1 00:00:02,800 --> 00:00:05,367 Narrator: THE UNIVERSE WAS BORN TO DIE. 2 00:00:05,367 --> 00:00:09,767 BUT HOW AND WHEN WILL IT ALL END? 3 00:00:09,767 --> 00:00:11,600 THAT'S THE REASON I BECAME A COSMOLOGIST. 4 00:00:11,600 --> 00:00:13,333 I WANTED TO BE THE FIRST PERSON THAT WOULD KNOW 5 00:00:13,333 --> 00:00:15,300 HOW THE UNIVERSE WOULD END. 6 00:00:15,300 --> 00:00:19,067 TWO COSMIC HEAVYWEIGHTS WRESTLE FOR CONTROL. 7 00:00:19,067 --> 00:00:21,567 THE WINNER SEALS OUR FATE. 8 00:00:21,567 --> 00:00:24,367 THE TUG OF WAR IS GRAVITY, 9 00:00:24,367 --> 00:00:26,033 WHICH IS TRYING TO SHRINK IT DOWN, 10 00:00:26,033 --> 00:00:28,833 AND THE EXPANSION OF SPACE AND TIME ITSELF. 11 00:00:28,833 --> 00:00:31,167 WILL GRAVITY TRIUMPH? 12 00:00:31,167 --> 00:00:34,333 THE UNIVERSE WILL GET SMALLER AND SMALLER, HOTTER AND HOTTER. 13 00:00:34,333 --> 00:00:37,333 Narrator: OR WILL EXPANSION GET THE UPPER HAND? 14 00:00:37,333 --> 00:00:41,300 EVEN THE ELECTRONS AROUND YOUR ATOMS WILL BE RIPPED APART. 15 00:00:41,300 --> 00:00:42,767 Narrator: THE END IS COMING, 16 00:00:42,767 --> 00:00:46,300 AND IT COULD BE SOONER THAN YOU THINK. 17 00:00:50,600 --> 00:00:53,600 -- Captions by VITAC -- www.vitac.com 18 00:00:53,600 --> 00:00:56,633 CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS 19 00:01:01,133 --> 00:01:04,200 Narrator: THE UNIVERSE IS EVERYTHING -- 20 00:01:04,200 --> 00:01:07,900 ALL SPACE, ALL TIME, ALL MATTER. 21 00:01:10,767 --> 00:01:13,733 THE EARTH IS A SPECK BY COMPARISON, 22 00:01:13,733 --> 00:01:18,300 A GRAIN OF ROCK ORBITING JUST ONE OF THE 200 BILLION STARS 23 00:01:18,300 --> 00:01:21,367 IN OUR HOME GALAXY, THE MILKY WAY. 24 00:01:24,667 --> 00:01:28,467 IN TURN, THIS ENORMOUS STRUCTURE IS JUST A DROP 25 00:01:28,467 --> 00:01:31,067 IN AN OCEAN OF GALAXIES THAT STRETCH 26 00:01:31,067 --> 00:01:33,600 FOR 90 BILLION LIGHT YEARS. 27 00:01:35,700 --> 00:01:37,800 AND ALL OF THIS, 28 00:01:37,800 --> 00:01:41,967 FROM THE BIGGEST GALAXY TO THE SMALLEST ATOM, 29 00:01:41,967 --> 00:01:44,167 WILL ONE DAY DIE. 30 00:01:46,067 --> 00:01:48,400 WE DON'T SEE EVIDENCE OF ANYTHING BEING ETERNAL. 31 00:01:48,400 --> 00:01:50,100 ETERNITY DOESN'T EXIST. 32 00:01:50,100 --> 00:01:52,367 EVEN SPACE AND TIME WILL COME TO AN END. 33 00:01:54,600 --> 00:01:58,533 Narrator: THE UNIVERSE HAS BEEN EXPANDING SINCE ITS BIRTH, 34 00:01:58,533 --> 00:02:02,767 GRADUALLY BURNING THROUGH THE FUEL THAT LIGHTS ITS STARS. 35 00:02:02,767 --> 00:02:05,767 BUT WHAT HAPPENS WHEN THE FUEL RUNS OUT? 36 00:02:05,767 --> 00:02:08,267 WILL IT ALL JUST FADE AWAY? 37 00:02:08,267 --> 00:02:10,667 STARS DIE OUT, USE UP THEIR NUCLEAR FUEL. 38 00:02:10,667 --> 00:02:13,267 WE HAVE AN EMPTY, COLD, DESOLATE UNIVERSE. 39 00:02:13,267 --> 00:02:15,333 Thaller: JUST DEAD REMNANTS OF STARS -- 40 00:02:15,333 --> 00:02:17,433 BLACK HOLES, NEUTRON STARS. 41 00:02:17,433 --> 00:02:18,967 EVENTUALLY, THEY DECAY AWAY, 42 00:02:18,967 --> 00:02:21,900 AND YOU'RE LEFT WITH A THIN HAZE OF VERY LOW ENERGY LIGHT. 43 00:02:21,900 --> 00:02:23,233 THAT'S IT. 44 00:02:23,233 --> 00:02:25,067 Narrator: WE USED TO THINK THE UNIVERSE 45 00:02:25,067 --> 00:02:27,767 WOULD CRUISE GENTLY INTO OLD AGE. 46 00:02:27,767 --> 00:02:29,867 BUT OVER THE PAST FEW DECADES, 47 00:02:29,867 --> 00:02:33,333 ASTRONOMERS HAVE REVEALED A VERY DIFFERENT 48 00:02:33,333 --> 00:02:35,100 AND DISTURBING PICTURE. 49 00:02:35,100 --> 00:02:38,067 THE UNIVERSE ISN'T CRUISING. 50 00:02:38,067 --> 00:02:39,867 IT'S FIGHTING FOR ITS LIFE. 51 00:02:39,867 --> 00:02:42,133 IT MAY SEEM PEACEFUL HERE ON EARTH ON A NICE, SUNNY DAY, 52 00:02:42,133 --> 00:02:43,967 BUT IN FACT, ABOVE US AND ALL AROUND US, 53 00:02:43,967 --> 00:02:47,100 THROUGHOUT THE UNIVERSE, A BATTLE IS RAGING, 54 00:02:47,100 --> 00:02:49,133 AND IT HAS RAGED SINCE THE BEGINNING OF TIME. 55 00:02:51,400 --> 00:02:54,967 Narrator: TWO DEADLY FORCES GRAPPLE FOR CONTROL. 56 00:02:54,967 --> 00:02:59,500 THE FIRST, EXPANSION, PULLS GALAXIES APART, 57 00:02:59,500 --> 00:03:02,600 COOLING THE UNIVERSE AND THREATENING IT 58 00:03:02,600 --> 00:03:05,667 WITH A FROZEN EXTINCTION. 59 00:03:05,667 --> 00:03:10,200 THE SECOND, GRAVITY, TRIES TO CRUSH EVERYTHING BACK TOGETHER, 60 00:03:10,200 --> 00:03:14,067 ANNIHILATING THE UNIVERSE IN A DENSE BALL OF FIRE. 61 00:03:14,067 --> 00:03:16,600 [ RUMBLING ] 62 00:03:16,600 --> 00:03:20,200 WILL GRAVITY OR EXPANSION WIN? 63 00:03:20,200 --> 00:03:22,233 OR WILL IT END IN A TIE? 64 00:03:22,233 --> 00:03:26,067 THESE TWO COLOSSAL FORCES YIELD THREE ENDGAMES. 65 00:03:27,233 --> 00:03:29,300 Oluseyi: ONE IS THE BIG FREEZE. 66 00:03:29,300 --> 00:03:32,267 EXPANSION WINS, AND THE UNIVERSE JUST EXPANDS FOREVER. 67 00:03:32,267 --> 00:03:34,867 THE SECOND IS THAT THERE IS A DELICATE BALANCE 68 00:03:34,867 --> 00:03:36,133 BETWEEN THE EXPANSION 69 00:03:36,133 --> 00:03:37,800 AND THE AMOUNT OF GRAVITATIONAL ATTRACTION, 70 00:03:37,800 --> 00:03:39,900 AND THE UNIVERSE GETS TO A PARTICULAR SIZE, 71 00:03:39,900 --> 00:03:41,367 AND IT PRETTY MUCH STAYS THERE. 72 00:03:41,367 --> 00:03:43,067 AND THE THIRD OUTCOME IS THAT 73 00:03:43,067 --> 00:03:44,867 THE GRAVITATIONAL ATTRACTION WINS, 74 00:03:44,867 --> 00:03:46,500 AND THE EXPANSION STOPS, 75 00:03:46,500 --> 00:03:48,233 AND THE UNIVERSE BEGINS TO GET SMALLER 76 00:03:48,233 --> 00:03:51,400 UNTIL, EVENTUALLY, IT GOES BACK TO A BIG CRUNCH. 77 00:03:54,500 --> 00:03:56,833 Narrator: SO FAR, THE UNIVERSE SEEMS BALANCED 78 00:03:56,833 --> 00:04:00,833 ON A TIGHTROPE BETWEEN EXPANSION AND CONTRACTION. 79 00:04:00,833 --> 00:04:04,233 BUT WILL IT KEEP ITS EQUILIBRIUM UNTIL IT RUNS OUT OF STEAM, 80 00:04:04,233 --> 00:04:07,067 OR WILL SOMETHING TIP THE BALANCE? 81 00:04:09,067 --> 00:04:12,067 I DON'T THINK THERE'S ANY BIGGER QUESTION THAN, 82 00:04:12,067 --> 00:04:14,233 WHERE IS THE UNIVERSE GOING? 83 00:04:14,233 --> 00:04:17,767 Narrator: TO PREDICT THE FUTURE, COSMOLOGISTS HAVE ALWAYS LOOKED 84 00:04:17,767 --> 00:04:21,967 TO THE PAST, BACK TO THE BEGINNING OF EXPANSION, 85 00:04:21,967 --> 00:04:26,733 THE BEGINNING OF GRAVITY, THE BEGINNING OF EVERYTHING. 86 00:04:29,333 --> 00:04:34,300 13.8 BILLION YEARS AGO, AN INFINITELY DENSE, 87 00:04:34,300 --> 00:04:39,067 HOT SPECK IGNITES AND SUDDENLY EXPANDS OUTWARD -- 88 00:04:39,067 --> 00:04:41,067 THE BIG BANG. 89 00:04:43,333 --> 00:04:46,900 ALL ENERGY, ALL SPACE, AND ALL MATTER... 90 00:04:46,900 --> 00:04:48,633 [ RUMBLING ] 91 00:04:48,633 --> 00:04:51,667 ...THE BUILDING BLOCKS OF THE UNIVERSE WE SEE TODAY, 92 00:04:51,667 --> 00:04:54,133 ARE CREATED AND SET IN MOTION. 93 00:04:56,433 --> 00:04:58,667 Kaku: THINK OF IT. 94 00:04:58,667 --> 00:05:01,067 EVERYTHING YOU SEE AROUND US 95 00:05:01,067 --> 00:05:05,667 CONCENTRATED INTO A PRIMORDIAL FIREBALL THAT EXPLODED, 96 00:05:05,667 --> 00:05:08,467 SENDING ALL THE GALAXIES INTO MOTION. 97 00:05:12,533 --> 00:05:16,200 Narrator: THAT OUTWARD BLAST, THE BIRTH OF EXPANSION, 98 00:05:16,200 --> 00:05:18,867 IS STILL GOING ON TODAY. 99 00:05:18,867 --> 00:05:22,267 WITHOUT IT, WE WOULDN'T HAVE A UNIVERSE BIG ENOUGH 100 00:05:22,267 --> 00:05:25,067 FOR STARS AND GALAXIES TO EXIST IN. 101 00:05:25,067 --> 00:05:28,333 EXPANSION IS AN ASTONISHING FORCE OF NATURE. 102 00:05:28,333 --> 00:05:32,633 IT WORKS BY INFLATING THE FABRIC OF SPACE-TIME. 103 00:05:32,633 --> 00:05:36,300 Kaku: SPACE BETWEEN GALAXIES EXPANDS, 104 00:05:36,300 --> 00:05:38,600 AND IT PUSHES THE GALAXIES APART. 105 00:05:38,600 --> 00:05:43,700 SPACE CARRIES OBJECTS WITH IT LIKE A SURFER ON A WAVE. 106 00:05:43,700 --> 00:05:46,100 IT'S GOING ON IN EVERY PART OF SPACE. 107 00:05:46,100 --> 00:05:47,767 EVEN INSIDE YOUR BODY RIGHT NOW, 108 00:05:47,767 --> 00:05:49,700 THERE'S A PRESSURE FOR SPACE TO EXPAND. 109 00:05:51,367 --> 00:05:54,400 Narrator: EXPANSION GENERATED THE VAST, MOVING STAGE 110 00:05:54,400 --> 00:05:57,067 ON WHICH TODAY'S UNIVERSE PLAYS OUT. 111 00:05:57,067 --> 00:06:00,067 BUT LEFT UNCHECKED, IT COULD HAVE BEEN A FORCE 112 00:06:00,067 --> 00:06:02,133 FOR UTTER ANNIHILATION. 113 00:06:02,133 --> 00:06:04,367 Carroll: IF THE UNIVERSE HAD BEEN EXPANDING MUCH FASTER, 114 00:06:04,367 --> 00:06:06,133 IT WOULD HAVE EMPTIED OUT SO FAST, 115 00:06:06,133 --> 00:06:08,400 YOU WOULDN'T HAVE HAD TIME TO MAKE GALAXIES, 116 00:06:08,400 --> 00:06:09,533 PLANETS, PEOPLE. 117 00:06:12,200 --> 00:06:13,800 Narrator: THE FACT THAT WE'RE HERE 118 00:06:13,800 --> 00:06:16,367 MEANS THAT SOMETHING MUST HAVE PUT ON THE BRAKES. 119 00:06:16,367 --> 00:06:20,967 IT WAS, OF COURSE, OUR UNIVERSAL GLUE -- GRAVITY. 120 00:06:20,967 --> 00:06:24,433 GRAVITY AND MATTER GO HAND IN HAND. 121 00:06:24,433 --> 00:06:27,333 THE MORE MASSIVE THE OBJECT, 122 00:06:27,333 --> 00:06:30,433 THE MORE PULL IT EXERTS ON EVERYTHING AROUND IT. 123 00:06:30,433 --> 00:06:36,067 IT DRAWS ATOM TO ATOM, PARTICLE TO PARTICLE... 124 00:06:36,067 --> 00:06:37,933 [ BURSTING, RUMBLING ] 125 00:06:37,933 --> 00:06:43,233 ...BUILDING STARS, NEBULAS, 126 00:06:43,233 --> 00:06:45,567 GALAXIES -- 127 00:06:45,567 --> 00:06:49,700 THE HARDWARE OF THE UNIVERSE WE SEE TODAY. 128 00:06:49,700 --> 00:06:52,533 BUT GRAVITY IS A DOUBLE-EDGED SWORD. 129 00:06:52,533 --> 00:06:55,433 TOO MUCH, AND THE EARLY UNIVERSE WOULD NEVER HAVE GOTTEN 130 00:06:55,433 --> 00:06:57,600 OUT OF THE STARTING BLOCKS. 131 00:06:57,600 --> 00:06:59,633 Carroll: IF IT HAD BEEN EXPANDING MORE SLOWLY, 132 00:06:59,633 --> 00:07:01,967 IT WOULD HAVE RE-COLLAPSED INTO ANOTHER SINGULARITY. 133 00:07:01,967 --> 00:07:04,733 AND AGAIN, YOU WOULDN'T HAVE HAD THE TIME TO MAKE GALAXIES, 134 00:07:04,733 --> 00:07:06,533 PLANETS, OR PEOPLE. 135 00:07:06,533 --> 00:07:08,167 SO WE LIVE IN THE GOLDILOCKS UNIVERSE. 136 00:07:08,167 --> 00:07:10,300 WE LIVE IN THE UNIVERSE THAT LASTS LONG ENOUGH 137 00:07:10,300 --> 00:07:12,800 THAT WE CAN BE HERE, BUT EXPANDS GENTLY ENOUGH 138 00:07:12,800 --> 00:07:14,733 THAT WE HAVE TIME TO FORM. 139 00:07:18,100 --> 00:07:21,900 Narrator: THE UNIVERSE HAS LASTED FOR 13.8 BILLION YEARS, 140 00:07:21,900 --> 00:07:25,867 THANKS TO THE OPPOSING FORCES OF GRAVITY AND EXPANSION. 141 00:07:25,867 --> 00:07:29,933 BUT JUST HOW STABLE IS THIS BALANCING ACT? 142 00:07:29,933 --> 00:07:33,433 DOES OUR UNIVERSE HAVE JUST THE RIGHT AMOUNT OF STUFF IN IT 143 00:07:33,433 --> 00:07:35,533 TO KEEP IT FROM RUNAWAY EXPANSION 144 00:07:35,533 --> 00:07:37,600 OR CATASTROPHIC COLLAPSE? 145 00:07:39,067 --> 00:07:41,867 IN THE 1920s, SCIENTISTS DID THE MATH, 146 00:07:41,867 --> 00:07:45,700 AND THE RESULTS WERE ANYTHING BUT REASSURING. 147 00:07:45,700 --> 00:07:48,933 Kaku: THE MORE MATTER YOU HAVE, THE MORE GRAVITY YOU HAVE. 148 00:07:48,933 --> 00:07:52,267 IF YOU HAVE LOTS OF MATTER IN A VERY DENSE UNIVERSE, 149 00:07:52,267 --> 00:07:55,333 PERHAPS THE UNIVERSE BEGINS TO RE-COLLAPSE. 150 00:07:55,333 --> 00:07:57,433 OR, IF YOU HAVE VERY LITTLE MATTER, 151 00:07:57,433 --> 00:07:59,800 THE UNIVERSE WOULD FREEZE TO DEATH. 152 00:07:59,800 --> 00:08:04,067 SO WHAT IS THE CRITICAL DENSITY, THE BORDER BETWEEN THE TWO? 153 00:08:04,067 --> 00:08:08,567 IT'S APPROXIMATELY FIVE HYDROGEN ATOMS PER CUBIC METER. 154 00:08:08,567 --> 00:08:13,967 SO THINK OF A CUBIC YARD, AND PUT JUST FIVE HYDROGEN ATOMS 155 00:08:13,967 --> 00:08:16,800 INSIDE, AND THAT IS THE TIPPING POINT. 156 00:08:16,800 --> 00:08:18,933 IF YOU PUT MORE THAN FIVE ATOMS, 157 00:08:18,933 --> 00:08:20,933 THEN THE UNIVERSE WILL BEGIN TO COLLAPSE. 158 00:08:20,933 --> 00:08:22,467 IF YOU HAVE LESS THAN FIVE ATOMS, 159 00:08:22,467 --> 00:08:25,667 THEN THE UNIVERSE JUST KEEPS ON GOING. 160 00:08:25,667 --> 00:08:27,867 Narrator: IF WE THOUGHT THE UNIVERSE WAS BALANCED 161 00:08:27,867 --> 00:08:31,067 ON A TIGHTROPE BEFORE, THE CRITICAL DENSITY QUESTION 162 00:08:31,067 --> 00:08:35,300 SHOWED US THAT THE ROPE WAS MORE LIKE A RAZOR BLADE. 163 00:08:36,667 --> 00:08:39,600 YET, WHEN ASTRONOMERS TOOK ADDITIONAL MEASUREMENTS, 164 00:08:39,600 --> 00:08:42,067 THEY LIKED WHAT THEY SAW. 165 00:08:42,067 --> 00:08:45,433 THE UNIVERSE APPEARED TO CONTAIN JUST THE RIGHT AMOUNT 166 00:08:45,433 --> 00:08:48,367 OF MATTER TO STAY AT THE CRITICAL DENSITY. 167 00:08:49,500 --> 00:08:51,600 Krauss: MORE AND MORE, THE INDIRECT EVIDENCE 168 00:08:51,600 --> 00:08:54,433 AND THE THEORETICAL ARGUMENTS SUGGESTED 169 00:08:54,433 --> 00:08:57,133 THAT THE UNIVERSE MUST BE EXACTLY AT THE BOUNDARY 170 00:08:57,133 --> 00:08:58,967 BETWEEN A UNIVERSE THAT WOULD COLLAPSE 171 00:08:58,967 --> 00:09:01,333 AND ONE THAT WOULD EXPAND FOREVER, 172 00:09:01,333 --> 00:09:04,967 THAT WE WERE TEETERING ON THE HAIRY EDGE OF EXPANSION. 173 00:09:04,967 --> 00:09:09,233 Narrator: THE UNIVERSE SEEMED SO PERFECTLY BALANCED 174 00:09:09,233 --> 00:09:13,133 THAT IT WOULD HEAD QUIETLY INTO OLD AGE. 175 00:09:13,133 --> 00:09:16,667 THEN, IN THE 1970s, ASTRONOMERS MADE AN OBSERVATION 176 00:09:16,667 --> 00:09:18,667 THAT SHOCKED THEM. 177 00:09:18,667 --> 00:09:22,567 THE COSMOS WAS FILLED WITH INVISIBLE STUFF, 178 00:09:22,567 --> 00:09:27,267 AND ITS GRAVITY COULD CAUSE A CATASTROPHIC COLLAPSE. 179 00:09:39,867 --> 00:09:43,067 Narrator: THE UNIVERSE IS BALANCED ON A TIGHTROPE. 180 00:09:43,067 --> 00:09:47,133 ON EACH SIDE OF THE DROP LIES AN EARLY DEATH -- 181 00:09:47,133 --> 00:09:50,867 A BIG FREEZE, FUELED BY THE RUNAWAY STRETCHING OF SPACE, 182 00:09:50,867 --> 00:09:56,767 OR A BIG CRUNCH, THE RESULT OF GRAVITY OVERCOMING EXPANSION. 183 00:09:56,767 --> 00:10:00,233 40 YEARS AGO, SCIENTISTS BELIEVED WE'D STAY BALANCED 184 00:10:00,233 --> 00:10:03,800 BETWEEN THESE FATES FOR ETERNITY. 185 00:10:03,800 --> 00:10:06,033 NOW THINGS HAVE CHANGED TREMENDOUSLY, 186 00:10:06,033 --> 00:10:08,767 BECAUSE WE'VE DISCOVERED SOMETHING WE NEVER KNEW ABOUT 187 00:10:08,767 --> 00:10:10,767 40 YEARS AGO. 188 00:10:10,767 --> 00:10:15,433 Narrator: IN THE 1970s, ASTRONOMERS ARE STUNNED. 189 00:10:15,433 --> 00:10:19,133 SOME UNKNOWN FORM OF MATTER, INVISIBLE TO TELESCOPES, 190 00:10:19,133 --> 00:10:21,833 DWARFS WHAT WE THOUGHT WAS OUT THERE, 191 00:10:21,833 --> 00:10:25,600 NOT A FRACTION MORE, BUT FIVE TIMES MORE. 192 00:10:25,600 --> 00:10:28,767 WE USED TO THINK THAT GRAVITY CAME FROM STARS 193 00:10:28,767 --> 00:10:31,767 AND OBJECTS YOU CAN SEE -- END OF STORY. 194 00:10:31,767 --> 00:10:35,133 NOW, WE REALIZE THAT THAT NAIVE PICTURE IS ACTUALLY WRONG. 195 00:10:37,667 --> 00:10:39,967 Narrator: ASTRONOMERS MAKE THE DISCOVERY, 196 00:10:39,967 --> 00:10:43,333 STUDYING THE CLOCKWORK NATURE OF OUR UNIVERSE. 197 00:10:44,733 --> 00:10:47,400 THE HUGE GRAVITY OF THE SUN HOLDS THE EARTH 198 00:10:47,400 --> 00:10:51,533 AND ALL THE OTHER PLANETS IN A DELICATE CIRCULAR DANCE. 199 00:10:55,400 --> 00:10:58,933 THE SUN'S MASS CONTROLS THE SPEED OF THESE ORBITS. 200 00:10:58,933 --> 00:11:02,167 IF IT WERE MORE MASSIVE, THE PLANETS WOULD ORBIT 201 00:11:02,167 --> 00:11:03,833 MUCH MORE QUICKLY. 202 00:11:03,833 --> 00:11:06,400 AND IF IT WERE SMALLER, IT WOULD TAKE MUCH LONGER 203 00:11:06,400 --> 00:11:09,067 FOR A PLANET TO COMPLETE AN ORBIT. 204 00:11:11,233 --> 00:11:14,500 GALAXIES RUN LIKE CLOCKWORK, TOO. 205 00:11:14,500 --> 00:11:17,767 THE VAST MASS AT THE CENTER PULLS THE OUTER STARS 206 00:11:17,767 --> 00:11:21,167 INTO CIRCULAR, PLANET-LIKE ORBITS. 207 00:11:21,167 --> 00:11:23,667 ASTRONOMERS MAKE PRECISE MEASUREMENTS 208 00:11:23,667 --> 00:11:27,333 OF THESE GALACTIC ORBITS IN THE 1970s. 209 00:11:27,333 --> 00:11:30,500 THE RESULTS CHANGE EVERYTHING. 210 00:11:32,100 --> 00:11:34,667 THE GALAXIES WERE SPINNING TOO FAST. 211 00:11:34,667 --> 00:11:36,200 WAY TOO FAST. 212 00:11:39,467 --> 00:11:42,333 EVEN ACCOUNTING FOR THE SUPERMASSIVE BLACK HOLES 213 00:11:42,333 --> 00:11:46,633 AT THEIR CENTER, NINE-TENTHS OF THEIR MASS WAS MISSING. 214 00:11:46,633 --> 00:11:49,467 Kaku: BY RIGHTS, THE GALAXY SHOULD FLY APART. 215 00:11:49,467 --> 00:11:51,633 BY RIGHTS, THE EARTH SHOULD HAVE BEEN FLUNG 216 00:11:51,633 --> 00:11:54,600 INTO INTERGALACTIC SPACE BILLIONS OF YEARS AGO. 217 00:11:54,600 --> 00:11:57,800 WE SHOULD HAVE NO MILKY WAY GALAXY, AND YET, 218 00:11:57,800 --> 00:11:59,533 OUR UNIVERSE IS FULL OF GALAXIES. 219 00:12:03,667 --> 00:12:06,600 Narrator: AN IMMENSE ADDITIONAL SOURCE OF GRAVITY 220 00:12:06,600 --> 00:12:09,500 MUST BE HOLDING GALAXIES TOGETHER. 221 00:12:09,500 --> 00:12:12,733 BUT NO MATTER WHERE ASTRONOMERS POINT THEIR TELESCOPES, 222 00:12:12,733 --> 00:12:14,667 THEY SEE NOTHING. 223 00:12:14,667 --> 00:12:18,200 NOT A GLIMMER, NOT A SHADOW. 224 00:12:18,200 --> 00:12:23,067 WHATEVER THIS NEW STUFF IS, IT DOESN'T EMIT LIGHT, 225 00:12:23,067 --> 00:12:26,700 REFLECT LIGHT, OR EVEN BLOCK LIGHT. 226 00:12:26,700 --> 00:12:29,700 THEY CALL IT DARK MATTER. 227 00:12:31,433 --> 00:12:34,767 WHAT WE'VE LEARNED IS THAT MOST OF THE MATTER IN THE UNIVERSE 228 00:12:34,767 --> 00:12:37,400 IS NOT ORDINARY STUFF. IT'S NOT ATOMS. 229 00:12:37,400 --> 00:12:40,200 IT'S NOT PARTICLES WE'VE YET DETECTED IN ANY EXPERIMENT 230 00:12:40,200 --> 00:12:41,900 DONE HERE ON EARTH. 231 00:12:41,900 --> 00:12:44,533 IT'S SOME NEW KIND OF PARTICLE THAT WE CALL THE DARK MATTER. 232 00:12:47,667 --> 00:12:49,567 Narrator: DARK MATTER FILLS THE UNIVERSE, 233 00:12:49,567 --> 00:12:52,667 OUTSTRIPPING NORMAL MATTER BY 5-TO-1. 234 00:12:56,267 --> 00:13:00,833 VAST FILAMENTS SPREAD OUT THROUGHOUT THE COSMOS, 235 00:13:00,833 --> 00:13:05,300 AND BRIGHT GALAXIES CLUSTER WHERE DARK MATTER IS THICKEST. 236 00:13:07,633 --> 00:13:11,967 DARK MATTER PROVIDES THE SCAFFOLDING THAT UNDERLIES 237 00:13:11,967 --> 00:13:14,833 HOW THE MATTER IN THE UNIVERSE STRUCTURES ITSELF, 238 00:13:14,833 --> 00:13:16,733 WHERE IT GOES, AND WHAT IT DOES. 239 00:13:18,500 --> 00:13:20,433 Narrator: SO, DARK MATTER DICTATED 240 00:13:20,433 --> 00:13:23,067 HOW THE UNIVERSE UNFOLDED. 241 00:13:23,067 --> 00:13:26,133 Kaku: IT SEEMS AS IF OUT OF THE HOT BIG BANG, 242 00:13:26,133 --> 00:13:29,767 DARK MATTER CONDENSED FIRST, BEFORE ATOMS, 243 00:13:29,767 --> 00:13:32,733 AND DARK MATTER BEGAN TO BECOME CLUMPY. 244 00:13:32,733 --> 00:13:35,933 THE CLUMPINESS THEN BEGAN TO ATTRACT ATOMS 245 00:13:35,933 --> 00:13:39,633 AS THEY WERE FORMED LATER, AND THAT FORMED GALAXIES. 246 00:13:39,633 --> 00:13:41,667 AND IN SOME SENSE, THE DARK MATTER THEREFORE 247 00:13:41,667 --> 00:13:45,267 PROVIDES KIND OF A WOMB THAT ALLOWS THE BIRTH OF OUR GALAXY. 248 00:13:48,500 --> 00:13:51,667 Narrator: DARK MATTER HOLDS THE UNIVERSE TOGETHER, 249 00:13:51,667 --> 00:13:54,133 BUT IT ALSO THREATENS TO DESTROY IT. 250 00:13:55,967 --> 00:13:57,667 ONE OF THE MOST AMAZING DISCOVERIES 251 00:13:57,667 --> 00:14:00,167 OF THE PAST FEW DECADES IS DARK MATTER, 252 00:14:00,167 --> 00:14:02,133 THE FACT THAT THERE'S MUCH MORE MATTER IN THE UNIVERSE 253 00:14:02,133 --> 00:14:03,600 THAN WE WERE AWARE OF. 254 00:14:03,600 --> 00:14:06,100 AND ALL OF THAT MATTER HAS A LOT OF GRAVITY. 255 00:14:06,100 --> 00:14:08,233 SO ALL THIS NEW MATTER, ALL THIS NEW GRAVITY 256 00:14:08,233 --> 00:14:10,633 MUST BE SLOWING DOWN THE EXPANSION OF THE UNIVERSE. 257 00:14:12,300 --> 00:14:15,233 Narrator: DARK MATTER MAY EVEN TIP THE COSMIC SCALES 258 00:14:15,233 --> 00:14:17,233 IN FAVOR OF GRAVITY, 259 00:14:17,233 --> 00:14:21,067 DEFEATING EXPANSION AND PULLING THE ENTIRE UNIVERSE 260 00:14:21,067 --> 00:14:23,600 TOWARDS A DEATH BY FIRE. 261 00:14:23,600 --> 00:14:26,400 IT'S CALLED THE BIG CRUNCH, 262 00:14:26,400 --> 00:14:28,767 AND THIS IS HOW IT WOULD PLAY OUT. 263 00:14:30,467 --> 00:14:34,800 FOR A FRACTION OF A SECOND, THE UNIVERSE STALLS, 264 00:14:34,800 --> 00:14:38,533 POISED BETWEEN EXPANSION AND CONTRACTION. 265 00:14:38,533 --> 00:14:42,633 THEN, GRAVITY KICKS OFF A CATACLYSM. 266 00:14:42,633 --> 00:14:45,100 Krauss: WHEN YOU LOOKED OUT, THE VERY FIRST THINGS 267 00:14:45,100 --> 00:14:47,067 AS IT BEGAN TO TURN AROUND THAT YOU BEGAN TO SEE 268 00:14:47,067 --> 00:14:49,667 IS THAT GALAXIES, INSTEAD OF MOVING AWAY FROM US ON AVERAGE, 269 00:14:49,667 --> 00:14:52,167 WOULD BEGIN TO BE MOVING TOWARDS US ON AVERAGE. 270 00:14:54,600 --> 00:14:57,567 THE WHOLE UNIVERSE WOULD LOOK LIKE IT WAS COMING TO GET US. 271 00:14:59,367 --> 00:15:02,067 Narrator: AS SPACE CONTRACTS FURTHER, 272 00:15:02,067 --> 00:15:05,867 THE DENSITY OF MATTER INCREASES, GRAVITY GETS STRONGER, 273 00:15:05,867 --> 00:15:11,067 TEMPERATURES SOAR AS THE CRUNCH GATHERS MOMENTUM. 274 00:15:11,067 --> 00:15:13,367 Kaku: GALAXIES BEGIN TO COLLIDE, 275 00:15:13,367 --> 00:15:16,333 GAS CLOUDS BEGIN TO COLLIDE, 276 00:15:16,333 --> 00:15:19,433 PLANETS SLAM INTO THE EARTH. 277 00:15:20,867 --> 00:15:23,200 [ EXPLOSION ] 278 00:15:23,200 --> 00:15:26,767 BLACK HOLES WILL EXECUTE A DEATH DANCE AROUND EACH OTHER. 279 00:15:26,767 --> 00:15:30,200 TEMPERATURES, OF COURSE, WILL CONTINUE TO SKYROCKET. 280 00:15:30,200 --> 00:15:34,067 Narrator: MATTER, SPACE, AND TIME IMPLODE 281 00:15:34,067 --> 00:15:36,967 UNTIL EVERYTHING IN THE UNIVERSE IS COMPRESSED 282 00:15:36,967 --> 00:15:42,800 INTO A TINY SPECK OF INFINITE MASS, HEAT, AND PRESSURE. 283 00:15:42,800 --> 00:15:45,567 FOR THE LAST STAGES OF THE BIG CRUNCH, 284 00:15:45,567 --> 00:15:48,767 GALAXIES WILL COLLIDE AND FORM A PRIMORDIAL ATOM. 285 00:15:48,767 --> 00:15:53,133 AND THEN, LIFE AS WE KNOW IT WILL BE IMPOSSIBLE. 286 00:15:53,133 --> 00:15:55,567 Narrator: WE'RE BACK TO WHERE IT ALL BEGAN, 287 00:15:55,567 --> 00:15:58,700 BACK AT THE BIG BANG. 288 00:15:58,700 --> 00:16:02,500 THE UNIVERSE THAT WE LIVE IN WILL CEASE TO EXIST. 289 00:16:06,067 --> 00:16:11,800 BUT SOME BELIEVE A BIG CRUNCH COULD HERALD A NEW BEGINNING. 290 00:16:11,800 --> 00:16:14,133 WE DON'T KNOW WHAT THE END POINT OF A BIG CRUNCH WOULD BE, 291 00:16:14,133 --> 00:16:16,867 BECAUSE THE LAWS OF PHYSICS BREAK DOWN. 292 00:16:16,867 --> 00:16:20,333 IT'S POSSIBLE, AND INDEED, PHILOSOPHICALLY VERY PLEASANT, 293 00:16:20,333 --> 00:16:24,567 TO IMAGINE THAT THAT CRUNCH WOULD SOMEHOW END UP EVOLVING 294 00:16:24,567 --> 00:16:27,867 INTO AN EXPANSION AGAIN, AND YOU COULD HAVE A CYCLIC UNIVERSE 295 00:16:27,867 --> 00:16:29,400 WHICH GOES ON FOREVER. 296 00:16:29,400 --> 00:16:33,133 PERHAPS AT THAT POINT, WE WILL RECREATE ANOTHER BIG BANG. 297 00:16:37,067 --> 00:16:39,433 IT'S CONCEIVABLE THAT AS EVERYTHING COMES TOGETHER 298 00:16:39,433 --> 00:16:42,967 IN THE CRUNCH, SOMETHING SORT OF KEEPS IT FROM JUST CONTINUING 299 00:16:42,967 --> 00:16:46,633 AND PUSHES OUT IN A HOT, DENSE, SMOOTH STATE, 300 00:16:46,633 --> 00:16:49,333 AND FROM THE OTHER SIDE, IT LOOKS LIKE A BIG BANG, 301 00:16:49,333 --> 00:16:51,067 AND A NEW UNIVERSE HAS BEEN CREATED. 302 00:16:51,067 --> 00:16:54,733 OUR BIG BANG MIGHT HAVE BEEN SOMEONE ELSE'S BIG CRUNCH. 303 00:16:54,733 --> 00:16:57,067 Narrator: BUT JUST WHEN SCIENTISTS CAME TO TERMS 304 00:16:57,067 --> 00:17:00,567 WITH DARK MATTER'S BIG CRUNCH, THE UNIVERSE THREW THEM 305 00:17:00,567 --> 00:17:02,967 ANOTHER, EVEN BIGGER CURVE. 306 00:17:02,967 --> 00:17:07,500 SOME GHOSTLY FORCE SEEMED TO BE SENDING US HURTLING TOWARD 307 00:17:07,500 --> 00:17:09,600 A COMPLETELY DIFFERENT DEATH. 308 00:17:09,600 --> 00:17:12,400 Filippenko: MY POSTDOCTORAL SCHOLAR SHOWED ME THE RESULTS. 309 00:17:12,400 --> 00:17:14,467 I NEARLY FELL OFF MY CHAIR. 310 00:17:26,100 --> 00:17:28,433 Narrator: GRAVITY AND EXPANSION BATTLE FOR CONTROL 311 00:17:28,433 --> 00:17:31,900 OF OUR UNIVERSE FOR 14 BILLION YEARS... 312 00:17:31,900 --> 00:17:36,067 [ CRASHING, RUMBLING ] 313 00:17:36,067 --> 00:17:40,500 ...EXPANSION PUSHING IT OUTWARDS, 314 00:17:40,500 --> 00:17:43,100 GRAVITY PULLING IT IN. 315 00:17:44,600 --> 00:17:46,700 WITH DARK MATTER IN ITS CORNER, 316 00:17:46,700 --> 00:17:49,200 GRAVITY SEEMS TO BE THE INEVITABLE WINNER. 317 00:17:49,200 --> 00:17:53,767 THE EXTRA MASS WILL DRAG THE UNIVERSE INTO A BIG CRUNCH, 318 00:17:53,767 --> 00:17:55,800 UNTIL A STUNNING DISCOVERY 319 00:17:55,800 --> 00:18:00,367 REVOLUTIONIZES OUR UNDERSTANDING OF THE UNIVERSE. 320 00:18:02,700 --> 00:18:07,633 AROUND 1990, TWO TEAMS OF RESEARCHERS DECIDED TO MEASURE 321 00:18:07,633 --> 00:18:09,700 THE EXPANSION HISTORY OF THE UNIVERSE 322 00:18:09,700 --> 00:18:12,800 TO DETERMINE WHETHER IT'S BEEN SLOWING DOWN SO MUCH 323 00:18:12,800 --> 00:18:15,067 THAT IT'LL EVENTUALLY HAVE A BIG CRUNCH, 324 00:18:15,067 --> 00:18:17,567 OR WHETHER IT HASN'T BEEN SLOWING DOWN MUCH 325 00:18:17,567 --> 00:18:19,533 AND WILL ETERNALLY EXPAND. 326 00:18:19,533 --> 00:18:24,067 ASTRONOMER ALEX FILIPPENKO WAS ON ONE TEAM. 327 00:18:24,067 --> 00:18:26,633 SAUL PERLMUTTER LED THE OTHER. 328 00:18:26,633 --> 00:18:29,667 WE REALIZED THAT IT WAS POSSIBLE FOR THE FIRST TIME 329 00:18:29,667 --> 00:18:33,333 TO GO AND ACTUALLY MAKE A DIRECT MEASUREMENT 330 00:18:33,333 --> 00:18:35,833 OF HOW MUCH THE UNIVERSE HAD BEEN SLOWING DOWN IN THE PAST. 331 00:18:37,433 --> 00:18:38,967 Narrator: BOTH TEAMS WANT TO MEASURE 332 00:18:38,967 --> 00:18:41,267 THE SPEED OF DISTANT GALAXIES. 333 00:18:41,267 --> 00:18:45,133 BUT BECAUSE THE GALAXIES ARE TOO DIM AND TOO FAR AWAY, 334 00:18:45,133 --> 00:18:47,167 THEY LOOK FOR SOMETHING BRIGHTER. 335 00:18:52,067 --> 00:18:56,533 BILLIONS OF LIGHT YEARS FROM EARTH, A STAR DETONATES. 336 00:18:56,533 --> 00:18:59,200 THIS IS A SUPERNOVA, 337 00:18:59,200 --> 00:19:03,267 A DYING STAR'S BRILLIANT FINAL GASP. 338 00:19:03,267 --> 00:19:07,200 IT BURNS BRIGHTLY, 5 BILLION TIMES BRIGHTER THAN THE SUN, 339 00:19:07,200 --> 00:19:09,867 BUT BRIEFLY. 340 00:19:09,867 --> 00:19:12,067 PERLMUTTER AND FILIPPENKO HAVE A WINDOW 341 00:19:12,067 --> 00:19:14,600 OF JUST ONE OR TWO WEEKS TO MEASURE 342 00:19:14,600 --> 00:19:17,900 HOW MUCH THE GALAXY IT SITS IN IS SLOWING DOWN 343 00:19:17,900 --> 00:19:20,167 AS IT MOVES AWAY FROM US. 344 00:19:23,267 --> 00:19:25,867 [ RUMBLING ] 345 00:19:25,867 --> 00:19:29,100 THE TEAMS LOOK FOR SUPERNOVAS FOR EIGHT YEARS. 346 00:19:29,100 --> 00:19:34,900 THEY MEASURE 42, AND THE RESULTS SEEM IMPOSSIBLE. 347 00:19:34,900 --> 00:19:37,500 WE PLOTTED THE POINTS ON THE GRAPHS, 348 00:19:37,500 --> 00:19:40,233 AND...IT DIDN'T MAKE ANY SENSE. 349 00:19:40,233 --> 00:19:42,100 THEY WERE NOT SLOWING DOWN AT ALL. 350 00:19:42,100 --> 00:19:44,067 THEY WERE ACTUALLY SPEEDING UP. 351 00:19:45,200 --> 00:19:48,800 WHAT BOTH GROUPS FOUND STUNNED THE WORLD. 352 00:19:48,800 --> 00:19:51,633 IN THE LAST 4 OR 5 BILLION YEARS, 353 00:19:51,633 --> 00:19:55,800 THE UNIVERSE HAS ACTUALLY BEEN SPEEDING UP IN ITS EXPANSION. 354 00:19:55,800 --> 00:19:57,633 AN ACCELERATING UNIVERSE, 355 00:19:57,633 --> 00:20:01,600 PROPELLED BY SOMETHING MYSTERIOUS. 356 00:20:01,600 --> 00:20:04,067 FOR SO LONG, WE'VE BEEN ARGUING WHETHER THE UNIVERSE WOULD 357 00:20:04,067 --> 00:20:06,900 EXPAND FOREVER OR COLLAPSE BACK IN ON ITSELF, 358 00:20:06,900 --> 00:20:09,267 BUT NOBODY THOUGHT THE ANSWER WAS GOING TO BE 359 00:20:09,267 --> 00:20:11,567 THAT THE UNIVERSE WAS ACCELERATING, 360 00:20:11,567 --> 00:20:13,367 GOING FASTER AND FASTER ALL THE TIME. 361 00:20:16,133 --> 00:20:19,500 Narrator: THE ACCELERATION BEWILDERS THE SCIENTISTS. 362 00:20:19,500 --> 00:20:22,600 IT SEEMS TO DEFY THE LAWS OF PHYSICS. 363 00:20:22,600 --> 00:20:24,867 Oluseyi: IMAGINE I'VE GOT A BASEBALL 364 00:20:24,867 --> 00:20:26,533 AND I THROW IT STRAIGHT UP. 365 00:20:26,533 --> 00:20:29,333 AND INSTEAD OF SLOWING DOWN ONCE IT LEAVES MY HAND, 366 00:20:29,333 --> 00:20:31,167 WHICH IS WHAT NORMALLY IT WILL DO, 367 00:20:31,167 --> 00:20:33,033 IT BEGINS TO SLOW DOWN AT FIRST, 368 00:20:33,033 --> 00:20:34,933 BUT THEN IT STARTS SPEEDING AWAY. 369 00:20:34,933 --> 00:20:36,567 SOMEHOW, IT'S GETTING ENERGY. 370 00:20:36,567 --> 00:20:42,033 Narrator: THE NEW ENERGY SEEMED TO BE COMING FROM NOTHING, 371 00:20:42,033 --> 00:20:44,267 THE VACUUM OF SPACE. 372 00:20:44,267 --> 00:20:48,033 THE WORD "VACUUM" TO A SCIENTIST MEANS COMPLETELY EMPTY SPACE, 373 00:20:48,033 --> 00:20:50,633 NO PARTICLES THERE AT ALL, NO TEMPERATURE, 374 00:20:50,633 --> 00:20:52,233 NO ENERGY TO SPEAK OF. 375 00:20:52,233 --> 00:20:55,533 BUT THERE'S AN INTRINSIC ENERGY IN SPACE AND TIME. 376 00:20:55,533 --> 00:20:59,233 EMPTY SPACE HAS ENERGY, AND THAT ENERGY PRODUCES 377 00:20:59,233 --> 00:21:02,433 A GRAVITATIONAL REPULSION, A KIND OF ANTI-GRAVITY. 378 00:21:02,433 --> 00:21:06,867 Narrator: WITHOUT A CLUE WHAT THIS FORCE IS OR HOW IT WORKS, 379 00:21:06,867 --> 00:21:12,433 ALL SCIENTISTS CAN DO IS GIVE IT A NAME -- DARK ENERGY. 380 00:21:13,600 --> 00:21:16,067 WE COULD HAVE CALLED IT WE-DON'T-KNOW ENERGY. 381 00:21:16,067 --> 00:21:17,467 WE COULD HAVE CALLED IT ANYTHING. 382 00:21:17,467 --> 00:21:19,867 BUT WE DON'T KNOW WHAT IT IS, AND DARK OR NOT, 383 00:21:19,867 --> 00:21:22,067 IT'S THE BIGGEST MYSTERY IN PHYSICS. 384 00:21:25,167 --> 00:21:28,200 Narrator: NASA CALIBRATES ITS FINEST SPACE TELESCOPES 385 00:21:28,200 --> 00:21:31,333 TO MEASURE HOW MUCH DARK ENERGY IS OUT THERE, 386 00:21:31,333 --> 00:21:34,667 AND THE RESULT IS MIND-BLOWING. 387 00:21:34,667 --> 00:21:39,467 IT DOMINATES THE MASS OF THE UNIVERSE BY NEARLY 3-TO-1. 388 00:21:39,467 --> 00:21:41,933 AND THE MORE SPACE EXPANDS, 389 00:21:41,933 --> 00:21:45,100 THE MORE DARK ENERGY THERE SEEMS TO BE. 390 00:21:45,100 --> 00:21:48,067 Kaku: DARK ENERGY IS THE ENERGY OF NOTHING, 391 00:21:48,067 --> 00:21:49,567 AND IT'S REPULSIVE. 392 00:21:49,567 --> 00:21:53,367 THEREFORE, AS THIS DARK ENERGY REPELS GALAXIES, 393 00:21:53,367 --> 00:21:55,300 THERE'S MORE OF IT, THERE'S MORE VACUUM. 394 00:21:55,300 --> 00:21:57,400 AND SO THERE'S MORE REPULSION, 395 00:21:57,400 --> 00:22:00,400 AND PERHAPS THAT'S THE REASON WHY THE UNIVERSE IS ACCELERATING 396 00:22:00,400 --> 00:22:03,733 RIGHT NOW RATHER THAN SLOWING DOWN. 397 00:22:03,733 --> 00:22:07,200 Narrator: DARK ENERGY SEEMS TO KILL THE BIG CRUNCH THEORY, 398 00:22:07,200 --> 00:22:10,267 BUT SCIENTISTS AREN'T YET SURE HOW DARK ENERGY, 399 00:22:10,267 --> 00:22:13,800 EXPANSION, AND SPACE ARE CONNECTED. 400 00:22:13,800 --> 00:22:17,133 IF A VOLUME OF SPACE DOUBLES IN SIZE, 401 00:22:17,133 --> 00:22:20,067 DOES THE DARK ENERGY INSIDE IT DOUBLE, TOO? 402 00:22:20,067 --> 00:22:22,133 OR DOES IT INCREASE MORE? 403 00:22:22,133 --> 00:22:25,667 A 1-TO-1 RELATIONSHIP LEADS TO A STEADY EXPANSION. 404 00:22:25,667 --> 00:22:28,800 THE UNIVERSE ENDS IN A BIG FREEZE. 405 00:22:28,800 --> 00:22:33,367 BUT IF DARK ENERGY INCREASES ABOVE AND BEYOND EXPANSION, 406 00:22:33,367 --> 00:22:37,867 A NEW, EVEN MORE TERRIFYING END AWAITS THE UNIVERSE -- 407 00:22:37,867 --> 00:22:39,933 A BIG RIP. 408 00:22:39,933 --> 00:22:43,967 Kaku: IN A BIG RIP SCENARIO, THE EXPANSION IS SO GREAT 409 00:22:43,967 --> 00:22:48,167 THAT EVEN THE GALAXIES BEGIN TO EXPAND INTERNALLY, 410 00:22:48,167 --> 00:22:49,500 WHICH MEANS THAT LITERALLY 411 00:22:49,500 --> 00:22:51,433 OUR BODIES ARE GOING TO BE RIPPED APART. 412 00:22:52,733 --> 00:22:54,233 Narrator: SCIENTISTS CALCULATE 413 00:22:54,233 --> 00:22:56,567 JUST HOW THE BIG RIP WILL PLAY OUT. 414 00:22:58,900 --> 00:23:03,067 ONE BY ONE, THE GALAXIES IN THE NIGHT SKY WILL BLINK OUT 415 00:23:03,067 --> 00:23:06,067 AS SPACE PULLS THEM AWAY FROM THE EARTH 416 00:23:06,067 --> 00:23:07,800 FASTER THAN THE SPEED OF LIGHT. 417 00:23:07,800 --> 00:23:09,500 [ WHOOSHING ] 418 00:23:09,500 --> 00:23:13,900 60 MILLION YEARS BEFORE THE END, DARK ENERGY OVERCOMES GRAVITY 419 00:23:13,900 --> 00:23:16,833 ON SMALLER AND SMALLER SCALES. 420 00:23:16,833 --> 00:23:20,133 FIRST GALAXIES START TO RIP APART, 421 00:23:20,133 --> 00:23:24,067 THEN INSIDES OF GALAXIES WILL BEGIN TO RIP APART, 422 00:23:24,067 --> 00:23:26,667 AND THEN SOLAR SYSTEMS WILL BEGIN TO RIP APART... 423 00:23:30,133 --> 00:23:33,100 THEN PLANETS... 424 00:23:33,100 --> 00:23:38,500 AND THEN ROCKS, PEOPLE, ATOMS. 425 00:23:38,500 --> 00:23:41,800 Narrator: THE END WILL BE MERCIFULLY QUICK. 426 00:23:43,700 --> 00:23:45,967 IN THE SPACE OF A FEW MINUTES, 427 00:23:45,967 --> 00:23:50,133 ALL THE STARS AND PLANETS IN THE UNIVERSE WILL BE DESTROYED, 428 00:23:50,133 --> 00:23:54,900 THEIR REMAINS PULLED APART INTO EVER-SMALLER PIECES 429 00:23:54,900 --> 00:23:57,567 UNTIL FINALLY, WHEN THE UNIVERSE HAS 430 00:23:57,567 --> 00:23:59,300 LESS THAN A SECOND TO LIVE, 431 00:23:59,300 --> 00:24:02,833 THE SUBATOMIC PARTICLES THAT MADE ALL MATTER 432 00:24:02,833 --> 00:24:04,500 WILL BE DESTROYED, 433 00:24:04,500 --> 00:24:07,800 AND ALL THAT REMAINS WILL BE INDIVIDUAL PHOTONS 434 00:24:07,800 --> 00:24:10,100 BECOMING SCARCER AND SCARCER 435 00:24:10,100 --> 00:24:12,833 AS THE SPACE BETWEEN THEM EXPANDS. 436 00:24:12,833 --> 00:24:15,300 ALL YOU'RE LEFT WITH IS VERY LOW ENERGY LIGHT 437 00:24:15,300 --> 00:24:16,767 THAT GETS STRETCHED AND STRETCHED 438 00:24:16,767 --> 00:24:18,867 UNTIL IT MIGHT AS WELL NOT EXIST AT ALL. 439 00:24:18,867 --> 00:24:20,867 Narrator: THE LAST THING TO GO -- 440 00:24:20,867 --> 00:24:24,367 THE EMPTY VACUUM OF SPACE ITSELF. 441 00:24:26,500 --> 00:24:29,067 IT'LL BE PULLING ON THE UNIVERSE SO HARD, 442 00:24:29,067 --> 00:24:31,900 IT COULD TEAR THE FABRIC OF THE UNIVERSE APART. 443 00:24:31,900 --> 00:24:35,300 REALITY COULD DISSOLVE. 444 00:24:35,300 --> 00:24:38,633 Narrator: WILL THE UNIVERSE END WITH A BIG RIP, 445 00:24:38,633 --> 00:24:40,967 OR A BIG FREEZE? 446 00:24:40,967 --> 00:24:45,433 THE ANSWER IS LOCKED INSIDE THE MYSTERY OF DARK ENERGY. 447 00:24:45,433 --> 00:24:50,200 SOLVE THAT, AND THE FATE OF THE UNIVERSE BECOMES CLEAR. 448 00:25:04,433 --> 00:25:06,800 Narrator: THE END OF THE UNIVERSE IS COMING. 449 00:25:06,800 --> 00:25:08,967 BUT HOW WILL IT PLAY OUT? 450 00:25:08,967 --> 00:25:12,833 FOR A TIME, A BIG CRUNCH WAS THE LIKELY ANSWER. 451 00:25:12,833 --> 00:25:16,600 DARK MATTER, THE INVISIBLE BULK OF THE UNIVERSE, 452 00:25:16,600 --> 00:25:19,900 CAUSES SPACE TO FALL IN ON ITSELF. 453 00:25:21,167 --> 00:25:25,533 GALAXIES COLLIDE. PLANET MERGES WITH PLANET. 454 00:25:25,533 --> 00:25:30,300 EVERYTHING BECOMES HOTTER AND HOTTER, DENSER AND DENSER. 455 00:25:30,300 --> 00:25:32,867 THE UNIVERSE IS LIKE ONE GIANT STAR. 456 00:25:36,633 --> 00:25:40,667 Narrator: DARK ENERGY KILLS THE BIG CRUNCH THEORY. 457 00:25:40,667 --> 00:25:43,800 IT ACTS LIKE ROCKET FUEL FOR THE EXPANSION OF SPACE 458 00:25:43,800 --> 00:25:46,067 BETWEEN GALAXIES. 459 00:25:46,067 --> 00:25:49,267 THEY'RE NOT JUST COASTING. THEY'RE GETTING PUSHED OUTWARD. 460 00:25:52,600 --> 00:25:54,800 ONLY TWO POSSIBLE FATES REMAIN -- 461 00:25:54,800 --> 00:25:57,500 A BIG RIP OR A BIG FREEZE. 462 00:25:57,500 --> 00:26:00,467 BOTH SCENARIOS RELY ON DARK ENERGY. 463 00:26:00,467 --> 00:26:03,400 FOR THE UNIVERSE TO BE TORN TO SHREDS IN A BIG RIP, 464 00:26:03,400 --> 00:26:07,100 DARK ENERGY MUST INCREASE EXPONENTIALLY IN THE FUTURE. 465 00:26:07,100 --> 00:26:10,433 BUT A BIG FREEZE REQUIRES A STEADY INCREASE 466 00:26:10,433 --> 00:26:11,933 IN DARK ENERGY, 467 00:26:11,933 --> 00:26:14,933 PUSHING GALAXIES AWAY FROM EACH OTHER. 468 00:26:14,933 --> 00:26:17,900 WE CAN'T WRITE THE LAST CHAPTER OF OUR UNIVERSE 469 00:26:17,900 --> 00:26:21,367 UNTIL WE UNDERSTAND THE NATURE OF DARK ENERGY. 470 00:26:21,367 --> 00:26:23,867 [ ROCKETS FIRING ] 471 00:26:23,867 --> 00:26:26,733 Narrator: MAY 2009. 472 00:26:26,733 --> 00:26:30,333 THE EUROPEAN SPACE AGENCY LAUNCHES THE PLANCK SATELLITE 473 00:26:30,333 --> 00:26:34,233 TO SEARCH FOR THE BIRTH OF DARK ENERGY. 474 00:26:34,233 --> 00:26:38,700 ITS ULTRA-SENSITIVE TELESCOPE PEERS THROUGH SPACE AND TIME 475 00:26:38,700 --> 00:26:41,233 BACK THROUGH BILLIONS OF YEARS, 476 00:26:41,233 --> 00:26:45,800 TOWARDS THE BEGINNING OF EVERYTHING, TO CAPTURE THIS. 477 00:26:45,800 --> 00:26:48,300 THIS IS OUR UNIVERSE AS IT APPEARED 478 00:26:48,300 --> 00:26:51,233 OVER 13 BILLION YEARS AGO, 479 00:26:51,233 --> 00:26:55,267 380,000 YEARS AFTER THE BIG BANG. 480 00:26:56,833 --> 00:26:59,433 SO WHAT PLANCK HAS DONE IS TAKE A PICTURE 481 00:26:59,433 --> 00:27:01,767 OF THE EARLY UNIVERSE 482 00:27:01,767 --> 00:27:04,900 AND TOLD US ABOUT WHAT THE EARLY UNIVERSE IS LIKE 483 00:27:04,900 --> 00:27:07,333 AND GIVEN US OUR MOST DETAILED AND ACCURATE PICTURE 484 00:27:07,333 --> 00:27:08,667 OF THAT MOMENT IN TIME. 485 00:27:08,667 --> 00:27:11,100 Narrator: THE UNIVERSE IN THIS PICTURE 486 00:27:11,100 --> 00:27:15,600 IS A HOT SOUP OF PROTONS, ELECTRONS, AND PHOTONS. 487 00:27:15,600 --> 00:27:18,667 HYDROGEN ATOMS HAVE JUST STARTED TO FORM, 488 00:27:18,667 --> 00:27:21,400 AND IT'S THE LIGHT FROM THIS GENESIS OF MATTER 489 00:27:21,400 --> 00:27:23,267 THAT WE SEE HERE. 490 00:27:25,333 --> 00:27:28,567 BLUE AREAS ARE COLDER. REDS ARE WARM. 491 00:27:30,067 --> 00:27:32,100 EVENTUALLY, THOSE HOT SPOTS, 492 00:27:32,100 --> 00:27:34,300 THOSE RED SPOTS YOU SEE IN THE MAP, 493 00:27:34,300 --> 00:27:36,933 ARE GOING TO FORM LARGE SUPERCLUSTERS 494 00:27:36,933 --> 00:27:41,400 MADE UP OF HUNDREDS OR THOUSANDS OF GALAXIES. 495 00:27:41,400 --> 00:27:45,533 EACH ONE OF THOSE GALAXIES WILL CONTAIN BILLIONS OF STARS. 496 00:27:47,167 --> 00:27:49,467 Narrator: GRAVITY AND EXPANSION ALONE 497 00:27:49,467 --> 00:27:54,167 APPEAR TO DRIVE THE FORMATION OF THESE EMBRYONIC GALAXIES. 498 00:27:54,167 --> 00:27:58,433 DARK ENERGY DOESN'T SEEM TO HAVE SWITCHED ON YET. 499 00:27:58,433 --> 00:28:03,333 SO, WHEN DID DARK ENERGY TAKE CONTROL OF THE UNIVERSE? 500 00:28:10,633 --> 00:28:13,833 ASTRONOMER BRENDA FRYE IS PART OF A TEAM 501 00:28:13,833 --> 00:28:16,433 USING MASSIVE GROUND-BASED TELESCOPES 502 00:28:16,433 --> 00:28:19,233 LIKE THIS ONE AT KITT PEAK, ARIZONA. 503 00:28:19,233 --> 00:28:23,600 SHE PEERS BACK IN TIME TO CAPTURE THE UNIVERSE 504 00:28:23,600 --> 00:28:26,500 THROUGH ITS CHILDHOOD AS IT WAS GROWING. 505 00:28:28,533 --> 00:28:31,100 RIGHT. SO THIS IS AN ALUMINUM PLATE, 506 00:28:31,100 --> 00:28:35,300 AND INTO THIS PLATE ARE DRILLED 640 INDIVIDUAL HOLES. 507 00:28:35,300 --> 00:28:38,367 EACH ONE IS PUT AT A VERY SPECIFIC PLACE ON THE MASK 508 00:28:38,367 --> 00:28:42,433 WHICH WILL CORRESPOND TO ONE PARTICULAR GALAXY IN THE SKY. 509 00:28:44,800 --> 00:28:46,533 Narrator: DURING EACH OBSERVATION, 510 00:28:46,533 --> 00:28:51,067 THE LIGHT FROM 640 INDIVIDUAL GALAXIES IS COLLECTED 511 00:28:51,067 --> 00:28:54,433 USING FIBER OPTIC CABLES. 512 00:28:54,433 --> 00:28:57,900 THE SPEED AND RELATIVE POSITION OF EACH GALAXY IS MEASURED 513 00:28:57,900 --> 00:29:01,833 TO PINPOINT EXACTLY WHERE IT IS IN SPACE. 514 00:29:03,133 --> 00:29:05,767 SO FAR, THE TEAM HAS ACCURATELY MAPPED 515 00:29:05,767 --> 00:29:08,600 AROUND A MILLION GALAXIES IN 3D, 516 00:29:08,600 --> 00:29:10,467 AND THIS IS WHAT THEY LOOK LIKE. 517 00:29:11,700 --> 00:29:14,333 EACH ONE OF THESE FUZZY PATCHES 518 00:29:14,333 --> 00:29:16,167 IS A FULLY GROWN GALAXY 519 00:29:16,167 --> 00:29:20,200 CONTAINING AROUND 200 BILLION STARS. 520 00:29:20,200 --> 00:29:21,867 THIS IS A VERY BASIC MEASUREMENT, 521 00:29:21,867 --> 00:29:24,067 AND WE THINK THAT THIS WILL BE ABLE TO HELP US 522 00:29:24,067 --> 00:29:27,067 TO GET A GRASP INTO THE NATURE OF DARK ENERGY. 523 00:29:27,067 --> 00:29:31,333 Narrator: SCIENTISTS COMPARE THIS ADOLESCENT UNIVERSE 524 00:29:31,333 --> 00:29:33,200 TO ITS BABY PICTURES. 525 00:29:33,200 --> 00:29:35,433 IT SHOWS DARK ENERGY EMERGING 526 00:29:35,433 --> 00:29:38,733 WHEN THE UNIVERSE IS HALF AS OLD AS IT IS TODAY. 527 00:29:40,900 --> 00:29:43,633 ABOUT 8 BILLION YEARS AFTER THE BIG BANG, 528 00:29:43,633 --> 00:29:47,867 THIS EXPANSION OF THE UNIVERSE BEGINS TO ACCELERATE, 529 00:29:47,867 --> 00:29:50,500 AND WE'RE IN THE MIDDLE OF THIS ACCELERATION. 530 00:29:50,500 --> 00:29:55,200 Narrator: THE DATA ALSO SHOWS THAT AS SPACE EXPANDS, 531 00:29:55,200 --> 00:29:59,833 DARK ENERGY INCREASES IN LOCKSTEP WITH IT. 532 00:29:59,833 --> 00:30:02,167 IF YOU HAD A BOX AND YOU PUT SOME DARK ENERGY IN IT, 533 00:30:02,167 --> 00:30:04,500 AND THEN YOU WENT AND YOU WEIGHED THAT BOX... 534 00:30:04,500 --> 00:30:06,400 NOW YOU TAKE THE BOX, YOU MAKE IT TWICE AS BIG. 535 00:30:06,400 --> 00:30:08,267 YOU DON'T OPEN IT. YOU DON'T PUT ANYTHING IN IT. 536 00:30:08,267 --> 00:30:10,800 YOU WEIGH IT AGAIN, IT'S GONNA WEIGH TWICE AS MUCH. 537 00:30:10,800 --> 00:30:13,133 Narrator: THIS REMARKABLE OBSERVATION MEANS 538 00:30:13,133 --> 00:30:16,600 THAT WE SHOULD BE SAFE FROM A BIG RIP. 539 00:30:16,600 --> 00:30:20,033 DARK ENERGY WILL CONTINUE TO INCREASE GRADUALLY. 540 00:30:20,033 --> 00:30:23,600 THE UNIVERSE IS HEADING FOR A BIG FREEZE, 541 00:30:23,600 --> 00:30:27,633 AND SCIENTISTS CAN FINALLY CALCULATE A TIMELINE 542 00:30:27,633 --> 00:30:30,500 FOR THE END OF EVERYTHING. 543 00:30:41,667 --> 00:30:43,200 Narrator: IT NOW SEEMS THAT WE LIVE 544 00:30:43,200 --> 00:30:45,833 IN AN ALMOST PERFECT UNIVERSE, 545 00:30:45,833 --> 00:30:49,400 WITH JUST ENOUGH GRAVITY TO HOLD THE GALAXIES TOGETHER 546 00:30:49,400 --> 00:30:53,300 AND JUST ENOUGH DARK ENERGY THAT IT WILL EXPAND FOREVER 547 00:30:53,300 --> 00:30:55,933 WITHOUT RIPPING ITSELF TO SHREDS. 548 00:30:57,867 --> 00:31:02,600 COSMOLOGISTS CAN FINALLY ENVISION THE END OF IT ALL. 549 00:31:03,933 --> 00:31:06,500 Oluseyi: 30 YEARS AGO, IT WAS DEBATABLE. 550 00:31:06,500 --> 00:31:09,367 BUT NOW, IT APPEARS THAT THE UNIVERSE MOST LIKELY 551 00:31:09,367 --> 00:31:10,933 WILL SUFFER A DEEP FREEZE. 552 00:31:10,933 --> 00:31:14,233 IF YOU LOOK AT THE DATA, IT STARES OUT AT YOU. 553 00:31:15,400 --> 00:31:16,967 Narrator: IN A BIG FREEZE, 554 00:31:16,967 --> 00:31:21,100 DARK ENERGY PUSHES GALAXIES FURTHER AND FURTHER APART, 555 00:31:21,100 --> 00:31:24,067 BUT THEY REMAIN INTACT. 556 00:31:25,400 --> 00:31:29,067 THE STARS INSIDE THEM FADE AWAY. 557 00:31:29,067 --> 00:31:31,600 EVERY STAR YOU SEE IN THE SKY, INCLUDING OUR SUN, 558 00:31:31,600 --> 00:31:33,700 IS BURNING THROUGH ITS NUCLEAR FUEL. 559 00:31:33,700 --> 00:31:36,900 THE GAS WILL RUN OUT, STARS WILL STOP BEING MADE, 560 00:31:36,900 --> 00:31:40,533 AND THE ONES THAT EXIST ARE IT. THOSE ARE THE LAST ONES. 561 00:31:44,933 --> 00:31:47,233 Narrator: A HUNDRED TRILLION YEARS FROM NOW, 562 00:31:47,233 --> 00:31:51,533 THE BIGGEST STARS WILL BE THE FIRST TO GO EXTINCT. 563 00:31:51,533 --> 00:31:54,667 BIG STARS BURN BRIGHT AND DIE HARD. 564 00:31:54,667 --> 00:31:59,100 [ RUMBLING ] THE STAR'S CORE COLLAPSES, 565 00:31:59,100 --> 00:32:01,300 UNLEASHING A SUPERNOVA. 566 00:32:02,600 --> 00:32:05,933 THEN GRAVITY CRUSHES THE DEAD STAR DOWN 567 00:32:05,933 --> 00:32:08,600 TO A SINGLE DENSE SPOT. 568 00:32:08,600 --> 00:32:12,067 THE BRIGHT STAR IS NOW A BLACK HOLE. 569 00:32:15,200 --> 00:32:17,767 SUN-LIKE STARS GO NEXT. 570 00:32:19,233 --> 00:32:21,833 AS THEIR SUPPLY OF HYDROGEN RUNS OUT, 571 00:32:21,833 --> 00:32:24,200 THEY SWELL TO A BLOATED FIREBALL 572 00:32:24,200 --> 00:32:27,133 OVER 200 TIMES THEIR CURRENT SIZE. 573 00:32:33,800 --> 00:32:36,067 Thaller: AND WHEN THE CORE HAS NO MORE HYDROGEN, 574 00:32:36,067 --> 00:32:39,300 IT'S GOING TO BLOAT UP INTO A RED GIANT STAR. 575 00:32:39,300 --> 00:32:41,667 NOW, RED GIANT STARS ARE SO BIG, THEY WILL ACTUALLY 576 00:32:41,667 --> 00:32:43,667 EAT UP THEIR OWN PLANETS. 577 00:32:43,667 --> 00:32:45,500 WE KNOW OF EXAMPLES OF RED GIANTS 578 00:32:45,500 --> 00:32:47,567 THAT GO ALL THE WAY OUT TO WHERE THE ORBIT OF JUPITER IS 579 00:32:47,567 --> 00:32:49,500 IN OUR SOLAR SYSTEM. 580 00:32:49,500 --> 00:32:52,467 Narrator: ITS FUEL EXHAUSTED, 581 00:32:52,467 --> 00:32:55,167 THE SUN-LIKE STAR GIVES IN TO GRAVITY 582 00:32:55,167 --> 00:32:57,267 AND SHRINKS TO A WHITE DWARF, 583 00:32:57,267 --> 00:32:59,067 A DENSE BALL OF MATTER 584 00:32:59,067 --> 00:33:02,233 JUST A FEW THOUSAND MILES IN DIAMETER. 585 00:33:02,233 --> 00:33:06,267 IT WILL GLOW WITH HEAT FOR A FURTHER 10 BILLION YEARS 586 00:33:06,267 --> 00:33:08,833 BEFORE COOLING TO A BLACK DWARF, 587 00:33:08,833 --> 00:33:13,867 A BALL OF COMPRESSED CARBON, PERHAPS EVEN DIAMOND. 588 00:33:17,367 --> 00:33:19,700 AS THE BIGGEST STARS DIE, 589 00:33:19,700 --> 00:33:23,233 THE UNIVERSE WILL SLOWLY TURN RED. 590 00:33:23,233 --> 00:33:25,067 Plait: THE BLUE STARS WILL BLOW UP, 591 00:33:25,067 --> 00:33:27,167 AND THEN THE SLIGHTLY LESS BLUE STARS WILL BLOW UP, 592 00:33:27,167 --> 00:33:29,533 AND THEN STARS LIKE THE SUN WILL FADE AWAY AND DIE, 593 00:33:29,533 --> 00:33:32,200 LEAVING JUST THE RED STARS TO EXIST. 594 00:33:34,767 --> 00:33:36,600 Narrator: RED STARS ARE THE SMALLEST 595 00:33:36,600 --> 00:33:38,500 AND COOLEST IN THE UNIVERSE. 596 00:33:38,500 --> 00:33:40,767 THEY BURN THEIR FUEL SLOWLY. 597 00:33:40,767 --> 00:33:43,500 BUT, AFTER ANOTHER 10 TRILLION YEARS, 598 00:33:43,500 --> 00:33:45,900 EVEN THESE SMALLEST OF DWARF STARS 599 00:33:45,900 --> 00:33:48,167 WILL USE UP THEIR FUEL. 600 00:33:48,167 --> 00:33:51,733 Kaku: STARS AS WE KNOW THEM WILL CEASE TO BURN ENERGY, 601 00:33:51,733 --> 00:33:54,200 AND THE NIGHT SKY WILL TURN BLACK. 602 00:33:54,200 --> 00:33:58,067 Narrator: BLACK HOLES, THE CORPSES OF DEAD STARS, 603 00:33:58,067 --> 00:34:02,767 AND COLD CLOUDS OF GAS AND DUST ARE ALL THAT REMAINS. 604 00:34:05,167 --> 00:34:07,933 THE AGE OF STARS IS OVER. 605 00:34:07,933 --> 00:34:11,667 THE AGE OF BLACK HOLES BEGINS. 606 00:34:11,667 --> 00:34:13,867 Plait: BLACK HOLES BECOME THE FUNDAMENTAL BUILDING BLOCK 607 00:34:13,867 --> 00:34:15,533 OF THE UNIVERSE. 608 00:34:15,533 --> 00:34:17,900 A GALAXY WILL BASICALLY BE A SUPERMASSIVE BLACK HOLE 609 00:34:17,900 --> 00:34:19,933 IN THE CENTER, WITH SMALLER BLACK HOLES ORBITING IT. 610 00:34:19,933 --> 00:34:22,467 IN SOME WAYS, IT'S KIND OF A GHOST UNIVERSE. 611 00:34:22,467 --> 00:34:24,300 IT'S THE CORPSES, THE ZOMBIE STARS, 612 00:34:24,300 --> 00:34:26,067 THAT WILL TAKE US INTO THE FUTURE. 613 00:34:26,067 --> 00:34:29,167 Narrator: ZOMBIE GALAXIES FILLED WITH BLACK HOLES 614 00:34:29,167 --> 00:34:30,967 CONTINUE TO EVOLVE. 615 00:34:30,967 --> 00:34:34,333 THEY SWEEP UP THE DEAD REMAINS OF STARS. 616 00:34:34,333 --> 00:34:38,433 BLACK HOLE MERGES WITH BLACK HOLE. 617 00:34:38,433 --> 00:34:40,533 Plait: THEY'LL EAT EACH OTHER AND THEY'LL GET BIGGER, 618 00:34:40,533 --> 00:34:42,367 AND MAYBE THEY'LL FALL INTO THE SUPERMASSIVE BLACK HOLE 619 00:34:42,367 --> 00:34:43,833 AND IT'LL GET BIGGER. 620 00:34:43,833 --> 00:34:46,833 THE UNIVERSE WILL STILL BE AN EXCITING, DYNAMIC PLACE, 621 00:34:46,833 --> 00:34:49,133 IT'S JUST THAT THE TIME SCALES YOU'RE TALKING ABOUT 622 00:34:49,133 --> 00:34:50,700 ARE NOW TRILLIONS OF YEARS 623 00:34:50,700 --> 00:34:53,400 INSTEAD OF THOUSANDS OR MILLIONS OF YEARS. 624 00:34:53,400 --> 00:34:57,567 Narrator: ANY MATERIAL THAT EVADES THE PULL OF A BLACK HOLE 625 00:34:57,567 --> 00:35:02,900 EVENTUALLY DIES AWAY AS ITS PROTONS DISINTEGRATE. 626 00:35:02,900 --> 00:35:06,067 A PROTON, ONE OF THE FUNDAMENTAL BUILDING BLOCKS 627 00:35:06,067 --> 00:35:08,867 OF ATOMIC MATTER, OF WHAT MAKES US UP, 628 00:35:08,867 --> 00:35:11,367 CAN JUST SPONTANEOUSLY FALL APART, 629 00:35:11,367 --> 00:35:15,233 AND IT TURNS OUT THIS TAKES A TREMENDOUSLY LONG TIME. 630 00:35:15,233 --> 00:35:17,333 BUT EVEN THAT WILL GO AWAY. 631 00:35:17,333 --> 00:35:22,400 Narrator: ALL THAT WILL BE LEFT IS A SEA OF BLACK HOLES. 632 00:35:22,400 --> 00:35:25,667 SCIENTISTS USED TO THINK BLACK HOLES WERE IMMORTAL, 633 00:35:25,667 --> 00:35:28,833 BUT EVEN THESE WILL ONE DAY DIE. 634 00:35:28,833 --> 00:35:31,533 NOW WE'RE TALKING ABOUT TIME SCALES 635 00:35:31,533 --> 00:35:33,200 OF UNIMAGINABLE LENGTH -- 636 00:35:33,200 --> 00:35:35,633 QUADRILLIONS OF YEARS INTO THE FUTURE. 637 00:35:35,633 --> 00:35:37,200 BUT ON THAT TIME SCALE, 638 00:35:37,200 --> 00:35:41,300 EVEN THE BLACK HOLES BEGIN TO EVAPORATE. 639 00:35:41,300 --> 00:35:43,533 THEY'LL GET SMALLER AND SMALLER AND SMALLER, 640 00:35:43,533 --> 00:35:45,467 AND THEN, POOF, THEY'LL BE GONE. 641 00:35:45,467 --> 00:35:47,933 Narrator: THE UNIVERSE WILL END 642 00:35:47,933 --> 00:35:50,767 WHEN THE LAST REMAINING BLACK HOLE DIES. 643 00:35:50,767 --> 00:35:53,567 AS IT GETS SMALLER, THE EVAPORATION RATE 644 00:35:53,567 --> 00:35:55,600 INCREASES EXPONENTIALLY. 645 00:35:55,600 --> 00:35:57,800 BEFORE LONG, IT REACHES A SIZE 646 00:35:57,800 --> 00:36:02,867 A BILLIONTH OF A TRILLIONTH OF A TRILLIONTH OF AN INCH. 647 00:36:02,867 --> 00:36:06,267 AT THAT INSTANT, THE LAWS OF PHYSICS BREAK DOWN, 648 00:36:06,267 --> 00:36:10,433 AND THE LAST BLACK HOLE EXPLODES IN A FLASH OF GAMMA RAYS, 649 00:36:10,433 --> 00:36:13,200 LEAVING NOTHING. 650 00:36:13,200 --> 00:36:16,800 AND IT WILL DIE IN A SUDDEN BURST OF LIGHT, 651 00:36:16,800 --> 00:36:18,467 THE LAST BURST OF LIGHT 652 00:36:18,467 --> 00:36:20,800 IN THE ENTIRE HISTORY OF THE UNIVERSE. 653 00:36:22,833 --> 00:36:24,833 Narrator: THE BIG FREEZE IS COMING. 654 00:36:24,833 --> 00:36:29,133 THE UNIVERSE WILL SUFFER A COLD, SLOW, DARK DEATH 655 00:36:29,133 --> 00:36:30,500 WHICH WILL PLAY OUT 656 00:36:30,500 --> 00:36:34,233 OVER TRILLIONS UPON TRILLIONS OF YEARS. 657 00:36:34,233 --> 00:36:37,633 BUT QUANTUM PHYSICS LEAVES THE DOOR OPEN 658 00:36:37,633 --> 00:36:39,400 FOR AN ALTERNATIVE END, 659 00:36:39,400 --> 00:36:42,833 AN EVENT SO POWERFUL, SO DESTRUCTIVE, 660 00:36:42,833 --> 00:36:48,533 THAT IT COULD DESTROY EVERYTHING WE SEE IN THE BLINK OF AN EYE. 661 00:36:48,533 --> 00:36:51,700 AND IT COULD HAPPEN TOMORROW. 662 00:37:02,800 --> 00:37:04,633 Narrator: THE END OF THE UNIVERSE -- 663 00:37:04,633 --> 00:37:06,167 IT'S COMING. 664 00:37:06,167 --> 00:37:09,567 DARK ENERGY ACCELERATES THE SPACE BETWEEN GALAXIES, 665 00:37:09,567 --> 00:37:13,133 PUSHING EVERYTHING WE SEE TO A LONG, COLD, 666 00:37:13,133 --> 00:37:15,867 AND VERY SLOW DEATH. 667 00:37:15,867 --> 00:37:19,733 UNLESS, THAT IS, SOMETHING BIZARRE HAPPENS FIRST. 668 00:37:19,733 --> 00:37:23,533 A MONSTER CALLED PHASE TRANSITION 669 00:37:23,533 --> 00:37:25,167 IS LURKING IN THE SHADOWS, 670 00:37:25,167 --> 00:37:29,100 AND IT COULD ANNIHILATE THE FABRIC OF SPACE AND TIME 671 00:37:29,100 --> 00:37:32,200 AT ANY MOMENT. 672 00:37:32,200 --> 00:37:35,967 WHEN WE COOL DOWN WATER, IT TURNS INTO ICE. 673 00:37:35,967 --> 00:37:37,467 THE PROPERTIES CHANGE. 674 00:37:37,467 --> 00:37:39,667 IF YOU LIVED IN THE WATER, WHEN IT CHANGED TO ICE, 675 00:37:39,667 --> 00:37:41,500 YOUR WORLD WOULD BE VERY DIFFERENT. 676 00:37:41,500 --> 00:37:46,700 Narrator: WATER PHASE CHANGES INTO ICE WHEN IT LOSES ENERGY. 677 00:37:46,700 --> 00:37:49,733 Tegmark: I ONCE LEFT A WATER BOTTLE IN MY CAR OVERNIGHT. 678 00:37:49,733 --> 00:37:52,633 IT WAS STILL LIQUID, BUT THE MOMENT I TOUCHED IT, 679 00:37:52,633 --> 00:37:54,067 THE SLIGHT IMPERFECTION, 680 00:37:54,067 --> 00:37:55,900 THE LITTLE BIT OF ICE THAT IT FORMED, SPREAD, 681 00:37:55,900 --> 00:37:57,767 POOF, AND FILLED UP THE WHOLE BOTTLE. 682 00:37:57,767 --> 00:38:01,733 Narrator: THAT RAPID CHANGE TO SOMETHING NEW 683 00:38:01,733 --> 00:38:03,900 IS CALLED A PHASE TRANSITION, 684 00:38:03,900 --> 00:38:09,300 AND BIZARRELY, THE SAME THING COULD HAPPEN TO EMPTY SPACE. 685 00:38:09,300 --> 00:38:12,067 WE'VE REALLY COME TO UNDERSTAND 686 00:38:12,067 --> 00:38:15,200 THAT WE SHOULDN'T TAKE FOR GRANTED THAT...VACUUM, 687 00:38:15,200 --> 00:38:17,933 WHAT WE CALL NOTHING, IS ACTUALLY STABLE. 688 00:38:17,933 --> 00:38:20,833 IT COULD BE THAT THE ENERGY STORED IN EMPTY SPACE 689 00:38:20,833 --> 00:38:23,633 IS JUST WAITING TO BE RELEASED IN A PHASE TRANSITION. 690 00:38:23,633 --> 00:38:26,767 IF IT IS, THE LAWS OF PHYSICS WILL CHANGE. 691 00:38:28,633 --> 00:38:32,333 Narrator: A SPONTANEOUS GLITCH IN THE FABRIC OF SPACE-TIME 692 00:38:32,333 --> 00:38:36,233 COULD TRIGGER A PHASE TRANSITION OF SPACE, 693 00:38:36,233 --> 00:38:40,633 A TINY BUBBLE OF NEW UNIVERSE THAT SPREADS OUT, 694 00:38:40,633 --> 00:38:42,933 OVERWRITING THE OLD. 695 00:38:42,933 --> 00:38:46,600 WE KNOW IT CAN HAPPEN, BECAUSE IT'S HAPPENED BEFORE. 696 00:38:46,600 --> 00:38:51,400 [ BURSTING, WHOOSHING ] 697 00:38:51,400 --> 00:38:53,400 AT THE MOMENT OF THE BIG BANG, 698 00:38:53,400 --> 00:38:55,467 THE UNIVERSE THAT'S FIRST CREATED 699 00:38:55,467 --> 00:38:58,833 IS COMPLETELY DIFFERENT TO THE ONE WE SEE TODAY. 700 00:38:58,833 --> 00:39:01,833 HOT AND WITHOUT FORM, 701 00:39:01,833 --> 00:39:04,433 THERE'S NO MATTER, NO TIME. 702 00:39:04,433 --> 00:39:08,067 THE LAWS OF PHYSICS ARE DIFFERENT. 703 00:39:08,067 --> 00:39:11,700 SUDDENLY, LESS THAN A TRILLIONTH OF A SECOND LATER, 704 00:39:11,700 --> 00:39:14,767 A GLITCH TRIGGERS A PHASE TRANSITION. 705 00:39:14,767 --> 00:39:18,400 A TINY BUBBLE OF THE UNIVERSE WE LIVE IN TODAY FORMS, 706 00:39:18,400 --> 00:39:20,633 AND IT RACES OUTWARD, 707 00:39:20,633 --> 00:39:22,600 DESTROYING EVERYTHING IT TOUCHES 708 00:39:22,600 --> 00:39:25,767 LIKE ICE SPREADING THROUGH WATER. 709 00:39:25,767 --> 00:39:29,500 THE ENERGY THAT SPILLS OUT CREATES THE SPACE AND TIME 710 00:39:29,500 --> 00:39:31,133 THAT WE EXIST IN, 711 00:39:31,133 --> 00:39:35,733 THE BUILDING BLOCKS OF MATTER AND THE FORCES THAT GOVERN THEM. 712 00:39:35,733 --> 00:39:38,467 ALL THAT ENERGY WAS RELEASED, PRODUCING ALL THE MATTER 713 00:39:38,467 --> 00:39:40,300 AND RADIATION WE OBSERVE IN THE UNIVERSE TODAY. 714 00:39:41,800 --> 00:39:44,633 Narrator: THE OLD UNIVERSE GIVES UP ITS ENERGY 715 00:39:44,633 --> 00:39:46,267 TO CREATE THE NEW. 716 00:39:46,267 --> 00:39:48,400 BUT IT HOLDS SOME BACK. 717 00:39:48,400 --> 00:39:52,833 THE VACUUM OF SPACE STILL HAS ENERGY BOUND TO IT. 718 00:39:52,833 --> 00:39:57,367 PERHAPS THIS IS THE DARK ENERGY WE SEE TODAY. 719 00:39:57,367 --> 00:40:00,667 PHYSICISTS BELIEVE THAT SOMEDAY IN THE FUTURE, 720 00:40:00,667 --> 00:40:04,167 A BRAND NEW GLITCH IN THE FABRIC OF SPACE-TIME 721 00:40:04,167 --> 00:40:07,100 MAY TRIGGER ANOTHER PHASE TRANSITION, 722 00:40:07,100 --> 00:40:10,667 ONE THAT WIPES US AND EVERYTHING WE SEE 723 00:40:10,667 --> 00:40:12,600 OUT OF EXISTENCE. 724 00:40:12,600 --> 00:40:16,100 THIS IS A WAY TO DESTROY AN ENTIRE UNIVERSE, 725 00:40:16,100 --> 00:40:17,867 BECAUSE WITHIN YOUR UNIVERSE 726 00:40:17,867 --> 00:40:20,367 ARE THE SEEDS OF ITS OWN DESTRUCTION. 727 00:40:20,367 --> 00:40:23,333 IT WOULD SPREAD OUT AT THE SPEED OF LIGHT IN A DEATH BUBBLE, 728 00:40:23,333 --> 00:40:26,300 RUINING ALL THE GALAXIES AS IT PASSES THROUGH, 729 00:40:26,300 --> 00:40:30,000 AND ULTIMATELY COMPLETELY DESTROYING OUR UNIVERSE. 730 00:40:30,000 --> 00:40:33,500 Narrator: NOTHING CAN SURVIVE THE EXPANDING PHASE TRANSITION. 731 00:40:33,500 --> 00:40:38,300 PLANETS, NEBULAS, GALAXIES -- ALL ARE RIPPED APART 732 00:40:38,300 --> 00:40:40,600 AS THE BOUNDARY OF THE BUBBLE REACHES THEM. 733 00:40:40,600 --> 00:40:43,833 INSIDE THIS BUBBLE, PROTONS ARE UNSTABLE, 734 00:40:43,833 --> 00:40:47,667 ATOMS BEGIN TO REARRANGE IN A NEW FORM OF MATTER. 735 00:40:47,667 --> 00:40:49,700 AS THESE BUBBLES BEGIN TO EXPAND, 736 00:40:49,700 --> 00:40:52,333 A NEW UNIVERSE IS BEING BORN 737 00:40:52,333 --> 00:40:55,000 IN THE CORPSE OF THE OLD UNIVERSE, 738 00:40:55,000 --> 00:40:59,333 AND THE BEGINNING OF A NEW LAW OF PHYSICS. 739 00:40:59,333 --> 00:41:03,067 AND SO, THE EXPANDING UNIVERSE WE NOW SEE 740 00:41:03,067 --> 00:41:06,467 MAY END IN A PHASE TRANSITION, BUT WE WON'T KNOW WHAT HIT US, 741 00:41:06,467 --> 00:41:08,400 'CAUSE THE LAWS OF PHYSICS WILL CHANGE, 742 00:41:08,400 --> 00:41:11,133 AND WE WILL ESSENTIALLY MOST LIKELY DISAPPEAR 743 00:41:11,133 --> 00:41:12,900 AT THE INSTANT IT HAPPENS. 744 00:41:12,900 --> 00:41:16,567 Kaku: THIS BUBBLE WILL EXPAND AT THE SPEED OF LIGHT, 745 00:41:16,567 --> 00:41:18,433 AND AS THE BUBBLE PASSES YOU, 746 00:41:18,433 --> 00:41:21,467 ALL THE ATOMS OF YOUR BODY REARRANGE THEMSELVES, 747 00:41:21,467 --> 00:41:23,167 AND YOU WOULD NEVER KNOW IT. 748 00:41:23,167 --> 00:41:25,867 YOU WOULD HAVE NO WARNING, BECAUSE THE BUBBLE ITSELF 749 00:41:25,867 --> 00:41:27,733 IS EXPANDING AT THE SPEED OF LIGHT. 750 00:41:27,733 --> 00:41:30,333 YOU CAN'T PREDICT PRECISELY WHEN IT COULD HAPPEN. 751 00:41:30,333 --> 00:41:31,967 YOU ONLY HAVE A PROBABILITY. 752 00:41:31,967 --> 00:41:34,200 SO WHAT YOU REALLY ARE PREDICTING IS A RATE. 753 00:41:34,200 --> 00:41:37,367 DOES IT HAPPEN ONCE A YEAR? ONCE EVERY 10 BILLION YEARS? 754 00:41:37,367 --> 00:41:39,600 ONCE EVERY GOOGOL YEARS? OR WHATEVER. 755 00:41:39,600 --> 00:41:42,900 IT'S VERY POSSIBLE THAT THESE BUBBLES GET NUCLEATED 756 00:41:42,900 --> 00:41:46,533 AND GROW ABOUT ONCE EVERY 10 OR 20 BILLION YEARS. 757 00:41:46,533 --> 00:41:49,167 SO IT HASN'T HAPPENED YET BECAUSE WE GOT LUCKY. 758 00:41:49,167 --> 00:41:52,100 IT'S UNLIKELY IT WOULD HAPPEN THE NEXT YEAR OR THE NEXT DAY, 759 00:41:52,100 --> 00:41:54,167 BUT THE LAWS OF PHYSICS ABSOLUTELY ALLOW IT. 760 00:41:58,500 --> 00:42:02,833 Narrator: A PHASE CHANGE MAY HAPPEN, OR IT MAY NOT. 761 00:42:03,967 --> 00:42:08,100 THE UNIVERSE PLAYS ITS CARDS CLOSE TO ITS CHEST. 762 00:42:11,933 --> 00:42:15,133 AND, LIKE DARK ENERGY AND DARK MATTER, 763 00:42:15,133 --> 00:42:17,100 THERE MAY BE MORE SURPRISES TO COME... 764 00:42:17,100 --> 00:42:18,900 [ RUMBLING ] 765 00:42:18,900 --> 00:42:23,767 ...SURPRISES THAT WILL ONLY ADD TO THE MYSTERY AND WONDER 766 00:42:23,767 --> 00:42:26,400 OUR UNIVERSE HOLDS FOR US. 767 00:42:29,767 --> 00:42:31,400 Oluseyi: WHATEVER THE UNIVERSE IS UP TO, 768 00:42:31,400 --> 00:42:32,767 WE STILL DON'T KNOW ENOUGH. 769 00:42:32,767 --> 00:42:34,867 WE'RE IN AN AGE OF DISCOVERY RIGHT NOW. 770 00:42:34,867 --> 00:42:36,767 PERHAPS THERE IS SOMETHING ELSE OUT THERE 771 00:42:36,767 --> 00:42:38,133 THAT WE DON'T KNOW ABOUT. 772 00:42:38,133 --> 00:42:40,533 SO, I'M NOT GOING TO DRAW ANY CONCLUSIONS 773 00:42:40,533 --> 00:42:42,233 UNTIL THINGS ARE CONCLUSIVE. 774 00:42:42,233 --> 00:42:44,933 [ WHOOSHING ] 775 00:42:44,933 --> 00:42:47,433 Krauss: WE DON'T UNDERSTAND THE NATURE OF DARK ENERGY. 776 00:42:47,433 --> 00:42:51,067 AND WITHOUT THAT UNDERSTANDING, VIRTUALLY ANYTHING IS POSSIBLE. 777 00:42:51,067 --> 00:42:53,067 THE FUTURE IS STILL UNCERTAIN, 778 00:42:53,067 --> 00:42:55,400 AND THAT MEANS THERE'S STILL A MYSTERY. 779 00:42:55,400 --> 00:42:58,767 AND FOR ME, THAT'S THE MOST EXCITING POSSIBILITY OF ALL.