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"Hiding In The Light"
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The age and size of the cosmos
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are written in light.
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The nature of beauty and
the substance of the stars,
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the laws of space and time...
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they were there all along,
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but we never saw them...
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until we devised
a more powerful way of seeing.
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The story of this awakening
has many beginnings
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and no ending.
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Its heroes come from many times
and places--
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an Ancient Chinese philosopher,
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a wizard who amazed the caliphs
of 11th-century Iraq,
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a poor German orphan enslaved
to a harsh master.
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Each one brought us
a little closer
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to unlocking the secrets
hidden in light.
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Most of their names
are forever lost to us,
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but somewhere, long ago,
someone glanced up
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to see light perform
one of its magic tricks.
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Who knows?
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Maybe that quirk of light
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inspired the very first artist.
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Where did all this come from?
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How did we evolve
from small wandering bands
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of hunters and gatherers living
beneath the stars
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to become the builders
of a global civilization?
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How did we get from there
to here?
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There's no one answer.
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Climate change,
the domestication of fire,
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the invention of tools,
language, agriculture
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all played a role.
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Maybe there was
something else, too.
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In China,
more than 2,000 years ago,
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a philosopher named Mo Tze
is said to have observed
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that light could be made
to paint a picture
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inside a locked treasure room.
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This was the description
of the first camera...
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the camera obscura,
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the prototype of all
image-forming cameras,
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including the one that's
bringing you this picture.
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Taking advantage of this funny
thing that light does
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resulted in what could be
called the first movie.
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Mo Tze, master of light, worked
against all forms of darkness.
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A military genius
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who only used his talents
to prevent violence,
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he was legendary for traveling
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among the kingdoms
of the warring states,
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employing ingenious strategies
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to talk kings out
of going to war.
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He was one of the first
to dream of universal love
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and an end to poverty
and other forms of inequality;
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of government for the people...
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and to argue against
blind obedience
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to ritual and authority.
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In his writings, you can find
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early stirrings
of the scientific approach.
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00:05:01,724 --> 00:05:04,659
By Mo Tze's time, the Chinese
had already been recording
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00:05:04,693 --> 00:05:08,029
their thoughts in books
for at least a thousand years.
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Still, our knowledge of him
is only fragmentary.
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It consists largely
of the collection of essays
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attributed to him
and his disciples.
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In one of them,
entitled "Against Fate,"
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a three-pronged test
for every doctrine is proposed.
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Question its basis--
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ask if it can be verified
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by the sights and senses
of common people--
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ask how it is to be applied
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and if it will benefit
the greatest number.
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Mo Tze was extremely popular,
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but a few hundred years
after his death,
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Qin Shi Huang,
the first emperor,
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and unifier of China,
took power.
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He took a continent
and turned it into a nation
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that now bears his name... China.
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Most of us know Emperor Qin
for the army of 7,000
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terra cotta warriors
that guard his tomb.
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In Emperor Qin's drive
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to consolidate
his far-flung empire,
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he took drastic measures
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to standardize everything
within it.
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This included mandating
a single coinage,
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making uniform all weights
and measures,
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the widths of carts and roads,
as well as the precise way
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the Chinese language was
to be written,
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including what you were
allowed to write and think.
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Emperor Qin's philosophy--
the only one permitted--
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was called "legalism,"
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which is just what
it sounded like,
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do as the law says... or else.
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It's a philosophy that's
not highly conducive
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to questioning authority.
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...that all the books of
the hundred schools of thought
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shall be be burned,
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that anyone who uses history
to criticize the present
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shall have his family executed.
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The works of
MoTze and Confucius
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and other philosophers
were destroyed
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in the world's first
book burning.
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Hundreds of scholars
bravely resisted
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by trying to preserve
the forbidden books.
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They were buried alive
in the capitol.
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Science needs the light
of free expression to flourish.
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It depends on the fearless
questioning of authority,
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the open exchange of ideas.
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Sparks of curiosity
in the writings of Mo Tze
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and his disciples were
effectively stomped out.
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It would be another thousand
years before the next movie.
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Luckily, our Ship
of the Imagination
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can take us anywhere
in space... and time.
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The ancient Chinese
and Greeks observed
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that light could be made
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to do wonderful things--
but no one asked that question
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favored by small children
and geniuses alike. Why?
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Until a thousand years ago...
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In the city of Basra, Iraq,
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there lived
another master of light.
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Ibn al-Hazen had a passionate
desire to understand nature.
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He questioned everything,
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especially those things that
everyone else took for granted.
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"How do we see?" he asked.
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Some of the great authorities
who came before him
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had taught that rays come out
of our eyes and travel
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to the objects we see
before returning to our eyes.
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But al-Hazen reasoned that
the stars were too far distant
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for something in our eyes
to travel all the way to them
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and back in the blink
of an eye.
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Excellent reasoning,
but al-Hazen didn't stop there.
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He searched for ways to compel
nature to divulge her secrets.
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His culture was open
to new ideas and questioning.
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It was the golden age
of science
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in the Islamic world.
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One that stretched from Cordoba
in Spain
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all the way to Samarkand
in Central Asia.
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Christian and Jewish scholars
were honored guests
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at the research institutes
of Baghdad, Cairo,
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and other Islamic capitols.
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Instead of burning books,
the caliphs sent emissaries
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around the world
in search of books.
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The caliphs lavishly funded
projects to translate, study,
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00:09:59,756 --> 00:10:01,958
and preserve them
for future generations.
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00:10:01,992 --> 00:10:04,927
Much of the light of Ancient
Greek science would have been
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permanently extinguished
without their efforts.
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00:10:07,431 --> 00:10:10,233
The reawakening to science
that took place in Europe,
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hundreds of years later,
was kindled by a flame
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that had been long tended
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by Islamic scholars
and scientists.
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00:10:17,508 --> 00:10:21,043
The Arabs also imported ideas
from India to the West,
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including the so-called
Arabic numerals
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that we all use today,
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00:10:25,983 --> 00:10:28,784
and the concept of zero...
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which comes in handy
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when you want to write
"billions and billions."
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Arabic astronomy was
so influential,
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that we still call most
of the bright stars
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by their Arabic names.
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And the "al's" in algebra,
algorithm, alchemy, and alcohol
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are just some
of the traces left
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from the time when Arabic
was the language of science.
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In the 11th century,
Ibn al-Hazen set about trying
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to test his ideas about light
and how we see.
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So we devised an experiment
to determine how light moves.
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We erected a tent
in full daylight
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and sealed it tightly so that
only a single ray of light
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could pierce its inner darkness.
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With little more than his brains
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and a straight
piece of wood-- a ruler--
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al-Hazen had accomplished
a great leap forward
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in the history of science.
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He discovered that
light moves in straight lines.
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But he was just getting started.
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Al-Hazen figured out that
the key to forming any image--
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whether you're talking about
an eye or camera obscura--
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is a small opening to restrict
the light that can enter
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an otherwise darkened chamber.
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That aperture
excludes the chaos
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of extraneous light rays
that surround us.
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The smaller the aperture,
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the fewer directions
that light can come from.
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And that makes
the image sharper.
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00:11:57,374 --> 00:12:00,142
So instead of being blinded
by the light,
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we can see everything
it has to show us.
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Al-Hazen made his own
camera obscura
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and dazzled the caliphs.
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A camera obscura works best
in bright light.
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The stars of the night sky
are way too dim for this.
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We somehow need a bigger
opening to collect light,
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but we also need
to maintain focus.
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A telescope collects light
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from any spot
in its field of view
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across the entire lens
or mirror,
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an opening much larger
than the camera obscura hole.
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00:12:33,277 --> 00:12:37,180
This is one
of the first telescopes...
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the one that Galileo looked
through in 1609.
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With it, he pulled aside
the heavy curtain of night
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and began to discover
the cosmos.
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00:13:01,104 --> 00:13:03,105
The lens made it possible
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00:13:03,140 --> 00:13:06,209
for a telescope to have a much
larger light-collecting area
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00:13:06,243 --> 00:13:08,544
than our eyes have.
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00:13:08,579 --> 00:13:11,981
Big buckets catch more rain
than small ones.
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00:13:12,015 --> 00:13:14,917
Modern telescopes have larger
collecting areas,
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00:13:14,952 --> 00:13:16,619
highly sensitive detectors,
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00:13:16,653 --> 00:13:19,555
and they track the same object
for hours at a time
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to accumulate as much
of its light as possible.
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00:13:22,960 --> 00:13:25,728
Space-based telescopes
such as the Hubble,
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00:13:25,762 --> 00:13:27,597
have captured light
from the most distant
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00:13:27,631 --> 00:13:29,265
and ancient galaxies,
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00:13:29,299 --> 00:13:32,468
giving us vastly clearer
pictures of the cosmos.
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00:13:34,104 --> 00:13:37,807
Al-Hazen discovered how images
are formed by light,
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00:13:37,841 --> 00:13:40,176
but that was far
from his greatest achievement.
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00:13:40,210 --> 00:13:42,912
Ibn al-Hazen was the first
person ever
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00:13:42,946 --> 00:13:45,615
to set down
the rules of science.
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00:13:45,649 --> 00:13:48,150
He created
an error-correcting mechanism,
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00:13:48,185 --> 00:13:50,653
a systematic and relentless way
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00:13:50,687 --> 00:13:53,322
to sift out misconceptions
in our thinking.
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00:13:53,357 --> 00:13:58,327
Finding truth is difficult...
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00:13:58,362 --> 00:14:01,330
and the road to it is rough.
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00:14:01,365 --> 00:14:03,633
As seekers after truth,
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00:14:03,667 --> 00:14:06,769
you will be wise to withhold
judgment and not simply put
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00:14:06,803 --> 00:14:09,672
your trust in the writings
of the ancients.
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00:14:09,706 --> 00:14:13,509
You must question and critically
examine those writings
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from every side.
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00:14:16,079 --> 00:14:19,315
You must submit only
to argument and experiment
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00:14:19,349 --> 00:14:22,718
and not to the sayings
of any person.
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00:14:22,753 --> 00:14:25,288
For every human being
is vulnerable
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to all kinds of imperfection.
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00:14:28,025 --> 00:14:30,459
As seekers after truth,
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00:14:30,494 --> 00:14:32,828
we must also suspect
and question
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00:14:32,863 --> 00:14:36,465
our own ideas as we perform
our investigations,
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00:14:36,500 --> 00:14:41,404
to avoid falling into prejudice
or careless thinking.
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00:14:41,438 --> 00:14:46,676
Take this course, and truth
will be revealed to you.
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This is the method of science.
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00:15:06,763 --> 00:15:09,565
So powerful that it's carried
our robotic emissaries
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00:15:09,600 --> 00:15:13,035
to the edge of
the solar system and beyond.
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00:15:14,771 --> 00:15:17,073
It has doubled our lifespan,
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00:15:17,107 --> 00:15:18,874
made the lost worlds
of the past
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00:15:18,909 --> 00:15:20,910
come alive.
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00:15:22,312 --> 00:15:24,547
Science has enabled us
to predict events
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00:15:24,581 --> 00:15:27,049
in the distant future...
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00:15:27,084 --> 00:15:30,553
and to communicate with each
other at the speed of light,
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00:15:30,587 --> 00:15:33,189
as I am with you,
right at this moment.
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00:15:33,223 --> 00:15:35,258
This way of thinking
has given us powers
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00:15:35,292 --> 00:15:38,928
that al-Hazen himself
would have regarded as wizardry.
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00:15:42,432 --> 00:15:46,802
But it was he who put us
on this rough, endless road.
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00:15:48,672 --> 00:15:51,540
And now it has taken us
to a place
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00:15:51,575 --> 00:15:56,279
where even light itself
is enshrouded in darkness.
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00:16:06,708 --> 00:16:08,843
Light has properties unlike
anything else
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00:16:08,877 --> 00:16:10,745
in the realm
of human existence.
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00:16:10,779 --> 00:16:12,914
Take the speed of light.
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00:16:12,948 --> 00:16:15,049
The basic particle of light,
the photon,
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00:16:15,083 --> 00:16:17,752
is born traveling
at the speed of light
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00:16:17,786 --> 00:16:20,555
as it emerges from
an atom or a molecule.
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00:16:20,589 --> 00:16:22,723
A photon never knows
any other speed,
253
00:16:22,758 --> 00:16:25,560
and we've not found another
phenomenon that accelerates
254
00:16:25,594 --> 00:16:28,529
from zero to top speed
instantaneously.
255
00:16:28,564 --> 00:16:30,765
Nothing else
could move as fast.
256
00:16:30,799 --> 00:16:33,434
When we try to accelerate other
particles closer and closer
257
00:16:33,468 --> 00:16:36,170
to the speed of light,
they resist more and more,
258
00:16:36,205 --> 00:16:37,939
as though they're getting
heavier and heavier.
259
00:16:37,973 --> 00:16:39,407
No experiment yet devised
260
00:16:39,441 --> 00:16:43,444
has ever made a particle
move as fast as light.
261
00:16:50,118 --> 00:16:52,753
What was that?
262
00:16:52,788 --> 00:16:54,956
You hear something?
263
00:16:54,990 --> 00:16:57,124
Where was I? Oh, yeah.
264
00:16:57,159 --> 00:17:01,229
I don't know anything else
in life that behaves like light.
265
00:17:01,263 --> 00:17:04,699
I cannot reconcile
its strange properties
266
00:17:04,733 --> 00:17:07,368
with everything else
my senses tell me.
267
00:17:07,402 --> 00:17:10,371
Our urge to trust
our senses overpowers
268
00:17:10,405 --> 00:17:12,473
what our measuring devices
tell us about
269
00:17:12,508 --> 00:17:14,408
the actual nature of reality.
270
00:17:14,443 --> 00:17:16,611
Our senses work fine
for life-size objects
271
00:17:16,645 --> 00:17:18,446
moving at mammal speeds,
272
00:17:18,480 --> 00:17:23,084
but are ill-adapted for the
wonderland laws of lightspeed.
273
00:17:27,256 --> 00:17:30,625
We don't even know why
there's a cosmic speed limit.
274
00:17:30,659 --> 00:17:34,095
Time stands still when you're
traveling at the speed of light.
275
00:17:34,129 --> 00:17:36,597
What is light, anyway?
276
00:17:40,135 --> 00:17:43,638
Isaac Newton's enduring
fascination with light
277
00:17:43,672 --> 00:17:45,840
began when he was a child...
278
00:17:48,277 --> 00:17:50,711
in this very house.
279
00:17:55,784 --> 00:17:59,954
By the time he was in his 20s,
Newton became the first person
280
00:17:59,988 --> 00:18:03,157
to decipher the mystery
of the rainbow.
281
00:18:06,862 --> 00:18:10,164
Newton discovered that some
light, or white light,
282
00:18:10,199 --> 00:18:13,167
is a mixture of all the colors
of the rainbow.
283
00:18:15,704 --> 00:18:17,772
Major discovery.
284
00:18:17,806 --> 00:18:20,341
He named the displays of colors
a "spectrum"
285
00:18:20,375 --> 00:18:24,645
from the Latin for "phantom"
or "apparition."
286
00:18:36,892 --> 00:18:38,860
Begging your pardon,
Master Newton,
287
00:18:38,894 --> 00:18:41,596
the cook frets that your dinner
will spoil, sir.
288
00:18:44,500 --> 00:18:46,667
No, Isaac, don't
put the magnifying glass down!
289
00:18:46,702 --> 00:18:50,471
Something even more amazing
is hidden in the light--
290
00:18:50,506 --> 00:18:53,007
a code, a key to the cosmos.
291
00:18:59,781 --> 00:19:03,684
Isaac Newton didn't miss much,
but that one was a beaut.
292
00:19:03,719 --> 00:19:06,821
He just walked right past
the door to a hidden universe;
293
00:19:06,855 --> 00:19:10,892
a door that would not swing open
again for another 150 years.
294
00:19:10,926 --> 00:19:13,227
It would fall
on another scientist,
295
00:19:13,262 --> 00:19:14,929
working in the year 1800,
296
00:19:14,963 --> 00:19:16,931
to stumble
on a piece of evidence
297
00:19:16,965 --> 00:19:19,967
for the unseen worlds
that surround us.
298
00:19:23,539 --> 00:19:25,972
By night, William Herschel
scanned the heavens
299
00:19:26,006 --> 00:19:28,475
with the largest telescope
of his time.
300
00:19:28,509 --> 00:19:31,445
By day, Herschel performed
experiments.
301
00:19:31,479 --> 00:19:34,114
From Newton's earlier work,
it was known that sunlight
302
00:19:34,148 --> 00:19:36,516
is a blend of different colors.
303
00:19:36,551 --> 00:19:38,918
And everyone knew,
just from being outside,
304
00:19:38,953 --> 00:19:41,153
that sunlight carries heat.
305
00:19:42,689 --> 00:19:44,690
William Herschel asked
306
00:19:44,724 --> 00:19:47,293
whether some colors of light
carry more heat than others.
307
00:19:47,327 --> 00:19:51,430
The nature of scientific genius
is to question
308
00:19:51,465 --> 00:19:54,266
what the rest of us
take for granted...
309
00:19:54,301 --> 00:19:56,867
and then do the experiment.
310
00:19:58,904 --> 00:20:02,340
The thermometer that Herschel
placed outside the spectrum
311
00:20:02,374 --> 00:20:04,375
was his control.
312
00:20:06,078 --> 00:20:07,979
The control in any experiment
313
00:20:08,013 --> 00:20:10,648
always lacks
the factor being tested.
314
00:20:10,682 --> 00:20:12,782
That way, you know
if what you're testing is
315
00:20:12,817 --> 00:20:14,918
really the thing responsible
for the observation.
316
00:20:16,053 --> 00:20:17,354
In Herschel's experiment,
317
00:20:17,388 --> 00:20:18,989
the relationship between
318
00:20:19,023 --> 00:20:20,390
color and temperature
was being tested,
319
00:20:20,425 --> 00:20:23,494
and so his control was
a thermometer
320
00:20:23,528 --> 00:20:25,195
over the part
of the white sheet
321
00:20:25,230 --> 00:20:28,531
that was not illuminated
by sunlight at all.
322
00:20:30,867 --> 00:20:32,401
There's that sound again.
323
00:20:32,436 --> 00:20:35,171
What is that?
324
00:20:40,910 --> 00:20:43,412
Okay, red light is warmer
than blue light.
325
00:20:43,447 --> 00:20:48,517
Interesting discovery,
but not exactly revolutionary.
326
00:21:10,038 --> 00:21:13,740
No, there's nothing wrong
with your thermometer.
327
00:21:13,775 --> 00:21:17,143
You've just discovered
a new kind of light.
328
00:21:25,986 --> 00:21:29,055
Herschel was the first
to detect this unseen presence
329
00:21:29,089 --> 00:21:32,291
lurking just below
the red end of the spectrum.
330
00:21:32,325 --> 00:21:35,227
That's why it came
to be called "infrared."
331
00:21:35,261 --> 00:21:37,429
"Infra" is Latin
for the word "below."
332
00:21:37,463 --> 00:21:39,030
It's invisible.
333
00:21:39,065 --> 00:21:41,433
Our eyes are not sensitive
to this kind of light,
334
00:21:41,467 --> 00:21:44,336
but our skin is--
we feel it as heat.
335
00:21:44,370 --> 00:21:46,171
Now, that's
a really big discovery.
336
00:21:46,206 --> 00:21:48,606
But far greater secrets
were still hiding
337
00:21:48,640 --> 00:21:51,108
deep inside the light.
338
00:21:59,062 --> 00:22:01,096
At about the
same time that William Herschel
339
00:22:01,130 --> 00:22:04,031
was discovering infrared light
in his parlor in England,
340
00:22:04,066 --> 00:22:06,534
a young boy named
Joseph Fraunhofer
341
00:22:06,569 --> 00:22:09,036
was trapped
in hopeless drudgery.
342
00:22:09,071 --> 00:22:12,006
He stood over a cauldron
of toxic chemicals
343
00:22:12,040 --> 00:22:14,409
and endlessly stirred.
344
00:22:16,311 --> 00:22:19,113
Joseph had been orphaned
at the age of 11
345
00:22:19,147 --> 00:22:22,949
and given to a harsh master
named Weichselberger,
346
00:22:22,984 --> 00:22:25,919
the royal mirror-maker.
347
00:22:25,953 --> 00:22:28,221
He prevented Joseph
from going to school.
348
00:22:28,256 --> 00:22:31,458
Instead, Joseph labored in
349
00:22:31,493 --> 00:22:33,427
the glass-making
workshop by day,
350
00:22:33,461 --> 00:22:35,928
and tended to the master's
household chores by night.
351
00:22:41,435 --> 00:22:42,935
Hurry up, stupid!
352
00:22:42,969 --> 00:22:45,905
And remember, no reading.
353
00:22:50,277 --> 00:22:53,111
Until Joseph got his big break.
354
00:22:53,145 --> 00:22:57,238
Weichselberger's
house collapsed.
355
00:23:15,297 --> 00:23:17,165
Maximilian, the future
king of Bavaria,
356
00:23:17,199 --> 00:23:19,100
hurried to the scene
of the calamity
357
00:23:19,134 --> 00:23:20,668
to see if he could help.
358
00:23:20,703 --> 00:23:23,137
Maximilian was known for
359
00:23:23,172 --> 00:23:24,772
taking an interest
in his subjects,
360
00:23:24,807 --> 00:23:27,008
which was highly unusual
for its time.
361
00:23:40,890 --> 00:23:44,025
In attracting the concern
of the future king of Bavaria,
362
00:23:44,059 --> 00:23:45,660
young Joseph Fraunhofer
363
00:23:45,694 --> 00:23:48,496
found an aperture into
a different universe.
364
00:23:48,530 --> 00:23:50,965
And not just for himself.
365
00:23:53,769 --> 00:23:55,537
Prince Maximilian
gave Joseph money
366
00:23:55,571 --> 00:23:57,372
and asked his privy councilor
367
00:23:57,406 --> 00:23:58,840
to provide further
help to the boy,
368
00:23:58,874 --> 00:24:01,242
should it be needed.
369
00:24:06,115 --> 00:24:08,817
Weichselberger continued
to exploit him
370
00:24:08,851 --> 00:24:11,152
and prevent him
from attending school.
371
00:24:11,187 --> 00:24:13,221
But the prince's councilor
intervened,
372
00:24:13,255 --> 00:24:16,758
offering Joseph a position
at the Optical Institute.
373
00:24:16,792 --> 00:24:21,930
This small gesture of kindness
really paid off.
374
00:24:34,276 --> 00:24:37,112
By the time he was 27,
375
00:24:37,146 --> 00:24:39,381
Joseph Fraunhofer was
the world's leading designer
376
00:24:39,415 --> 00:24:41,416
of high-quality lenses,
377
00:24:41,450 --> 00:24:44,119
telescopes and other
optical instruments.
378
00:24:44,153 --> 00:24:48,023
His firm was housed here,
in the old Benediktbeuren Abbey.
379
00:24:48,057 --> 00:24:50,225
In the early 19th century,
380
00:24:50,259 --> 00:24:53,561
this was top-secret,
ultra-high technology.
381
00:24:56,599 --> 00:24:58,800
The Benedictine monks
of earlier times
382
00:24:58,834 --> 00:25:00,802
had taken a vow of secrecy.
383
00:25:00,836 --> 00:25:02,804
This local tradition,
384
00:25:02,838 --> 00:25:04,305
and the ability
to restrict access
385
00:25:04,340 --> 00:25:05,874
to Fraunhofer's laboratory,
386
00:25:05,908 --> 00:25:07,876
allowed him to maintain control
387
00:25:07,910 --> 00:25:10,979
of trade and state secrets.
388
00:25:16,085 --> 00:25:18,386
Fraunhofer was experimenting
with prisms
389
00:25:18,421 --> 00:25:21,823
to find the best types of glass
for precision lenses.
390
00:25:21,857 --> 00:25:24,559
How, he wondered,
could he get a better look
391
00:25:24,593 --> 00:25:26,594
at the spectrum that
a prism produced?
392
00:25:29,765 --> 00:25:33,568
Friedrich, bring me
the theodolite, please.
393
00:25:33,602 --> 00:25:36,504
Okay, while Fraunhofer
sets up his theodolite--
394
00:25:36,539 --> 00:25:38,340
it's a kind of telescope--
395
00:25:38,374 --> 00:25:41,676
I want to show you something
in another part of the abbey.
396
00:25:46,315 --> 00:25:50,051
Sound waves are
so beautiful to hear.
397
00:25:51,887 --> 00:25:56,591
Imagine how beautiful
they'd be to see.
398
00:25:56,625 --> 00:25:59,828
You ever wondered why organ
pipes have different lengths?
399
00:26:02,064 --> 00:26:03,298
I press a key...
400
00:26:05,801 --> 00:26:07,202
it sends compressed air
401
00:26:07,236 --> 00:26:08,470
into a particular pipe,
402
00:26:08,504 --> 00:26:10,305
producing sound waves.
403
00:26:10,339 --> 00:26:13,041
If we could slow the sound waves
down a few hundred times,
404
00:26:13,075 --> 00:26:15,210
they would look like this.
405
00:26:18,914 --> 00:26:20,548
The length of the pipe
406
00:26:20,583 --> 00:26:22,017
determines the length
of the sound wave
407
00:26:22,051 --> 00:26:23,518
that can fit inside it.
408
00:26:23,552 --> 00:26:25,620
A short pipe gives you
a short sound wave.
409
00:26:27,656 --> 00:26:30,392
Short sounds waves have
high pitch, or frequency.
410
00:26:35,898 --> 00:26:38,566
Let's stop the waves
for a better look.
411
00:26:42,938 --> 00:26:44,873
The distance between
adjacent waves
412
00:26:44,907 --> 00:26:46,675
is called the wavelength.
413
00:26:46,709 --> 00:26:49,210
A long pipe gives you
a long sound wave
414
00:26:49,245 --> 00:26:51,613
with a low pitch,
or low frequency.
415
00:27:43,165 --> 00:27:46,067
The medieval manuscript of
this music, "Carmina Burana,"
416
00:27:46,102 --> 00:27:49,270
was discovered
in this very abbey.
417
00:27:52,475 --> 00:27:54,909
Sound waves can't travel
through a vacuum.
418
00:27:54,944 --> 00:27:56,811
They need matter to ride on,
419
00:27:56,846 --> 00:28:00,315
like molecules of air,
or water, or rock.
420
00:28:00,349 --> 00:28:02,450
But light waves fly solo.
421
00:28:02,485 --> 00:28:04,653
They can move
through empty space.
422
00:28:04,687 --> 00:28:06,287
And fast--
423
00:28:06,322 --> 00:28:09,424
a million times faster
than sound waves in air.
424
00:28:09,458 --> 00:28:11,426
And the wavelengths
of the light we see
425
00:28:11,460 --> 00:28:13,962
are so much shorter
than sound waves.
426
00:28:13,996 --> 00:28:16,831
About 50,000 light waves
427
00:28:16,866 --> 00:28:19,300
would fit right in here.
428
00:28:20,469 --> 00:28:22,003
Oh, yeah.
429
00:28:22,038 --> 00:28:23,471
Fraunhofer.
430
00:28:30,112 --> 00:28:31,446
Just in time.
431
00:28:31,480 --> 00:28:33,114
We didn't miss it.
432
00:28:33,149 --> 00:28:35,316
Just as the wavelength of sound
433
00:28:35,351 --> 00:28:37,318
determines the pitch
that we hear,
434
00:28:37,353 --> 00:28:38,820
the wavelength of light
435
00:28:38,854 --> 00:28:41,289
determines the color
that we see.
436
00:28:41,323 --> 00:28:43,758
But how does a prism
spread out the colors
437
00:28:43,793 --> 00:28:46,294
concealed in
a beam of sunlight?
438
00:28:46,328 --> 00:28:50,265
When light travels
through air or space,
439
00:28:50,299 --> 00:28:52,667
all its colors move
at the same speed.
440
00:28:54,704 --> 00:28:57,472
But when it hits glass
at an angle,
441
00:28:57,506 --> 00:28:59,908
the light slows down
and changes direction.
442
00:29:01,477 --> 00:29:03,445
Inside the prism,
443
00:29:03,479 --> 00:29:05,480
each color moves
at a different speed.
444
00:29:09,819 --> 00:29:11,619
In glass, violet light,
445
00:29:11,654 --> 00:29:13,822
which is carried by
the shortest waves we see,
446
00:29:13,856 --> 00:29:15,857
slows down more than red light,
447
00:29:15,891 --> 00:29:18,326
which has the longest waves.
448
00:29:20,162 --> 00:29:22,564
These changes in speed
449
00:29:22,598 --> 00:29:25,133
pry the colors apart,
450
00:29:25,167 --> 00:29:26,968
sending their waves off
451
00:29:27,002 --> 00:29:29,404
in slightly different
directions.
452
00:29:30,606 --> 00:29:32,607
That's how a prism works.
453
00:29:34,744 --> 00:29:37,011
If I seem unduly
emotional about this,
454
00:29:37,046 --> 00:29:39,848
it's because Joseph Fraunhofer
is about to do
455
00:29:39,882 --> 00:29:43,385
what Isaac Newton
could've done, but didn't.
456
00:29:43,419 --> 00:29:45,487
And it'll have a powerful effect
457
00:29:45,521 --> 00:29:47,355
on the course of my own life.
458
00:30:10,379 --> 00:30:12,414
You are witnessing the marriage
459
00:30:12,448 --> 00:30:14,049
of physics and astronomy,
460
00:30:14,083 --> 00:30:17,952
the birth of my own
field of science,
461
00:30:17,987 --> 00:30:20,422
astrophysics.
462
00:30:22,425 --> 00:30:24,192
Written in the light,
463
00:30:24,226 --> 00:30:27,629
in those vertical black lines...
464
00:30:29,065 --> 00:30:32,033
is secret code.
465
00:30:32,068 --> 00:30:34,869
Fraunhofer looked at them,
and wondered...
466
00:30:34,904 --> 00:30:36,905
Why?
467
00:30:39,750 --> 00:30:43,085
A code that comes to us
468
00:30:43,120 --> 00:30:45,554
from an alien universe.
469
00:30:57,283 --> 00:30:58,530
What is the message
470
00:30:58,616 --> 00:31:02,220
written in these dark,
vertical lines?
471
00:31:07,293 --> 00:31:09,360
It took a hundred years
of thinking,
472
00:31:09,395 --> 00:31:12,697
questioning, searching
to decipher it.
473
00:31:32,251 --> 00:31:34,385
Lovely, isn't it?
474
00:31:34,420 --> 00:31:35,954
Why?
475
00:31:35,988 --> 00:31:39,457
There are many layers to
the fine structure of beauty...
476
00:31:39,492 --> 00:31:42,627
the chemistry of the Earth
and its atmosphere...
477
00:31:42,661 --> 00:31:45,597
the evolution of life...
478
00:31:45,631 --> 00:31:49,200
Many distinct threads.
479
00:31:49,235 --> 00:31:52,303
Let's just examine one,
at the surface...
480
00:31:52,338 --> 00:31:54,739
the colors of nature
that dazzle us.
481
00:31:54,773 --> 00:31:57,876
What's really happening?
482
00:31:57,910 --> 00:31:59,777
How does the red, the blue...
483
00:31:59,812 --> 00:32:02,780
the astonishing palette
of nature's colors...
484
00:32:06,785 --> 00:32:09,420
how do they happen?
485
00:32:12,091 --> 00:32:14,259
Light waves of different lengths
from the Sun
486
00:32:14,293 --> 00:32:15,693
strike the Earth.
487
00:32:17,096 --> 00:32:19,130
The petals of these
particular flowers
488
00:32:19,165 --> 00:32:20,732
absorb all the low-energy,
489
00:32:20,766 --> 00:32:23,001
long red wavelengths of light.
490
00:32:23,035 --> 00:32:24,736
But the petals reflect
491
00:32:24,770 --> 00:32:28,072
the shorter, high-energy
blue wavelengths.
492
00:32:28,107 --> 00:32:30,842
That interaction
between starlight and petal--
493
00:32:30,876 --> 00:32:32,844
or water, or Van Gogh--
494
00:32:32,878 --> 00:32:34,445
is what makes blue.
495
00:32:34,480 --> 00:32:36,614
The longest waves,
496
00:32:36,649 --> 00:32:38,449
the ones we see as red,
497
00:32:38,484 --> 00:32:41,052
have the lowest energy.
498
00:32:43,989 --> 00:32:46,324
Color is the way
our eyes perceive
499
00:32:46,358 --> 00:32:48,226
how energetic light waves are.
500
00:32:50,062 --> 00:32:51,763
A sunset...
501
00:32:51,797 --> 00:32:53,932
a flag...
502
00:32:53,966 --> 00:32:56,367
the eyes of your beloved...
503
00:32:56,402 --> 00:32:58,136
that shiny new car.
504
00:32:58,170 --> 00:33:00,138
The feelings they inspire
505
00:33:00,172 --> 00:33:01,973
happen when something inside you
506
00:33:02,007 --> 00:33:04,476
is triggered by
a particular variation
507
00:33:04,510 --> 00:33:07,979
in the frequency and
energy of light waves.
508
00:33:09,748 --> 00:33:10,882
And the secret message?
509
00:33:10,916 --> 00:33:12,617
Those black vertical lines
510
00:33:12,651 --> 00:33:14,652
in Fraunhofer's spectrum?
511
00:33:14,687 --> 00:33:16,788
What makes them?
512
00:33:16,822 --> 00:33:18,990
They occur when the light waves
513
00:33:19,024 --> 00:33:21,793
of those particular colors
are being absorbed.
514
00:33:21,827 --> 00:33:24,362
It happens on another level
of reality,
515
00:33:24,396 --> 00:33:27,398
far smaller than the world
we're used to operating in.
516
00:33:27,433 --> 00:33:30,001
To get there,
we'll need to become
517
00:33:30,035 --> 00:33:32,770
ten billion times smaller
than we are.
518
00:33:35,541 --> 00:33:37,909
We could pick
any one of these atoms.
519
00:33:37,943 --> 00:33:41,012
But let's go
for the hydrogen atom.
520
00:33:41,046 --> 00:33:43,515
The hydrogen atom is
the most plentiful kind
521
00:33:43,549 --> 00:33:45,917
of atom in the cosmos.
522
00:33:45,951 --> 00:33:48,353
And the simplest.
523
00:33:55,861 --> 00:33:59,030
It has only one electron.
524
00:33:59,064 --> 00:34:01,566
And only one proton.
525
00:34:01,600 --> 00:34:03,668
We've entered
the quantum realm.
526
00:34:03,702 --> 00:34:05,503
It doesn't correspond
527
00:34:05,538 --> 00:34:08,273
to ordinary human experience.
528
00:34:08,307 --> 00:34:11,509
Common sense is
no help here at all.
529
00:34:11,544 --> 00:34:14,546
Take the hydrogen atom's
electron, for example.
530
00:34:16,482 --> 00:34:18,716
In an atom, an electron
531
00:34:18,751 --> 00:34:20,451
doesn't exist between orbitals.
532
00:34:20,486 --> 00:34:22,253
It disappears from one orbital
533
00:34:22,288 --> 00:34:24,923
and reappears in another.
534
00:34:24,957 --> 00:34:26,758
It's as if you took an elevator
from the second floor
535
00:34:26,792 --> 00:34:30,061
to the fourth floor,
but ceased to exist in between.
536
00:34:30,095 --> 00:34:31,796
And another thing.
537
00:34:31,831 --> 00:34:34,766
Quantum elevators only stop
at certain floors.
538
00:34:34,800 --> 00:34:38,203
The sizes of the electron
orbits are strictly limited,
539
00:34:38,237 --> 00:34:41,072
and different
for the atoms of every element.
540
00:34:42,608 --> 00:34:44,943
That's why the elements
are different.
541
00:34:44,977 --> 00:34:46,311
The chemistry
of anything is determined
542
00:34:46,345 --> 00:34:47,912
by its electron orbits.
543
00:34:47,947 --> 00:34:50,815
The force that holds
an electron in orbit
544
00:34:50,850 --> 00:34:52,650
has nothing to do with gravity.
545
00:34:52,685 --> 00:34:56,221
It's a force
of electrical attraction.
546
00:34:56,255 --> 00:34:58,556
The electron dances a wavy ring
547
00:34:58,591 --> 00:35:00,825
around the central nucleus
of a hydrogen atom.
548
00:35:00,860 --> 00:35:03,628
And makes quantum leaps
from orbit to orbit.
549
00:35:03,662 --> 00:35:04,929
Up or down.
550
00:35:04,964 --> 00:35:06,331
The larger the orbit,
551
00:35:06,365 --> 00:35:08,399
the greater the energy
of an electron.
552
00:35:08,434 --> 00:35:10,802
An electron has
553
00:35:10,836 --> 00:35:12,971
to get energy to leap
to a larger orbit.
554
00:35:13,005 --> 00:35:15,807
And it has to lose energy
to jump back down.
555
00:35:15,841 --> 00:35:19,143
Every upward leap
is caused by...
556
00:35:19,178 --> 00:35:22,580
an atom absorbing a light wave.
557
00:35:22,615 --> 00:35:26,417
But we have no idea what causes
the downward leaps.
558
00:35:26,452 --> 00:35:30,021
What we do know that such leaps
always produce a light wave
559
00:35:30,055 --> 00:35:32,690
whose color matches
the energy difference
560
00:35:32,725 --> 00:35:34,492
between the orbitals.
561
00:35:39,398 --> 00:35:43,801
The Sun's surface radiates
light waves of all colors.
562
00:35:43,836 --> 00:35:45,637
If you look at sunlight
through a prism,
563
00:35:45,671 --> 00:35:47,672
you'll see its spectrum.
564
00:35:50,309 --> 00:35:53,144
When you magnify the spectrum
with a telescope,
565
00:35:53,179 --> 00:35:55,046
as Joseph Fraunhofer did,
566
00:35:55,080 --> 00:35:56,648
you raise the curtain
567
00:35:56,682 --> 00:35:59,884
on the electron dance
within the atom.
568
00:35:59,919 --> 00:36:02,120
When the energy
of the electron flags,
569
00:36:02,154 --> 00:36:03,821
and it drops
to a lower orbital,
570
00:36:03,856 --> 00:36:06,224
the light wave
it emits scatters.
571
00:36:06,258 --> 00:36:08,660
Most of it doesn't reach us.
572
00:36:08,694 --> 00:36:10,228
That leaves a dark gap
573
00:36:10,262 --> 00:36:13,164
or black vertical line
in the spectrum.
574
00:36:13,199 --> 00:36:15,733
These dark lines
are the shadows
575
00:36:15,768 --> 00:36:17,368
cast by hydrogen atoms
576
00:36:17,403 --> 00:36:19,337
in the atmosphere of the Sun.
577
00:36:19,371 --> 00:36:22,073
Sodium atoms cast
different shadows.
578
00:36:22,107 --> 00:36:25,176
Their electrons dance
to a different tune.
579
00:36:25,211 --> 00:36:27,078
A grain of table salt
is composed
580
00:36:27,112 --> 00:36:28,913
of sodium and chlorine atoms.
581
00:36:28,948 --> 00:36:31,382
Ten million billion of them
582
00:36:31,417 --> 00:36:33,384
doing their crazy dances
583
00:36:33,419 --> 00:36:36,254
in a single grain of salt.
584
00:36:36,288 --> 00:36:39,190
And a single iron atom
with 26 electrons
585
00:36:39,225 --> 00:36:41,559
is like a great
big production number
586
00:36:41,594 --> 00:36:44,896
in a Broadway musical.
587
00:36:47,299 --> 00:36:51,202
When you look at a star
with a spectroscope,
588
00:36:51,237 --> 00:36:53,671
you see the dark lines
from all the elements
589
00:36:53,706 --> 00:36:55,340
in its atmosphere.
590
00:36:55,374 --> 00:36:57,242
Show me the spectrum
of anything,
591
00:36:57,276 --> 00:37:00,044
whether here on Earth
or from a distant star,
592
00:37:00,079 --> 00:37:03,114
and I'll tell you
what it's made of.
593
00:37:03,148 --> 00:37:06,751
Fraunhofer's lines are
the atomic signatures
594
00:37:06,785 --> 00:37:10,755
of the elements writ large
across the cosmos.
595
00:37:10,789 --> 00:37:12,857
As with every
other major revelation
596
00:37:12,892 --> 00:37:15,393
in the history of science,
it opened the way
597
00:37:15,427 --> 00:37:18,396
to newer and deeper mysteries.
598
00:37:18,430 --> 00:37:21,399
And to the revelation
that there were
599
00:37:21,433 --> 00:37:24,469
many more secrets
hiding in the light.
600
00:37:40,472 --> 00:37:43,408
When Joseph Fraunhofer combined
a prism with a telescope
601
00:37:43,410 --> 00:37:45,677
and turned it toward the skies,
602
00:37:45,679 --> 00:37:49,180
he brought the stars
much closer to us.
603
00:38:00,159 --> 00:38:02,894
When he was only 39,
604
00:38:02,896 --> 00:38:05,063
he contracted a fatal illness.
605
00:38:05,065 --> 00:38:07,732
Perhaps as a result of his
early and long-term exposure
606
00:38:07,734 --> 00:38:10,668
to the toxic chemicals
of glassmaking.
607
00:38:10,670 --> 00:38:14,672
You never know where
the next genius will come from.
608
00:38:18,611 --> 00:38:23,114
How many of them do we leave
in the rubble?
609
00:38:23,116 --> 00:38:26,384
The prince and his kingdom
were immeasurably enriched
610
00:38:26,386 --> 00:38:29,754
by that act of kindness
to a poor orphan.
611
00:38:29,756 --> 00:38:32,190
Fraunhofer's discoveries
transformed Bavaria
612
00:38:32,192 --> 00:38:36,461
from a rural backwater
to a technological powerhouse.
613
00:38:38,297 --> 00:38:40,732
As he lay dying,
the government was desperate
614
00:38:40,734 --> 00:38:43,635
to preserve every shred
of his precious knowledge
615
00:38:43,637 --> 00:38:45,937
about the high technology
of optical glass.
616
00:38:48,974 --> 00:38:50,909
But it could only be divulged
to a person
617
00:38:50,911 --> 00:38:53,111
with top security clearance--
618
00:38:53,113 --> 00:38:54,879
the director of the mint.
619
00:39:11,964 --> 00:39:14,565
The government kept
Fraunhofer's technology
620
00:39:14,567 --> 00:39:16,467
for making perfect
optical glass
621
00:39:16,469 --> 00:39:19,737
a State secret
for another hundred years.
622
00:39:19,739 --> 00:39:21,739
This would prove
to be a major obstacle
623
00:39:21,774 --> 00:39:24,242
for someone we'll meet later
in our journey.
624
00:39:24,276 --> 00:39:26,811
But Fraunhofer would allow
no such secrecy
625
00:39:26,845 --> 00:39:29,414
where his pure scientific
research was concerned.
626
00:39:29,448 --> 00:39:33,051
He knew that science requires
openness to flourish;
627
00:39:33,085 --> 00:39:37,121
that our understanding of nature
belongs to the world.
628
00:39:37,156 --> 00:39:40,058
As soon as Fraunhofer discovered
the spectral lines,
629
00:39:40,092 --> 00:39:42,627
he published everything
he knew about them.
630
00:39:42,661 --> 00:39:45,463
And the reverberations
of his momentous discovery
631
00:39:45,497 --> 00:39:48,266
echo still.
632
00:39:51,437 --> 00:39:55,406
His spectral lines revealed
that the visible cosmos
633
00:39:55,441 --> 00:39:58,710
is all made
of the same elements.
634
00:40:01,747 --> 00:40:04,215
The planets...
635
00:40:12,357 --> 00:40:14,826
The stars...
636
00:40:19,198 --> 00:40:21,332
The galaxies...
637
00:40:25,571 --> 00:40:28,573
We, ourselves,
and all of life...
638
00:40:35,247 --> 00:40:38,783
The same star stuff.
639
00:40:44,223 --> 00:40:45,890
He made it possible
for us to know
640
00:40:45,924 --> 00:40:48,392
what's in the atmosphere
of other worlds.
641
00:40:50,863 --> 00:40:54,499
And in galaxies millions
of light-years away.
642
00:40:54,533 --> 00:40:56,534
Spectral lines revealed
not only the composition
643
00:40:56,568 --> 00:40:59,036
of far-off objects,
but also their motion
644
00:40:59,071 --> 00:41:01,239
towards or away from us.
645
00:41:01,273 --> 00:41:04,342
Using them, we discovered
that our universe is expanding.
646
00:41:04,376 --> 00:41:07,945
But perhaps the greatest
revelation of spectroscopy
647
00:41:07,980 --> 00:41:10,781
is the discovery
of the thing it cannot see.
648
00:41:16,789 --> 00:41:18,956
A hidden universe
of dark matter
649
00:41:18,991 --> 00:41:22,226
six times more massive
than the familiar cosmos.
650
00:41:22,261 --> 00:41:24,428
It's made
of some mysterious substance
651
00:41:24,463 --> 00:41:29,033
that does not emit, reflect
or absorb any kind of light.
652
00:41:29,067 --> 00:41:31,536
We only know it's there
because of its gravity,
653
00:41:31,570 --> 00:41:33,638
which pulls on all the galaxies
654
00:41:33,672 --> 00:41:36,407
and speeds up
the visible stars within them.
655
00:41:40,412 --> 00:41:43,881
There are many more kinds of
light than our eyes can see.
656
00:41:43,916 --> 00:41:47,318
Confining our perception
of nature to visible light
657
00:41:47,352 --> 00:41:49,654
is like listening to music
658
00:41:49,688 --> 00:41:51,255
in only one octave.
659
00:41:53,826 --> 00:41:55,827
There are so many more.
660
00:41:55,861 --> 00:41:57,795
They differ only in wavelength,
661
00:41:57,830 --> 00:41:59,931
but over a huge range.
662
00:41:59,965 --> 00:42:02,533
For instance, infrared light...
663
00:42:07,873 --> 00:42:11,008
the kind that
William Herschel discovered
664
00:42:11,043 --> 00:42:12,810
Or X-ray light.
665
00:42:17,883 --> 00:42:19,951
Or radio light.
666
00:42:24,690 --> 00:42:26,524
Or in gamma-ray light.
667
00:42:32,331 --> 00:42:35,600
These are not just different
ways of seeing the same thing.
668
00:42:35,634 --> 00:42:37,201
These other kinds of light
669
00:42:37,236 --> 00:42:40,838
reveal different objects
and phenomena in the cosmos.
670
00:42:40,873 --> 00:42:44,041
In gamma-ray light, for example,
we can see mysterious explosions
671
00:42:44,076 --> 00:42:45,810
in distant galaxies
672
00:42:45,844 --> 00:42:48,145
that we would otherwise miss.
673
00:42:51,083 --> 00:42:53,951
And in microwave light,
we can see all the way back
674
00:42:53,986 --> 00:42:56,387
to the birth of the universe.
675
00:42:58,924 --> 00:43:02,226
We have only
just opened our eyes.
54818
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