♪♪
Narrator: IN 1998,
A YOUNG SCIENTIST
NAMED SAUL PERLMUTTER
WAS THINKING
SOME VERY BIG THOUGHTS, INDEED.
Perlmutter: THE QUESTION
THAT'S BEEN REALLY EXCITING ME
IS WHETHER THE UNIVERSE
WILL LAST FOREVER.
DO WE LIVE IN A UNIVERSE
THAT IS INFINITE,
OR IT WILL SOMEDAY
COME TO AN END?
THE TWO BIG OPTIONS AT THAT TIME
WERE THAT THE UNIVERSE
COULD EXPAND FOREVER,
BUT JUST SLOW AND SLOW AND SLOW,
BUT FOREVER BE EXPANDING,
OR, IF THERE WAS ENOUGH STUFF
IN THE UNIVERSE
TO GRAVITATIONALLY ATTRACT IT,
IT COULD SLOW TO A HALT
AND THEN COLLAPSE
AND COME TO AN END.
Narrator:
PERLMUTTER WAS MEASURING
THE WAY THE UNIVERSE
WAS EXPANDING
BY OBSERVING EXPLODING STARS
CALLED SUPERNOVAE.
ONE PARTICULAR KIND OF SUPERNOVA
ALWAYS EXPLODES THE SAME WAY
BECAUSE IT WAITS UNTIL
JUST A CRITICAL AMOUNT OF MASS
HAS FALLEN ON IT,
AND THEN IT EXPLODES.
SO, THEY ALL LOOK VERY SIMILAR
TO EACH OTHER.
THEY BRIGHTEN AS A FIREWORK,
THEN FADE AWAY,
AND THEY REACH
THE SAME BRIGHTNESS.
AND YOU CAN THEN USE THAT AS AN
INDICATOR OF HOW FAR AWAY IT IS
BY JUST LOOKING TO SEE
HOW BRIGHT IT APPEARS TO YOU.
Narrator: EVENTUALLY,
AFTER THE TEAM HAD IDENTIFIED
42 SUCH DYING STARS,
THE CALCULATIONS BEGAN.
WHAT PERLMUTTER DISCOVERED
SHOCKED HIM.
THE DATA WAS TELLING
THE WRONG STORY.
THE UNIVERSE DIDN'T APPEAR
TO BE SLOWING DOWN.
WE THOUGHT THAT
THAT'S WHAT WE WOULD SEE,
AND IT LOOKED LIKE
THE OPPOSITE WAS TAKING PLACE,
THAT, IN FACT, THE UNIVERSE WAS
SPEEDING UP IN ITS EXPANSION.
THESE DISTANT SUPERNOVA
WERE FAINTER
THAN YOU WOULD HAVE THOUGHT,
AND VERY SIGNIFICANTLY FAINTER.
THEY WERE, YOU KNOW,
PROBABLY 20% OR MORE,
AND THAT'S THE HALLMARK
OF A UNIVERSE
THAT'S ACTUALLY SPEEDING UP
IN ITS EXPANSION.
Narrator: ON THE ONE HAND,
THIS WAS A GOOD RESULT.
IT WAS NEW SCIENCE
AND PRODUCED A NOBEL PRIZE
FOR SAUL PERLMUTTER.
ON THE OTHER,
IT RAISED AN OBVIOUS QUESTION.
ONCE YOU KNOW THAT THE UNIVERSE
IS ACTUALLY SPEEDING UP,
THEN YOU'RE FACED
WITH THE QUESTION OF,
"WELL, WHAT COULD MAKE IT
SPEED UP?"
Narrator: SO FAR, THE ONLY
REAL PROGRESS ON THAT QUESTION
HAS BEEN TO GIVE THE PHENOMENON
A NAME.
IT'S BECOME KNOWN AS
DARK ENERGY.
DARK ENERGY IS JUST THE TERM WE
USE TO DESCRIBE WHATEVER IT IS
THAT MAKES THE UNIVERSE
ACCELERATE IN ITS EXPANSION.
WHAT MAKES IT EXPAND
FASTER AND FASTER?
WE DON'T KNOW WHAT THAT IS.
IT'S A MYSTERY.
AND, SO, WE CALL IT "DARK"
TO REFLECT OUR IGNORANCE,
NOT BECAUSE THE COLOR IS DARK.
