE
TO IMAGE BLUE X-RAYS,
GOING FROM A PINHOLE-CAMERA TECHNOLOGY
TO A REAL FOCUSING TELESCOPE.
NOW WE CAN PAINT THE HIGH-ENERGY X-RAY SKY IN ITS FULL GLORY.
USING THE SAME ENERGY OR COLOR X-RAYS
THAT YOUR DOCTOR AND DENTISTS USE TO X-RAY YOUR BODY,
NuSTAR OBSERVES SOME OF THE HOTTEST, DENSEST,
AND MOST ENERGETIC REGIONS IN THE UNIVERSE.
BECAUSE HIGH-ENERGY X-RAYS PROBE THROUGH YOUR SKIN,
THEY ALSO PROBE THROUGH DUST AND GAS IN THE UNIVERSE,
ILLUMINATING OBJECTS
THAT WOULD OTHERWISE BE HIDDEN FROM OUR VIEW.
BY EMPLOYING NEW TECHNOLOGIES DEVELOPED OVER MANY YEARS,
ON A SMALL MISSION,
NuSTAR IS MAKING IMAGES THAT ARE HUNDREDS OF TIMES
DEEPER AND CRISPER THAN PREVIOUS HIGH-ENERGY MISSIONS
THAT WERE 10 TIMES THE COST AND SIZE.
SO, NuSTAR IS A SMALL EXPLORER.
THIS IS THE SMALLEST SCALE STANDALONE ASTROPHYSICS MISSION
THAT NASA SUPPORTS,
AND SO IT HAS TO LAUNCH ON A SMALL ROCKET.
NuSTAR WAS ATTACHED TO THE BELLY OF AN L-1011 AIRCRAFT
AND LAUNCHED INTO SPACE ON A SMALL ROCKET CALLED A PEGASUS.
THERE'S NOT MUCH ROOM FOR THE PAYLOAD,
WHICH HAS TO BE A SMALL FRACTION OF THE LENGTH OF THE AIRPLANE,
SO THE PROBLEM HERE IS THAT X-RAY TELESCOPES
ARE INHERENTLY BIG,
USUALLY THE LENGTH OF A SCHOOL BUS.
THE WAY NuSTAR ACHIEVED SCHOOL-BUS LENGTH
WAS THE FOLLOWING.
NINE DAYS AFTER LAUNCH,
WE EXTENDED A TINKER-TOY-LIKE STRUCTURE
CONSISTING OF TENS OF THOUSANDS OF PIECE PARTS, PIECE BY PIECE,
LOCKING THEM ALL INTO PLACE
UNTIL, 24 MINUTES LATER,
WE HAD A STIFF TELESCOPE WITH WHICH TO VIEW THE HEAVENS.
MIND YOU, WE WERE NEVER ACTUALLY
ABLE TO DEPLOY THIS FULLY ASSEMBLED ON THE GROUND.
SO, WHEN THE MARS GUYS
TALK ABOUT THEIR SEVEN MINUTES OF TERROR --
THIS WAS MY 24 MINUTES OF TERROR.
BUT IT ALL WORKED PERFECTLY,
AND NuSTAR'S BEEN ON ORBIT,
MAKING UNPRECEDENTED IMAGES OF THE HIGH-ENERGY X-RAY SKIES
SINCE JUNE OF 2012.
SO, MAKING SUCH A HUGE OBSERVATIONAL LEAP
MEANS YOU'RE GONNA DISCOVER NEW AND EXCITING THINGS.
NuSTAR WAS ABLE TO MAKE THE VERY FIRST HIGH-QUALITY IMAGES
IN HIGH-ENERGY X-RAYS
OF THE REGION AROUND THE SUPERMASSIVE BLACK HOLE
THAT RESIDES IN THE HEART OF OUR OWN MILKY WAY GALAXY.
WHAT WE DISCOVERED WAS A SWARM OF DEAD STARS,
CREATING A HAZE AROUND THE SUPERMASSIVE BLACK HOLE.
THIS HAZE HAD NEVER BEEN SEEN BEFORE
BECAUSE WE DIDN'T HAVE HIGH ENOUGH RESOLUTION IMAGES
IN PENETRATING HIGH-ENERGY X-RAYS.
AS YOU CAN SEE, THE PRESS PICKED UP ON THIS
IN AN INTERESTING WAY. [ CLEARS THROAT ]
[ LAUGHTER ]
SO, WHAT I'M GONNA SPEND THE REST OF MY TIME
TELLING YOU ABOUT IS THE FUNDAMENTALLY NEW THINGS
THAT WE'RE LEARNING ABOUT THE PROCESSES
THAT CREATED THE PLACE
WE LIVE TODAY FROM THE SOUP OF HOT HYDROGEN AND HELIUM
THAT EXISTED SHORTLY AFTER THE UNIVERSE WAS BORN.
TODAY, 13.8 BILLION YEARS AFTER THE BIG BANG,
WE HAVE A RICH MIX OF CHEMICAL ELEMENTS,
RANGING FROM THE NITROGEN IN THE ATMOSPHERE,
THE CALCIUM IN YOUR BONES,
AND THE GOLD IN YOUR WEDDING RING.
THIS MOVIE FOLLOWS THE EVOLUTION OF THE UNIVERSE,
AS IMAGINED BY THEORISTS USING SUPERCOMPUTERS.
FILAMENTS OF HYDROGEN AND HELIUM FORM,
SHAPED BY THE GRAVITY OF DARK MATTER.
IN THESE FILAMENTS, CLOUDS OF DUST AND GAS CONDENSE
AND FORM STARS.
THE MASSIVE ONES BURN HYDROGEN AND HELIUM
TO PROGRESSIVELY HEAVIER ELEMENTS,
LIKE CARBON, NITROGEN, OXYGEN,
AND EVENTUALLY IRON.
AND FINALLY, THESE STARS RUN OUT OF NUCLEAR FUEL
AND EXPLODE IN DRAMATIC EVENTS CALLED SUPERNOVAE.
WHEN THE UNIVERSE IS OLDER,
SUPERNOVAE EXPLODE ALL OVER, AS YOU SEE IN THIS VIDEO,
MANUFACTURING ELEMENTS,
SPEWING THEM OUT INTO THE COSMOS,
WHERE THEY CAN CONDENSE INTO GALAXIES, STARS, PLANETS,
AND LIFE.
THIS MOVIE IS BASED ON SOME GOVERNING PRINCIPLES,
WHAT SCIENTISTS THINK IS REASONABLE,
BUT KEY COMPONENTS ARE LARGELY BASED ON THEORY.
HOW THIS ALL WORKS IN PRACTICE IS A DANCE --
A BACK AND FORTH BETWEEN THEORISTS
AND OBSERVERS WITH TELESCOPES, INCLUDING NASA's
PANCHROMATIC FLEET OF INFRARED, OPTICAL, X-RAY,
AND GAMMA-RAY MISSIONS.
SO, HOW STARS ACTUALLY EXPLODE IS A PROFOUND MYSTERY.
IT TURNS OUT TO BE REALLY HARD TO MAKE A STAR
THAT'S IMPLODING UNDER THE FORCE OF GRAVITY
TO EXPLODE AND EXPAND OUT INTO THE UNIVERSE.
STELLAR EXPLOSIONS HAVE A LOT OF SIMILARITIES TO ATOMIC BOMBS.
AND SIMILAR TO BOMBS, HUGE COMPUTATIONAL POWER
AND THEORETICAL RESOURCES HAVE GONE IN TO UNDERSTANDING THEM.
BUT IN A HUGE FAILURE OF THEORY,
MOST COMPUTERS CAN'T ACTUALLY MAKE A STAR EXPLODE.
WHAT YOU SEE HERE IS AN EXAMPLE.
THIS IS A NUMERICAL SIMULATION ON A COMPUTER
OF A STELLAR EXPLOSION.
WE CAN SEE HERE THAT THE EXPLOSION HALTS
UNTIL AN AD HOC MECHANISM --
HERE, THE SLOSHING AROUND OF THE CENTRAL PART OF THE STAR --
IS PUT IN BY THEORISTS TO MAKE THE STAR FLY APART.
THIS CAN MAKE THE STAR EXPLODE, BUT IS IT IMAGINATION
OR IS IT REALLY WHAT HAPPENS IN NATURE?
TO DECIDE THIS, WE NEED OBSERVATIONS.
SO, PREVIOUS LOW-ENERGY X-RAY TELESCOPES,
LIKE NASA's CHANDRA MISSION,
HAVE TAKEN PICTURES OF THE REMNANTS
OF SUPERNOVA EXPLOSIONS HUNDREDS TO THOUSANDS OF YEARS
AFTER THE EVENT.
AND LIKE CRIME-SCENE INVESTIGATORS
WHO LOOK AT THE SHRAPNEL AND OTHER DEBRIS
TO FIGURE OUT HOW AN EXPLOSION HAPPENED,
ASTRONOMICAL TELESCOPES PIECE TOGETHER THE WORKINGS
OF THE BOMB FROM WHAT'S LEFT OVER,
WHAT'S STILL VISIBLE LONG AFTER THE EVENT.
AND AS YOU SEE HERE, PREVIOUS X-RAY MISSIONS
HAVE BEEN ABLE TO LOOK AT THE HOT, GLOWING DEBRIS
OF THESE EXPLOSIONS,
BUT BECAUSE OF THE LIMITED RANGE OF COLORS,
THEY COULD NOT SEE WHAT THE HEART OF THE EXPLOSION
ACTUALLY LOOKS LIKE.
NuSTAR HAS PROVIDED A COMPLETELY NEW TOOL --
THE ABILITY TO LOOK AT THE RADIOACTIVE MATERIAL
CREATED IN THESE COSMIC BOMBS.
THE RADIOACTIVE EMBERS GLOW
AS ONE CHEMICAL ELEMENT CHANGES INTO ANOTHER.
HERE, TITANIUM IS CHANGING INTO CALCIUM.
ON COSMIC SCALES, IN ONLY GLOWS FOR A SHORT TIME --
A FEW HUNDRED YEARS --
BUT THE RESULTING RADIATION IS ONLY VISIBLE
IN THE HIGH-ENERGY X-RAYS.
AND SO NuSTAR CAN USE THESE TO DIAGNOSE THE NATURE
OF THE EXPLOSION.
HERE ARE IMAGES OF THE DEBRIS
FROM THE HISTORICAL SUPERNOVA REMNANT CASSIOPEIA A,
THAT ED SHOWED YOU BEFORE, IN DIFFERENT X-RAY COLORS,
SHOWING DIFFERENT ELEMENTS.
THE RED AND THE GREEN IMAGES
WERE MADE FROM THE LOW-ENERGY CHANDRA X-RAY TELESCOPE,
WHICH SEES THE UNIVERSE IN RED AND YELLOW AND GREEN COLORS.
NuSTAR HAS ADDED THE BLUE,
THE FIRST IMAGE IN RADIOACTIVITY.
THIS ENABLES US TO SEE THE VERY HEART OF THE EXPLOSION
FOR THE FIRST TIME,
AND YOU CAN SEE IT LOOKS QUITE DIFFERENT
THAN WHAT YOU SEE IN RED AND GREEN.
THIS NEW EVIDENCE IS TELLING US
THAT THE SHAPE OF THE EXPLOSION WAS BUBBLY,
LIKE WHAT YOU WOULD EXPECT OF THAT SLOSHING MECHANISM
THEORISTS PREDICTED REALLY HAPPENS IN LIFE.
THE CRIME-SCENE INVESTIGATORS HAVE DETERMINED
THAT THE SLOSHING AROUND OF THE CORE OF THIS STAR
WAS KEY TO MAKING IT EXPLODE.
SO, FILLING IN THE PIECES OF THIS COSMIC PUZZLE OF HOW
WE GET FROM AN AMORPHOUS SOUP TO WHERE WE ARE TODAY.
SO, HERE'S CASSIOPEIA A IN ITS PANCHROMATIC X-RAY GLORY.
WHAT MADE THIS STAR EXPLODE IS UNDERSTOOD FOR THE FIRST TIME
THANKS TO THE BROAD PALETTE OF X-RAY COLORS
FROM NASA's SUITE OF HIGH-ENERGY X-RAY MISSIONS.
AND NEXT, NEIL GEHRELS IS GONNA TELL YOU
ABOUT EXTREME AND UNUSUAL KINDS OF COSMIC EXPLOSIONS.
[ APPLAUSE ]
-THANK YOU, FIONA.
IT'S A PLEASURE TO BE HERE THIS EVENING
TO TALK TO YOU ABOUT SPECTACULAR EXPLOSIONS
CALLED GAMMA-RAY BURSTS AND THE BIRTH OF BLACK HOLES.
AND I'D LIKE TO START OUT WITH A COUPLE OF COOL MOVIES
THAT WE PUT TOGETHER,
THE FIRST ONE BEING AN ATOMIC BOMB EXPLOSION
THAT FIONA MENTIONED.
SO, AN H-BOMB IS THE MOST POWERFUL
AND DESTRUCTIVE EXPLOSION THAT WE HAVE HERE ON THE EARTH.
[ RUMBLING ]
THESE EXPLOSIONS PALE IN COMPARISON
TO THAT OF AN EXPLODING STAR.
THIS IS A GAMMA-RAY BURST WITH THE ENERGY EQUIVALENT
OF 1 TO THE POWER OF 30 H-BOMBS.
THAT'S 1 WITH 30 ZEROES AFTER IT.
GAMMA-RAY BURST IS A RARE TYPE OF SUPERNOVA EXPLOSION
IN WHICH A BLACK HOLE FORMS AT THE CENTER.
AND THEY'RE THE MOST ENERGETIC EXPLOSIONS IN THE UNIVERSE.
I'D LIKE TO TELL YOU ABOUT THE HISTORY OF GAMMA-RAY BURSTS.
THEY WERE FIRST DISCOVERED BY THE VELA SATELLITES,
BUILT AT LOS ALAMOS NATIONAL LABORATORIES.
THE VELAS WERE DESIGNED TO MONITOR THE TEST BAN TREATY
THAT THE U.S. SIGNED WITH THE SOVIET UNION
TO PROHIBIT EXPLOSIONS IN OUTER SPACE.
THEY ACTUALLY DISCOVERED FLASHES OF GAMMA RAYS.
THE FIRST ONE OCCURRED IN 1967.
BUT LUCKILY, IT WAS NOT A NUCLEAR WEAPON.
IT WAS THE DISCOVERY OF GAMMA RAY BURSTS.
SO, GAMMA-RAY BURSTS ARE EXPLOSIONS
THAT ARE BRIGHT FLASHES OF X-RAYS AND GAMMA RAYS.
THEY OCCUR ABOUT ONCE PER DAY
AND SPREAD OUT UNIFORMLY ACROSS THE SKY.
IN THE EARLY DAYS,
THERE WAS NO UNDERSTANDING OF WHAT COULD CAUSE THESE EVENTS.
IN FACT, I REMEMBER A TIME WHEN THERE WERE MORE THEORIES --
PUBLISHED THEORIES --
OF WHAT COULD CAUSE A GAMMA-RAY BURST
THAN THERE WERE GAMMA-RAY BURSTS DETECTED.
THIS IS ONE OF MY FAVORITE ONES ON THE NEXT SLIDE,
WHICH WERE ALIENS IN OUTER SPACE.
THIS WAS AN ACTUAL NEWSPAPER ARTICLE.
ALIEN WARS.
IN 1998,
AN ITALIAN AND DUTCH SATELLITE
MADE AN IMPORTANT DISCOVERY --
THAT GAMMA-RAY BURSTS WERE NOT OCCURRING NEAR THE SOLAR SYSTEM
OR EVEN IN OUR OWN GALAXY,
BUT WERE OCCURRING IN DISTANT, FAR-AWAY GALAXIES.
SO, THEY'RE EXTREMELY BRIGHT EVENTS --
THE BRIGHTEST EVENTS WE KNOW OF IN THE SKY
IN THE GAMMA-RAY BAND.
BUT THEY'RE OCCURRING FAR AWAY.
SO, THAT MEANS THAT THEY'RE INCREDIBLY POWERFUL EXPLOSIONS.
THIS IS AN HST IMAGE.
YOU CAN SEE THE GAMMA-RAY BURST IS THE WHITE LIGHT
AND THE FUZZ IS THE GALAXY IN THE DISTANCE.
AND SO, THIS WAS REALLY PROOF
THAT THE GAMMA-RAY BURSTS WERE OCCURRING IN DISTANT GALAXIES.
IN THAT SAME YEAR, IN 1998,
I PUT TOGETHER A TEAM OF SCIENTISTS
TO PROPOSE A MISSION CALLED SWIFT.
AND WE PROPOSED THIS MISSION TO THE NASA EXPLORER PROGRAM,
WHICH HAS OPPORTUNITIES EVERY COUPLE OF YEARS.
THERE WERE 40 PROPOSALS SUBMITTED.
EACH ONE IS A PRETTY THICK DOCUMENT.
I STILL HAVE THE SWIFT PROPOSAL IN MY OFFICE.
AND WE WERE LUCKY ENOUGH TO BE SELECTED.
SO, WITH A TEAM OF NASA, UNIVERSITY,
AND INDUSTRY PARTNERS,
WE BUILD THIS MISSION IN A VERY FAST TIME --
ABOUT FOUR YEARS FROM THE TIME
WE STARTED WORKING ON IT UNTIL WE LAUNCHED IT.
IT WAS LAUNCHED IN 2004,
AND IT'S BEEN WORKING SPLENDIDLY SINCE THAT TIME,
EVEN AS WE SPEAK TONIGHT.
SWIFT IS A STATE-OF-THE-ART OBSERVATORY PUSHING
THE FRONTIERS OF ASTROPHYSICS IN MANY DIFFERENT WAYS.
YOU SEE ON THIS SLIDE HERE
AN ULTRAVIOLET IMAGE WE TOOK WITH OUR ULTRAVIOLET TELESCOPE
ON BOARD OF THE NEARBY GALAXY CALLED THE LMC.
IT'S A BEAUTIFUL PICTURE.
BUT I'D LIKE TO GET BACK TO GAMMA-RAY BURSTS.
AS OF TODAY, WE'VE DETECTED 991 BURSTS,
AND WE'LL CELEBRATE DETECTING 1,000 BURSTS
IN THE NEXT COUPLE OF WEEKS.
WE'VE SIMULATED WHAT THAT LOOKS LIKE ON THIS ANIMATION
OF THE SKY.
EACH BURST IS A FLASH OF LIGHT.
AND IT'S SHOWN ON THE BACKGROUND OF THE BEAUTIFUL IMAGE
OF THE GAMMA-RAY SKY FROM THE FERMI SATELLITE.
EVERY TIME THAT SWIFT OR FERMI DETECTS A GAMMA-RAY BURST,
WE'RE PAGED ON OUR CELLPHONES.
AND SCIENTISTS GET THE PAGE, AND THEY GO RUNNING
TO THEIR COMPUTERS TO SEE WHAT THE UNIVERSE HAS SENT US
AND WHAT WE CAN LEARN ABOUT THE UNIVERSE.
AND I WAS AT A RECENT GAMMA-RAY BURST CONFERENCE
WHEN A BURST WENT OFF,
AND YOU COULD SEE PEOPLE IN THE AUDIENCE SLOWLY FILTERING OUT.
AND THEN, AT SOME POINT, THE SPEAKER LEFT, SO...
[ LAUGHTER ] YEAH.
YOU KNOW, THIS WAS AN EVENT THAT EVERYBODY WANTED TO LOOK AT.
ONE OF THE THINGS WE'RE LEARNING FROM SWIFT AND FERMI
IS WHAT'S CAUSING GAMMA-RAY BURSTS.
WHEN A STAR EXPLODES,
ITS CORE COLLAPSES TO A BLACK HOLE,
AND THE GAS IN THE REGION AROUND IT IN THIS GALAXY
FLOWS ONTO THE BLACK HOLE AND DISAPPEARS FOREVER,
AS WE HEARD FROM JEREMY SCHNITTMAN.
BUT A SMALL FRACTION OF IT GETS ENERGIZED AND ESCAPES IN JETS.
WE SAW BEAUTIFUL IMAGES FROM HST THAT ED SHOWED US.
AND THESE JETS ARE WHAT CAUSE GAMMA-RAY BURSTS.
IT'S WHEN THE JET IS AIMED AT US THAT WE SEE A BURST.
ANOTHER IMPORTANT DISCOVERY
COMES FROM USING GAMMA-RAY BURSTS AS DISTANT BEACONS.
THEY'RE SO BRIGHT WE CAN SEE STARS --
YOU KNOW, THEY'RE THE EVIDENCE OF STARS OCCURRING
IN THE VERY EARLY UNIVERSE.
IT'S REALLY THE ONLY WAY WE CAN DETECT EARLY STARS EXPLODING.
AND WE CAN USE GAMMA-RAY BURSTS AS TRACERS
TO SEE HOW MANY SUPERNOVAE WERE OCCURRING
IN THIS EARLY PART OF THE UNIVERSE
AND HOW MANY STARS WERE BEING FORMED.
THESE EXPLOSIONS SPEW MATERIAL OUT INTO SPACE AROUND THEM,
AND FROM THEM, NEW STARS AND NEW ELEMENTS ARE MADE.
AND THEY'RE SPEWED OUT INTO SPACE.
GENERATION BY GENERATION, THE ABUNDANCE OF ELEMENTS
EVOLVES UNTIL WE END UP WITH THE MIX
THAT WE HAVE IN OUR SOLAR SYSTEM
AND THAT OUR BODIES ARE MADE OF.
WE'RE ALSO LEARNING ABOUT THE EFFECTS
OF GAMMA-RAY BURSTS ON LIFE IN THE UNIVERSE.
THEY'RE SO INTENSE THAT THEY AFFECT
AND DESTROY THE ATMOSPHERE ON PLANETS THAT ARE NEARBY.
LUCKILY FOR US, THIS IS AN EXTREMELY RARE PROCESS,
AND SO THE CHANCE OF THAT HAPPENING IS INFINITESIMAL --
YOU KNOW, IT'S MUCH LESS PROBABLE
THAN AN ASTEROID CAUSING AN EXTINCTION ON THE EARTH --
IN THE CURRENT ERA.
BUT IF WE GO BACK SEVERAL BILLION YEARS AGO,
SORT OF IN THE MIDDLE AGE OF THE UNIVERSE,
THE MATERIAL IS MUCH CLOSER TOGETHER,
AND GAMMA-RAY BURSTS WERE A MAJOR FORCE IN PREVENTING LIFE
FROM FORMING THROUGH MUCH OF THE HISTORY OF THE UNIVERSE.
SO, ON THAT CHEERY NOTE,
I'M GONNA END MY TALK ABOUT GAMMA-RAY BURSTS,
AND WE'LL TURN OVER TO JOAN CENTRELLA,
WHO WILL GIVE US CLOSING REMARKS.
THANK YOU.
[ APPLAUSE ]
[ INSECTS CHIRPING ]
-THANK YOU, NEIL.
[ OWL HOOTING ]
IT IS A DARK, QUIET NIGHT.
YOU LOOK UP AND SEE OVERHEARD THE MILKY WAY SPREADING
ACROSS THE NIGHT SKY.
SURVEYING THE BEAUTY AND GRANDEUR
OF JUST THIS ONE PORTION OF OUR OWN GALAXY,
YOU ARE MOVED TO ASK SOME VERY IMPORTANT
AND VERY DEEP QUESTIONS.
WHAT IS THIS MARVELOUS UNIVERSE?
HOW BIG IS IT?
WHAT MAKES IT TICK?
HOW DID ALL THIS COME TO BE?
ARE WE ALONE IN THIS VAST COSMOS?
OR ARE THERE OTHER PLANETS THAT HAVE LIFE, AS WELL?
AND HOW DO WE FIT IN TO ALL OF THIS?
ASTROPHYSICS, THE STUDY OF THE UNIVERSE
AND HOW IT WORKS, HELPS US TO PROBE FOR ANSWERS.
AS WE'VE HEARD TONIGHT,
THE BEAUTIFUL AND MAJESTIC NIGHT SKY
THAT WE SEE LOOKING OUT FROM THE SURFACE OF THE EARTH
IS JUST THE BEGINNING.
MUCH OF THE STORY CAN ONLY BE LEARNED USING INSTRUMENTS
THAT ARE NOT SUBJECT TO THE LIMITATIONS
IMPOSED BY OUR ATMOSPHERE.
AND SO WE GO OUT INTO SPACE WITH NASA's ASTROPHYSICS MISSIONS,
SUCH AS FERMI, NuSTAR,
AND SWIFT.
THESE HIGH-ENERGY MISSIONS UNCOVER A DYNAMIC UNIVERSE,
ONE DRAMATICALLY DIFFERENT FROM THE TRANQUIL TAPESTRY
WE SEE ABOVE ON A NIGHT SKY FROM EARTH.
BY OBSERVING COSMIC GAMMA RAYS AND X-RAYS, THESE MISSIONS
REVEAL THAT THE COLD, DARK REACHES OF SPACE
AND PUNCTUATED BY TURBULENT FORCES --
BLACK HOLES, BURSTS OF RADIATION,
COSMIC EXPLOSIONS.
TONIGHT, YOU HAVE SEEN AND HEARD
ABOUT SOME OF THESE EXOTIC EVENTS.
YOU HAVE ENCOUNTERED THE MOST POWERFUL COSMIC EXPLOSIONS
AND THE INFINITE DEPTHS OF BLACK HOLES.
YOU'VE LEARNED THAT THE ELEMENTS
THAT MAKE UP OUR BODIES --
THE CALCIUM IN OUR BONES,
THE IRON IN OUR BLOOD --
THESE ELEMENTS ARE PRODUCED IN THE FIERY FURNACES OF STARS
AND HURLED OUT INTO THE COSMOS THROUGH GIGANTIC EXPLOSIONS.
THESE AND OTHER DYNAMIC PHENOMENA HAVE TAUGHT US
THAT VIOLENT ENERGY IS VERY MUCH A PART OF THE UNIVERSE.
SO, WHEN WE GO OUTSIDE ON A CLEAR NIGHT,
WE LOOK UP AND ASK OURSELVES THE GREAT QUESTIONS OF THE COSMOS.
AND WE KNOW THAT WHAT WE SEE WITH OUR EYES
IS JUST THE BEGINNING OF A MARVELOUS STORY --
A STORY THAT IS STILL UNFOLDING, FAR FROM FINISHED,
AND EVER MORE EXCITING AS WE EXPLORE AND OBSERVE,
QUESTION AND REFLECT,
DISCOVER AND LEARN.
THANK YOU ALL FOR COMING WITH US
ON THIS MARVELOUS JOURNEY, AND GOOD NIGHT.
[ APPLAUSE ]