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00:00:00I'm sorry.
00:00:30There is one experience
00:00:55that every human shares
00:00:57of every language and culture.
00:01:00The experience of birth.
00:01:03Our recollections of birth
00:01:04are hazy at best.
00:01:07They have the feel and aura
00:01:08not so much of memories
00:01:11as of mystical transfigurations.
00:01:15It would be astonishing
00:01:17if this profound early experience
00:01:19did not influence our myths
00:01:21and religions,
00:01:23our philosophy,
00:01:24and our science.
00:01:25The birth of a child
00:01:27evokes the mystery of other origins,
00:01:30the beginnings and ends of worlds,
00:01:33infinity and eternity.
00:01:37How did the universe arise?
00:01:43What was around before that?
00:01:47Might there have been no beginning?
00:01:50Could the universe be infinitely old?
00:01:54Are there boundaries to the cosmos?
00:01:57The current scientific story
00:02:00of the origin of the universe
00:02:01begins with an explosion
00:02:03which made space itself expand.
00:02:06About 15 billion years ago,
00:02:08all the matter and energy
00:02:09that today make up
00:02:10the observable universe
00:02:11were concentrated
00:02:12into a space smaller
00:02:14than the head of a pin.
00:02:16The cosmos blew apart
00:02:18in one inconceivably
00:02:20colossal explosion,
00:02:22the Big Bang.
00:02:23And the stuff of the universe,
00:02:25together with the fabric
00:02:26of space itself,
00:02:27began expanding
00:02:28in all directions
00:02:29as they do today.
00:02:31We can visualize this process
00:02:33with a three-dimensional grid
00:02:34attached to the expanding
00:02:36fabric of space.
00:02:37The early cosmos
00:02:40was everywhere white-hot.
00:02:43But as time passed,
00:02:44the radiation expanded
00:02:46and cooled,
00:02:46and in ordinary visible light,
00:02:48space became dark
00:02:49as it is today.
00:02:52But then,
00:02:53little pockets of gas
00:02:54began to grow.
00:02:56Tendrils of gossamer clouds formed.
00:02:59Colonies of great lumbering,
00:03:01slowly spinning things,
00:03:03steadily brightening,
00:03:05each a kind of beast
00:03:06composed of a hundred billion
00:03:08shining points.
00:03:13The largest recognizable structures
00:03:16in the universe
00:03:17had formed.
00:03:18We see them today.
00:03:19We ourselves inhabit
00:03:21some lost corner of one.
00:03:23We call them the galaxies.
00:03:25We inhabit a universe of galaxies.
00:03:28There are unstructured blobs,
00:03:31the irregular galaxies,
00:03:33globular or elliptical galaxies,
00:03:35and the graceful blue arms
00:03:37of spiral galaxies.
00:03:40We've been investigating the galaxies,
00:03:43their origins, evolution, and motions
00:03:45for less than a century.
00:03:47These studies extend our understanding
00:03:50to the farthest reaches of the universe.
00:03:52Our ship of the imagination carries us
00:03:58to that ultimate frontier.
00:04:00We view the cosmos
00:04:01on the grandest of scales.
00:04:04The majesty of the galaxies
00:04:05is revealed by science.
00:04:09There are many different ways
00:04:10in which stars are arrayed
00:04:12into galaxies.
00:04:13When, by chance,
00:04:18the face of a spiral galaxy
00:04:20is turned towards us,
00:04:22we see the spiral arms
00:04:23made luminous
00:04:24by billions of stars.
00:04:27When, in other cases,
00:04:29the edge of a galaxy
00:04:30is towards us,
00:04:32we see the central lanes
00:04:33of gas and dust
00:04:34from which the stars are forming.
00:04:36In barred spirals,
00:04:40a river of star stuff
00:04:42extends through the galactic center,
00:04:45connecting opposite spiral arms.
00:04:48Elliptical galaxies
00:04:49come in giant
00:04:50and dwarf sizes.
00:04:55There are many mysterious galaxies,
00:04:58places where something
00:04:59has gone terribly wrong,
00:05:01where there are explosions
00:05:03and collisions
00:05:03and streamers of gas
00:05:06and stars,
00:05:07bridges between the galaxies.
00:05:11The galaxies look rigid
00:05:13and unmoving,
00:05:15but we see them only
00:05:16for a single frame
00:05:17of the cosmic movie.
00:05:19Their parts are dissipating
00:05:21and reforming
00:05:22on a timescale
00:05:23of hundreds of millions
00:05:24of years.
00:05:26A galaxy is a fluid
00:05:28made of billions of suns
00:05:30all bound together
00:05:31by gravity.
00:05:33These giant galactic forms
00:05:35exist throughout the universe
00:05:37and may be a common source
00:05:39of wonderment
00:05:40and instruction
00:05:41for billions of species
00:05:43of intelligent life.
00:05:48Their evolution
00:05:49is governed everywhere
00:05:50by the same laws of physics.
00:05:57We need a computer
00:05:58to illustrate
00:06:00the collective motion
00:06:01of so many stars,
00:06:02each under the gravitational influence
00:06:05of all the others.
00:06:10A billion years
00:06:11is here
00:06:12compressed
00:06:13into a few seconds.
00:06:17In some cases,
00:06:19spiral arms
00:06:20form all by themselves.
00:06:22In other cases,
00:06:33the close gravitational encounter
00:06:36of two galaxies
00:06:37will draw out
00:06:39spiral arms.
00:06:40into a swarm of bees.
00:06:41But when two nearby galaxies
00:06:49collide,
00:06:50like a bullet
00:06:51through a swarm
00:06:52of bees,
00:06:53the stars hardly collide
00:06:55at all,
00:06:55but the shapes
00:06:56of the galaxies
00:06:57can be severely distorted.
00:06:59A direct collision
00:07:06of two galaxies
00:07:07can last
00:07:08a hundred million years
00:07:10and spill
00:07:11the constituent stars
00:07:12careening
00:07:14through intergalactic space.
00:07:18When a dense,
00:07:20compact galaxy
00:07:21runs into a larger one
00:07:22face-on,
00:07:23it can produce
00:07:24one of the loveliest
00:07:25of the rare irregulars,
00:07:27a ring galaxy.
00:07:28thousands of light-years
00:07:39across,
00:07:40a ring galaxy
00:07:41is set
00:07:42against the velvet
00:07:44of intergalactic space.
00:07:50It's a temporary configuration
00:07:52of disrupted stars,
00:07:55a splash
00:07:55in the cosmic pond.
00:07:58galaxy is sometimes
00:08:05blow themselves up.
00:08:07The quasars,
00:08:08probably
00:08:09dunions of light-years away,
00:08:11may be the colossal explosions
00:08:13of young galaxies,
00:08:15but we're not sure.
00:08:16quasars are a mystery still.
00:08:24The galaxies reveal
00:08:26a universal order
00:08:27and beauty,
00:08:29but also
00:08:30violence
00:08:31on a scale
00:08:31never before imagined.
00:08:33The universe
00:08:34seems neither benign
00:08:36nor hostile,
00:08:38merely
00:08:38indifferent
00:08:39to the concerns
00:08:41of such creatures
00:08:42of such creatures
00:08:42as we.
00:08:46Quasars
00:08:47may be monster
00:08:48versions
00:08:48of rapidly rotating
00:08:49pulsars,
00:08:51or due to multiple
00:08:51collisions
00:08:52of millions of stars
00:08:53densely packed
00:08:55in the galactic core,
00:08:56or a chain reaction
00:08:58of supernova explosions
00:09:00in such a core.
00:09:04Some astronomers
00:09:05think a quasar
00:09:06is caused
00:09:06by millions
00:09:07of stars
00:09:08falling into
00:09:09an immense black hole
00:09:10in the core
00:09:11of a galaxy.
00:09:12Something like
00:09:13a black hole,
00:09:15something very massive,
00:09:17very dense,
00:09:17and very small,
00:09:19is ticking
00:09:20and purring away
00:09:22in the cores
00:09:23of nearby galaxies.
00:09:34Even a well-behaved
00:09:36galaxy like the Milky Way
00:09:38has its stirrings
00:09:40and its dances.
00:09:43The stars of the Milky Way
00:09:45move with systematic grace.
00:09:48The sun takes 250 million years
00:09:51to go once
00:09:52around the core.
00:09:55The outer provinces
00:09:56of the galaxy
00:09:56revolve more slowly
00:09:58than the inner regions.
00:10:00As a result,
00:10:01gas and dust
00:10:01pile up
00:10:02in spiral patterns.
00:10:04These places
00:10:05of greater density
00:10:06are where
00:10:07young, hot,
00:10:08bright stars form,
00:10:09the stars which
00:10:10outline the spiral arms.
00:10:12These hot stars
00:10:13shine for only
00:10:1410 million years or so
00:10:16and then
00:10:17blow up.
00:10:18But as the stars
00:10:22which outline
00:10:22a spiral arm
00:10:23burn out,
00:10:24new young stars
00:10:25are formed
00:10:25from the debris
00:10:26just behind them
00:10:27and the spiral pattern
00:10:28persists.
00:10:32The sun,
00:10:33marked here
00:10:34with a circle,
00:10:35has been in and out
00:10:36of spiral arms
00:10:37often in the 20 times
00:10:38it has gone around
00:10:39the Milky Way.
00:10:40In this epoch,
00:10:41we live at the edge
00:10:43of a spiral arm.
00:10:49We've looked at
00:10:50internal galactic motion
00:10:52on a small scale
00:10:53across a million
00:10:55light years or less.
00:10:56But the motion
00:10:57of the galaxies
00:10:58themselves
00:10:59across billions
00:11:00of light years
00:11:01is different.
00:11:03That motion
00:11:03is a relic
00:11:04of the Big Bang.
00:11:07The key to cosmology,
00:11:09the study
00:11:09of the entire universe,
00:11:10turns out to be
00:11:12a commonplace
00:11:12of nature,
00:11:14an experience
00:11:15of everyday life.
00:11:21Imagine a moving object
00:11:23sending out waves.
00:11:24It could be light waves,
00:11:26it could be sound waves,
00:11:29it could be
00:11:30any kind of wave.
00:11:31When that moving object
00:11:38passes us,
00:11:39we sense a change
00:11:40in pitch.
00:11:42That's called
00:11:42the Doppler effect.
00:11:48If you're the engineer
00:11:49in the cab,
00:11:51then the pitch
00:11:51of your locomotive whistle
00:11:52always sounds the same
00:11:53to you.
00:11:54That's because
00:11:55you're moving along
00:11:56with the source
00:11:57of the sound.
00:11:58But if you're standing
00:11:59alongside the track
00:12:00when the train passes,
00:12:02you hear that familiar
00:12:03shift in pitch,
00:12:05the Doppler shift.
00:12:12The reason this happens
00:12:14is easy to understand
00:12:15once you visualize
00:12:16the waves.
00:12:18A stationary train
00:12:20sends out sound waves
00:12:21in perfect circles
00:12:22like the ripples
00:12:23on a pond.
00:12:26Let's start
00:12:27the train again.
00:12:30Now, the waves
00:12:34spreading out
00:12:35ahead of it
00:12:35get squashed together
00:12:37and those spreading
00:12:38out behind it
00:12:38get stretched apart.
00:12:40The compressed waves
00:12:41have a higher frequency
00:12:42or pitch
00:12:42than the stretched out waves.
00:12:46The same thing is true
00:12:47for light waves.
00:12:49Color is to light,
00:12:50precisely what pitch is
00:12:51to sound.
00:12:53Compressed light waves
00:12:54are made bluer,
00:12:55they're blue shifted.
00:12:56Stretched out light waves
00:12:57are made redder,
00:12:58they're red shifted.
00:13:02At the speed of a train,
00:13:04you can sense the change
00:13:05of pitch for sound,
00:13:06but not for light.
00:13:08The train is traveling
00:13:09about a million times
00:13:10too slow for that.
00:13:11It turns out
00:13:17that the Doppler effect
00:13:19for light waves
00:13:20is the key
00:13:21to the cosmos.
00:13:24The evidence for this
00:13:25was gathered
00:13:26unexpectedly
00:13:27by a former
00:13:28mule team driver
00:13:29who never went
00:13:31beyond the eighth grade.
00:13:33During the second decade
00:13:35of this century,
00:13:36the world's largest
00:13:36telescope was being
00:13:38assembled on Mount Wilson
00:13:39overlooking what were then
00:13:40the clear skies
00:13:42of Los Angeles.
00:13:44Large pieces
00:13:45of the telescope
00:13:46had to be hauled
00:13:47to the top of the mountain,
00:13:48a job for mule teams.
00:13:53One of the drivers
00:13:54was a young man
00:13:55named Milton Hummison,
00:13:57the ne'er-do-well son
00:13:59of a California banker.
00:14:01But he was bright
00:14:02and naturally curious
00:14:03about the equipment
00:14:04he had carted up
00:14:05Mount Wilson,
00:14:06and after the telescope
00:14:07was completed in 1917,
00:14:09he managed to stay on here
00:14:11as janitor
00:14:12and electrician.
00:14:14One evening,
00:14:15so the story goes,
00:14:17the observatory's
00:14:18night assistant
00:14:18was ill
00:14:19and Hummison
00:14:19was asked to fill in.
00:14:28Hummison was a gambling man,
00:14:31celebrated for his skill
00:14:32at poker
00:14:33and at the pool table,
00:14:34but his touch
00:14:35with the telescope
00:14:36was admired even more.
00:14:39He discovered
00:14:39he had a natural talent
00:14:40for using
00:14:41astronomical instruments.
00:14:42He became
00:14:43the virtuoso
00:14:44of the 100-inch telescope.
00:14:48In this instrument,
00:14:49the light from distant galaxies
00:14:50is focused
00:14:51on a glass photographic plate
00:14:53by a great encased mirror
00:14:55100 inches across.
00:14:56by the late 1920s,
00:15:00Hummison
00:15:01was making
00:15:01observations himself.
00:15:02Mr. Nolson!
00:15:12Hummison by now
00:15:13had his own
00:15:14night assistant
00:15:15to help him
00:15:16with the observations.
00:15:17Afternoon, Mr. Nolson!
00:15:21Afternoon, Mr. Hummison!
00:15:23We'll start at 6.
00:15:25I'll be making
00:15:25a spectrogram
00:15:26at the gas-of-rain focus.
00:15:28Yes, sir.
00:15:30The telescope
00:15:31must be able
00:15:32to point with high accuracy
00:15:33to a designated region
00:15:35of the sky
00:15:35and to keep on
00:15:36pointing there.
00:15:39A machine weighing
00:15:40about 75 tons,
00:15:42as massive as a locomotive,
00:15:44must move
00:15:44with a precision
00:15:45greater than that
00:15:46of the finest
00:15:47pocket watch.
00:15:52Everything
00:15:52must be checked
00:15:53thoroughly.
00:15:59The electrical power
00:16:01system must work
00:16:02flawlessly.
00:16:11Hours before observations
00:16:12are to begin,
00:16:13the dome is opened
00:16:14to allow the temperature
00:16:16inside and outside
00:16:17to be equalized.
00:16:25Hummison prepared
00:16:27the sensitive photographic
00:16:28emulsions
00:16:29sheathed in their metal holders
00:16:31to capture with the giant telescope
00:16:33the faint light
00:16:34from remote galaxies.
00:16:36which was part of a systematic program
00:16:40which Hummison
00:16:42and his mentor,
00:16:43the astronomer Edwin Hubble
00:16:45were pursuing
00:16:46to measure the Doppler shift
00:16:47of light from the most distant galaxies
00:16:50then known.
00:16:51but the most distant galaxies
00:16:56are very faint.
00:16:57That's why
00:16:58even with the largest telescope
00:17:00in the world
00:17:01it was necessary
00:17:02to take very long time exposures
00:17:04often lasting the whole night
00:17:06and sometimes requiring
00:17:07several successive nights.
00:17:11Hummison would give
00:17:12the night assistant
00:17:12the celestial coordinates
00:17:14of the target galaxy.
00:17:25Through the long cold night
00:17:27he would have to make
00:17:28fine adjustments
00:17:29so the telescope
00:17:30would precisely track
00:17:31the target galaxy.
00:17:33The galaxy itself
00:17:34was much too faint
00:17:35to see through
00:17:36the great telescope
00:17:36although it could be recorded
00:17:38photographically
00:17:39with a long time exposure.
00:17:41So the telescope
00:17:43would be pointed
00:17:44at a nearby bright star
00:17:46and then offset
00:17:47to a featureless patch of sky
00:17:50from which
00:17:51over the long night
00:17:52the light from the unseen galaxy
00:17:54would slowly accumulate.
00:17:57The telescope focused
00:17:59the faint white light
00:17:59from the galaxy
00:18:00into the spectrometer
00:18:01where it was spread out
00:18:03into its rainbow
00:18:04of constituent colors.
00:18:06The spectrum
00:18:07would be recorded
00:18:08on the little glass plates.
00:18:09All right,
00:18:11would you clap in the drive
00:18:12and slew to the focus star,
00:18:13please?
00:18:14Are you clear?
00:18:16I'm going to slew
00:18:17to the east.
00:18:18Yes, I think I'm clear.
00:18:21Just take it easy.
00:18:22All right.
00:18:39All right, I have it.
00:18:45Now let's go to
00:18:46MGC 7619.
00:18:48I'm clear.
00:18:53Going to do
00:18:54a 10-hour exposure.
00:18:59What time is it?
00:19:01Uh, 7.15.
00:19:03All right, lights out, please.
00:19:04All right, lights out, please.
00:19:04All right.
00:19:04All right.
00:19:09Dark slide is open.
00:19:23A large telescope
00:19:24views only a tiny patch of sky.
00:19:28As the Earth turns,
00:19:29a guide star or a galaxy
00:19:31would drift out
00:19:32of the telescope's field of view
00:19:33in only a few minutes.
00:19:36Hummison had to stay awake,
00:19:37tracking the galaxy
00:19:38while elaborate machinery
00:19:40moved the telescope
00:19:42slowly in the opposite direction
00:19:43to compensate
00:19:44for the Earth's rotation.
00:19:46The telescope
00:19:46is a kind of clock.
00:19:50How's the door?
00:19:55You're clear.
00:19:56This work was difficult,
00:20:04routine,
00:20:05tedious,
00:20:06but although they didn't yet know it,
00:20:09Hubble and Hummison
00:20:09were meticulously accumulating
00:20:11the evidence
00:20:12for the Big Bang.
00:20:15They had found
00:20:16that the more distant the galaxy,
00:20:19the more its spectrum of colors
00:20:21was shifted to the red.
00:20:22All right.
00:20:27Clear the telescope.
00:20:29I'm coming down now.
00:20:31If this redshift
00:20:33were due to the Doppler effect,
00:20:35the distant galaxies
00:20:36must be running away from us.
00:20:39At the end of his vigil,
00:20:41Hummison would retrieve
00:20:42the tiny galactic spectrum
00:20:44and carefully carry it down
00:20:46to be developed.
00:20:47Thank you, Mr. Nelson.
00:20:56I'm going to the darkroom now.
00:21:01Good day.
00:21:02Good day, sir.
00:21:10Hummison found a redshift
00:21:11in almost every galaxy
00:21:12he examined,
00:21:13like the Doppler shift
00:21:15and the sound
00:21:15of a receding locomotive.
00:21:17And the farther away
00:21:18from us they were,
00:21:19the faster they were receding.
00:21:25Tied to the fabric of space,
00:21:27the outward rushing galaxies
00:21:29were tracing the expansion
00:21:32of the universe itself.
00:21:34An awesome conclusion
00:21:35had been captured
00:21:36on these tiny glass slides.
00:21:40Hummison and Hubble
00:21:41had discovered
00:21:42the Big Bang.
00:21:43At top and bottom
00:21:50are calibration lines
00:21:51that Hummison
00:21:52had earlier photographed.
00:21:53In the middle
00:21:54is the spectrum
00:21:55of a relatively nearby galaxy.
00:21:58Every element
00:21:59has a characteristic
00:22:00spectral fingerprint,
00:22:02a set of frequencies
00:22:03where light is absorbed.
00:22:05Prominent here
00:22:05are two dark lines
00:22:07in the violet
00:22:08due to calcium
00:22:09in the atmospheres
00:22:10of the hundreds
00:22:11of billions of stars
00:22:12that constitute
00:22:14this galaxy.
00:22:15Nearby galaxies
00:22:16showed very little
00:22:17Doppler shift.
00:22:19But when he recorded
00:22:20the spectrum
00:22:21of a fainter
00:22:22and more distant galaxy,
00:22:23he found the same
00:22:24telltale pair of lines
00:22:26but shifted farther right
00:22:28toward the red.
00:22:29And when he examined
00:22:30a remote galaxy
00:22:31four billion light years away,
00:22:33he found that the lines
00:22:34were redshifted even more.
00:22:36This galaxy
00:22:37must be receding
00:22:38at 200 million kilometers an hour.
00:22:43The painstaking observations
00:22:45of Milton Hummison,
00:22:47astronomer
00:22:48and former mule team driver,
00:22:50established
00:22:51the expansion
00:22:52of the universe.
00:23:00In discussing
00:23:01the large-scale structure
00:23:03of the cosmos,
00:23:04astronomers sometimes say
00:23:05that space is curved
00:23:07or that the universe
00:23:11is finite
00:23:12but unbounded.
00:23:14Whatever are they
00:23:15talking about?
00:23:16Let's imagine
00:23:17that we are
00:23:18perfectly flat.
00:23:19I mean absolutely flat.
00:23:22And that we live,
00:23:23appropriately enough,
00:23:24in a flat land.
00:23:26A land
00:23:28designed and named
00:23:29by Edwin Abbott,
00:23:31a Shakespearean scholar
00:23:32who lived in
00:23:33Victorian England.
00:23:34Everybody in flat land
00:23:36is, of course,
00:23:37exceptionally flat.
00:23:39We have squares,
00:23:40circles,
00:23:40triangles,
00:23:41and we all
00:23:42scurry about
00:23:43and we can go
00:23:45into our houses
00:23:45and do our
00:23:47flat business.
00:23:49Now,
00:23:50we
00:23:51have
00:23:52width
00:23:53and length
00:23:55but no height
00:23:56at all.
00:23:58Now,
00:23:58these little cutouts
00:23:59have some little height
00:24:00but let's ignore that.
00:24:01Let's imagine
00:24:02that these are
00:24:02absolutely flat land.
00:24:04That being the case,
00:24:06we know,
00:24:07us flat landers,
00:24:08about left-right
00:24:09and we know
00:24:10about forward-back
00:24:11but we have
00:24:12never heard of
00:24:14up-down.
00:24:15Let us imagine
00:24:15that into flat land,
00:24:19hovering above it,
00:24:20comes a strange
00:24:22three-dimensional creature
00:24:23which,
00:24:24oddly enough,
00:24:25looks like an apple.
00:24:26and the three-dimensional
00:24:28creature sees
00:24:29an attractive,
00:24:30congenial-looking square,
00:24:33watches it
00:24:33enter its house
00:24:35and decides
00:24:36in a gesture
00:24:37of inter-dimensional
00:24:39amity
00:24:40to say hello.
00:24:42Hello,
00:24:43says the three-dimensional
00:24:44creature.
00:24:45How are you?
00:24:46I am a visitor
00:24:46from the third dimension.
00:24:49Well,
00:24:49the poor square
00:24:50looks around
00:24:52his closed house,
00:24:54sees no one there,
00:24:55and what's more,
00:24:57has witnessed
00:24:58a greeting
00:24:59coming from his insides,
00:25:01a voice from within.
00:25:03He surely
00:25:04is getting a little worried
00:25:06about his sanity.
00:25:08The three-dimensional creature
00:25:09is unhappy
00:25:11about being considered
00:25:12a psychological aberration
00:25:14and so he descends
00:25:16to actually
00:25:18enter
00:25:19flat land.
00:25:20Now,
00:25:20a three-dimensional creature
00:25:21exists in flat land
00:25:22only partially,
00:25:24only a plane,
00:25:26a cross-section
00:25:27through him
00:25:28can be seen.
00:25:29So,
00:25:30when the three-dimensional
00:25:31creature first
00:25:32reaches flat land,
00:25:33it's only the points
00:25:34of contact
00:25:34which can be seen,
00:25:36and we'll represent that
00:25:36by stamping
00:25:37the apple
00:25:39in this
00:25:39ink pad
00:25:40and placing that image
00:25:44in flat land.
00:25:46And
00:25:46as the apple
00:25:48were to descend
00:25:49through,
00:25:50slither by
00:25:51flat land,
00:25:52we would progressively
00:25:53see higher and higher
00:25:54slices,
00:25:55which we can represent
00:25:56by
00:25:58cutting
00:25:59the apple.
00:26:01so the square
00:26:05as time
00:26:07goes on
00:26:07sees a
00:26:09set of objects
00:26:11mysteriously appear
00:26:12from nowhere
00:26:13and
00:26:14inside a closed
00:26:15room
00:26:16and change
00:26:17their shape
00:26:18dramatically.
00:26:19His only conclusion
00:26:21could be
00:26:21that he's gone
00:26:22bunkers.
00:26:23Well,
00:26:24the apple might be
00:26:24a little annoyed
00:26:25at this conclusion
00:26:26and so
00:26:26not
00:26:28such a friendly
00:26:29gesture
00:26:30from dimension
00:26:30to dimension,
00:26:32makes a
00:26:32contact
00:26:33with the square
00:26:34from below
00:26:34and sends
00:26:36our flat creature
00:26:36fluttering
00:26:37and spinning
00:26:38above flat land.
00:26:40At first,
00:26:41the square
00:26:41has no idea
00:26:42what's happening.
00:26:43It's terribly
00:26:44confused.
00:26:45This is utterly
00:26:45outside his experience.
00:26:47But after a while,
00:26:49he comes to realize
00:26:50that he is seeing
00:26:51inside
00:26:52closed rooms
00:26:54in flat land.
00:26:55He is looking
00:26:56inside his
00:26:57fellow flat creatures.
00:26:58He is seeing
00:27:00flat land
00:27:00from a perspective
00:27:01no one has ever
00:27:02seen it before
00:27:03to his knowledge.
00:27:04Getting into
00:27:05another dimension
00:27:05provides as an
00:27:07incidental benefit
00:27:08a kind of
00:27:08x-ray vision.
00:27:10Now,
00:27:11our flat creature
00:27:12slowly descends
00:27:13to the surface
00:27:14and
00:27:16his
00:27:17friends
00:27:18rush up
00:27:18to see him.
00:27:19From their point
00:27:20of view,
00:27:20he has mysteriously
00:27:21appeared from nowhere.
00:27:23He hasn't
00:27:23walked from
00:27:24somewhere else.
00:27:25He's come
00:27:25from some other
00:27:26place.
00:27:27They say,
00:27:28for heaven's sake,
00:27:29what's happened
00:27:29to you?
00:27:30And the poor
00:27:31square has to say,
00:27:32well,
00:27:33I was in
00:27:33some other
00:27:35mystic dimension
00:27:36called up.
00:27:38And they will
00:27:39pat him on
00:27:40his side
00:27:41and comfort him
00:27:43or else he'll
00:27:43ask,
00:27:44well,
00:27:44show us.
00:27:45Where is that
00:27:45third dimension?
00:27:47Point to it.
00:27:48And the poor
00:27:49square will be
00:27:50unable to comply.
00:27:52But maybe
00:27:52more interesting
00:27:53is the other
00:27:55direction
00:27:55in dimensionality.
00:27:57What about
00:27:58the fourth
00:27:59dimension?
00:28:01Now,
00:28:01to approach
00:28:02that,
00:28:02let's consider
00:28:03a cube.
00:28:04We can
00:28:05imagine a cube
00:28:06in the following
00:28:06way.
00:28:07You take
00:28:07a line segment
00:28:08and move it
00:28:09at right angles
00:28:10to itself
00:28:11in equal length.
00:28:11That makes
00:28:12a square.
00:28:13Move that
00:28:14square in equal
00:28:15length at right angles
00:28:15to itself
00:28:16and you have
00:28:17a cube.
00:28:18Now,
00:28:20this cube,
00:28:21we understand,
00:28:23casts a shadow.
00:28:27And
00:28:27that shadow
00:28:30we recognize.
00:28:32It's, you know,
00:28:33ordinarily drawn
00:28:34in third grade
00:28:36classrooms as
00:28:37two squares
00:28:37with their
00:28:39vertices connected.
00:28:40Now, if we
00:28:41look at the
00:28:41shadow of a
00:28:42three-dimensional
00:28:43object in two
00:28:43dimensions,
00:28:44we see that
00:28:45in this case
00:28:46not all the
00:28:47lines appear
00:28:48equal.
00:28:49Not all the
00:28:49angles are
00:28:50right angles.
00:28:51The three-dimensional
00:28:51object has not
00:28:52been perfectly
00:28:53represented in its
00:28:54projection in two
00:28:55dimensions,
00:28:55but that's part
00:28:57of the cost
00:28:58of losing a
00:28:59dimension in the
00:29:00projection.
00:29:01Now,
00:29:03let's take
00:29:04this three-dimensional
00:29:05cube and
00:29:07project it,
00:29:08carry it,
00:29:09through a fourth
00:29:10physical dimension.
00:29:11Not that way.
00:29:12Not that way.
00:29:14Not that way.
00:29:15But at
00:29:16right angles to
00:29:17those three
00:29:17directions,
00:29:18I can't show you
00:29:19what direction
00:29:19that is,
00:29:20but imagine that
00:29:20there is a
00:29:21fourth physical
00:29:22dimension.
00:29:23In that case,
00:29:23we would generate
00:29:24a four-dimensional
00:29:26hypercube,
00:29:27which is also
00:29:28called a
00:29:28tesseract.
00:29:29I cannot show you
00:29:30a tesseract,
00:29:31because I and
00:29:33you are trapped
00:29:34in three dimensions.
00:29:35But what I can
00:29:36show you is the
00:29:37shadow in three
00:29:39dimensions of a
00:29:40four-dimensional
00:29:41hypercube, or
00:29:42tesseract.
00:29:43this is it.
00:29:45And you can see
00:29:46it's two nested
00:29:47cubes, all the
00:29:49vertices connected
00:29:50by lines, and
00:29:52now the real
00:29:53tesseract in
00:29:55four dimensions
00:29:56would have all
00:29:57the lines of
00:29:57equal length and
00:29:58all the angles
00:29:59right angles.
00:30:00That's not what we
00:30:01see here, but
00:30:01that's the penalty
00:30:02of projection.
00:30:05So, you see,
00:30:07while we cannot
00:30:07imagine the world
00:30:09of four dimensions,
00:30:10we can certainly
00:30:12think about it
00:30:13perfectly well.
00:30:16Now, imagine a
00:30:18universe just like
00:30:19Flatland, truly
00:30:20two-dimensional, and
00:30:21entirely flat in
00:30:23every direction, but
00:30:24with one exception.
00:30:27Unbeknownst to the
00:30:28inhabitants, their
00:30:29two-dimensional
00:30:30universe is curved
00:30:31into a third
00:30:32physical dimension,
00:30:34maybe into a
00:30:35sphere, but at any
00:30:36rate, into something
00:30:37entirely outside their
00:30:39experience.
00:30:41Locally, their
00:30:42universe still looks
00:30:44flat enough, but
00:30:45if one of them, much
00:30:47smaller and flatter
00:30:48than me, takes a
00:30:50very long walk along
00:30:51what seems to be a
00:30:52straight line, he
00:30:53would uncover a
00:30:55great mystery.
00:30:56Suppose he marked
00:30:57his starting point
00:30:58here and set off
00:31:01to explore his
00:31:02universe.
00:31:04He never turns
00:31:05around, and he
00:31:06never reaches an
00:31:07edge.
00:31:07He doesn't know
00:31:09that his apparently
00:31:10flat universe is
00:31:12actually curved into
00:31:13an enormous sphere.
00:31:15He doesn't sense
00:31:16that he's walking
00:31:17around a globe.
00:31:20Why should his
00:31:21space be curved?
00:31:23Because there's so
00:31:24much matter in this
00:31:24universe that it
00:31:25gravitationally warps
00:31:27space, closing it back
00:31:28on itself into a
00:31:30sphere.
00:31:30But our Flatlander
00:31:32doesn't know this.
00:31:33After a long while,
00:31:35you'll find he somehow
00:31:36returns to his starting
00:31:37point.
00:31:38There must be a third
00:31:40dimension.
00:31:42Our Flatlander couldn't
00:31:43imagine a third
00:31:45dimension, but he could
00:31:46sure deduce it.
00:31:48Now, increase all the
00:31:49dimensions in this story
00:31:50by one, and you have
00:31:51something like the
00:31:52situation which many
00:31:53cosmologists think may
00:31:55actually apply to us.
00:31:57We are three-dimensional
00:32:00creatures trapped in
00:32:01three dimensions.
00:32:02We imagine our universe
00:32:04to be flat in three
00:32:05dimensions, but maybe
00:32:07it's curved into a
00:32:09fourth.
00:32:10We can talk about a
00:32:11fourth physical dimension,
00:32:13but we can't experience
00:32:14it.
00:32:14No one can point to the
00:32:16fourth dimension.
00:32:17I mean, there's left-right,
00:32:19and there's forward-back,
00:32:20there's up-down, and
00:32:22there's some other
00:32:24direction simultaneously at
00:32:26right angles to those
00:32:27familiar three dimensions.
00:32:30Now, imagine this
00:32:31universe is expanding.
00:32:34If we blow it up like a
00:32:36four-dimensional balloon,
00:32:37what happens?
00:32:39An astronomer in a given
00:32:40galaxy thinks all the
00:32:42other galaxies are running
00:32:43away from him.
00:32:45The more distant the
00:32:46galaxy, the faster it seems
00:32:48to be moving.
00:32:49This is just what
00:32:50Hummison and Hubble found.
00:32:52On the surface of this
00:32:56curved universe, there is
00:32:57no boundary or center.
00:32:59The universe can be both
00:33:01finite and unbounded.
00:33:07The red shift of the
00:33:09distant galaxies seemed to
00:33:10imply to Hummison's
00:33:12contemporaries that we were
00:33:13at the center of an
00:33:14expanding universe, that our
00:33:16place in space was somehow
00:33:17privileged.
00:33:18But if the universe is
00:33:19expanding, whether or not it's
00:33:21curved into a fourth
00:33:22dimension, observers on
00:33:24every galaxy will see
00:33:25precisely the same thing.
00:33:27All the galaxies rushing
00:33:28away from them as if they
00:33:30had made some dreadful
00:33:31intergalactic social blunder.
00:33:35If there's enough matter to
00:33:36close the universe
00:33:37gravitationally, then it's
00:33:39wrapped in on itself like a
00:33:40sphere.
00:33:41If there isn't enough matter
00:33:45to close the cosmos, then our
00:33:48universe has an open shape
00:33:50extending forever in all
00:33:52directions.
00:33:54This saddle universe is only
00:33:57one of an infinite number of
00:33:59possible kinds of open
00:34:00universes.
00:34:02Unlike such closed universes as
00:34:03the sphere, open universes have
00:34:06in them an infinite amount of
00:34:08space.
00:34:08If our universe is in fact
00:34:13closed off, then nothing can
00:34:16get out, not matter, not
00:34:17light.
00:34:18We would then be living inside
00:34:20a black hole.
00:34:21There is one possible way out
00:34:23though, a hypothetical tunnel or
00:34:25wormhole to the next higher
00:34:28dimension, a place sucking in
00:34:30matter and light.
00:34:33Can we find such a wormhole?
00:34:35Could we survive the trip?
00:34:37We might emerge in some other
00:34:42place in time, perhaps in another
00:34:44universe, or perhaps somewhere
00:34:46else in our own.
00:34:50If you want to know what it's like
00:34:52inside a black hole, look around.
00:34:55But we don't yet know whether the
00:34:59universe is open or closed.
00:35:02More than that, there are a few
00:35:03astronomers who doubt that the
00:35:05redshift of distant galaxies is due
00:35:07to the Doppler effect, who are
00:35:09skeptical about the expanding
00:35:11universe and the Big Bang.
00:35:14Perhaps our descendants will regard
00:35:17our present ignorance with as much
00:35:19sympathy as we feel to the ancients
00:35:22for not knowing whether the earth
00:35:23went around the sun.
00:35:25If the general picture, however, of a
00:35:27Big Bang followed by an expanding
00:35:29universe is correct, what happened
00:35:32before that?
00:35:34Was the universe devoid of all matter
00:35:36and then the matter suddenly somehow
00:35:39created?
00:35:40How did that happen?
00:35:42In many cultures, the customary answer
00:35:45is that a god or gods created the
00:35:48universe out of nothing.
00:35:51But if we wish to pursue this question
00:35:53courageously, we must, of course,
00:35:56ask the next question.
00:35:58Where did God come from?
00:35:59If we decide that this is an unanswerable
00:36:02question, why not save a step and
00:36:04conclude that the origin of the universe
00:36:07is an unanswerable question?
00:36:09Or, if we say that God always existed,
00:36:13why not save a step and conclude that
00:36:16the universe always existed?
00:36:18There's no need for a creation.
00:36:19It was always here.
00:36:21These are not easy questions.
00:36:23Cosmology brings us face to face
00:36:24with the deepest mysteries, with
00:36:28questions that were once treated only
00:36:29in religion and myth.
00:36:37Who knows for certain?
00:36:46Who shall here declare it?
00:36:48Whence was it born?
00:36:49Whence came creation?
00:36:52The gods are later than this world's
00:36:55formation.
00:36:56Who then can know the origins of the world?
00:37:02None knows whence creation arose,
00:37:04or whether he has or has not made it,
00:37:07he who surveys it from the lofty skies.
00:37:11Only he knows, or perhaps he knows not.
00:37:20These words are 3,500 years old.
00:37:24They're taken from the Rig Veda,
00:37:26a collection of early Sanskrit hymns.
00:37:29The most sophisticated ancient cosmological ideas
00:37:32came from Asia, and particularly from India.
00:37:36Here, there's a tradition of skeptical questioning
00:37:39and unselfconscious humility
00:37:41before the great cosmic mysteries.
00:37:45Amidst the routine of daily life,
00:37:49in, say, the harvesting and winnowing of grain,
00:37:51people all over the world have wondered,
00:37:53where did the universe come from?
00:37:58Asking this question is a hallmark of our species.
00:38:08There's a natural tendency to understand
00:38:10the origin of the cosmos in familiar biological terms,
00:38:14the mating of cosmic deities,
00:38:17or the hatching of a cosmic egg,
00:38:19or maybe the intonation of some magic phrase.
00:38:30The Big Bang is our modern scientific creation myth.
00:38:35It comes from the same human need
00:38:37to solve the cosmological riddle.
00:38:41Most cultures imagined the world
00:38:43to be only a few hundred human generations old.
00:38:45Hardly anyone guessed
00:38:47that the cosmos might be far older,
00:38:50but the ancient Hindus did.
00:38:57They, like every other society,
00:39:01noted and calibrated the cycles in nature.
00:39:05The rising and setting of the sun and stars,
00:39:09the phases of the moon,
00:39:12the passing of the seasons.
00:39:29All over South India,
00:39:31an age-old ceremony takes place every January,
00:39:35a rejoicing in the generosity of nature
00:39:37in the annual harvesting of the crops.
00:39:39Every January, nature provides the rice
00:39:43to celebrate pangal.
00:39:46Even the draft animals are given the day off
00:39:49and garlanded with flowers.
00:40:02Colorful designs are painted on the ground
00:40:05to attract harmony and good fortune
00:40:08for the coming year.
00:40:09for the coming year.
00:40:11Pangal, a simple porridge, a mixture of rice
00:40:41and sweet milk symbolizes the harvest, the return of the seasons.
00:40:58However, this is not merely a harvest festival.
00:41:02It has ties to an elegant and much deeper cosmological tradition.
00:41:18The Pangal festival is a rejoicing in the fact that there are cycles in nature.
00:41:25But how could such cycles come about unless the gods will them?
00:41:28And if there are cycles in the years of humans, might there not be cycles in the eons of the
00:41:35gods?
00:41:37The Hindu religion is the only one of the world's great faiths dedicated to the idea that the
00:41:42cosmos itself undergoes an immense, indeed an infinite number of deaths and rebirths.
00:41:50It is the only religion in which the timescales correspond, no doubt by accident, to those
00:42:12of modern scientific cosmology.
00:42:14Cycles run from our ordinary day and night to a day and night of Brahma, 8.64 billion
00:42:22years long, longer than the age of the earth or the sun, and about half the time since the
00:42:29Big Bang.
00:42:31And there are much longer timescales still.
00:42:43There is the deep and appealing notion that the universe is but the dream of the god who,
00:42:52after a hundred Brahma years, dissolves himself into a dreamless sleep, and the universe dissolves
00:43:01with him until, after another Brahma century, he stirs, recomposes himself, and begins again
00:43:11to dream the great cosmic lotus dream.
00:43:19Meanwhile, elsewhere, there are an infinite number of other universes, each with its own
00:43:27god dreaming the cosmic dream.
00:43:35These great ideas are tempered by another, perhaps still greater.
00:43:41It is said that men may not be the dreams of the gods, but rather that the gods are the
00:43:50dreams of men.
00:43:58In India, there are many gods, and each god has many manifestations.
00:44:04These Chola bronzes cast in the 11th century include several different incarnations of the
00:44:10god Shiva, seen here at his wedding.
00:44:15The most elegant and sublime of these bronzes is a representation of the creation of the universe
00:44:22at the beginning of each cosmic cycle, a motif known as the cosmic dance of Shiva.
00:44:30The god has four hands.
00:44:32In the upper right hand is a drum whose sound is the sound of creation.
00:44:40In the upper left hand is a tongue of flame, a reminder that the universe, now newly created,
00:44:48will, billions of years from now, be utterly destroyed, creation, destruction.
00:45:16These profound and lovely ideas are central to ancient Hindu beliefs, as exemplified in this
00:45:29Chola temple at Dharas Asuram.
00:45:32They are a kind of premonition of modern astronomical ideas.
00:45:38Without doubt, the universe has been expanding since the Big Bang.
00:45:42But it is by no means clear that it will continue to expand forever.
00:45:47If there is less than a certain amount of matter in the universe, then the mutual gravitation
00:45:54of the receding galaxies will be insufficient to stop the expansion, and the universe will
00:46:00run away forever.
00:46:02But if there is more matter than we can see, hidden away in black holes, say, or in hot but
00:46:09invisible gas between the galaxies, then the universe holds together and partakes of a
00:46:16very Indian succession of cycles, expansion followed by contraction, cosmos upon cosmos,
00:46:24universes without end.
00:46:26If we live in such an oscillating universe, then the Big Bang is not the creation of the
00:46:30cosmos, but merely the end of the previous cycle, the destruction of the last incarnation
00:46:38of the cosmos.
00:46:40Neither of these modern cosmologies may be altogether to our liking.
00:46:46In one cosmology, the universe is created somehow from nothing 15 to 20 billion years ago and expands forever,
00:46:56the galaxies mutually receding until the last one disappears over our cosmic horizon.
00:47:05Then, the galactic astronomers are out of business, the stars cool and die, matter itself decays, and the universe
00:47:15becomes a thin, cold haze of elementary particles.
00:47:21In the other, the oscillating universe, the cosmos has no beginning and no end, and we are in the midst of an infinite
00:47:29cycle of cosmic deaths and rebirths, with no information trickling through the cusps of the oscillation.
00:47:38Nothing of the galaxies, stars, planets, lifeforms, civilizations evolved in the previous incarnation of the universe
00:47:48trickles through the cusp, flitters past the Big Bang to be known in our universe.
00:47:59The death of the universe in either cosmology may seem a little depressing,
00:48:06but we may take some solace in the timescales involved.
00:48:10These events will take tens of billions of years or more.
00:48:15Human beings, or our descendants, whoever they might be,
00:48:20can do a great deal of good in tens of billions of years before the cosmos dies.
00:48:29If the universe truly oscillates, if the modern scientific version of the old Hindu cosmology is valid,
00:48:51then still stranger questions arise.
00:48:54Some scientists think that when redshift is followed by blueshift, causality will be inverted,
00:49:02and effects will precede causes.
00:49:06First, the ripples spread out from a point on the water's surface.
00:49:10Then I throw the stone into the pond.
00:49:18Some scientists wonder, in an oscillating universe, about what happens at the cusps,
00:49:25at the transition from contraction to expansion.
00:49:30Some think that the laws of nature are then randomly reshuffled,
00:49:34that the kinds of physics and chemistry we have in this universe represent only one of an infinite range of possible natural laws.
00:49:45It is easy to see that only a very restricted range of laws of nature are consistent with galaxies and stars, planets, life, and intelligence.
00:49:57If the laws of nature are randomly reshuffled at the cusps,
00:50:02then it is only the most extraordinary coincidence that the cosmic slot machine has this time come up with a universe consistent with us.
00:50:13Do we live in a universe which expands forever, or in one where there is a nested set of infinite cycles?
00:50:23There is a way to find out the answer to that question, not by mysticism, but through science,
00:50:29by making an accurate census of the total amount of matter in the universe,
00:50:33or by seeing to the very edge of the cosmos.
00:50:42Radio telescopes are able to detect distant quasars billions of light years away, expanding with the fabric of space.
00:51:05By looking far out into space, we are also looking far back into time,
00:51:10back toward the horizon of the universe, back toward the epoch of the Big Bang.
00:51:17Radio telescopes have even detected the cosmic background radiation,
00:51:23the fires of the Big Bang, cooled and redshifted, faintly echoing down the corridors of time.
00:51:30This is the very large array, a collection of 17 separate radio telescopes all working collectively in a remote region of New Mexico.
00:51:50Modern radio telescopes are exquisitely sensitive.
00:51:55A distant quasar is so faint that its received radiation by some such telescope amounts to maybe a quadrillionth of a watt.
00:52:07In fact, this is a reasonably stunning piece of information.
00:52:13The total amount of energy ever received by all the radio telescopes on the planet Earth is less than the energy of a single snowflake striking the ground.
00:52:24In detecting the cosmic background radiation, in counting quasars, in searching for intelligent signals from space,
00:52:34radio astronomers are dealing with amounts of energy which are barely there at all.
00:52:39These radio telescopes, rising like giant flowers from the New Mexico desert, are monuments to human ingenuity.
00:52:54The faint radio waves are collected, focused, assembled, and amplified, and then converted into pictures of nebulae, galaxies, and quasars.
00:53:13If you had eyes that worked in radio light, they'd probably be bigger than wagon wheels, and this is the universe you'd see.
00:53:21An elliptical galaxy, for example, leaving behind it a long wake glowing in radio waves.
00:53:34Radio waves reveal a universe of quasars, interacting galaxies, titanic explosions.
00:53:40Every time we use another kind of light to view the cosmos, we open a new door of perception.
00:53:55As the murmurs from the edge of the cosmos slowly accumulate, our understanding grows.
00:54:01This is an exploration of the ancient and the invisible, a continuing human inquiry into the grand cosmological questions.
00:54:17Another important recent finding was made by X-ray observatories in Earth orbit.
00:54:35Artificial satellites launched to view the sky, not in ordinary visible light, not in radio waves, but in X-ray light.
00:54:46There seems to be an immense cloud of extremely hot hydrogen glowing in X-rays between some galaxies.
00:54:56Now, if this amount of intergalactic matter were typical of all clusters of galaxies, then there may be just enough matter to close the cosmos and to trap us forever in an oscillating universe.
00:55:11If the cosmos is closed, there's a strange, haunting, evocative possibility, one of the most exquisite conjectures in science or religion.
00:55:28It's entirely undemonstrated, it may never be proved, but it's stirring.
00:55:33Our entire universe, to the furthest galaxy, we are told, is no more than a closed electron in a far grander universe we can never see.
00:55:45And that universe is only an elementary particle in another still greater universe, and so on, forever.
00:55:51Also, every electron in our universe, it is claimed, is an entire miniature cosmos, containing galaxies and stars and life and electrons.
00:56:04Every one of those electrons contains a still smaller universe, an infinite regression, up and down.
00:56:11Every human generation has asked about the origin and fate of the cosmos.
00:56:21Ours is the first generation with a real chance of finding some of the answers.
00:56:28One way or another, we are poised at the edge of forever.
00:56:33Except for planetary exploration, the study of galaxies and cosmology, what this episode was about, have undergone the greatest advances since cosmos was first broadcast.
00:56:54For one thing, at last we have a good photograph of our own Milky Way galaxy, about 100,000 light years across.
00:57:03Here it is.
00:57:09It was taken by NASA's COBE satellite.
00:57:13We see it edge on, of course, since we're embedded in the plane of the galaxy.
00:57:18But you don't need a spacecraft to see it.
00:57:20If it's a clear night tonight, why not go out and take a look at the Milky Way?
00:57:26There's also new evidence suggesting that the Milky Way is not so much an ordinary spiral galaxy as a barred spiral, like this.
00:57:40Important work has now been done on mapping how the galaxies are scattered through intergalactic space.
00:57:47To the surprise of a lot of scientists, on a scale of hundreds of millions of light years, the galaxies turn out not to be strewn at random or concentrated in clusters of galaxies, but instead strung out along odd, irregular surfaces, like this.
00:58:08Every dot in this computer animation is a galaxy.
00:58:15The computer lets us look at this distribution of galaxies from many points of view, but this is how it looks, from the Earth.
00:58:22There's an odd mannequin shape that is presented by the distribution of galaxies.
00:58:32This work has been done mainly by Margaret Geller with her collaborator John Huckra at Harvard University and the Smithsonian Institution.
00:58:41It's a little like soap bubbles in a bathtub or in dishwashing detergent.
00:58:56The galaxies are on the surfaces of the bubbles.
00:59:01The insides of the bubbles seem to have almost no galaxies in them at all.
00:59:05An average bubble is about a hundred million light years across, and that means that we've mapped still only a very small volume of the accessible universe.
00:59:14The galaxies nearest to us, but pretty soon we should be able to extend this search out to enormous distances, out to distances so far away in space that we're looking back to the time that galaxies and their structures were first forming.
00:59:31And this poses a real problem.
00:59:33Most cosmologists hold that the galaxies arise from a pre-existing lumpiness in the early universe, with little lumps growing into galaxies.
00:59:44But the background radiation from the Big Bang that fills all of space has now been carefully measured by that same COBE satellite that took that picture.
00:59:54Now those radio waves seem almost perfectly uniform across the sky, as if the Big Bang weren't lumpy or granular at all.
01:00:04But if the early radiation and matter in the universe weren't lumpy, how could individual galaxies form? How could the bubbles form?
01:00:12Is there a contradiction between the uniformity of the Big Bang radio waves and the bubble structures formed by the galaxies? That's the question.
01:00:20When our survey of the galaxies reaches out to billions of light years, we'll have the answer to this question.
01:00:27Incidentally, maybe you're thinking that the bubbles imply a bubble maker.
01:00:36But then I'd have to ask you, who made the bubble maker?
01:00:40There's another infinite regress lurking here.
01:00:43And to one of the grandest questions, whether there's enough matter in the universe to close it, the only fair answer is that we still don't know.
01:00:52If it is closed, what is the hidden matter that's closing it?
01:00:56Is it faint stars, black holes, massive neutrinos, some exotic kind of dark matter unknown on Earth?
01:01:03We don't know.
01:01:04But there are reasons to think that we'll soon find out the answers.
01:01:08We'll soon find out the answers.
01:01:38The questions we'll find out the answers.
01:01:41With the answers.
01:01:42There may not be gaps in the answers.
01:01:44It only allows us to think of the answers.
01:01:49Up at 7 possible, we'll ask if the answers answer will.
01:01:56The answers are the questions.
01:01:58The answers are the answers.
01:02:00The answers are the answers.
01:02:03The answers are the answers.
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