[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:02.00,Default,,0000,0000,0000,,A few months ago
Dialogue: 0,0:00:02.00,0:00:04.00,Default,,0000,0000,0000,,the Nobel Prize in physics
Dialogue: 0,0:00:04.00,0:00:06.00,Default,,0000,0000,0000,,was awarded to two teams of astronomers
Dialogue: 0,0:00:06.00,0:00:09.00,Default,,0000,0000,0000,,for a discovery that has been hailed
Dialogue: 0,0:00:09.00,0:00:11.00,Default,,0000,0000,0000,,as one of the most important
Dialogue: 0,0:00:11.00,0:00:13.00,Default,,0000,0000,0000,,astronomical observations ever.
Dialogue: 0,0:00:13.00,0:00:15.00,Default,,0000,0000,0000,,And today, after briefly describing what they found,
Dialogue: 0,0:00:15.00,0:00:18.00,Default,,0000,0000,0000,,I'm going to tell you about a highly controversial framework
Dialogue: 0,0:00:18.00,0:00:21.00,Default,,0000,0000,0000,,for explaining their discovery,
Dialogue: 0,0:00:21.00,0:00:23.00,Default,,0000,0000,0000,,namely the possibility
Dialogue: 0,0:00:23.00,0:00:25.00,Default,,0000,0000,0000,,that way beyond the Earth,
Dialogue: 0,0:00:25.00,0:00:28.00,Default,,0000,0000,0000,,the Milky Way and other distant galaxies,
Dialogue: 0,0:00:28.00,0:00:30.00,Default,,0000,0000,0000,,we may find that our universe
Dialogue: 0,0:00:30.00,0:00:32.00,Default,,0000,0000,0000,,is not the only universe,
Dialogue: 0,0:00:32.00,0:00:34.00,Default,,0000,0000,0000,,but is instead
Dialogue: 0,0:00:34.00,0:00:36.00,Default,,0000,0000,0000,,part of a vast complex of universes
Dialogue: 0,0:00:36.00,0:00:38.00,Default,,0000,0000,0000,,that we call the multiverse.
Dialogue: 0,0:00:38.00,0:00:41.00,Default,,0000,0000,0000,,Now the idea of a multiverse is a strange one.
Dialogue: 0,0:00:41.00,0:00:43.00,Default,,0000,0000,0000,,I mean, most of us were raised to believe
Dialogue: 0,0:00:43.00,0:00:46.00,Default,,0000,0000,0000,,that the word "universe" means everything.
Dialogue: 0,0:00:46.00,0:00:49.00,Default,,0000,0000,0000,,And I say most of us with forethought,
Dialogue: 0,0:00:49.00,0:00:52.00,Default,,0000,0000,0000,,as my four-year-old daughter has heard me speak of these ideas since she was born.
Dialogue: 0,0:00:52.00,0:00:54.00,Default,,0000,0000,0000,,And last year I was holding her
Dialogue: 0,0:00:54.00,0:00:56.00,Default,,0000,0000,0000,,and I said, "Sophia,
Dialogue: 0,0:00:56.00,0:00:59.00,Default,,0000,0000,0000,,I love you more than anything in the universe."
Dialogue: 0,0:00:59.00,0:01:01.00,Default,,0000,0000,0000,,And she turned to me and said, "Daddy,
Dialogue: 0,0:01:01.00,0:01:03.00,Default,,0000,0000,0000,,universe or multiverse?"
Dialogue: 0,0:01:03.00,0:01:06.00,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:01:06.00,0:01:09.00,Default,,0000,0000,0000,,But barring such an anomalous upbringing,
Dialogue: 0,0:01:09.00,0:01:11.00,Default,,0000,0000,0000,,it is strange to imagine
Dialogue: 0,0:01:11.00,0:01:13.00,Default,,0000,0000,0000,,other realms separate from ours,
Dialogue: 0,0:01:13.00,0:01:15.00,Default,,0000,0000,0000,,most with fundamentally different features,
Dialogue: 0,0:01:15.00,0:01:18.00,Default,,0000,0000,0000,,that would rightly be called universes of their own.
Dialogue: 0,0:01:18.00,0:01:20.00,Default,,0000,0000,0000,,And yet,
Dialogue: 0,0:01:20.00,0:01:22.00,Default,,0000,0000,0000,,speculative though the idea surely is,
Dialogue: 0,0:01:22.00,0:01:24.00,Default,,0000,0000,0000,,I aim to convince you
Dialogue: 0,0:01:24.00,0:01:26.00,Default,,0000,0000,0000,,that there's reason for taking it seriously,
Dialogue: 0,0:01:26.00,0:01:28.00,Default,,0000,0000,0000,,as it just might be right.
Dialogue: 0,0:01:28.00,0:01:31.00,Default,,0000,0000,0000,,I'm going to tell the story of the multiverse in three parts.
Dialogue: 0,0:01:31.00,0:01:33.00,Default,,0000,0000,0000,,In part one,
Dialogue: 0,0:01:33.00,0:01:35.00,Default,,0000,0000,0000,,I'm going to describe those Nobel Prize-winning results
Dialogue: 0,0:01:35.00,0:01:37.00,Default,,0000,0000,0000,,and to highlight a profound mystery
Dialogue: 0,0:01:37.00,0:01:39.00,Default,,0000,0000,0000,,which those results revealed.
Dialogue: 0,0:01:39.00,0:01:41.00,Default,,0000,0000,0000,,In part two,
Dialogue: 0,0:01:41.00,0:01:43.00,Default,,0000,0000,0000,,I'll offer a solution to that mystery.
Dialogue: 0,0:01:43.00,0:01:45.00,Default,,0000,0000,0000,,It's based on an approach called string theory,
Dialogue: 0,0:01:45.00,0:01:47.00,Default,,0000,0000,0000,,and that's where the idea of the multiverse
Dialogue: 0,0:01:47.00,0:01:49.00,Default,,0000,0000,0000,,will come into the story.
Dialogue: 0,0:01:49.00,0:01:51.00,Default,,0000,0000,0000,,Finally, in part three,
Dialogue: 0,0:01:51.00,0:01:53.00,Default,,0000,0000,0000,,I'm going to describe a cosmological theory
Dialogue: 0,0:01:53.00,0:01:55.00,Default,,0000,0000,0000,,called inflation,
Dialogue: 0,0:01:55.00,0:01:58.00,Default,,0000,0000,0000,,which will pull all the pieces of the story together.
Dialogue: 0,0:01:58.00,0:02:02.00,Default,,0000,0000,0000,,Okay, part one starts back in 1929
Dialogue: 0,0:02:02.00,0:02:04.00,Default,,0000,0000,0000,,when the great astronomer Edwin Hubble
Dialogue: 0,0:02:04.00,0:02:07.00,Default,,0000,0000,0000,,realized that the distant galaxies
Dialogue: 0,0:02:07.00,0:02:09.00,Default,,0000,0000,0000,,were all rushing away from us,
Dialogue: 0,0:02:09.00,0:02:11.00,Default,,0000,0000,0000,,establishing that space itself is stretching,
Dialogue: 0,0:02:11.00,0:02:13.00,Default,,0000,0000,0000,,it's expanding.
Dialogue: 0,0:02:13.00,0:02:16.00,Default,,0000,0000,0000,,Now this was revolutionary.
Dialogue: 0,0:02:16.00,0:02:19.00,Default,,0000,0000,0000,,The prevailing wisdom was that on the largest of scales
Dialogue: 0,0:02:19.00,0:02:21.00,Default,,0000,0000,0000,,the universe was static.
Dialogue: 0,0:02:21.00,0:02:23.00,Default,,0000,0000,0000,,But even so,
Dialogue: 0,0:02:23.00,0:02:26.00,Default,,0000,0000,0000,,there was one thing that everyone was certain of:
Dialogue: 0,0:02:26.00,0:02:29.00,Default,,0000,0000,0000,,The expansion must be slowing down.
Dialogue: 0,0:02:29.00,0:02:32.00,Default,,0000,0000,0000,,That, much as the gravitational pull of the Earth
Dialogue: 0,0:02:32.00,0:02:35.00,Default,,0000,0000,0000,,slows the ascent of an apple tossed upward,
Dialogue: 0,0:02:35.00,0:02:37.00,Default,,0000,0000,0000,,the gravitational pull
Dialogue: 0,0:02:37.00,0:02:39.00,Default,,0000,0000,0000,,of each galaxy on every other
Dialogue: 0,0:02:39.00,0:02:41.00,Default,,0000,0000,0000,,must be slowing
Dialogue: 0,0:02:41.00,0:02:43.00,Default,,0000,0000,0000,,the expansion of space.
Dialogue: 0,0:02:43.00,0:02:46.00,Default,,0000,0000,0000,,Now let's fast-forward to the 1990s
Dialogue: 0,0:02:46.00,0:02:48.00,Default,,0000,0000,0000,,when those two teams of astronomers
Dialogue: 0,0:02:48.00,0:02:50.00,Default,,0000,0000,0000,,I mentioned at the outset
Dialogue: 0,0:02:50.00,0:02:52.00,Default,,0000,0000,0000,,were inspired by this reasoning
Dialogue: 0,0:02:52.00,0:02:54.00,Default,,0000,0000,0000,,to measure the rate
Dialogue: 0,0:02:54.00,0:02:56.00,Default,,0000,0000,0000,,at which the expansion has been slowing.
Dialogue: 0,0:02:56.00,0:02:58.00,Default,,0000,0000,0000,,And they did this
Dialogue: 0,0:02:58.00,0:03:00.00,Default,,0000,0000,0000,,by painstaking observations
Dialogue: 0,0:03:00.00,0:03:02.00,Default,,0000,0000,0000,,of numerous distant galaxies,
Dialogue: 0,0:03:02.00,0:03:04.00,Default,,0000,0000,0000,,allowing them to chart
Dialogue: 0,0:03:04.00,0:03:07.00,Default,,0000,0000,0000,,how the expansion rate has changed over time.
Dialogue: 0,0:03:07.00,0:03:10.00,Default,,0000,0000,0000,,Here's the surprise:
Dialogue: 0,0:03:10.00,0:03:13.00,Default,,0000,0000,0000,,They found that the expansion is not slowing down.
Dialogue: 0,0:03:13.00,0:03:15.00,Default,,0000,0000,0000,,Instead they found that it's speeding up,
Dialogue: 0,0:03:15.00,0:03:17.00,Default,,0000,0000,0000,,going faster and faster.
Dialogue: 0,0:03:17.00,0:03:19.00,Default,,0000,0000,0000,,That's like tossing an apple upward
Dialogue: 0,0:03:19.00,0:03:21.00,Default,,0000,0000,0000,,and it goes up faster and faster.
Dialogue: 0,0:03:21.00,0:03:23.00,Default,,0000,0000,0000,,Now if you saw an apple do that,
Dialogue: 0,0:03:23.00,0:03:25.00,Default,,0000,0000,0000,,you'd want to know why.
Dialogue: 0,0:03:25.00,0:03:27.00,Default,,0000,0000,0000,,What's pushing on it?
Dialogue: 0,0:03:27.00,0:03:29.00,Default,,0000,0000,0000,,Similarly, the astronomers' results
Dialogue: 0,0:03:29.00,0:03:32.00,Default,,0000,0000,0000,,are surely well-deserving of the Nobel Prize,
Dialogue: 0,0:03:32.00,0:03:36.00,Default,,0000,0000,0000,,but they raised an analogous question.
Dialogue: 0,0:03:36.00,0:03:38.00,Default,,0000,0000,0000,,What force is driving all galaxies
Dialogue: 0,0:03:38.00,0:03:41.00,Default,,0000,0000,0000,,to rush away from every other
Dialogue: 0,0:03:41.00,0:03:44.00,Default,,0000,0000,0000,,at an ever-quickening speed?
Dialogue: 0,0:03:44.00,0:03:46.00,Default,,0000,0000,0000,,Well the most promising answer
Dialogue: 0,0:03:46.00,0:03:49.00,Default,,0000,0000,0000,,comes from an old idea of Einstein's.
Dialogue: 0,0:03:49.00,0:03:51.00,Default,,0000,0000,0000,,You see, we are all used to gravity
Dialogue: 0,0:03:51.00,0:03:54.00,Default,,0000,0000,0000,,being a force that does one thing,
Dialogue: 0,0:03:54.00,0:03:56.00,Default,,0000,0000,0000,,pulls objects together.
Dialogue: 0,0:03:56.00,0:03:58.00,Default,,0000,0000,0000,,But in Einstein's theory of gravity,
Dialogue: 0,0:03:58.00,0:04:00.00,Default,,0000,0000,0000,,his general theory of relativity,
Dialogue: 0,0:04:00.00,0:04:03.00,Default,,0000,0000,0000,,gravity can also push things apart.
Dialogue: 0,0:04:03.00,0:04:06.00,Default,,0000,0000,0000,,How? Well according to Einstein's math,
Dialogue: 0,0:04:06.00,0:04:08.00,Default,,0000,0000,0000,,if space is uniformly filled
Dialogue: 0,0:04:08.00,0:04:10.00,Default,,0000,0000,0000,,with an invisible energy,
Dialogue: 0,0:04:10.00,0:04:13.00,Default,,0000,0000,0000,,sort of like a uniform, invisible mist,
Dialogue: 0,0:04:13.00,0:04:16.00,Default,,0000,0000,0000,,then the gravity generated by that mist
Dialogue: 0,0:04:16.00,0:04:18.00,Default,,0000,0000,0000,,would be repulsive,
Dialogue: 0,0:04:18.00,0:04:20.00,Default,,0000,0000,0000,,repulsive gravity,
Dialogue: 0,0:04:20.00,0:04:23.00,Default,,0000,0000,0000,,which is just what we need to explain the observations.
Dialogue: 0,0:04:23.00,0:04:25.00,Default,,0000,0000,0000,,Because the repulsive gravity
Dialogue: 0,0:04:25.00,0:04:27.00,Default,,0000,0000,0000,,of an invisible energy in space --
Dialogue: 0,0:04:27.00,0:04:29.00,Default,,0000,0000,0000,,we now call it dark energy,
Dialogue: 0,0:04:29.00,0:04:32.00,Default,,0000,0000,0000,,but I've made it smokey white here so you can see it --
Dialogue: 0,0:04:32.00,0:04:34.00,Default,,0000,0000,0000,,its repulsive gravity
Dialogue: 0,0:04:34.00,0:04:36.00,Default,,0000,0000,0000,,would cause each galaxy to push against every other,
Dialogue: 0,0:04:36.00,0:04:38.00,Default,,0000,0000,0000,,driving expansion to speed up,
Dialogue: 0,0:04:38.00,0:04:40.00,Default,,0000,0000,0000,,not slow down.
Dialogue: 0,0:04:40.00,0:04:42.00,Default,,0000,0000,0000,,And this explanation
Dialogue: 0,0:04:42.00,0:04:44.00,Default,,0000,0000,0000,,represents great progress.
Dialogue: 0,0:04:44.00,0:04:47.00,Default,,0000,0000,0000,,But I promised you a mystery
Dialogue: 0,0:04:47.00,0:04:49.00,Default,,0000,0000,0000,,here in part one.
Dialogue: 0,0:04:49.00,0:04:51.00,Default,,0000,0000,0000,,Here it is.
Dialogue: 0,0:04:51.00,0:04:53.00,Default,,0000,0000,0000,,When the astronomers worked out
Dialogue: 0,0:04:53.00,0:04:56.00,Default,,0000,0000,0000,,how much of this dark energy
Dialogue: 0,0:04:56.00,0:04:58.00,Default,,0000,0000,0000,,must be infusing space
Dialogue: 0,0:04:58.00,0:05:00.00,Default,,0000,0000,0000,,to account for the cosmic speed up,
Dialogue: 0,0:05:00.00,0:05:02.00,Default,,0000,0000,0000,,look at what they found.
Dialogue: 0,0:05:09.00,0:05:11.00,Default,,0000,0000,0000,,This number is small.
Dialogue: 0,0:05:11.00,0:05:13.00,Default,,0000,0000,0000,,Expressed in the relevant unit,
Dialogue: 0,0:05:13.00,0:05:15.00,Default,,0000,0000,0000,,it is spectacularly small.
Dialogue: 0,0:05:15.00,0:05:18.00,Default,,0000,0000,0000,,And the mystery is to explain this peculiar number.
Dialogue: 0,0:05:18.00,0:05:20.00,Default,,0000,0000,0000,,We want this number
Dialogue: 0,0:05:20.00,0:05:22.00,Default,,0000,0000,0000,,to emerge from the laws of physics,
Dialogue: 0,0:05:22.00,0:05:25.00,Default,,0000,0000,0000,,but so far no one has found a way to do that.
Dialogue: 0,0:05:25.00,0:05:28.00,Default,,0000,0000,0000,,Now you might wonder,
Dialogue: 0,0:05:28.00,0:05:30.00,Default,,0000,0000,0000,,should you care?
Dialogue: 0,0:05:30.00,0:05:32.00,Default,,0000,0000,0000,,Maybe explaining this number
Dialogue: 0,0:05:32.00,0:05:34.00,Default,,0000,0000,0000,,is just a technical issue,
Dialogue: 0,0:05:34.00,0:05:37.00,Default,,0000,0000,0000,,a technical detail of interest to experts,
Dialogue: 0,0:05:37.00,0:05:39.00,Default,,0000,0000,0000,,but of no relevance to anybody else.
Dialogue: 0,0:05:39.00,0:05:42.00,Default,,0000,0000,0000,,Well it surely is a technical detail,
Dialogue: 0,0:05:42.00,0:05:44.00,Default,,0000,0000,0000,,but some details really matter.
Dialogue: 0,0:05:44.00,0:05:46.00,Default,,0000,0000,0000,,Some details provide
Dialogue: 0,0:05:46.00,0:05:48.00,Default,,0000,0000,0000,,windows into uncharted realms of reality,
Dialogue: 0,0:05:48.00,0:05:51.00,Default,,0000,0000,0000,,and this peculiar number may be doing just that,
Dialogue: 0,0:05:51.00,0:05:54.00,Default,,0000,0000,0000,,as the only approach that's so far made headway to explain it
Dialogue: 0,0:05:54.00,0:05:57.00,Default,,0000,0000,0000,,invokes the possibility of other universes --
Dialogue: 0,0:05:57.00,0:06:00.00,Default,,0000,0000,0000,,an idea that naturally emerges from string theory,
Dialogue: 0,0:06:00.00,0:06:03.00,Default,,0000,0000,0000,,which takes me to part two: string theory.
Dialogue: 0,0:06:03.00,0:06:07.00,Default,,0000,0000,0000,,So hold the mystery of the dark energy
Dialogue: 0,0:06:07.00,0:06:09.00,Default,,0000,0000,0000,,in the back of your mind
Dialogue: 0,0:06:09.00,0:06:11.00,Default,,0000,0000,0000,,as I now go on to tell you
Dialogue: 0,0:06:11.00,0:06:14.00,Default,,0000,0000,0000,,three key things about string theory.
Dialogue: 0,0:06:14.00,0:06:16.00,Default,,0000,0000,0000,,First off, what is it?
Dialogue: 0,0:06:16.00,0:06:19.00,Default,,0000,0000,0000,,Well it's an approach to realize Einstein's dream
Dialogue: 0,0:06:19.00,0:06:22.00,Default,,0000,0000,0000,,of a unified theory of physics,
Dialogue: 0,0:06:22.00,0:06:24.00,Default,,0000,0000,0000,,a single overarching framework
Dialogue: 0,0:06:24.00,0:06:26.00,Default,,0000,0000,0000,,that would be able to describe
Dialogue: 0,0:06:26.00,0:06:28.00,Default,,0000,0000,0000,,all the forces at work in the universe.
Dialogue: 0,0:06:28.00,0:06:30.00,Default,,0000,0000,0000,,And the central idea of string theory
Dialogue: 0,0:06:30.00,0:06:32.00,Default,,0000,0000,0000,,is quite straightforward.
Dialogue: 0,0:06:32.00,0:06:34.00,Default,,0000,0000,0000,,It says that if you examine
Dialogue: 0,0:06:34.00,0:06:36.00,Default,,0000,0000,0000,,any piece of matter ever more finely,
Dialogue: 0,0:06:36.00,0:06:38.00,Default,,0000,0000,0000,,at first you'll find molecules
Dialogue: 0,0:06:38.00,0:06:41.00,Default,,0000,0000,0000,,and then you'll find atoms and subatomic particles.
Dialogue: 0,0:06:41.00,0:06:43.00,Default,,0000,0000,0000,,But the theory says that if you could probe smaller,
Dialogue: 0,0:06:43.00,0:06:46.00,Default,,0000,0000,0000,,much smaller than we can with existing technology,
Dialogue: 0,0:06:46.00,0:06:49.00,Default,,0000,0000,0000,,you'd find something else inside these particles --
Dialogue: 0,0:06:49.00,0:06:52.00,Default,,0000,0000,0000,,a little tiny vibrating filament of energy,
Dialogue: 0,0:06:52.00,0:06:55.00,Default,,0000,0000,0000,,a little tiny vibrating string.
Dialogue: 0,0:06:55.00,0:06:57.00,Default,,0000,0000,0000,,And just like the strings on a violin,
Dialogue: 0,0:06:57.00,0:06:59.00,Default,,0000,0000,0000,,they can vibrate in different patterns
Dialogue: 0,0:06:59.00,0:07:01.00,Default,,0000,0000,0000,,producing different musical notes.
Dialogue: 0,0:07:01.00,0:07:03.00,Default,,0000,0000,0000,,These little fundamental strings,
Dialogue: 0,0:07:03.00,0:07:05.00,Default,,0000,0000,0000,,when they vibrate in different patterns,
Dialogue: 0,0:07:05.00,0:07:07.00,Default,,0000,0000,0000,,they produce different kinds of particles --
Dialogue: 0,0:07:07.00,0:07:09.00,Default,,0000,0000,0000,,so electrons, quarks, neutrinos, photons,
Dialogue: 0,0:07:09.00,0:07:11.00,Default,,0000,0000,0000,,all other particles
Dialogue: 0,0:07:11.00,0:07:13.00,Default,,0000,0000,0000,,would be united into a single framework,
Dialogue: 0,0:07:13.00,0:07:16.00,Default,,0000,0000,0000,,as they would all arise from vibrating strings.
Dialogue: 0,0:07:16.00,0:07:19.00,Default,,0000,0000,0000,,It's a compelling picture,
Dialogue: 0,0:07:19.00,0:07:21.00,Default,,0000,0000,0000,,a kind of cosmic symphony,
Dialogue: 0,0:07:21.00,0:07:23.00,Default,,0000,0000,0000,,where all the richness
Dialogue: 0,0:07:23.00,0:07:25.00,Default,,0000,0000,0000,,that we see in the world around us
Dialogue: 0,0:07:25.00,0:07:27.00,Default,,0000,0000,0000,,emerges from the music
Dialogue: 0,0:07:27.00,0:07:30.00,Default,,0000,0000,0000,,that these little, tiny strings can play.
Dialogue: 0,0:07:30.00,0:07:32.00,Default,,0000,0000,0000,,But there's a cost
Dialogue: 0,0:07:32.00,0:07:34.00,Default,,0000,0000,0000,,to this elegant unification,
Dialogue: 0,0:07:34.00,0:07:36.00,Default,,0000,0000,0000,,because years of research
Dialogue: 0,0:07:36.00,0:07:39.00,Default,,0000,0000,0000,,have shown that the math of string theory doesn't quite work.
Dialogue: 0,0:07:39.00,0:07:41.00,Default,,0000,0000,0000,,It has internal inconsistencies,
Dialogue: 0,0:07:41.00,0:07:43.00,Default,,0000,0000,0000,,unless we allow
Dialogue: 0,0:07:43.00,0:07:46.00,Default,,0000,0000,0000,,for something wholly unfamiliar --
Dialogue: 0,0:07:46.00,0:07:49.00,Default,,0000,0000,0000,,extra dimensions of space.
Dialogue: 0,0:07:49.00,0:07:52.00,Default,,0000,0000,0000,,That is, we all know about the usual three dimensions of space.
Dialogue: 0,0:07:52.00,0:07:54.00,Default,,0000,0000,0000,,And you can think about those
Dialogue: 0,0:07:54.00,0:07:57.00,Default,,0000,0000,0000,,as height, width and depth.
Dialogue: 0,0:07:57.00,0:08:00.00,Default,,0000,0000,0000,,But string theory says that, on fantastically small scales,
Dialogue: 0,0:08:00.00,0:08:02.00,Default,,0000,0000,0000,,there are additional dimensions
Dialogue: 0,0:08:02.00,0:08:04.00,Default,,0000,0000,0000,,crumpled to a tiny size so small
Dialogue: 0,0:08:04.00,0:08:06.00,Default,,0000,0000,0000,,that we have not detected them.
Dialogue: 0,0:08:06.00,0:08:08.00,Default,,0000,0000,0000,,But even though the dimensions are hidden,
Dialogue: 0,0:08:08.00,0:08:11.00,Default,,0000,0000,0000,,they would have an impact on things that we can observe
Dialogue: 0,0:08:11.00,0:08:14.00,Default,,0000,0000,0000,,because the shape of the extra dimensions
Dialogue: 0,0:08:14.00,0:08:17.00,Default,,0000,0000,0000,,constrains how the strings can vibrate.
Dialogue: 0,0:08:17.00,0:08:19.00,Default,,0000,0000,0000,,And in string theory,
Dialogue: 0,0:08:19.00,0:08:22.00,Default,,0000,0000,0000,,vibration determines everything.
Dialogue: 0,0:08:22.00,0:08:24.00,Default,,0000,0000,0000,,So particle masses, the strengths of forces,
Dialogue: 0,0:08:24.00,0:08:27.00,Default,,0000,0000,0000,,and most importantly, the amount of dark energy
Dialogue: 0,0:08:27.00,0:08:29.00,Default,,0000,0000,0000,,would be determined
Dialogue: 0,0:08:29.00,0:08:31.00,Default,,0000,0000,0000,,by the shape of the extra dimensions.
Dialogue: 0,0:08:31.00,0:08:34.00,Default,,0000,0000,0000,,So if we knew the shape of the extra dimensions,
Dialogue: 0,0:08:34.00,0:08:37.00,Default,,0000,0000,0000,,we should be able to calculate these features,
Dialogue: 0,0:08:37.00,0:08:40.00,Default,,0000,0000,0000,,calculate the amount of dark energy.
Dialogue: 0,0:08:40.00,0:08:42.00,Default,,0000,0000,0000,,The challenge
Dialogue: 0,0:08:42.00,0:08:44.00,Default,,0000,0000,0000,,is we don't know
Dialogue: 0,0:08:44.00,0:08:47.00,Default,,0000,0000,0000,,the shape of the extra dimensions.
Dialogue: 0,0:08:47.00,0:08:49.00,Default,,0000,0000,0000,,All we have
Dialogue: 0,0:08:49.00,0:08:51.00,Default,,0000,0000,0000,,is a list of candidate shapes
Dialogue: 0,0:08:51.00,0:08:54.00,Default,,0000,0000,0000,,allowed by the math.
Dialogue: 0,0:08:54.00,0:08:56.00,Default,,0000,0000,0000,,Now when these ideas were first developed,
Dialogue: 0,0:08:56.00,0:08:58.00,Default,,0000,0000,0000,,there were only about five different candidate shapes,
Dialogue: 0,0:08:58.00,0:09:00.00,Default,,0000,0000,0000,,so you can imagine
Dialogue: 0,0:09:00.00,0:09:02.00,Default,,0000,0000,0000,,analyzing them one-by-one
Dialogue: 0,0:09:02.00,0:09:04.00,Default,,0000,0000,0000,,to determine if any yield
Dialogue: 0,0:09:04.00,0:09:06.00,Default,,0000,0000,0000,,the physical features we observe.
Dialogue: 0,0:09:06.00,0:09:08.00,Default,,0000,0000,0000,,But over time the list grew
Dialogue: 0,0:09:08.00,0:09:10.00,Default,,0000,0000,0000,,as researchers found other candidate shapes.
Dialogue: 0,0:09:10.00,0:09:13.00,Default,,0000,0000,0000,,From five, the number grew into the hundreds and then the thousands --
Dialogue: 0,0:09:13.00,0:09:16.00,Default,,0000,0000,0000,,A large, but still manageable, collection to analyze,
Dialogue: 0,0:09:16.00,0:09:18.00,Default,,0000,0000,0000,,since after all,
Dialogue: 0,0:09:18.00,0:09:21.00,Default,,0000,0000,0000,,graduate students need something to do.
Dialogue: 0,0:09:21.00,0:09:23.00,Default,,0000,0000,0000,,But then the list continued to grow
Dialogue: 0,0:09:23.00,0:09:26.00,Default,,0000,0000,0000,,into the millions and the billions, until today.
Dialogue: 0,0:09:26.00,0:09:28.00,Default,,0000,0000,0000,,The list of candidate shapes
Dialogue: 0,0:09:28.00,0:09:33.00,Default,,0000,0000,0000,,has soared to about 10 to the 500.
Dialogue: 0,0:09:33.00,0:09:36.00,Default,,0000,0000,0000,,So, what to do?
Dialogue: 0,0:09:36.00,0:09:39.00,Default,,0000,0000,0000,,Well some researchers lost heart,
Dialogue: 0,0:09:39.00,0:09:42.00,Default,,0000,0000,0000,,concluding that was so many candidate shapes for the extra dimensions,
Dialogue: 0,0:09:42.00,0:09:45.00,Default,,0000,0000,0000,,each giving rise to different physical features,
Dialogue: 0,0:09:45.00,0:09:47.00,Default,,0000,0000,0000,,string theory would never make
Dialogue: 0,0:09:47.00,0:09:49.00,Default,,0000,0000,0000,,definitive, testable predictions.
Dialogue: 0,0:09:49.00,0:09:53.00,Default,,0000,0000,0000,,But others turned this issue on its head,
Dialogue: 0,0:09:53.00,0:09:55.00,Default,,0000,0000,0000,,taking us to the possibility of a multiverse.
Dialogue: 0,0:09:55.00,0:09:57.00,Default,,0000,0000,0000,,Here's the idea.
Dialogue: 0,0:09:57.00,0:10:00.00,Default,,0000,0000,0000,,Maybe each of these shapes is on an equal footing with every other.
Dialogue: 0,0:10:00.00,0:10:02.00,Default,,0000,0000,0000,,Each is as real as every other,
Dialogue: 0,0:10:02.00,0:10:04.00,Default,,0000,0000,0000,,in the sense
Dialogue: 0,0:10:04.00,0:10:06.00,Default,,0000,0000,0000,,that there are many universes,
Dialogue: 0,0:10:06.00,0:10:09.00,Default,,0000,0000,0000,,each with a different shape, for the extra dimensions.
Dialogue: 0,0:10:09.00,0:10:11.00,Default,,0000,0000,0000,,And this radical proposal
Dialogue: 0,0:10:11.00,0:10:14.00,Default,,0000,0000,0000,,has a profound impact on this mystery:
Dialogue: 0,0:10:14.00,0:10:17.00,Default,,0000,0000,0000,,the amount of dark energy revealed by the Nobel Prize-winning results.
Dialogue: 0,0:10:17.00,0:10:19.00,Default,,0000,0000,0000,,Because you see,
Dialogue: 0,0:10:19.00,0:10:22.00,Default,,0000,0000,0000,,if there are other universes,
Dialogue: 0,0:10:22.00,0:10:24.00,Default,,0000,0000,0000,,and if those universes
Dialogue: 0,0:10:24.00,0:10:28.00,Default,,0000,0000,0000,,each have, say, a different shape for the extra dimensions,
Dialogue: 0,0:10:28.00,0:10:30.00,Default,,0000,0000,0000,,then the physical features of each universe will be different,
Dialogue: 0,0:10:30.00,0:10:32.00,Default,,0000,0000,0000,,and in particular,
Dialogue: 0,0:10:32.00,0:10:34.00,Default,,0000,0000,0000,,the amount of dark energy in each universe
Dialogue: 0,0:10:34.00,0:10:36.00,Default,,0000,0000,0000,,will be different.
Dialogue: 0,0:10:36.00,0:10:38.00,Default,,0000,0000,0000,,Which means that the mystery
Dialogue: 0,0:10:38.00,0:10:40.00,Default,,0000,0000,0000,,of explaining the amount of dark energy we've now measured
Dialogue: 0,0:10:40.00,0:10:43.00,Default,,0000,0000,0000,,would take on a wholly different character.
Dialogue: 0,0:10:43.00,0:10:45.00,Default,,0000,0000,0000,,In this context,
Dialogue: 0,0:10:45.00,0:10:48.00,Default,,0000,0000,0000,,the laws of physics can't explain one number for the dark energy
Dialogue: 0,0:10:48.00,0:10:51.00,Default,,0000,0000,0000,,because there isn't just one number,
Dialogue: 0,0:10:51.00,0:10:53.00,Default,,0000,0000,0000,,there are many numbers.
Dialogue: 0,0:10:53.00,0:10:55.00,Default,,0000,0000,0000,,Which means
Dialogue: 0,0:10:55.00,0:10:58.00,Default,,0000,0000,0000,,we have been asking the wrong question.
Dialogue: 0,0:10:58.00,0:11:00.00,Default,,0000,0000,0000,,It's that the right question to ask is,
Dialogue: 0,0:11:00.00,0:11:03.00,Default,,0000,0000,0000,,why do we humans find ourselves in a universe
Dialogue: 0,0:11:03.00,0:11:06.00,Default,,0000,0000,0000,,with a particular amount of dark energy we've measured
Dialogue: 0,0:11:06.00,0:11:09.00,Default,,0000,0000,0000,,instead of any of the other possibilities
Dialogue: 0,0:11:09.00,0:11:11.00,Default,,0000,0000,0000,,that are out there?
Dialogue: 0,0:11:11.00,0:11:14.00,Default,,0000,0000,0000,,And that's a question on which we can make headway.
Dialogue: 0,0:11:14.00,0:11:16.00,Default,,0000,0000,0000,,Because those universes
Dialogue: 0,0:11:16.00,0:11:18.00,Default,,0000,0000,0000,,that have much more dark energy than ours,
Dialogue: 0,0:11:18.00,0:11:21.00,Default,,0000,0000,0000,,whenever matter tries to clump into galaxies,
Dialogue: 0,0:11:21.00,0:11:24.00,Default,,0000,0000,0000,,the repulsive push of the dark energy is so strong
Dialogue: 0,0:11:24.00,0:11:26.00,Default,,0000,0000,0000,,that it blows the clump apart
Dialogue: 0,0:11:26.00,0:11:28.00,Default,,0000,0000,0000,,and galaxies don't form.
Dialogue: 0,0:11:28.00,0:11:31.00,Default,,0000,0000,0000,,And in those universes that have much less dark energy,
Dialogue: 0,0:11:31.00,0:11:33.00,Default,,0000,0000,0000,,well they collapse back on themselves so quickly
Dialogue: 0,0:11:33.00,0:11:36.00,Default,,0000,0000,0000,,that, again, galaxies don't form.
Dialogue: 0,0:11:36.00,0:11:39.00,Default,,0000,0000,0000,,And without galaxies, there are no stars, no planets
Dialogue: 0,0:11:39.00,0:11:41.00,Default,,0000,0000,0000,,and no chance
Dialogue: 0,0:11:41.00,0:11:43.00,Default,,0000,0000,0000,,for our form of life
Dialogue: 0,0:11:43.00,0:11:45.00,Default,,0000,0000,0000,,to exist in those other universes.
Dialogue: 0,0:11:45.00,0:11:47.00,Default,,0000,0000,0000,,So we find ourselves in a universe
Dialogue: 0,0:11:47.00,0:11:50.00,Default,,0000,0000,0000,,with the particular amount of dark energy we've measured
Dialogue: 0,0:11:50.00,0:11:53.00,Default,,0000,0000,0000,,simply because our universe has conditions
Dialogue: 0,0:11:53.00,0:11:57.00,Default,,0000,0000,0000,,hospitable to our form of life.
Dialogue: 0,0:11:57.00,0:11:59.00,Default,,0000,0000,0000,,And that would be that.
Dialogue: 0,0:11:59.00,0:12:01.00,Default,,0000,0000,0000,,Mystery solved,
Dialogue: 0,0:12:01.00,0:12:03.00,Default,,0000,0000,0000,,multiverse found.
Dialogue: 0,0:12:03.00,0:12:08.00,Default,,0000,0000,0000,,Now some find this explanation unsatisfying.
Dialogue: 0,0:12:08.00,0:12:10.00,Default,,0000,0000,0000,,We're used to physics
Dialogue: 0,0:12:10.00,0:12:13.00,Default,,0000,0000,0000,,giving us definitive explanations for the features we observe.
Dialogue: 0,0:12:13.00,0:12:15.00,Default,,0000,0000,0000,,But the point is,
Dialogue: 0,0:12:15.00,0:12:18.00,Default,,0000,0000,0000,,if the feature you're observing
Dialogue: 0,0:12:18.00,0:12:20.00,Default,,0000,0000,0000,,can and does take on
Dialogue: 0,0:12:20.00,0:12:22.00,Default,,0000,0000,0000,,a wide variety of different values
Dialogue: 0,0:12:22.00,0:12:25.00,Default,,0000,0000,0000,,across the wider landscape of reality,
Dialogue: 0,0:12:25.00,0:12:27.00,Default,,0000,0000,0000,,then thinking one explanation
Dialogue: 0,0:12:27.00,0:12:29.00,Default,,0000,0000,0000,,for a particular value
Dialogue: 0,0:12:29.00,0:12:32.00,Default,,0000,0000,0000,,is simply misguided.
Dialogue: 0,0:12:32.00,0:12:34.00,Default,,0000,0000,0000,,An early example
Dialogue: 0,0:12:34.00,0:12:37.00,Default,,0000,0000,0000,,comes from the great astronomer Johannes Kepler
Dialogue: 0,0:12:37.00,0:12:39.00,Default,,0000,0000,0000,,who was obsessed with understanding
Dialogue: 0,0:12:39.00,0:12:41.00,Default,,0000,0000,0000,,a different number --
Dialogue: 0,0:12:41.00,0:12:45.00,Default,,0000,0000,0000,,why the Sun is 93 million miles away from the Earth.
Dialogue: 0,0:12:45.00,0:12:48.00,Default,,0000,0000,0000,,And he worked for decades trying to explain this number,
Dialogue: 0,0:12:48.00,0:12:51.00,Default,,0000,0000,0000,,but he never succeeded, and we know why.
Dialogue: 0,0:12:51.00,0:12:53.00,Default,,0000,0000,0000,,Kepler was asking
Dialogue: 0,0:12:53.00,0:12:55.00,Default,,0000,0000,0000,,the wrong question.
Dialogue: 0,0:12:55.00,0:12:58.00,Default,,0000,0000,0000,,We now know that there are many planets
Dialogue: 0,0:12:58.00,0:13:01.00,Default,,0000,0000,0000,,at a wide variety of different distances from their host stars.
Dialogue: 0,0:13:01.00,0:13:04.00,Default,,0000,0000,0000,,So hoping that the laws of physics
Dialogue: 0,0:13:04.00,0:13:07.00,Default,,0000,0000,0000,,will explain one particular number, 93 million miles,
Dialogue: 0,0:13:07.00,0:13:10.00,Default,,0000,0000,0000,,well that is simply wrongheaded.
Dialogue: 0,0:13:10.00,0:13:12.00,Default,,0000,0000,0000,,Instead the right question to ask is,
Dialogue: 0,0:13:12.00,0:13:15.00,Default,,0000,0000,0000,,why do we humans find ourselves on a planet
Dialogue: 0,0:13:15.00,0:13:17.00,Default,,0000,0000,0000,,at this particular distance,
Dialogue: 0,0:13:17.00,0:13:20.00,Default,,0000,0000,0000,,instead of any of the other possibilities?
Dialogue: 0,0:13:20.00,0:13:23.00,Default,,0000,0000,0000,,And again, that's a question we can answer.
Dialogue: 0,0:13:23.00,0:13:26.00,Default,,0000,0000,0000,,Those planets which are much closer to a star like the Sun
Dialogue: 0,0:13:26.00,0:13:28.00,Default,,0000,0000,0000,,would be so hot
Dialogue: 0,0:13:28.00,0:13:30.00,Default,,0000,0000,0000,,that our form of life wouldn't exist.
Dialogue: 0,0:13:30.00,0:13:33.00,Default,,0000,0000,0000,,And those planets that are much farther away from the star,
Dialogue: 0,0:13:33.00,0:13:35.00,Default,,0000,0000,0000,,well they're so cold
Dialogue: 0,0:13:35.00,0:13:37.00,Default,,0000,0000,0000,,that, again, our form of life would not take hold.
Dialogue: 0,0:13:37.00,0:13:39.00,Default,,0000,0000,0000,,So we find ourselves
Dialogue: 0,0:13:39.00,0:13:41.00,Default,,0000,0000,0000,,on a planet at this particular distance
Dialogue: 0,0:13:41.00,0:13:43.00,Default,,0000,0000,0000,,simply because it yields conditions
Dialogue: 0,0:13:43.00,0:13:46.00,Default,,0000,0000,0000,,vital to our form of life.
Dialogue: 0,0:13:46.00,0:13:49.00,Default,,0000,0000,0000,,And when it comes to planets and their distances,
Dialogue: 0,0:13:49.00,0:13:53.00,Default,,0000,0000,0000,,this clearly is the right kind of reasoning.
Dialogue: 0,0:13:53.00,0:13:55.00,Default,,0000,0000,0000,,The point is,
Dialogue: 0,0:13:55.00,0:13:58.00,Default,,0000,0000,0000,,when it comes to universes and the dark energy that they contain,
Dialogue: 0,0:13:58.00,0:14:02.00,Default,,0000,0000,0000,,it may also be the right kind of reasoning.
Dialogue: 0,0:14:02.00,0:14:05.00,Default,,0000,0000,0000,,One key difference, of course,
Dialogue: 0,0:14:05.00,0:14:07.00,Default,,0000,0000,0000,,is we know that there are other planets out there,
Dialogue: 0,0:14:07.00,0:14:10.00,Default,,0000,0000,0000,,but so far I've only speculated on the possibility
Dialogue: 0,0:14:10.00,0:14:12.00,Default,,0000,0000,0000,,that there might be other universes.
Dialogue: 0,0:14:12.00,0:14:14.00,Default,,0000,0000,0000,,So to pull it all together,
Dialogue: 0,0:14:14.00,0:14:16.00,Default,,0000,0000,0000,,we need a mechanism
Dialogue: 0,0:14:16.00,0:14:19.00,Default,,0000,0000,0000,,that can actually generate other universes.
Dialogue: 0,0:14:19.00,0:14:22.00,Default,,0000,0000,0000,,And that takes me to my final part, part three.
Dialogue: 0,0:14:22.00,0:14:25.00,Default,,0000,0000,0000,,Because such a mechanism has been found
Dialogue: 0,0:14:25.00,0:14:28.00,Default,,0000,0000,0000,,by cosmologists trying to understand the Big Bang.
Dialogue: 0,0:14:28.00,0:14:30.00,Default,,0000,0000,0000,,You see, when we speak of the Big Bang,
Dialogue: 0,0:14:30.00,0:14:32.00,Default,,0000,0000,0000,,we often have an image
Dialogue: 0,0:14:32.00,0:14:34.00,Default,,0000,0000,0000,,of a kind of cosmic explosion
Dialogue: 0,0:14:34.00,0:14:36.00,Default,,0000,0000,0000,,that created our universe
Dialogue: 0,0:14:36.00,0:14:39.00,Default,,0000,0000,0000,,and set space rushing outward.
Dialogue: 0,0:14:39.00,0:14:41.00,Default,,0000,0000,0000,,But there's a little secret.
Dialogue: 0,0:14:41.00,0:14:44.00,Default,,0000,0000,0000,,The Big Bang leaves out something pretty important,
Dialogue: 0,0:14:44.00,0:14:46.00,Default,,0000,0000,0000,,the Bang.
Dialogue: 0,0:14:46.00,0:14:49.00,Default,,0000,0000,0000,,It tells us how the universe evolved after the Bang,
Dialogue: 0,0:14:49.00,0:14:51.00,Default,,0000,0000,0000,,but gives us no insight
Dialogue: 0,0:14:51.00,0:14:55.00,Default,,0000,0000,0000,,into what would have powered the Bang itself.
Dialogue: 0,0:14:55.00,0:14:57.00,Default,,0000,0000,0000,,And this gap was finally filled
Dialogue: 0,0:14:57.00,0:14:59.00,Default,,0000,0000,0000,,by an enhanced version of the Big Bang theory.
Dialogue: 0,0:14:59.00,0:15:02.00,Default,,0000,0000,0000,,It's called inflationary cosmology,
Dialogue: 0,0:15:02.00,0:15:06.00,Default,,0000,0000,0000,,which identified a particular kind of fuel
Dialogue: 0,0:15:06.00,0:15:08.00,Default,,0000,0000,0000,,that would naturally generate
Dialogue: 0,0:15:08.00,0:15:10.00,Default,,0000,0000,0000,,an outward rush of space.
Dialogue: 0,0:15:10.00,0:15:13.00,Default,,0000,0000,0000,,The fuel is based on something called a quantum field,
Dialogue: 0,0:15:13.00,0:15:16.00,Default,,0000,0000,0000,,but the only detail that matters for us
Dialogue: 0,0:15:16.00,0:15:19.00,Default,,0000,0000,0000,,is that this fuel proves to be so efficient
Dialogue: 0,0:15:19.00,0:15:21.00,Default,,0000,0000,0000,,that it's virtually impossible
Dialogue: 0,0:15:21.00,0:15:23.00,Default,,0000,0000,0000,,to use it all up,
Dialogue: 0,0:15:23.00,0:15:25.00,Default,,0000,0000,0000,,which means in the inflationary theory,
Dialogue: 0,0:15:25.00,0:15:28.00,Default,,0000,0000,0000,,the Big Bang giving rise to our universe
Dialogue: 0,0:15:28.00,0:15:31.00,Default,,0000,0000,0000,,is likely not a one-time event.
Dialogue: 0,0:15:31.00,0:15:34.00,Default,,0000,0000,0000,,Instead the fuel not only generated our Big Bang,
Dialogue: 0,0:15:34.00,0:15:40.00,Default,,0000,0000,0000,,but it would also generate countless other Big Bangs,
Dialogue: 0,0:15:40.00,0:15:43.00,Default,,0000,0000,0000,,each giving rise to its own separate universe
Dialogue: 0,0:15:43.00,0:15:45.00,Default,,0000,0000,0000,,with our universe becoming but one bubble
Dialogue: 0,0:15:45.00,0:15:48.00,Default,,0000,0000,0000,,in a grand cosmic bubble bath of universes.
Dialogue: 0,0:15:48.00,0:15:50.00,Default,,0000,0000,0000,,And now, when we meld this with string theory,
Dialogue: 0,0:15:50.00,0:15:52.00,Default,,0000,0000,0000,,here's the picture we're led to.
Dialogue: 0,0:15:52.00,0:15:54.00,Default,,0000,0000,0000,,Each of these universes has extra dimensions.
Dialogue: 0,0:15:54.00,0:15:57.00,Default,,0000,0000,0000,,The extra dimensions take on a wide variety of different shapes.
Dialogue: 0,0:15:57.00,0:16:00.00,Default,,0000,0000,0000,,The different shapes yield different physical features.
Dialogue: 0,0:16:00.00,0:16:03.00,Default,,0000,0000,0000,,And we find ourselves in one universe instead of another
Dialogue: 0,0:16:03.00,0:16:06.00,Default,,0000,0000,0000,,simply because it's only in our universe
Dialogue: 0,0:16:06.00,0:16:09.00,Default,,0000,0000,0000,,that the physical features, like the amount of dark energy,
Dialogue: 0,0:16:09.00,0:16:13.00,Default,,0000,0000,0000,,are right for our form of life to take hold.
Dialogue: 0,0:16:13.00,0:16:16.00,Default,,0000,0000,0000,,And this is the compelling but highly controversial picture
Dialogue: 0,0:16:16.00,0:16:18.00,Default,,0000,0000,0000,,of the wider cosmos
Dialogue: 0,0:16:18.00,0:16:20.00,Default,,0000,0000,0000,,that cutting-edge observation and theory
Dialogue: 0,0:16:20.00,0:16:24.00,Default,,0000,0000,0000,,have now led us to seriously consider.
Dialogue: 0,0:16:24.00,0:16:28.00,Default,,0000,0000,0000,,One big remaining question, of course, is,
Dialogue: 0,0:16:28.00,0:16:31.00,Default,,0000,0000,0000,,could we ever confirm
Dialogue: 0,0:16:31.00,0:16:34.00,Default,,0000,0000,0000,,the existence of other universes?
Dialogue: 0,0:16:34.00,0:16:36.00,Default,,0000,0000,0000,,Well let me describe
Dialogue: 0,0:16:36.00,0:16:39.00,Default,,0000,0000,0000,,one way that might one day happen.
Dialogue: 0,0:16:39.00,0:16:41.00,Default,,0000,0000,0000,,The inflationary theory
Dialogue: 0,0:16:41.00,0:16:43.00,Default,,0000,0000,0000,,already has strong observational support.
Dialogue: 0,0:16:43.00,0:16:45.00,Default,,0000,0000,0000,,Because the theory predicts
Dialogue: 0,0:16:45.00,0:16:47.00,Default,,0000,0000,0000,,that the Big Bang would have been so intense
Dialogue: 0,0:16:47.00,0:16:50.00,Default,,0000,0000,0000,,that as space rapidly expanded,
Dialogue: 0,0:16:50.00,0:16:52.00,Default,,0000,0000,0000,,tiny quantum jitters from the micro world
Dialogue: 0,0:16:52.00,0:16:55.00,Default,,0000,0000,0000,,would have been stretched out to the macro world,
Dialogue: 0,0:16:55.00,0:16:58.00,Default,,0000,0000,0000,,yielding a distinctive fingerprint,
Dialogue: 0,0:16:58.00,0:17:00.00,Default,,0000,0000,0000,,a pattern of slightly hotter spots and slightly colder spots,
Dialogue: 0,0:17:00.00,0:17:02.00,Default,,0000,0000,0000,,across space,
Dialogue: 0,0:17:02.00,0:17:05.00,Default,,0000,0000,0000,,which powerful telescopes have now observed.
Dialogue: 0,0:17:05.00,0:17:08.00,Default,,0000,0000,0000,,Going further, if there are other universes,
Dialogue: 0,0:17:08.00,0:17:10.00,Default,,0000,0000,0000,,the theory predicts that every so often
Dialogue: 0,0:17:10.00,0:17:12.00,Default,,0000,0000,0000,,those universes can collide.
Dialogue: 0,0:17:12.00,0:17:14.00,Default,,0000,0000,0000,,And if our universe got hit by another,
Dialogue: 0,0:17:14.00,0:17:16.00,Default,,0000,0000,0000,,that collision
Dialogue: 0,0:17:16.00,0:17:18.00,Default,,0000,0000,0000,,would generate an additional subtle pattern
Dialogue: 0,0:17:18.00,0:17:20.00,Default,,0000,0000,0000,,of temperature variations across space
Dialogue: 0,0:17:20.00,0:17:22.00,Default,,0000,0000,0000,,that we might one day
Dialogue: 0,0:17:22.00,0:17:24.00,Default,,0000,0000,0000,,be able to detect.
Dialogue: 0,0:17:24.00,0:17:27.00,Default,,0000,0000,0000,,And so exotic as this picture is,
Dialogue: 0,0:17:27.00,0:17:29.00,Default,,0000,0000,0000,,it may one day be grounded
Dialogue: 0,0:17:29.00,0:17:31.00,Default,,0000,0000,0000,,in observations,
Dialogue: 0,0:17:31.00,0:17:34.00,Default,,0000,0000,0000,,establishing the existence of other universes.
Dialogue: 0,0:17:34.00,0:17:36.00,Default,,0000,0000,0000,,I'll conclude
Dialogue: 0,0:17:36.00,0:17:39.00,Default,,0000,0000,0000,,with a striking implication
Dialogue: 0,0:17:39.00,0:17:41.00,Default,,0000,0000,0000,,of all these ideas
Dialogue: 0,0:17:41.00,0:17:43.00,Default,,0000,0000,0000,,for the very far future.
Dialogue: 0,0:17:43.00,0:17:45.00,Default,,0000,0000,0000,,You see, we learned
Dialogue: 0,0:17:45.00,0:17:47.00,Default,,0000,0000,0000,,that our universe is not static,
Dialogue: 0,0:17:47.00,0:17:49.00,Default,,0000,0000,0000,,that space is expanding,
Dialogue: 0,0:17:49.00,0:17:51.00,Default,,0000,0000,0000,,that that expansion is speeding up
Dialogue: 0,0:17:51.00,0:17:53.00,Default,,0000,0000,0000,,and that there might be other universes
Dialogue: 0,0:17:53.00,0:17:55.00,Default,,0000,0000,0000,,all by carefully examining
Dialogue: 0,0:17:55.00,0:17:57.00,Default,,0000,0000,0000,,faint pinpoints of starlight
Dialogue: 0,0:17:57.00,0:18:00.00,Default,,0000,0000,0000,,coming to us from distant galaxies.
Dialogue: 0,0:18:00.00,0:18:03.00,Default,,0000,0000,0000,,But because the expansion is speeding up,
Dialogue: 0,0:18:03.00,0:18:05.00,Default,,0000,0000,0000,,in the very far future,
Dialogue: 0,0:18:05.00,0:18:08.00,Default,,0000,0000,0000,,those galaxies will rush away so far and so fast
Dialogue: 0,0:18:08.00,0:18:11.00,Default,,0000,0000,0000,,that we won't be able to see them --
Dialogue: 0,0:18:11.00,0:18:13.00,Default,,0000,0000,0000,,not because of technological limitations,
Dialogue: 0,0:18:13.00,0:18:15.00,Default,,0000,0000,0000,,but because of the laws of physics.
Dialogue: 0,0:18:15.00,0:18:17.00,Default,,0000,0000,0000,,The light those galaxies emit,
Dialogue: 0,0:18:17.00,0:18:20.00,Default,,0000,0000,0000,,even traveling at the fastest speed, the speed of light,
Dialogue: 0,0:18:20.00,0:18:22.00,Default,,0000,0000,0000,,will not be able to overcome
Dialogue: 0,0:18:22.00,0:18:25.00,Default,,0000,0000,0000,,the ever-widening gulf between us.
Dialogue: 0,0:18:25.00,0:18:27.00,Default,,0000,0000,0000,,So astronomers in the far future
Dialogue: 0,0:18:27.00,0:18:29.00,Default,,0000,0000,0000,,looking out into deep space
Dialogue: 0,0:18:29.00,0:18:32.00,Default,,0000,0000,0000,,will see nothing but an endless stretch
Dialogue: 0,0:18:32.00,0:18:36.00,Default,,0000,0000,0000,,of static, inky, black stillness.
Dialogue: 0,0:18:36.00,0:18:38.00,Default,,0000,0000,0000,,And they will conclude
Dialogue: 0,0:18:38.00,0:18:40.00,Default,,0000,0000,0000,,that the universe is static and unchanging
Dialogue: 0,0:18:40.00,0:18:43.00,Default,,0000,0000,0000,,and populated by a single central oasis of matter
Dialogue: 0,0:18:43.00,0:18:45.00,Default,,0000,0000,0000,,that they inhabit --
Dialogue: 0,0:18:45.00,0:18:47.00,Default,,0000,0000,0000,,a picture of the cosmos
Dialogue: 0,0:18:47.00,0:18:50.00,Default,,0000,0000,0000,,that we definitively know to be wrong.
Dialogue: 0,0:18:50.00,0:18:53.00,Default,,0000,0000,0000,,Now maybe those future astronomers will have records
Dialogue: 0,0:18:53.00,0:18:55.00,Default,,0000,0000,0000,,handed down from an earlier era,
Dialogue: 0,0:18:55.00,0:18:57.00,Default,,0000,0000,0000,,like ours,
Dialogue: 0,0:18:57.00,0:18:59.00,Default,,0000,0000,0000,,attesting to an expanding cosmos
Dialogue: 0,0:18:59.00,0:19:01.00,Default,,0000,0000,0000,,teeming with galaxies.
Dialogue: 0,0:19:01.00,0:19:03.00,Default,,0000,0000,0000,,But would those future astronomers
Dialogue: 0,0:19:03.00,0:19:06.00,Default,,0000,0000,0000,,believe such ancient knowledge?
Dialogue: 0,0:19:06.00,0:19:08.00,Default,,0000,0000,0000,,Or would they believe
Dialogue: 0,0:19:08.00,0:19:11.00,Default,,0000,0000,0000,,in the black, static empty universe
Dialogue: 0,0:19:11.00,0:19:15.00,Default,,0000,0000,0000,,that their own state-of-the-art observations reveal?
Dialogue: 0,0:19:15.00,0:19:17.00,Default,,0000,0000,0000,,I suspect the latter.
Dialogue: 0,0:19:17.00,0:19:19.00,Default,,0000,0000,0000,,Which means that we are living
Dialogue: 0,0:19:19.00,0:19:22.00,Default,,0000,0000,0000,,through a remarkably privileged era
Dialogue: 0,0:19:22.00,0:19:24.00,Default,,0000,0000,0000,,when certain deep truths about the cosmos
Dialogue: 0,0:19:24.00,0:19:26.00,Default,,0000,0000,0000,,are still within reach
Dialogue: 0,0:19:26.00,0:19:28.00,Default,,0000,0000,0000,,of the human spirit of exploration.
Dialogue: 0,0:19:28.00,0:19:33.00,Default,,0000,0000,0000,,It appears that it may not always be that way.
Dialogue: 0,0:19:33.00,0:19:35.00,Default,,0000,0000,0000,,Because today's astronomers,
Dialogue: 0,0:19:35.00,0:19:38.00,Default,,0000,0000,0000,,by turning powerful telescopes to the sky,
Dialogue: 0,0:19:38.00,0:19:41.00,Default,,0000,0000,0000,,have captured a handful of starkly informative photons --
Dialogue: 0,0:19:41.00,0:19:44.00,Default,,0000,0000,0000,,a kind of cosmic telegram
Dialogue: 0,0:19:44.00,0:19:46.00,Default,,0000,0000,0000,,billions of years in transit.
Dialogue: 0,0:19:46.00,0:19:50.00,Default,,0000,0000,0000,,and the message echoing across the ages is clear.
Dialogue: 0,0:19:50.00,0:19:53.00,Default,,0000,0000,0000,,Sometimes nature guards her secrets
Dialogue: 0,0:19:53.00,0:19:55.00,Default,,0000,0000,0000,,with the unbreakable grip
Dialogue: 0,0:19:55.00,0:19:57.00,Default,,0000,0000,0000,,of physical law.
Dialogue: 0,0:19:57.00,0:20:01.00,Default,,0000,0000,0000,,Sometimes the true nature of reality beckons
Dialogue: 0,0:20:01.00,0:20:04.00,Default,,0000,0000,0000,,from just beyond the horizon.
Dialogue: 0,0:20:04.00,0:20:06.00,Default,,0000,0000,0000,,Thank you very much.
Dialogue: 0,0:20:06.00,0:20:10.00,Default,,0000,0000,0000,,(Applause)
Dialogue: 0,0:20:10.00,0:20:12.00,Default,,0000,0000,0000,,Chris Anderson: Brian, thank you.
Dialogue: 0,0:20:12.00,0:20:14.00,Default,,0000,0000,0000,,The range of ideas you've just spoken about
Dialogue: 0,0:20:14.00,0:20:17.00,Default,,0000,0000,0000,,are dizzying, exhilarating, incredible.
Dialogue: 0,0:20:17.00,0:20:19.00,Default,,0000,0000,0000,,How do you think
Dialogue: 0,0:20:19.00,0:20:21.00,Default,,0000,0000,0000,,of where cosmology is now,
Dialogue: 0,0:20:21.00,0:20:23.00,Default,,0000,0000,0000,,in a sort of historical side?
Dialogue: 0,0:20:23.00,0:20:26.00,Default,,0000,0000,0000,,Are we in the middle of something unusual historically in your opinion?
Dialogue: 0,0:20:26.00,0:20:28.00,Default,,0000,0000,0000,,BG: Well it's hard to say.
Dialogue: 0,0:20:28.00,0:20:31.00,Default,,0000,0000,0000,,When we learn that astronomers of the far future
Dialogue: 0,0:20:31.00,0:20:34.00,Default,,0000,0000,0000,,may not have enough information to figure things out,
Dialogue: 0,0:20:34.00,0:20:37.00,Default,,0000,0000,0000,,the natural question is, maybe we're already in that position
Dialogue: 0,0:20:37.00,0:20:40.00,Default,,0000,0000,0000,,and certain deep, critical features of the universe
Dialogue: 0,0:20:40.00,0:20:43.00,Default,,0000,0000,0000,,already have escaped our ability to understand
Dialogue: 0,0:20:43.00,0:20:45.00,Default,,0000,0000,0000,,because of how cosmology evolves.
Dialogue: 0,0:20:45.00,0:20:47.00,Default,,0000,0000,0000,,So from that perspective,
Dialogue: 0,0:20:47.00,0:20:49.00,Default,,0000,0000,0000,,maybe we will always be asking questions
Dialogue: 0,0:20:49.00,0:20:51.00,Default,,0000,0000,0000,,and never be able to fully answer them.
Dialogue: 0,0:20:51.00,0:20:53.00,Default,,0000,0000,0000,,On the other hand, we now can understand
Dialogue: 0,0:20:53.00,0:20:55.00,Default,,0000,0000,0000,,how old the universe is.
Dialogue: 0,0:20:55.00,0:20:57.00,Default,,0000,0000,0000,,We can understand
Dialogue: 0,0:20:57.00,0:21:00.00,Default,,0000,0000,0000,,how to understand the data from the microwave background radiation
Dialogue: 0,0:21:00.00,0:21:03.00,Default,,0000,0000,0000,,that was set down 13.72 billion years ago --
Dialogue: 0,0:21:03.00,0:21:05.00,Default,,0000,0000,0000,,and yet, we can do calculations today to predict how it will look
Dialogue: 0,0:21:05.00,0:21:07.00,Default,,0000,0000,0000,,and it matches.
Dialogue: 0,0:21:07.00,0:21:09.00,Default,,0000,0000,0000,,Holy cow! That's just amazing.
Dialogue: 0,0:21:09.00,0:21:12.00,Default,,0000,0000,0000,,So on the one hand, it's just incredible where we've gotten,
Dialogue: 0,0:21:12.00,0:21:16.00,Default,,0000,0000,0000,,but who knows what sort of blocks we may find in the future.
Dialogue: 0,0:21:16.00,0:21:19.00,Default,,0000,0000,0000,,CA: You're going to be around for the next few days.
Dialogue: 0,0:21:19.00,0:21:21.00,Default,,0000,0000,0000,,Maybe some of these conversations can continue.
Dialogue: 0,0:21:21.00,0:21:23.00,Default,,0000,0000,0000,,Thank you. Thank you, Brian. (BG: My pleasure.)
Dialogue: 0,0:21:23.00,0:21:26.00,Default,,0000,0000,0000,,(Applause)