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TYSON: We inhabit a cosmos
of undiscovered dimensions
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and paradoxical realities.
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We live on one
level of perception,
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but there are others.
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Every once in a while,
a searcher happens upon
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the doorway to one
of these other levels.
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One of them discovered a
paradox about reality that
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proved to be so profound,
we have yet to understand
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how it could be possible.
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The universe,
or perhaps we should say,
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universes have
never been the same.
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♪ ♪
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(theme music plays)
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♪ ♪
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♪ ♪
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Nature writes her most
intimate secrets in light.
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The light from our star that
powers all life on this world.
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The light that
plants eat to make sugar.
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The light that is the
yardstick of the universe,
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stitching diamonds into
the fabric of space and time.
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The imprisoned light
that defines black holes.
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The absence of light
that prevents us from knowing
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what dark matter
and dark energy are.
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"Seeing the light" usually
refers to a religious epiphany,
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but no one is more
light-obsessed than astronomers.
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And as soon as they
began studying light,
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it challenged even
the very best of them.
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Take Isaac Newton,
for example.
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He was so desperate
to understand the nature
of light and colors,
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he was willing to
stick needles in his eyes.
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No, I mean literally.
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Newton was only
in his mid-20s,
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but he had already laid the
foundations of a new branch of
mathematics called "calculus,"
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and he was conducting a series
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of experiments that led
him to conclude that color
was an aspect of light.
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Newton wanted to find out
which of the things we see
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are properties of light and
which are caused by our nerves.
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Was color hiding
inside the light?
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Or was it in our eyes?
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With a burning
desire to know,
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he took a needle
called a bodkin and
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Newton carefully
noted that if he conducted
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the experiment in a
room filled with light,
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even with his eyes shut,
some light would pass through
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his eyelids and
he would see a great,
broad blue-ish circle.
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It may not sound like much of
a result considering the pain,
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but it was with simple
homemade experiments such
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as this one that
Isaac Newton became the first
person to explain rainbows,
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and how white
light hides a whole
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palette of
colors inside itself.
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Most people thought of
the events Newton studied as
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being just the way things were.
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The way an apple falls.
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The way a ray of light
shines through a window.
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Newton's greatness stemmed
from his questioning of the
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"why" and "how" of
ordinary things.
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Newton asked,
what was light made of?
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If you could break light apart
into its tiniest components,
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what would you see?
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Newton noticed that light
moved in straight lines.
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How else to explain
the edges of shadows?
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Or the straightness of
the inspiring rays of sunlight
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that poke through a cloud?
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Or the darkness that resulted
from a total solar eclipse?
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From these observations,
Newton reasoned that light
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must consist of a
stream of particles,
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or corpuscles
as he called them,
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that a ray of light was like
a stream of bullets striking
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the retina of the eye.
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But there was one
man over in Holland,
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who vigorously
disagreed with Newton's
particle theory of light.
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Christiaan Huygens
shared Isaac Newton's
insatiable curiosity,
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and when it came
to changing the world,
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he was no slouch himself.
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Despite a lifelong
struggle with depression,
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he managed to get a lot done.
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While looking through a
telescope that he designed
and built himself,
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he discovered
Saturn's moon, Titan.
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Huygens invented
the pendulum clock.
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He worked out the mathematical
formulas necessary to create
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a pendulum with an arc
that would accurately and
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consistently measure out
uniform increments of time.
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Huygens sketched a
prototype for a new machine
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that he thought
might have some promise.
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It was what he called
a "magic lantern."
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A few hundred years would
pass before it evolved into
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a working motion
picture projector.
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But back in the 17th century,
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Christiaan Huygens already
had an idea for a movie,
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possibly influenced
by his gloomy disposition.
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Huygens, like Newton,
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also invented his own
new branch of mathematics,
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a predictive theory of the
outcomes of games of chance,
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probability theory.
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A way to call heads or tails.
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And like Newton,
Christiaan Huygens had
his own theory of light,
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but it was
very different.
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He didn't think light
consisted of particles like
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bullets firing
along a single path.
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Huygens saw
light as a wave,
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spreading out
in all directions.
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(speaking in native language)
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TYSON: It was already known
in that time that sound
must travel as a wave.
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How?
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Because a voice
could be heard around a door
when it was slightly ajar,
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so sound must travel around
the door as water would,
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like a wave.
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(speaking in native language)
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TYSON: Huygens thought
that light moved
the same way sound did,
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spreading out as waves.
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♪ ♪
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So, which genius was right?
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The answer to that question
of whether light was a particle
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or a wave would
prove to be complicated.
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Now enter Thomas Young.
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The man who exposed the
enigma at the heart of light
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and unraveled the fabric of the
cosmos that we thought we knew.
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Come with me to one
of the greatest mysteries
in the history of science.
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It's a story about a man who
could do just about anything,
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and Thomas Young did.
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For 1500 years, no
one had been able to decipher
Egyptian hieroglyphics.
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By identifying six major
sounds that the
hieroglyphics represented,
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he was able to
decrypt six of the symbols,
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which led to the complete
translation of the ancient
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Egyptian language by others.
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He was the first to chart
the family tree of the
Indo-European languages.
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As a physician, he
identified a deformity
in the shape of the eye,
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the defective vision
he named astigmatism.
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But it was Young's design
of an experiment that sent
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physics down the rabbit
hole we still live in.
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It looks simple, right?
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How could three sheets
of cardboard set such
a catastrophe in motion?
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A green glass shade like
this one will only allow
the green light through,
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so that only
a single color,
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or frequency of light
will pass through the slits.
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Why was that important?
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Because he assumed that the
many overlapping colors would
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result in the same light
wave that Huygens imagined,
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called an
interference pattern.
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He forced that single
color of light to travel through
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two separate slits to see
what kind of pattern the light
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would make on that
last piece of cardboard.
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If light was a particle,
you'd expect to see two distinct
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clumps of light
on the opposite wall,
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where the individual
particles of light ended up
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after they passed
through the slits.
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But that's not what happened.
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Instead, a
completely unexpected pattern.
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The one that two waves would
make when they overlapped,
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or interfered with each other.
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That's why they're called
an interference pattern.
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Young had demonstrated
that light was actually a wave.
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That Newton, the greatest
genius in the history
of science was half wrong.
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That light was not a particle
as he confidently proclaimed.
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There's a reason that
arguments from authority
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hold little
weight in science.
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Nature and nature
only settles the argument.
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And she has so many
tricks up her sleeve,
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only a fool would ever
consider our understanding
of nature complete.
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Newton had missed
something fundamental.
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Surprising, but
we haven't gotten to the
really disturbing part yet.
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TYSON: Thomas Young left
a time bomb with a long fuse.
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One that took 100 years
to burn down before it exploded.
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It wasn't until the end of
the 19th century that science
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developed the necessary
tools to find an opening
to a hidden universe,
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a realm of
deeper mystery.
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You can hear the discoverer's
astonishment in his own account.
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THOMSON: Could anything,
at first sight,
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seem more impractical than
a body which is so small that
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its mass is an
insignificant fraction of the
mass of an atom of hydrogen?
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Which itself is so small that
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the crowd of these atoms equal
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in number to the
population of the whole
world would be too small
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to have been detected by any
means then known to science.
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TYSON: That voice, that
particular organization of
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sound waves frozen in
time nearly 100 years ago,
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belongs to J.J. Thomson.
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He's remembering his
discovery of the electron in
his cathode ray experiment.
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He had heated up
a metal electrode until
it spit out an electron.
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And another, and another.
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For the first time,
an elementary particle of
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the atom was made visible.
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Science was breaking into
nature's vault where she had
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kept her most
closely held secrets,
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and that's when
things got really crazy.
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If even the smallest
units of matter, atoms say,
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had even smaller components,
such as an electron,
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then could the same
thing be true of light?
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Scientists,
in their never-ending
fascination with light,
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set out to devise
ways of isolating smaller
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and smaller units of it.
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It proved to be the passage
way through the looking glass.
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It was the crossing of a
threshold into a wonderland
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where the known rules
of physics do not apply.
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For the first time,
they were able to isolate
the tiniest unit of light,
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a single photon.
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And to perform Young's
double slit experiment
on a whole new level,
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tracing its precise
path either through the
right slit or the left slit.
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We'll pull over to the
side of the road for the best
possible view of which slit,
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00:16:25,734 --> 00:16:27,000
the right or the left,
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the photon passes through
to get to the far wall.
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Left slit, right slit.
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Another right slit.
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Left slit.
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If we watched
them all day long,
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the pattern would be random.
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About half would go
through either slit.
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Wait a second.
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Where are the waves?
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Where is Young's
interference pattern?
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This is where
the weird begins.
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I cannot explain to you
what you're about to see.
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00:17:04,467 --> 00:17:08,266
That's because no one
on earth understands it yet.
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00:17:08,800 --> 00:17:10,667
If you can't live with that,
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00:17:10,800 --> 00:17:14,333
then you're not gonna be
happy with what lies up ahead.
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00:17:14,467 --> 00:17:17,567
On the smallest possible scale
that we've ever discovered,
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00:17:17,700 --> 00:17:22,667
the quantum universe,
the mere act of observation
changes reality.
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00:17:24,967 --> 00:17:30,000
Okay, photons,
keep on coming, and this
time we promise not to look.
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You're not gonna believe this,
but we can change the pattern
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00:17:35,200 --> 00:17:38,500
on the far wall simply by
not watching which slit the
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photons pass through.
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I know it sounds crazy, but
in every trial ever conducted,
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the outcome depends
on whether or not the
experiment was observed.
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So, the reason we didn't
get the interference pattern
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00:18:10,233 --> 00:18:14,700
earlier wasn't because
we chopped up the light
into single photons,
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00:18:14,834 --> 00:18:17,200
it was because we
were observing which slit
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the photons passed through,
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but how can a photon
know if someone is watching?
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A photon doesn't have eyes.
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A photon doesn't have a brain.
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How could it know
it was being watched?
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You might reasonably conclude
that a single photon is such
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00:18:35,767 --> 00:18:39,834
a tiny thing that it's
very hard to see without
using complex technology.
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This machinery does
violence to the delicate photon.
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It changes it, but that
doesn't explain why photons
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behave like particles
when we're watching
but waves when we're not.
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If light is
fundamentally a particle,
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then it should never
create a wave pattern,
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whether we're
observing it or not.
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00:19:01,467 --> 00:19:05,200
And how can individual photons
know where to take their places,
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00:19:05,333 --> 00:19:08,600
so that as a group they
create the interference
patterns of waves?
242
00:19:10,467 --> 00:19:15,133
This is a maddening conundrum
at the heart of quantum physics.
243
00:19:16,834 --> 00:19:19,433
Isaac Newton and
Christiaan Huygens were both
244
00:19:19,567 --> 00:19:23,767
equally right
and equally wrong.
245
00:19:25,000 --> 00:19:28,600
Light is both a wave
and a particle, and neither.
246
00:19:30,333 --> 00:19:32,166
Until we make
an observation,
247
00:19:32,300 --> 00:19:36,033
the photon exists in
a state of uncertainty,
248
00:19:36,166 --> 00:19:38,667
governed by laws
of probability.
249
00:19:38,800 --> 00:19:40,467
And when we do observe it,
250
00:19:40,600 --> 00:19:43,934
it becomes something
completely different.
251
00:19:45,834 --> 00:19:49,900
We would be lost in the
quantum universe without
Christiaan Huygens.
252
00:19:50,033 --> 00:19:52,967
His probability theory
provides, even now,
253
00:19:53,100 --> 00:19:57,934
the only key we have
to grasping the laws
of quantum reality.
254
00:19:58,367 --> 00:20:00,834
Every particle is at
the mercy of random chance
255
00:20:00,967 --> 00:20:03,500
and shifting probabilities.
256
00:20:03,633 --> 00:20:07,333
Thinking about it is like
looking at an optical illusion,
257
00:20:07,467 --> 00:20:09,233
you can only grab
hold of it for moments at
258
00:20:09,367 --> 00:20:12,834
a time before it pops
back into something else.
259
00:20:18,567 --> 00:20:20,633
In the quantum universe,
there's an undiscovered
260
00:20:20,767 --> 00:20:24,400
frontier where the laws of
our world give way to the ones
261
00:20:24,533 --> 00:20:27,266
that apply on the
tiniest scale we know.
262
00:20:28,500 --> 00:20:31,467
They're divorced from
our everyday experience.
263
00:20:32,400 --> 00:20:36,300
How can you think
about a world that has
different rules than ours?
264
00:20:36,433 --> 00:20:38,467
It's not easy.
265
00:20:38,600 --> 00:20:41,133
That's why I want to take you
to this place where it's not
266
00:20:41,266 --> 00:20:45,200
only possible to make
such a leap, it's mandatory.
267
00:20:46,100 --> 00:20:49,133
It's a world very
much like our own,
268
00:20:49,266 --> 00:20:51,767
except in one respect.
269
00:21:02,000 --> 00:21:06,367
It just happens to be
missing a spatial dimension,
270
00:21:06,500 --> 00:21:08,000
the third one.
271
00:21:12,367 --> 00:21:15,033
into the quantum cosmos,N: Ie
272
00:21:15,166 --> 00:21:17,500
we have to be able to
imagine another dimension.
273
00:21:18,300 --> 00:21:20,600
That's very hard to do.
274
00:21:20,734 --> 00:21:23,367
It's much easier to wrap
your mind around a world that's
275
00:21:23,500 --> 00:21:27,100
missing one of the
three dimensions that
we take for granted.
276
00:21:27,233 --> 00:21:31,333
The beings of the world we're
about to enter have only two.
277
00:21:31,467 --> 00:21:35,934
This world was first imagined
by a man named Edwin Abbott.
278
00:21:36,066 --> 00:21:39,233
Everyone and everything here
and everyone they know
279
00:21:39,367 --> 00:21:42,100
and love is flat.
280
00:21:42,233 --> 00:21:44,367
Their houses are flat.
281
00:21:44,500 --> 00:21:48,233
Some are squares,
others are triangles.
282
00:21:48,367 --> 00:21:52,266
Some have more complex shapes,
say octagons.
283
00:21:52,400 --> 00:21:55,633
But all are completely flat.
284
00:21:55,767 --> 00:21:58,967
They scurry about on
foot or in little vehicles,
285
00:21:59,100 --> 00:22:01,200
in and out of
their flat buildings,
286
00:22:01,333 --> 00:22:03,467
busy with their flat lives.
287
00:22:03,600 --> 00:22:07,300
Everyone on this
world has width and length,
288
00:22:07,433 --> 00:22:10,500
but no height whatsoever.
289
00:22:10,633 --> 00:22:13,900
These Flatworlders know about
left-right and forward-back,
290
00:22:15,100 --> 00:22:18,934
but have no hint, not
an inkling, about up-down,
291
00:22:19,066 --> 00:22:21,667
except for one tiny group,
292
00:22:21,800 --> 00:22:25,367
the mathematicians,
who imagine something more.
293
00:22:27,700 --> 00:22:31,800
The mathematicians dream of
a world in three dimensions,
294
00:22:31,934 --> 00:22:35,800
but it's too hard for most of
the Flatworlders to think about.
295
00:22:35,934 --> 00:22:37,834
The mathematician says,
296
00:22:37,967 --> 00:22:40,467
"Listen, it's
really very easy.
297
00:22:40,600 --> 00:22:42,066
We all know left-right.
298
00:22:42,200 --> 00:22:44,467
We all know forward-back.
299
00:22:44,600 --> 00:22:48,266
So let's just
imagine another dimension at
right-angles to the other two."
300
00:22:49,100 --> 00:22:50,900
But the Flatworlders say,
301
00:22:51,100 --> 00:22:52,500
"What are you talking about?
302
00:22:52,633 --> 00:22:54,667
At right angles
to the other two?
303
00:22:54,800 --> 00:22:58,166
Everybody knows that there
can only be two dimensions.
304
00:22:58,300 --> 00:23:01,667
Go ahead, wise guy, show
us that third dimension.
305
00:23:01,800 --> 00:23:04,066
Where is it?"
306
00:23:04,500 --> 00:23:06,834
So the mathematician
draws a picture.
307
00:23:14,166 --> 00:23:15,533
Poor teacher.
308
00:23:15,667 --> 00:23:18,967
Nobody listens
to mathematicians.
309
00:23:23,233 --> 00:23:27,667
Every creature on
flatworld sees its fellows
as merely short lines,
310
00:23:28,834 --> 00:23:32,333
which are the nearest
sides of their oblong bodies.
311
00:23:32,867 --> 00:23:36,500
But the insides
of a Flatworlder
are forever mysterious,
312
00:23:36,633 --> 00:23:40,467
unless exposed by some
terrible accident or autopsy.
313
00:23:42,100 --> 00:23:45,133
And then one day,
we came along.
314
00:23:49,200 --> 00:23:53,367
Hello? How are you?
315
00:23:54,166 --> 00:23:57,834
Hi, I'm a visitor from
the third dimension.
316
00:23:58,233 --> 00:24:02,233
Hello? I feel
sorry for the little guy.
317
00:24:02,367 --> 00:24:06,367
To him, it appears that
my greeting is emanating
from his own flat body,
318
00:24:07,700 --> 00:24:10,300
an alien voice from within.
319
00:24:10,433 --> 00:24:12,367
That's because
nothing can come from above.
320
00:24:12,500 --> 00:24:15,100
There is no
above in this world.
321
00:24:15,233 --> 00:24:18,266
A three-dimensional
creature like me can only exist
322
00:24:18,400 --> 00:24:22,734
on Flatworld where my feet
touch the surface of the plane.
323
00:24:26,767 --> 00:24:28,700
Sorry, little guy.
324
00:24:28,834 --> 00:24:31,600
I know how weird
this must be for you.
325
00:24:31,734 --> 00:24:33,266
Don't worry.
326
00:24:33,400 --> 00:24:37,233
You'll have a perfectly safe
trip to the third dimension.
327
00:24:37,767 --> 00:24:39,734
Nothing's gonna harm you.
328
00:24:39,867 --> 00:24:42,867
But this is your chance
to see a whole new perspective
329
00:24:43,000 --> 00:24:45,900
on where you live.
330
00:24:46,033 --> 00:24:49,400
At first, our Flatworlder
can make no sense
of what is happening.
331
00:24:49,533 --> 00:24:52,834
It's utterly outside the
realm of Flatworld experience.
332
00:24:53,667 --> 00:24:56,300
But eventually he realizes
that he's viewing Flatworld
333
00:24:56,433 --> 00:25:00,000
from a totally new
vantage point above.
334
00:25:00,367 --> 00:25:03,033
Now, he can see
into closed rooms.
335
00:25:03,166 --> 00:25:05,667
He can see into
his flat fellows.
336
00:25:05,800 --> 00:25:08,233
This unprecedented
three-dimensional view of
337
00:25:08,367 --> 00:25:12,066
his two-dimensional
universe is devastating.
338
00:25:12,800 --> 00:25:15,600
Traveling to another
dimension provides
as an incidental benefit,
339
00:25:15,734 --> 00:25:18,000
a kind of X-ray vision.
340
00:25:18,133 --> 00:25:21,100
Just as the Flatworld
houses can have no roofs,
341
00:25:21,233 --> 00:25:23,600
their inhabitants
can have no sky,
342
00:25:23,734 --> 00:25:27,333
because that sky could only
exist in a third-dimension.
343
00:25:28,333 --> 00:25:30,533
Little guy's suffered enough.
344
00:25:30,667 --> 00:25:34,500
Better put him down.
345
00:25:34,867 --> 00:25:36,633
From the point of
view of its spouse,
346
00:25:36,767 --> 00:25:39,367
this Flatworlder has
distressingly disappeared,
347
00:25:39,500 --> 00:25:43,100
then unaccountably
materialized
from out of nowhere.
348
00:26:08,333 --> 00:26:11,000
It's easier to imagine the
universe in fewer dimensions
349
00:26:11,133 --> 00:26:13,133
than our comfort
zone of three.
350
00:26:13,266 --> 00:26:16,834
A zero-dimensional
universe is just a point.
351
00:26:16,967 --> 00:26:19,867
A dot with no
dimension at all.
352
00:26:21,667 --> 00:26:25,667
Or a one-dimensional
universe where
everyone is a line segment.
353
00:26:26,633 --> 00:26:31,467
Or the
two-dimensional Flatworld.
354
00:26:32,867 --> 00:26:35,667
Or 3D, where we all live.
355
00:26:39,867 --> 00:26:41,266
We can laugh at
the cluelessness of
356
00:26:41,400 --> 00:26:43,100
two-dimensional creatures.
357
00:26:43,800 --> 00:26:46,166
Unable to imagine a
three-dimensional world.
358
00:26:46,300 --> 00:26:50,533
But, when it comes to quantum
reality, that inability,
359
00:26:50,667 --> 00:26:54,100
resembles the
problems we have.
360
00:26:54,233 --> 00:26:56,834
The best we can do for
now is to imagine this
361
00:26:56,967 --> 00:27:00,867
three-dimensional cube as
a four-dimensional hypercube.
362
00:27:03,400 --> 00:27:05,934
We're living in
our own Flatworld,
363
00:27:06,066 --> 00:27:08,433
just like the 19th Century
writer, Edwin Abbott,
364
00:27:08,567 --> 00:27:10,867
in his book
Flatland , was trying.
365
00:27:19,800 --> 00:27:21,934
TYSON: It's the
rarest of events,
366
00:27:22,066 --> 00:27:24,834
when a searcher happens
on a hole in the curtain
367
00:27:24,967 --> 00:27:28,166
that hides the matrix.
368
00:27:29,967 --> 00:27:33,100
It was not until Isaac Newton
that we began to understand
369
00:27:33,233 --> 00:27:36,166
the motions of the worlds.
370
00:27:36,300 --> 00:27:39,500
The variety of living
things always astonished us,
371
00:27:41,300 --> 00:27:44,700
but Charles Darwin discovered
how time and the environment
372
00:27:44,834 --> 00:27:47,700
sculpted these
forms, including us,
373
00:27:47,967 --> 00:27:52,367
from life's first living cell.
374
00:27:52,500 --> 00:27:55,367
We had no idea that the
quantum universe even existed
375
00:27:55,500 --> 00:27:58,500
until Albert Einstein
revealed it.
376
00:27:59,033 --> 00:28:04,000
The mysterious laws
of this paradoxical cosmos
deeply disturbed him.
377
00:28:04,133 --> 00:28:07,934
And we have yet to
understand them ourselves.
378
00:28:09,166 --> 00:28:11,233
At its heart, was a
relationship that seemed
379
00:28:11,367 --> 00:28:14,533
to violate the speed of light.
380
00:28:14,667 --> 00:28:18,300
The backbone of modern
physics and reality itself.
381
00:28:21,834 --> 00:28:24,767
That blue photon, a
quantum packet of light,
382
00:28:24,900 --> 00:28:27,800
will divide into two.
383
00:28:27,934 --> 00:28:31,800
Splitting its energy
and emerging as a
pair of red photons.
384
00:28:33,700 --> 00:28:37,700
These new red photons
are married in the most
profound physical sense or,
385
00:28:38,700 --> 00:28:42,100
as quantum physicists
say, entangled.
386
00:28:43,700 --> 00:28:46,066
And no matter how far
they wander from each other,
387
00:28:46,200 --> 00:28:50,000
in space and in time, the
bond between them will endure.
388
00:28:52,500 --> 00:28:55,834
It's a little like
Plato's Ancient Greek
explanation of love.
389
00:28:56,400 --> 00:28:59,834
A single being splits
into two and separates.
390
00:29:01,100 --> 00:29:02,834
For the rest
of their existence,
391
00:29:02,967 --> 00:29:06,100
each remains the one and
only soul mate of the other.
392
00:29:06,567 --> 00:29:09,600
Exquisitely attuned to
the inner life of its partner.
393
00:29:10,367 --> 00:29:14,200
Even if they are
separated from each other
by a whole universe.
394
00:29:15,600 --> 00:29:18,734
Observe the spin of one photon
and you will instantly know
395
00:29:18,867 --> 00:29:21,400
the spin of its
entangled partner.
396
00:29:21,533 --> 00:29:24,667
It's not something special
about these particular photons.
397
00:29:24,800 --> 00:29:27,834
As far as we know,
it's the rule.
398
00:29:29,100 --> 00:29:31,367
This kind of long distance
relationship has been going
399
00:29:31,500 --> 00:29:34,633
on for the whole
history of the universe.
400
00:29:39,166 --> 00:29:43,200
Two photons born in
the early universe nearly
14 billion years ago,
401
00:29:44,467 --> 00:29:47,333
separate and head
in opposite directions.
402
00:29:48,967 --> 00:29:52,133
They could end up tens of
billions of light-years
apart and yet,
403
00:29:52,266 --> 00:29:56,200
over all that time
and across all that space,
404
00:29:56,333 --> 00:29:59,400
the bond between them endures.
405
00:30:00,367 --> 00:30:02,867
What is it about a photon
or an electron or any other
406
00:30:03,000 --> 00:30:05,600
elementary particle,
once entangled,
407
00:30:05,734 --> 00:30:08,900
that makes them capable
of such lasting fidelity?
408
00:30:09,567 --> 00:30:11,633
And to me, an
even stranger fact,
409
00:30:11,767 --> 00:30:14,900
is that all it takes to
sever that awesome commitment,
410
00:30:15,033 --> 00:30:17,500
is the simple
act of measurement.
411
00:30:17,633 --> 00:30:21,200
All I have to do is measure
the spin of one of them.
412
00:30:22,700 --> 00:30:26,133
How can it be that only
one seemingly innocuous act
413
00:30:26,266 --> 00:30:30,800
by a third party
can forever sever such
a deep and enduring bond?
414
00:30:41,600 --> 00:30:42,667
There she is.
415
00:30:42,800 --> 00:30:45,233
Half of our cosmic couple.
416
00:30:45,734 --> 00:30:48,367
Somewhere, at
this very moment,
417
00:30:48,500 --> 00:30:51,266
many billions of
light-years away from us,
418
00:30:51,400 --> 00:30:54,934
her soul mate is suddenly
feeling something different.
419
00:30:55,667 --> 00:30:57,934
The thrill is gone.
420
00:30:58,433 --> 00:31:01,166
The bond has been broken.
421
00:31:01,767 --> 00:31:04,567
They are no long
entangled with each other.
422
00:31:06,166 --> 00:31:09,800
Our simple act of observing
one of them has ruined
423
00:31:09,934 --> 00:31:13,433
a marriage that has lasted
since the beginning of time.
424
00:31:14,533 --> 00:31:16,467
But, how could that be?
425
00:31:16,600 --> 00:31:19,367
And that's not the only
crazy thing about this.
426
00:31:19,500 --> 00:31:23,200
How could one photon,
a cosmos away from its partner,
427
00:31:23,333 --> 00:31:27,033
send a break-up message
across the universe and have
428
00:31:27,166 --> 00:31:30,734
the other photon
receive it instantaneously?
429
00:31:31,600 --> 00:31:34,333
Faster than the speed
of light could possibly carry
430
00:31:34,467 --> 00:31:37,266
such a message between them.
431
00:31:41,633 --> 00:31:46,100
These are two of the greatest
unanswered questions in science.
432
00:31:46,233 --> 00:31:49,367
So, don't worry
if they bother you.
433
00:31:49,500 --> 00:31:53,166
These questions haunted
a mind as great as Einstein's
for the rest of his life.
434
00:31:55,700 --> 00:31:59,567
There's nothing more intriguing
to a scientist than a paradox.
435
00:32:00,266 --> 00:32:02,700
If light, the
fastest thing there can be,
436
00:32:02,834 --> 00:32:05,900
has a cosmic speed limit,
then it would be impossible
437
00:32:06,033 --> 00:32:10,767
for one photon to communicate
with another instantly
across such vastness.
438
00:32:12,367 --> 00:32:15,834
Einstein found it
almost unbearable to live
in this kind of universe.
439
00:32:16,400 --> 00:32:19,834
Where what he called,
"spooky" action at
a distance was possible.
440
00:32:31,200 --> 00:32:34,200
Remember those particles
in the double slit experiment?
441
00:32:34,333 --> 00:32:37,200
Taking either the
left or the right slit?
442
00:32:37,333 --> 00:32:41,233
Those choices amounted to
nothing more than random chance,
443
00:32:41,367 --> 00:32:44,934
but even random chance
must follow certain rules.
444
00:32:45,066 --> 00:32:47,800
That's the basis for
Huygens's probability theory and
445
00:32:47,934 --> 00:32:51,734
for calculating
the odds in flipping a
coin or throwing dice.
446
00:32:53,333 --> 00:32:55,667
When Einstein applied
probability theory to the
447
00:32:55,800 --> 00:32:59,500
problem of entangled protons,
he was deeply disturbed.
448
00:33:00,633 --> 00:33:04,333
If these photons
could brazenly violate
the speed of light,
449
00:33:04,467 --> 00:33:07,500
then the universe and
all of creation was nothing
450
00:33:07,633 --> 00:33:11,500
more than a casino where the
laws of nature can be broken.
451
00:33:13,066 --> 00:33:16,100
Einstein dealt with his
discomfort by clinging to the
452
00:33:16,233 --> 00:33:20,066
idea that the dice was
somehow loaded in a way
we didn't yet understand.
453
00:33:21,900 --> 00:33:24,700
We had passed this way before.
454
00:33:24,834 --> 00:33:29,166
More than 100,000 years ago,
our ancestors domesticated fire.
455
00:33:30,734 --> 00:33:32,734
They didn't
know what fire was,
456
00:33:32,867 --> 00:33:36,467
but they used it anyway
to build a civilization.
457
00:33:36,600 --> 00:33:39,700
And so it was
with quantum physics.
458
00:33:39,834 --> 00:33:42,333
We didn't need to understand
it to exploit its countless
459
00:33:42,467 --> 00:33:45,734
practical applications,
scientific and technological.
460
00:33:47,400 --> 00:33:51,667
Much as our
ancestors used fire without
understanding how it worked,
461
00:33:51,800 --> 00:33:54,333
we lived with this
mystery for decades.
462
00:33:56,200 --> 00:34:00,033
We have entered
a territory beyond the
reach of classical physics.
463
00:34:00,166 --> 00:34:02,934
Where the elementary particles
that make up everything,
464
00:34:03,066 --> 00:34:06,934
including us, respond
to events they can't
possibly know about.
465
00:34:09,333 --> 00:34:12,834
In the outlaw casino
of the quantum universe,
466
00:34:12,967 --> 00:34:16,600
there is no
objective reality.
467
00:34:20,667 --> 00:34:23,667
And that's where
we're headed next.
468
00:34:31,333 --> 00:34:34,166
TYSON: We are made of atoms.
469
00:34:34,300 --> 00:34:37,834
The bizarre quantum
universe is inside us,
470
00:34:37,967 --> 00:34:40,467
tugged on by
undiscovered moons.
471
00:34:40,600 --> 00:34:44,433
Performing its impossible
magic on every level
of life and experience.
472
00:34:46,333 --> 00:34:48,467
What is this?
473
00:34:48,600 --> 00:34:52,066
A smattering of
stars or something else?
474
00:34:52,400 --> 00:34:55,967
We are sending an image
made of light to your eyes.
475
00:34:56,100 --> 00:34:59,133
It's arriving at your
retina at this very moment.
476
00:34:59,266 --> 00:35:02,367
The cells in your retina
are changing chemically right
477
00:35:02,500 --> 00:35:06,367
now because we are stimulating
some of them with photons.
478
00:35:06,500 --> 00:35:10,300
Your retina stores
these changes for
a fraction of a second.
479
00:35:10,433 --> 00:35:14,033
Now, it's erasing
them in readiness for
the next barrage of photons.
480
00:35:15,500 --> 00:35:18,300
Your retina doesn't
detect all of them, it can't.
481
00:35:19,266 --> 00:35:22,667
It picks up on
only a small percentage of
photons that come your way.
482
00:35:23,834 --> 00:35:26,800
It's impossible to predict
which particular cell in your
483
00:35:26,934 --> 00:35:29,900
retina will catch a photon.
484
00:35:30,033 --> 00:35:32,633
Even when it
comes to something as
vital as our vision,
485
00:35:32,767 --> 00:35:36,734
all we have is
our probabilities.
486
00:35:38,600 --> 00:35:41,633
Now, we're shooting
many more photons at you.
487
00:35:41,767 --> 00:35:43,700
More like, half a million.
488
00:35:43,834 --> 00:35:45,467
What are you looking at?
489
00:35:45,600 --> 00:35:48,734
The surface of some
planet orbiting another star?
490
00:35:48,867 --> 00:35:52,333
We need still more of
those photons to know for sure.
491
00:35:52,467 --> 00:35:55,066
Say, a couple
of million or more.
492
00:35:55,200 --> 00:35:58,166
Only when we send all
of those photons your way,
493
00:35:58,300 --> 00:36:00,233
tens of millions of them,
494
00:36:00,367 --> 00:36:03,467
does reality
begin to take shape.
495
00:36:03,600 --> 00:36:08,333
Over time, probabilities become
likelihoods and eventually,
496
00:36:08,467 --> 00:36:12,166
likelihoods become certainties.
497
00:36:12,300 --> 00:36:15,667
But is there really any
such thing as certainty.
498
00:36:15,800 --> 00:36:18,333
If everything,
even our own vision,
499
00:36:18,467 --> 00:36:20,700
is governed by probabilities,
500
00:36:20,834 --> 00:36:24,066
can there be any
absolute reality?
501
00:36:26,400 --> 00:36:29,800
Is there any hope of
rescuing our classical idea
502
00:36:29,934 --> 00:36:33,433
of reality in the
quantum universe?
503
00:36:34,166 --> 00:36:36,100
Scientists have come up
with one way to preserve our
504
00:36:36,233 --> 00:36:38,867
traditional understanding
of cause and effect called
505
00:36:39,000 --> 00:36:41,467
"The Many Worlds Hypothesis."
506
00:36:42,433 --> 00:36:45,834
That's a misnomer because it
can't be tested scientifically,
507
00:36:45,967 --> 00:36:48,133
but it goes like this.
508
00:36:48,266 --> 00:36:52,100
Every probability that
can happen does happen in
509
00:36:52,233 --> 00:36:56,533
some parallel cosmos
that is foreclosed to us.
510
00:36:56,667 --> 00:36:59,433
An infinite number of
ever branching realities.
511
00:36:59,567 --> 00:37:03,667
Unfolding at every
possible juncture.
512
00:37:04,367 --> 00:37:07,967
Every probability that
can happen does happen
513
00:37:08,100 --> 00:37:11,133
in some parallel cosmos...
514
00:37:13,033 --> 00:37:14,867
♪ MAN: Oh, we need the funk ♪
515
00:37:15,000 --> 00:37:16,600
♪ Gotta have that funk ♪
516
00:37:16,734 --> 00:37:18,900
♪ Oh, we want the funk ♪
517
00:37:19,033 --> 00:37:22,800
TYSON: Or is probability
just an illusion itself?
518
00:37:22,934 --> 00:37:25,700
A phantom of our ignorance?
519
00:37:25,834 --> 00:37:29,300
It is, if we live in a
universe where every single
520
00:37:29,433 --> 00:37:34,533
event was already foreordained
at the beginning of time.
521
00:37:34,667 --> 00:37:37,867
What is called,
superdeterminism.
522
00:37:53,300 --> 00:37:55,700
In a superdeterministic
universe,
523
00:37:55,834 --> 00:38:00,000
the catastrophic failure
of treaties, a sneeze.
524
00:38:00,133 --> 00:38:02,934
The asteroid that
wiped out the dinosaurs,
525
00:38:03,066 --> 00:38:07,100
one particular
bee pollinating
one particular flower.
526
00:38:07,233 --> 00:38:11,266
You listening to me right now,
all of these events were set
527
00:38:11,400 --> 00:38:15,266
in lockstep motion at the
moment the universe began.
528
00:38:15,700 --> 00:38:19,500
When it was all no
larger than a marble.
529
00:38:24,767 --> 00:38:27,900
Superdeterminism has
an additional virtue.
530
00:38:28,033 --> 00:38:31,467
It can explain
mystery of entanglement.
531
00:38:31,600 --> 00:38:36,133
The ability of entangled
particles to communicate
across the vastness,
532
00:38:36,266 --> 00:38:40,100
apparently violating
the speed limit of light.
533
00:38:40,233 --> 00:38:42,600
In a
superdeterministic cosmos,
534
00:38:42,734 --> 00:38:46,500
entangled partners
separated by whole galaxies,
535
00:38:46,633 --> 00:38:50,066
don't need to hear from
each other to change their spin.
536
00:38:50,200 --> 00:38:54,934
They were always destined
to do so at that precise moment.
537
00:38:55,867 --> 00:38:58,000
And so were their partners.
538
00:38:58,133 --> 00:38:59,667
And so was the intruder,
539
00:38:59,800 --> 00:39:02,967
who severed their bond
by observing one of them.
540
00:39:07,934 --> 00:39:09,200
Think of it.
541
00:39:09,333 --> 00:39:13,734
All these events
and trillions of others,
542
00:39:15,500 --> 00:39:20,333
inscribed in the
potential of the first
moment of the universe.
543
00:39:20,467 --> 00:39:22,900
Since everything in the
universe is made of those
544
00:39:23,033 --> 00:39:25,834
same elementary particles,
including us,
545
00:39:25,967 --> 00:39:30,000
we are subject to the
same laws as those that rule
546
00:39:30,133 --> 00:39:31,800
the quantum universe.
547
00:39:31,934 --> 00:39:36,333
And so it is,
for what will happen next.
548
00:39:36,767 --> 00:39:40,300
And what will
happen after that.
549
00:39:45,834 --> 00:39:48,533
The good news is
superdeterminism gives us
550
00:39:48,667 --> 00:39:51,633
a solution to the
mystery of entanglement,
551
00:39:51,767 --> 00:39:53,066
the bad news is,
552
00:39:53,200 --> 00:39:55,867
it seems to rob
us of all agency.
553
00:39:56,000 --> 00:39:57,967
Are we just going
through the motions,
554
00:39:58,100 --> 00:40:00,133
acting out a script that
was written for us nearly
555
00:40:00,266 --> 00:40:02,633
14 billion years ago?
556
00:40:02,767 --> 00:40:04,000
All the while,
557
00:40:04,133 --> 00:40:06,700
telling ourselves how
clever we were in that argument.
558
00:40:06,834 --> 00:40:09,767
How selfish, how brave.
559
00:40:10,300 --> 00:40:13,200
If you could only change that
one little thing about yourself.
560
00:40:15,033 --> 00:40:18,133
In a universe
devoid of free will,
561
00:40:18,266 --> 00:40:21,767
are we nothing more
than deterministic robots?
562
00:40:22,967 --> 00:40:27,300
(church bells ringing)
563
00:40:41,767 --> 00:40:45,900
We have found a way to hitch
a ride on the uncertainties.
564
00:40:46,033 --> 00:40:50,166
To forge technologies that
would otherwise be unattainable.
565
00:40:50,500 --> 00:40:52,800
We have built a quantum clock.
566
00:40:52,934 --> 00:40:55,066
One that you
never have to wind.
567
00:40:55,200 --> 00:41:00,700
It will only lose
a single second in the
next 15 billion years.
568
00:41:08,900 --> 00:41:12,567
A three-dimensional lattice
of laser light keeps isolated
569
00:41:12,700 --> 00:41:14,567
atoms of the
element strontium,
570
00:41:14,700 --> 00:41:17,767
suspended in space.
571
00:41:18,233 --> 00:41:20,834
For all we know, we
may be near collections
572
00:41:20,967 --> 00:41:24,467
of preprogrammed particles
in a deterministic universe.
573
00:41:26,133 --> 00:41:30,066
But I say, let's
not live like we are.
574
00:41:30,200 --> 00:41:33,400
Besides, we have no way
of knowing if that's true.
575
00:41:35,266 --> 00:41:37,467
And to think that,
in some sense,
576
00:41:37,600 --> 00:41:40,633
our freedom to explore
the quantum realm begins
577
00:41:40,767 --> 00:41:43,667
with Thomas Young.
578
00:41:44,333 --> 00:41:46,934
Remember, it was Young
who also found the key to
579
00:41:47,066 --> 00:41:50,333
decrypting the lost language
of the ancient Egyptians.
580
00:41:56,600 --> 00:42:00,200
With quantum encryption,
we are creating codes that
581
00:42:00,333 --> 00:42:03,867
vanish the moment someone
tries to hack into them.
582
00:42:04,000 --> 00:42:07,333
The key to the code, can
be sent via entangled photons.
583
00:42:08,633 --> 00:42:11,633
The observer effect is
our insurance policy that no
584
00:42:11,767 --> 00:42:14,867
spy can decipher the
message without causing the
585
00:42:15,000 --> 00:42:17,633
entanglement to break apart.
586
00:42:18,100 --> 00:42:20,567
Rendering the
message unintelligible.
587
00:42:23,800 --> 00:42:26,533
We still don't know how a
photon can be both a particle
588
00:42:26,667 --> 00:42:29,734
and a wave at the same time.
589
00:42:30,633 --> 00:42:33,000
What I love about science,
is that it demands of us,
590
00:42:33,133 --> 00:42:36,000
a tolerance for ambiguity.
591
00:42:36,133 --> 00:42:40,100
It requires us to live
with humility
regarding our ignorance,
592
00:42:40,233 --> 00:42:43,100
withholding judgement
until the evidence comes in.
593
00:42:44,600 --> 00:42:47,767
That needn't prevent us
from using the little we do know
594
00:42:47,900 --> 00:42:51,533
to search for and decrypt
new languages of reality.
595
00:42:55,633 --> 00:42:59,200
In this vast cosmos,
we are all Flatworlders.
596
00:43:02,667 --> 00:43:07,767
Science is the struggle
to imagine and find above.
597
00:43:51,367 --> 00:43:53,133
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