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We are surrounded by order.

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Over the last 300 years,

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we've developed amazing new ways
to harness energy.

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We've used this ability to
transform our environment.

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But all these structures that we
see around us are just

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one type of visible order that
we've created here on planet Earth.

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There's another
type of invisible order,

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every bit as complex that we are
only now beginning to understand.

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It's something that nature has been
harnessing for billions of years.

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Something we call information.

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The concept of information
is a very strange one.

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It's actually a very difficult idea
to get your head round.

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But in the journey to try
and understand it, scientists

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would discover that information is
a fundamental part of our universe.

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This film is the story
of information.

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And the immense power
released from manipulating it.

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It's the story of how
we discovered the power of symbols.

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And how writing, codes

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and computers would revolutionise
our understanding of the universe.

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It's the story of how, in a cosmos
collapsing into disorder,

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information can be used to create
order and structure.

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At first glance, information appears
to be a very straightforward idea.

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It exists everywhere in our world.

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Our brains are filled with it.

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And we constantly exchange
it between each other.

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But information has been
one of the subtlest

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and most difficult concepts that
science has had to grapple with.

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Understanding and harnessing it
has been an extremely long

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and difficult process.

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The power of information would first
be glimpsed over 5,000 years ago,

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when a revolutionary
technology was developed.

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One that would set the modern
world in motion.

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Over the years, mankind has come up
with some pretty remarkable stuff.

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But of all humanity's inventions,
there's one that really stands out.

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It's the most transformative,
destructive,

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creative technology ever conceived.

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It is also one of the simplest.

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That invention is the written word.

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At its heart, writing is all about
the transmission

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and storage of information.

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Words allow ideas to
endure through time.

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These are some of the earliest
texts in existence.

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They give us an incredible insight
into the development of writing.

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I've come to meet one of the few
people who can still read them -

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Dr Irving Finkel.

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We take writing
so much for granted these days,

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it's easy to forget that it
was invented.

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It certainly was.

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How did it first come about?

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The earliest writing that we have is
written on clay tablets

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and it comes from
Iraq, Ancient Mesopotamia.

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It comes from the culture
of the culture of the Sumerians.

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What happened here was that they
started off with purely

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pictographic signs
to express an idea.

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This lasted for quite a long time,
until it occurred to somebody,

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perhaps accidentally, that what you
could do is make one of these

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graphic symbols on the surface
of the clay not for what it

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looked like but for the sound
it represented.

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So not a picture of an object,
a picture of a sound?

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That's what we always called
the giant leap for mankind.

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By combining different
sounding pictures,

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the ancient Mesopotamians could
express any idea imaginable.

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The essence of their breakthrough
was to see, for example,

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that a picture of an eye

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and a picture of a deer didn't have
to mean an eye and a deer.

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The pictures could be used simply
for the sounds that they made.

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In this case, idea.

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Once this system was discovered,

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it meant anything that could be
spoken, even the most strange

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or abstract thoughts could be
transformed into symbols.

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Information could now live
outside of the human brain.

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This meant it could endure
over vast spans of time.

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It was an idea that fascinated
the ancient Mesopotamians.

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This lovely tablet here,
this king lived in about 2100 BC.

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He buried this in the foundations
of his temple as a message

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for the future.

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This King Ur-Nammu, the powerful
male, King of Sumer and Akkad -

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that's the south and north
part of Ancient Mesopotamia.

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Her house - he built for her
and he even restored it afterwards.

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This is a proud thing.

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He wants everybody to know about it

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and this is a real
message for the future.

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What's so remarkable for me

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is this is information stored
on clay for thousands of years.

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Yes. Ideas that someone
had 4,000 years ago are still there.

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You have ideas, you have speech,
human hopes, literature,

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prayers - all these sorts
of outpourings of the human soul

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fixed for ever in clay.

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By turning sounds into symbols,

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the Mesopotamian scribes had
discover that information could be

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changed very easily from one
form to another.

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From something that
existed as spoken sounds,

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to something that existed
as symbols on clay tablets.

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This was just the beginning.

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Humans were yet to realise
the true power of symbols.

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For 4,000 years, writing was pretty
much the only

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information technology people used.

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But in the 19th century, during
the great Industrial Revolution,

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things would begin to change.

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In the maelstrom of ideas
and inventions,

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a series of seemingly unconnected
technologies would emerge

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that all began to hint
at the immense power of information.

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These technologies would all
come from very practical,

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very un-theoretical origins.

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They would start to reveal that
information was a much deeper

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and more powerful concept
than anyone had realised.

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One of the first of a new breed
of information technologies would be

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developed in the French city of Lyon
at the end of the 18th century.

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18th-century Lyon was home to some
of the best craftsmen in the world.

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It was also a place
of great opulence,

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grandeur and, above all, money.

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Thanks to the rich
and fashionable aristocrats

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and bankers who lived there,

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it would become home to the greatest
silk-weaving industry in the world.

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Almost a third of the city's
inhabitants worked in

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the silk industry, and it was home
to over 14,000 looms.

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This is brocade.

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The material that made Lyon famous.

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It's a beautiful
and intricately woven fabric that,

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as you might imagine, is incredibly
labour intensive to produce.

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A two-man team,
working flat out for a day,

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could at best produce about an inch
of this amazing stuff.

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The demand for the fine fabrics
of Lyon was immense.

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But the silk weaving process
was painful slow.

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But thanks to a soldier and weaver
named Joseph Marie Jaquard,

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a device will be developed
to help speed up weaving.

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In the process, it would reveal a
fundamental truth about information.

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Building on the work of a number
of others, in 1804 Jaquard

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patented his invention.

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At the time, the loom was
the most complex mechanism

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ever built by humankind

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Jaquard's loom was
a miracle of ingenuity.

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You see, he had designed a single
machine, which without any

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alteration to its construction -
its hardware, to use a modem term -

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could be programmed to weave any
pattern a designer could think up.

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It fact, it could produce a whole
range of silk designs

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with barely a pause in production.

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Jaquard had found
the holy grail of weaving.

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And the secret was
a simple punched card.

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The punched card held within it
the essence of the designs

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that the loom would weave.

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When these punched cards
were fed into the loom

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they would act to lower
and lift the relevant threads...

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..recreating the pattern in silk.

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Any design you could think of could
be broken down and translated into

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a series of punch cards that could
then woven by the loom.

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Information was
being translated from

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picture to punch card
to the finished fabric.

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It's a machine for weaving
textiles, that's its task,

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but there is nothing specific
about what textile it should weave.

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That is contained
in the information,

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which is encoded on the cards.

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So if you like, the cards, programme
it, that is to say instruct it

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what to do. And this has huge
resonances for what came later.

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Jaquard's Loom revolutionised
the silk industry.

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But at its heart was something
deeper, something more universal

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than its industrial origins
and its ability to speed up weaving.

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The loom revealed the power of
abstracting information.

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It showed you can take the essence
of something, extract the vital

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information
and represent it in another form.

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Writing had revealed you could use
a set of symbols to capture

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spoken language.

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Now, Jaquard had shown that with
just two symbols -

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a hole or a blank space,
it was possible to capture

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the information in any picture
imaginable.

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This is a portrait of Jaquard that's
been woven in silk.

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It's spectacularly detailed with
hundreds of thousands of stitches.

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Yet all the information you need to
capture this life-like image can be

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stored in a series of punched cards.
24,000 of them to be precise.

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This picture is a fantastic example
of a really far-reaching idea.

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That the simplest of systems -

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in this case, cards with a series
of holes punched in them -

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can capture the essence of something
much, much more complicated.

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If 24,000 punched cards could create
an image like this...

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What would happen if you had
24 million?

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Or 24 trillion cards?

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What new types of complex
information

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might be able to be captured
and represented?

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Jacquard had stumbled on an
incredibly deep

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and far-reaching idea.

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As long as you have enough of them,
simple symbols can be used

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to describe anything
in the entire universe.

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Translating information
into abstract symbols

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to store and process, had proven
to be an extremely powerful idea.

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But the way information was sent,

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the way it was communicated, hadn't
changed for thousands of years.

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The world before
telecommunications technology

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was a very different place,

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cos you could only send messages as
fast as you could send objects.

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You'd write a message on a piece of
paper or something like that

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and then you'd give it to somebody
who could run very fast,

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or could go on horse
or on a ship very fast.

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The point was you could only send
information as fast as

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you could send matter.

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But in the 19th century,
the speed at which information

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could be sent would
dramatically increase,

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thanks to an incredible new
information-carrying medium -

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electricity.

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Very soon after electricity
was discovered,

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excitement grew about its potential
as a medium to transmit messages.

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It seemed that if it could be
controlled and summoned at will,

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electricity would be the perfect
medium for sending information.

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Electricity seemed to offer
many advantages

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as a way of sending messages.

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It was sent down a wire which means
it could pretty much go anywhere.

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It wasn't affected
by bad weather conditions

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and most importantly,
it could move very quickly.

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But there was one big problem facing
those in the early 19th century

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who wanted to use electricity
as a means to communicate.

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How could such a simple signal
be used to send complex messages?

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Here in the Science Museum archive,

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they have one of the most
impressive collections

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00:18:31,281 --> 00:18:35,001
of early electronic communications
technology in the world.

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Here are just some
of the early devices

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designed to send signals
using electricity.

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This one's particularly fun.

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It was developed in 1809
in Bavaria by Samuel Soemmering.

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So if the sender wants
to send letter A,

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he sends a current through
that corresponding wire.

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At the receiver's end
is a tank full of liquid

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and electric current forces
a chemical reaction

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causing bubbles to appear above
the corresponding letter A.

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The whole process is ingenious,
if a little laborious.

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But what's really fun is that the
sender has to let the receiver know

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he's about to send a signal.

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He does that by sending
extra electric currents

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so that more bubbles appear,

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forcing an arm upwards
which releases a ball...

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BELL RINGS

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..and triggers a bell.

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As you can imagine, this wouldn't
be the quickest of systems.

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After Soemmering, all sorts
of approaches were taken

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in trying to crack the problem of
sending messages using electricity.

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But they all suffered from having
over-complex codes.

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These devices, each cunning
and innovative in its own way,

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were all destined for
the scrap heap of history.

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And that's because in the 1840s,
they were superseded by a way

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of sending signals that still
endures to this day.

239
00:20:08,201 --> 00:20:13,041
It was developed by artist
and entrepreneur Samuel Morse,

240
00:20:13,041 --> 00:20:15,641
together with his colleague
Alfred Vale.

241
00:20:15,641 --> 00:20:19,361
What was so special about their
system wasn't the technology

242
00:20:19,361 --> 00:20:21,921
that was used
to carry their messages,

243
00:20:21,921 --> 00:20:25,481
but the incredibly simple
and effective code

244
00:20:25,481 --> 00:20:27,081
they used to send them.

245
00:20:36,361 --> 00:20:41,401
Just like Jacquard's punch cards,
the genius of Morse and Vale's code

246
00:20:41,401 --> 00:20:42,841
lay in its simplicity.

247
00:20:44,881 --> 00:20:48,721
Using a collection of short and long
pulses of electrical current,

248
00:20:48,721 --> 00:20:51,841
they could spell out the letters
of the alphabet.

249
00:20:54,441 --> 00:20:56,961
Vale suggested that
the most frequent letters

250
00:20:56,961 --> 00:20:59,801
in the English language
get the shortest code.

251
00:21:02,801 --> 00:21:06,081
So an E is sent like this.

252
00:21:08,241 --> 00:21:10,921
While an X is sent like this.

253
00:21:12,121 --> 00:21:16,001
This means that messages can be sent
quickly and efficiently.

254
00:21:17,681 --> 00:21:20,401
Figuring out the code part of it,
the software if you like,

255
00:21:20,401 --> 00:21:24,161
was as complicated as figuring out
the hardware side of things

256
00:21:24,161 --> 00:21:27,681
with the batteries and the wires, and
together they made an entirely new

257
00:21:27,681 --> 00:21:30,201
technology which is
the electric telegraph.

258
00:21:32,441 --> 00:21:35,201
The telegraph had once again
revealed the power

259
00:21:35,201 --> 00:21:39,361
of translating information
from one medium to another.

260
00:21:41,121 --> 00:21:45,801
Information had at first
been fixed in human brains.

261
00:21:45,801 --> 00:21:51,361
Then held in symbols in clay
and paper and punched cards.

262
00:21:53,201 --> 00:21:57,721
Now, thanks to Morse, information
could reside in electricity

263
00:21:57,721 --> 00:22:01,801
and this made it unimaginably
lighter and quicker

264
00:22:01,801 --> 00:22:03,281
than it had every been before.

265
00:22:07,721 --> 00:22:10,521
In just a few short years,
the telegraph network

266
00:22:10,521 --> 00:22:13,401
would spread around
the entire globe,

267
00:22:13,401 --> 00:22:17,241
laying the foundations
of the modern information age.

268
00:22:26,281 --> 00:22:32,041
Between them, Jacquard and Morse had
found new novel ways to manipulate,

269
00:22:32,041 --> 00:22:34,961
process and transmit information.

270
00:22:34,961 --> 00:22:38,841
What had begun with the invention
of writing thousands of years ago

271
00:22:38,841 --> 00:22:42,721
had culminated in the binding
of the entire planet

272
00:22:42,721 --> 00:22:46,641
in a lattice of wires carrying
highly abstracted information

273
00:22:46,641 --> 00:22:48,761
at incredible speeds.

274
00:22:48,761 --> 00:22:51,761
For people at the end
of the 19th century

275
00:22:51,761 --> 00:22:55,561
it may have seemed that humanity's
ability to manipulate

276
00:22:55,561 --> 00:22:59,281
and transmit information
was at its zenith.

277
00:22:59,281 --> 00:23:02,001
They couldn't have been more wrong.

278
00:23:02,001 --> 00:23:05,361
Information would reveal itself
to be a more important,

279
00:23:05,361 --> 00:23:09,761
more fundamental concept
than anyone could have imagined.

280
00:23:12,601 --> 00:23:15,121
It would soon become apparent
that information

281
00:23:15,121 --> 00:23:18,601
wasn't just about human
communication.

282
00:23:18,601 --> 00:23:21,801
It was a much further-reaching
idea than that.

283
00:23:23,201 --> 00:23:26,761
The true nature of information
would first be hinted at

284
00:23:26,761 --> 00:23:28,681
thanks to a strange problem,

285
00:23:28,681 --> 00:23:32,201
one dreamed up by a brilliant
Scottish physicist

286
00:23:32,201 --> 00:23:35,201
who appeared to be thinking about
something else entirely.

287
00:23:51,281 --> 00:23:56,321
James Clerk Maxwell was one of
the great minds of the 19th century.

288
00:23:59,881 --> 00:24:03,321
Among his many interests,
Maxwell became fascinated

289
00:24:03,321 --> 00:24:06,561
by the science of thermodynamics -

290
00:24:06,561 --> 00:24:09,041
the study of heat and motion
that had sprung up

291
00:24:09,041 --> 00:24:10,601
with the birth of the steam engine.

292
00:24:17,681 --> 00:24:20,321
Maxwell was one of the first
to understand

293
00:24:20,321 --> 00:24:23,841
that heat is really
just the motion of molecules.

294
00:24:23,841 --> 00:24:28,361
The hotter something is, the faster
its molecules are moving.

295
00:24:30,481 --> 00:24:34,881
This idea would lead Maxwell
to dream up a very bizarre

296
00:24:34,881 --> 00:24:39,001
thought experiment in which
information played a crucial role.

297
00:24:46,401 --> 00:24:50,481
Maxwell theorised that simply by
knowing what's going on

298
00:24:50,481 --> 00:24:55,921
inside a box full of air, it'll be
possible to make one half hotter

299
00:24:55,921 --> 00:24:58,521
and the other half colder.

300
00:24:58,521 --> 00:25:01,881
Think of it like building
an oven next to a fridge

301
00:25:01,881 --> 00:25:03,681
without using any energy.

302
00:25:15,761 --> 00:25:20,801
It sounds crazy, but Maxwell's
argument was extremely persuasive.

303
00:25:20,801 --> 00:25:22,121
It goes like this.

304
00:25:22,121 --> 00:25:25,801
Imagine a small demon
perched on to of the box,

305
00:25:25,801 --> 00:25:29,601
who has such excellent eye sight
that he could observe accurately

306
00:25:29,601 --> 00:25:33,441
the motion of all the molecules
of air inside the box.

307
00:25:50,361 --> 00:25:52,041
Now, crucially,

308
00:25:52,041 --> 00:25:57,161
he's in control of a partition that
divides the box into two halves.

309
00:25:57,161 --> 00:26:01,201
Every time he sees a fast-moving
molecule approaching the partition

310
00:26:01,201 --> 00:26:06,601
from the right-hand side he opens it
up, allowing it through to the left.

311
00:26:06,601 --> 00:26:10,321
And every time he sees a slow moving
molecule approaching the partition

312
00:26:10,321 --> 00:26:13,721
from the left, he opens it up,
allowing the molecule

313
00:26:13,721 --> 00:26:14,961
through to the right.

314
00:26:27,201 --> 00:26:29,921
Now, you can see
what's going to happen.

315
00:26:29,921 --> 00:26:34,521
Over time, all the fast-moving
hot molecules will accumulate

316
00:26:34,521 --> 00:26:36,761
on the left-hand side of the box,

317
00:26:36,761 --> 00:26:40,201
and all the slow-moving
cold molecules on the right.

318
00:26:41,281 --> 00:26:45,561
Crucially, the demon has done
this sorting with nothing more

319
00:26:45,561 --> 00:26:49,001
than information about the motion
of the molecules.

320
00:26:52,441 --> 00:26:57,321
Maxwell's demon seemed to say
that just by having information

321
00:26:57,321 --> 00:27:01,681
about the molecules, you could
create order from disorder.

322
00:27:03,001 --> 00:27:06,721
This idea flew in the face
of 19th-century thinking.

323
00:27:11,521 --> 00:27:15,001
The science of thermodynamics
had shown very clearly

324
00:27:15,001 --> 00:27:20,041
that over time, the entropy
of the universe, its disorder,

325
00:27:20,041 --> 00:27:25,121
would always increase.
Things were destined to fall apart.

326
00:27:30,641 --> 00:27:34,921
But the demon seemed to suggest that
you could put things back together

327
00:27:34,921 --> 00:27:38,081
without using any energy at all.

328
00:27:38,081 --> 00:27:42,681
Just by using information,
you could create order.

329
00:27:46,841 --> 00:27:50,761
It would prove to be a fiendishly
difficult problem to solve,

330
00:27:50,761 --> 00:27:54,681
not least because the brilliant
Maxwell had come up with an idea

331
00:27:54,681 --> 00:27:57,321
far, far ahead of its time.

332
00:28:00,441 --> 00:28:04,121
It's amazing, the impact
that he had on physics,

333
00:28:04,121 --> 00:28:07,681
and that he came up with
this very intricate concept

334
00:28:07,681 --> 00:28:14,401
and that he already in some sense
pre-anticipated the notion

335
00:28:14,401 --> 00:28:17,281
of information. It wasn't
actually there at the time,

336
00:28:17,281 --> 00:28:18,601
there was no such thing.

337
00:28:21,681 --> 00:28:24,041
I think this idea was astonishing.

338
00:28:24,041 --> 00:28:27,601
He didn't really have a resolution,
he raised it as a concern

339
00:28:27,601 --> 00:28:29,081
and he left it open.

340
00:28:30,201 --> 00:28:34,401
And I think what followed
is more or less 120 years

341
00:28:34,401 --> 00:28:38,281
of extremely exciting debate
and development

342
00:28:38,281 --> 00:28:41,561
to try to resolve
and address this concern.

343
00:28:52,801 --> 00:28:56,841
So what was going on
with Maxwell's demon?

344
00:28:56,841 --> 00:28:59,201
It may sound far-fetched
and fanciful,

345
00:28:59,201 --> 00:29:02,641
but imagine the possibilities
if we could build a machine

346
00:29:02,641 --> 00:29:07,161
in the real world that could mimic
the actions of the Demon.

347
00:29:07,161 --> 00:29:11,561
I could use it to heat a cup of
coffee, or run an engine,

348
00:29:11,561 --> 00:29:17,761
or power a city all using nothing
more than pure information.

349
00:29:17,761 --> 00:29:20,001
It's as though we could create
order in the universe

350
00:29:20,001 --> 00:29:21,601
without expending any energy.

351
00:29:22,641 --> 00:29:26,841
Scientists felt intuitively
that it had to be wrong.

352
00:29:26,841 --> 00:29:31,721
The problem was it would take over
100 years to solve the problem.

353
00:29:38,441 --> 00:29:40,601
While Maxwell's riddle rumbled on,

354
00:29:40,601 --> 00:29:43,201
something quite unexpected
was to happen,

355
00:29:43,201 --> 00:29:48,201
a new device was dreamt up that
could perform quite incredible

356
00:29:48,201 --> 00:29:52,281
and complex tasks simply by
processing information.

357
00:29:52,281 --> 00:29:55,561
What's more, this was a device
that could actually be built.

358
00:29:55,561 --> 00:30:00,201
The machine would come to be
known as the computer, and the idea

359
00:30:00,201 --> 00:30:04,881
behind it came from a quite
remarkable and visionary scientist.

360
00:30:18,161 --> 00:30:22,841
Alan Turing was the first person
to conceive of the modern computer,

361
00:30:22,841 --> 00:30:29,121
a machine whose sole function is to
manipulate and process information.

362
00:30:29,121 --> 00:30:33,401
A machine that harnesses
the power of abstract symbols.

363
00:30:33,401 --> 00:30:37,161
A machine that enables almost every
aspect of the modern world.

364
00:30:39,521 --> 00:30:43,801
Turing's incredible idea would
first appear in a now-legendary

365
00:30:43,801 --> 00:30:48,001
mathematical paper
published in 1936.

366
00:30:51,201 --> 00:30:55,961
In his brief life, Alan Turing
brought fresh, groundbreaking ideas

367
00:30:55,961 --> 00:30:58,681
to a whole range of topics,

368
00:30:58,681 --> 00:31:02,001
from cryptography
through to biology.

369
00:31:02,001 --> 00:31:05,761
The sheer breadth of his thinking
is breathtaking.

370
00:31:06,841 --> 00:31:10,841
But for most scientists,
it's the concepts he outlined

371
00:31:10,841 --> 00:31:18,041
in these 36 pages that
mark him out as truly special.

372
00:31:18,041 --> 00:31:23,241
It's this work that makes him worthy
of the title "Genius".

373
00:31:25,641 --> 00:31:29,041
Published when Turing
was just 24 years old,

374
00:31:29,041 --> 00:31:30,681
On Computable Numbers

375
00:31:30,681 --> 00:31:32,921
With An Application
To The Entscheidungsproblem

376
00:31:32,921 --> 00:31:35,241
tackles the foundations
of mathematical logic.

377
00:31:39,081 --> 00:31:43,481
What's amazing about it is that
the idea for the modern computer

378
00:31:43,481 --> 00:31:48,681
emerged simply as a consequence
of Turing's brilliant reasoning.

379
00:31:48,681 --> 00:31:50,761
He was thinking about something
else entirely,

380
00:31:50,761 --> 00:31:53,001
he wasn't, you know,
sitting there thinking,

381
00:31:53,001 --> 00:31:55,921
"I want to try and invent the modern
computer," he was thinking

382
00:31:55,921 --> 00:31:59,681
about this very abstract problem
in the foundations of mathematics.

383
00:31:59,681 --> 00:32:03,321
And the computer kind fell
sideways out of that research,

384
00:32:03,321 --> 00:32:04,721
completely unexpectedly.

385
00:32:04,721 --> 00:32:09,561
I mean, nobody could have guessed
that Turing's very abstract,

386
00:32:09,561 --> 00:32:13,241
abstruse research in the foundations
of mathematics could produce

387
00:32:13,241 --> 00:32:17,441
anything of any practical value
whatsoever, let alone a machine that

388
00:32:17,441 --> 00:32:21,161
was going to change the lives of, you
know, nearly everyone on the planet.

389
00:32:23,681 --> 00:32:26,961
Turing had set out to understand
if certain processes

390
00:32:26,961 --> 00:32:31,521
in mathematics could be done
simply by following a set of rules.

391
00:32:31,521 --> 00:32:36,241
And this is what would get him
thinking about computers.

392
00:32:38,601 --> 00:32:43,441
In 1936, the word "computer"
had a very different meaning

393
00:32:43,441 --> 00:32:45,161
to what it does today.

394
00:32:45,161 --> 00:32:48,601
It meant a real person
with a pencil and paper,

395
00:32:48,601 --> 00:32:51,161
engaged in arithmetical
calculations.

396
00:32:52,361 --> 00:32:55,801
Banks hired many such people,
often women,

397
00:32:55,801 --> 00:32:58,001
to work out interest payments.

398
00:32:58,001 --> 00:33:02,081
The Inland Revenue employed them
to work out how much tax to charge.

399
00:33:02,081 --> 00:33:05,521
Observatories hired them
to calculate navigational data.

400
00:33:07,241 --> 00:33:10,641
Human computers were vital
to the modern world,

401
00:33:10,641 --> 00:33:13,601
dealing with the huge amounts
of information produced

402
00:33:13,601 --> 00:33:17,601
as science and industry
grew ever more complex.

403
00:33:21,441 --> 00:33:25,521
What Turing did in his 1936 paper
was ask a simple

404
00:33:25,521 --> 00:33:27,521
but profound question.

405
00:33:27,521 --> 00:33:33,361
"What goes on in the mind of a
person carrying out a computation?"

406
00:33:33,361 --> 00:33:37,641
To do this, he first had to discard
all the superfluous detail,

407
00:33:37,641 --> 00:33:42,721
so that only the very essence of
the process of computation remained.

408
00:33:42,721 --> 00:33:45,881
So, first off went the inkpot.

409
00:33:45,881 --> 00:33:48,521
Then the pen, then the slide-rule.

410
00:33:48,521 --> 00:33:51,001
Then the pencils
and the pads of paper.

411
00:33:51,001 --> 00:33:53,721
All these things made it easier,
but none of them

412
00:33:53,721 --> 00:33:58,761
were absolutely crucial to the
person carrying out the computation.

413
00:34:02,801 --> 00:34:07,841
Now Turing asked, "What goes on in
the brain of a human computer?"

414
00:34:07,841 --> 00:34:10,441
It's a vastly complex
biological system,

415
00:34:10,441 --> 00:34:14,521
capable of consciousness, thoughts
and insights, but to Turing,

416
00:34:14,521 --> 00:34:18,881
none of these was critical to
the process of computation either.

417
00:34:18,881 --> 00:34:22,481
Turing realised
that to compute something,

418
00:34:22,481 --> 00:34:26,001
a set of rules
had to be followed precisely.

419
00:34:26,001 --> 00:34:27,921
That was all.

420
00:34:29,521 --> 00:34:31,801
It takes the higher level
intelligence

421
00:34:31,801 --> 00:34:34,721
that was presupposed to be
involved in calculation,

422
00:34:34,721 --> 00:34:39,321
which was thinking, and says you can
have a mechanical process -

423
00:34:39,321 --> 00:34:42,481
and by mechanical,
he means an unthinking process -

424
00:34:42,481 --> 00:34:44,001
to perform the same act.

425
00:34:44,001 --> 00:34:48,161
And therefore eliminates
the necessity of human agency,

426
00:34:48,161 --> 00:34:50,281
with all its high-level functions.

427
00:34:50,281 --> 00:34:53,681
And that is what is revolutionary
about what he tries to do.

428
00:34:56,881 --> 00:35:00,841
Turing's brilliant mind saw that any
calculation had two aspects...

429
00:35:02,201 --> 00:35:07,601
The data, and the instructions
for what to do with the data.

430
00:35:07,601 --> 00:35:10,681
And this would be the key
to his insight.

431
00:35:12,481 --> 00:35:16,881
Turing had to find a way of getting
machines to understand instructions

432
00:35:16,881 --> 00:35:20,081
like "add," "subtract,"
"multiply," "divide"

433
00:35:20,081 --> 00:35:23,481
and so on, in the same way
that humans do.

434
00:35:23,481 --> 00:35:26,521
In other words, he had to find
a way of translating instructions

435
00:35:26,521 --> 00:35:30,841
like these into a language that
machines could understand.

436
00:35:30,841 --> 00:35:35,281
And with flawless, impeccable logic,
Turing did exactly that.

437
00:35:41,321 --> 00:35:45,761
This may look like a random
series of ones and zeroes,

438
00:35:45,761 --> 00:35:48,681
but to a computing machine,
it's a set of instructions

439
00:35:48,681 --> 00:35:51,481
that can be read off step by step,

440
00:35:51,481 --> 00:35:55,521
telling the machine to behave
in a certain way.

441
00:35:55,521 --> 00:35:58,561
So, while a human computer could
look at this symbol

442
00:35:58,561 --> 00:36:00,881
and understand the process
that was required,

443
00:36:00,881 --> 00:36:05,521
the computing machine had to
have it explained, like this.

444
00:36:07,761 --> 00:36:11,081
This paper tape that Turing
envisaged is what

445
00:36:11,081 --> 00:36:13,641
we would now call
the memory of the computer.

446
00:36:14,881 --> 00:36:17,121
But Turing didn't stop there.

447
00:36:22,041 --> 00:36:25,761
Turing realised that feeding
a machine instructions in this way

448
00:36:25,761 --> 00:36:28,481
had an amazing consequence.

449
00:36:28,481 --> 00:36:32,761
It meant that just one machine is
needed to perform almost any task

450
00:36:32,761 --> 00:36:35,001
you can think of.

451
00:36:35,001 --> 00:36:37,761
It's a beautifully simple concept.

452
00:36:37,761 --> 00:36:41,401
In order to get the machine to do
something new, all you had to do

453
00:36:41,401 --> 00:36:45,641
was feed it a new set
of instructions, new information.

454
00:36:46,881 --> 00:36:50,881
This idea became known
as the Universal Turing Machine.

455
00:36:54,761 --> 00:37:00,961
The more you wanted your machine to
do, the longer the tape had to be.

456
00:37:00,961 --> 00:37:05,041
Bigger memories could hold complex,
multilayered instructions

457
00:37:05,041 --> 00:37:10,401
about how to process and order
any kind of information imaginable.

458
00:37:14,321 --> 00:37:15,561
With a big enough memory,

459
00:37:15,561 --> 00:37:20,241
the computer will be capable of an
almost limitless number of tasks.

460
00:37:25,161 --> 00:37:29,321
This idea of Turing's,
that a multitude of different tasks

461
00:37:29,321 --> 00:37:32,721
can be carried out
simply by giving a computing machine

462
00:37:32,721 --> 00:37:37,001
a long sequence of instructions,
is his greatest legacy.

463
00:37:37,001 --> 00:37:40,801
Since his paper,
Turing's dream has been realised.

464
00:37:40,801 --> 00:37:43,961
So, calculations,
making phone calls,

465
00:37:43,961 --> 00:37:48,121
recording moving images, writing
letters, listening to music -

466
00:37:48,121 --> 00:37:51,321
none of these require bespoke
machines.

467
00:37:51,321 --> 00:37:53,961
They can all be carried
out on a single device.

468
00:37:55,121 --> 00:37:56,961
A computing machine.

469
00:37:57,961 --> 00:38:02,561
This phone is a modern incarnation
of Turing's amazing idea.

470
00:38:02,561 --> 00:38:05,601
Inside here are many,
many instructions.

471
00:38:05,601 --> 00:38:08,601
What we call programmes,
or software, or apps,

472
00:38:08,601 --> 00:38:12,041
that are nothing more than a long
sequence of numbers

473
00:38:12,041 --> 00:38:14,641
telling the phone what to do.

474
00:38:17,041 --> 00:38:22,321
What's amazing about Turing's idea
is its incredible scope.

475
00:38:22,321 --> 00:38:25,441
The sets of instructions
that can be fed to a computer

476
00:38:25,441 --> 00:38:29,561
could tell it how to mimic
telephones or typewriters.

477
00:38:29,561 --> 00:38:32,561
But they could also describe
the rules of nature,

478
00:38:32,561 --> 00:38:34,921
the laws of physics.

479
00:38:34,921 --> 00:38:37,841
The processes of the natural world.

480
00:38:42,201 --> 00:38:45,961
This is a simulation of many
millions of particles

481
00:38:45,961 --> 00:38:48,281
behaving like a fluid.

482
00:38:48,281 --> 00:38:50,121
To work out how it flows,

483
00:38:50,121 --> 00:38:54,481
the computer simply follows a set
of instructions held in its memory.

484
00:38:56,161 --> 00:39:00,041
This only begins to hint
at the power of computing machines.

485
00:39:09,241 --> 00:39:13,481
This is a computer simulation
of the large-scale structure

486
00:39:13,481 --> 00:39:16,321
of the entire universe.

487
00:39:16,321 --> 00:39:19,921
And it reveals the true
power of Turing's idea.

488
00:39:22,081 --> 00:39:25,921
Turning instructions into symbols
that a machine can understand

489
00:39:25,921 --> 00:39:31,121
allows you to recreate not just
a simple picture or sound,

490
00:39:31,121 --> 00:39:36,601
but a process, a system, something
that is changing and evolving.

491
00:39:38,721 --> 00:39:41,481
By manipulating simple symbols,

492
00:39:41,481 --> 00:39:44,641
computers are capable
of capturing the essence,

493
00:39:44,641 --> 00:39:48,401
the order of
the natural world itself.

494
00:40:02,521 --> 00:40:06,281
By thinking about how
the human brain processes

495
00:40:06,281 --> 00:40:08,481
and computes information,

496
00:40:08,481 --> 00:40:12,681
Alan Turing had had one of the most
important ideas of the 20th century.

497
00:40:15,561 --> 00:40:19,601
The power of information
was revealing itself.

498
00:40:24,761 --> 00:40:28,401
GARBLED VOICES

499
00:40:33,561 --> 00:40:38,041
It would be very easy to think that
after Turing's ideas were made real,

500
00:40:38,041 --> 00:40:41,961
the true power of information
would be unleashed.

501
00:40:41,961 --> 00:40:44,481
But Turing was only half the story.

502
00:40:45,561 --> 00:40:49,041
The modern information age would
require another idea,

503
00:40:49,041 --> 00:40:52,361
one that would finally
pin down the nature of information,

504
00:40:52,361 --> 00:40:57,081
and its relationship to the order
and disorder of the universe.

505
00:40:57,081 --> 00:40:59,361
It was an idea that would be
dreamt up

506
00:40:59,361 --> 00:41:02,881
by a gifted and eccentric
mathematician and engineer.

507
00:41:12,081 --> 00:41:16,001
Claude Shannon was a true maverick,
and his desire to tackle

508
00:41:16,001 --> 00:41:20,361
unusual problems would lead to
a revolutionary new idea.

509
00:41:20,361 --> 00:41:24,721
One that would uncover the
fundamental nature of information,

510
00:41:24,721 --> 00:41:28,761
and the process of communication
in all its varied forms.

511
00:41:31,321 --> 00:41:34,161
This is Claude Shannon's paper,

512
00:41:34,161 --> 00:41:37,121
The Mathematical Theory
Of Communication.

513
00:41:37,121 --> 00:41:40,241
Now, the title may sound
a bit dry, but trust me,

514
00:41:40,241 --> 00:41:42,881
it's one of the most important
scientific papers

515
00:41:42,881 --> 00:41:46,001
of the 20th century.
Not only did it lay the foundations

516
00:41:46,001 --> 00:41:49,281
for the modern world's
communication network,

517
00:41:49,281 --> 00:41:52,721
it also gave us fresh insights
into human language,

518
00:41:52,721 --> 00:41:57,641
into things we do intuitively,
like speaking and writing.

519
00:42:03,281 --> 00:42:06,521
The paper was published in 1948,

520
00:42:06,521 --> 00:42:09,721
while Shannon was working
at the Bell Labs in New Jersey -

521
00:42:09,721 --> 00:42:13,841
the research arm of
the vast Bell Telephone Network.

522
00:42:13,841 --> 00:42:16,961
It was an institution
famous for its forward-thinking,

523
00:42:16,961 --> 00:42:19,921
relaxed atmosphere.

524
00:42:19,921 --> 00:42:25,201
The mathematicians were free to work
on any problem that interested them.

525
00:42:25,201 --> 00:42:30,841
The only thing that the laboratory
management required of them

526
00:42:30,841 --> 00:42:32,681
was that they keep an open door,

527
00:42:32,681 --> 00:42:37,001
and if anybody from any other
department came with a problem,

528
00:42:37,001 --> 00:42:39,841
that they would at least
think about it.

529
00:42:39,841 --> 00:42:45,401
Otherwise they were absolutely free,
and the atmosphere was incredible.

530
00:42:45,401 --> 00:42:48,721
People were playing,
and encouraged to play.

531
00:42:50,241 --> 00:42:51,921
Hello. I'm Claude Shannon,

532
00:42:51,921 --> 00:42:54,921
a mathematician here at
the Bell Telephone Laboratory.

533
00:42:54,921 --> 00:42:58,161
Claude Shannon in particular
was given free reign

534
00:42:58,161 --> 00:43:00,401
to do pretty much
whatever he wanted.

535
00:43:00,401 --> 00:43:01,841
This is Theseus.

536
00:43:01,841 --> 00:43:04,561
Theseus is an electrically
controlled mouse, mouse.

537
00:43:06,761 --> 00:43:08,961
Oh, they treated him
as their darling.

538
00:43:08,961 --> 00:43:13,921
I never saw him juggle, but I
certainly saw him ride his unicycle.

539
00:43:13,921 --> 00:43:15,681
He brought it to work one day,

540
00:43:15,681 --> 00:43:19,881
and he must have cost Bell Labs

541
00:43:19,881 --> 00:43:23,481
at least a hundred man-hours of time.

542
00:43:28,121 --> 00:43:30,121
But despite the frivolity,

543
00:43:30,121 --> 00:43:33,681
the Bell Telephone Network
faced a huge problem.

544
00:43:33,681 --> 00:43:36,841
Every day, they transmitted
vast amounts of electronic

545
00:43:36,841 --> 00:43:39,561
information all across the world.

546
00:43:39,561 --> 00:43:43,921
But they had no real idea of how to
measure this information properly,

547
00:43:43,921 --> 00:43:46,121
or how to quantify it.

548
00:43:48,761 --> 00:43:51,961
In short, their entire business
was built on something

549
00:43:51,961 --> 00:43:54,041
they didn't actually understand.

550
00:43:56,321 --> 00:44:00,041
Amazingly, their superstar
employee Claude Shannon

551
00:44:00,041 --> 00:44:03,241
would give them
exactly what they needed.

552
00:44:03,241 --> 00:44:06,681
GARBLED VOICES

553
00:44:10,561 --> 00:44:15,001
In this paper, Shannon did
something absolutely incredible -

554
00:44:15,001 --> 00:44:19,201
he took the vague and mysterious
concept of information

555
00:44:19,201 --> 00:44:21,401
and managed to pin it down.

556
00:44:21,401 --> 00:44:23,881
Now, he didn't do this using
some cleverly-worded,

557
00:44:23,881 --> 00:44:25,961
philosophical definition.

558
00:44:25,961 --> 00:44:28,081
He actually found a way to measure

559
00:44:28,081 --> 00:44:30,801
the information
contained in a message.

560
00:44:30,801 --> 00:44:33,801
GARBLED VOICES

561
00:44:35,801 --> 00:44:39,041
Amazingly, Shannon realised
that the quantity of information

562
00:44:39,041 --> 00:44:41,481
in a message had nothing
to do with its meaning.

563
00:44:42,841 --> 00:44:44,921
Instead, he showed
it was related solely

564
00:44:44,921 --> 00:44:47,081
to how unusual the message was.

565
00:44:51,281 --> 00:44:54,321
Information is related
to unexpectedness.

566
00:44:54,321 --> 00:44:56,801
So news is news
because it's unexpected

567
00:44:56,801 --> 00:45:00,001
and the more unexpected it is,
the more newsworthy it is.

568
00:45:00,001 --> 00:45:02,401
So if today's news was
the same as yesterday's news,

569
00:45:02,401 --> 00:45:04,001
there would be no news at all.

570
00:45:04,001 --> 00:45:06,801
And that information
content would be zero.

571
00:45:06,801 --> 00:45:09,881
So suddenly you have a
relationship between...

572
00:45:09,881 --> 00:45:14,961
unexpectedness and information.

573
00:45:14,961 --> 00:45:18,321
GARBLED VOICES

574
00:45:18,321 --> 00:45:20,241
But Shannon was to go further

575
00:45:20,241 --> 00:45:23,561
and give information its
very own unit of measurement.

576
00:45:24,881 --> 00:45:27,801
GARBLED VOICES

577
00:45:29,881 --> 00:45:32,801
So, how did he do this?

578
00:45:32,801 --> 00:45:36,201
Well, he showed that any message
you cared to send

579
00:45:36,201 --> 00:45:39,201
could be translated
into binary digits -

580
00:45:39,201 --> 00:45:42,161
a long sequence of ones and zeros.

581
00:45:42,161 --> 00:45:47,561
So a simple greeting like "Hello"
could be written like this.

582
00:45:48,961 --> 00:45:51,601
Or...like this.

583
00:45:51,601 --> 00:45:57,041
Just think of this as another
way of writing the same message.

584
00:45:58,281 --> 00:46:01,201
ELECTRONIC MUSIC

585
00:46:03,241 --> 00:46:07,601
Shannon realised that transforming
information into binary digits

586
00:46:07,601 --> 00:46:09,921
would be an immensely powerful act.

587
00:46:09,921 --> 00:46:12,201
It would make information

588
00:46:12,201 --> 00:46:16,361
manageable, exact,
controllable and precise.

589
00:46:19,641 --> 00:46:23,761
In his paper, Shannon showed
that a single binary digit -

590
00:46:23,761 --> 00:46:29,441
one of these ones or zeros - is
a fundamental unit of information.

591
00:46:29,441 --> 00:46:32,321
Think of it as an atom
of information -

592
00:46:32,321 --> 00:46:35,201
the smallest possible piece.

593
00:46:35,201 --> 00:46:37,641
Then, having defined
this basic unit,

594
00:46:37,641 --> 00:46:41,641
he even gave us a name for it,
one we're all familiar with today.

595
00:46:41,641 --> 00:46:46,321
He used a shortening of
the phrase, "binary digit" -

596
00:46:46,321 --> 00:46:47,961
"bit".

597
00:46:47,961 --> 00:46:52,761
The humble bit turned out to be
an enormously powerful idea.

598
00:46:55,961 --> 00:46:59,321
The bit is the smallest
quantity of information.

599
00:46:59,321 --> 00:47:02,481
It is highly significant
because it's the fundamental atom.

600
00:47:02,481 --> 00:47:05,361
It is the smallest unit
of information in which

601
00:47:05,361 --> 00:47:09,321
there's sufficient discrimination
to communicate anything at all.

602
00:47:14,321 --> 00:47:17,881
The power of the bit
lay in its universality.

603
00:47:19,601 --> 00:47:22,121
Any system that has two states,

604
00:47:22,121 --> 00:47:24,641
like a coin with heads or tails,

605
00:47:24,641 --> 00:47:27,601
can carry one bit of information.

606
00:47:29,481 --> 00:47:31,401
One or zero.

607
00:47:31,401 --> 00:47:33,521
Punched or not punched.

608
00:47:33,521 --> 00:47:35,361
On or off.

609
00:47:35,361 --> 00:47:37,121
Stop or go.

610
00:47:37,121 --> 00:47:42,001
All of these systems can
store one bit of information.

611
00:47:44,761 --> 00:47:46,281
Thanks to Shannon,

612
00:47:46,281 --> 00:47:50,921
the bit became the common
language of all information.

613
00:47:50,921 --> 00:47:56,281
Anything - sounds, pictures,
text - can be turned into bits

614
00:47:56,281 --> 00:48:01,441
and transmitted by any system
capable of being in just two states.

615
00:48:09,921 --> 00:48:14,281
Shannon had founded
a new, far-reaching theory.

616
00:48:14,281 --> 00:48:17,641
The ideas he began to explore
would form the cornerstone

617
00:48:17,641 --> 00:48:20,161
of what we now call,
"information theory".

618
00:48:20,161 --> 00:48:24,041
He'd taken an abstract
concept - information -

619
00:48:24,041 --> 00:48:26,761
and turned it into
something tangible.

620
00:48:26,761 --> 00:48:30,281
What had been just a vague notion

621
00:48:30,281 --> 00:48:34,361
was now measurable - something real.

622
00:48:39,201 --> 00:48:43,241
The idea of converting into bits,
into making things digital,

623
00:48:43,241 --> 00:48:47,241
would fundamentally transform
many aspects of human society.

624
00:48:48,521 --> 00:48:51,561
GARBLED VOICES

625
00:48:55,521 --> 00:48:59,841
But information isn't
just something humans create.

626
00:48:59,841 --> 00:49:03,001
We're beginning to understand
that this concept lies at the heart,

627
00:49:03,001 --> 00:49:06,641
not only of 21st-century
human society,

628
00:49:06,641 --> 00:49:09,841
but also at the heart
of the physical world itself.

629
00:49:09,841 --> 00:49:15,601
Every "bit" of information
we've ever created, every book,

630
00:49:15,601 --> 00:49:20,561
every film, the entire
contents of the internet,

631
00:49:20,561 --> 00:49:22,361
amounts to pretty much nothing

632
00:49:22,361 --> 00:49:25,601
when compared with
the information content of nature.

633
00:49:25,601 --> 00:49:29,681
And that's because even
the most insignificant event

634
00:49:29,681 --> 00:49:32,681
contains a spectacular
amount of information.

635
00:49:32,681 --> 00:49:34,481
Let me show you.

636
00:49:48,441 --> 00:49:53,761
Imagine how many bits of information
you would need to describe this.

637
00:50:00,841 --> 00:50:04,601
The beautiful and intricate
interplay of physical laws

638
00:50:04,601 --> 00:50:07,401
taking place
at scales and timeframes

639
00:50:07,401 --> 00:50:10,321
that are normally
imperceptible to us.

640
00:50:16,241 --> 00:50:19,001
But here you're still
only seeing a fraction

641
00:50:19,001 --> 00:50:21,201
of the complexity of nature.

642
00:50:39,961 --> 00:50:45,561
Imagine the interplay between the
trillions upon trillions of atoms.

643
00:50:47,961 --> 00:50:50,841
The amount of bits
you would need to describe this

644
00:50:50,841 --> 00:50:52,521
is almost unimaginable.

645
00:50:56,841 --> 00:50:59,361
But what's amazing is that now,

646
00:50:59,361 --> 00:51:04,201
thanks to the ideas of Turing and
Shannon, we're able to describe,

647
00:51:04,201 --> 00:51:07,961
model and simulate nature
in ever greater detail.

648
00:51:10,401 --> 00:51:13,921
But this isn't the end of the story.

649
00:51:13,921 --> 00:51:19,361
Information, it seems, isn't
just a way of describing reality.

650
00:51:21,281 --> 00:51:24,521
In the last few years,
we've discovered that information

651
00:51:24,521 --> 00:51:28,081
is actually an inseparable
part of the physical world.

652
00:51:41,961 --> 00:51:47,561
It's a really difficult idea to
get to grips with but information,

653
00:51:47,561 --> 00:51:52,121
everything from a Beethoven symphony
to the contents of a dictionary,

654
00:51:52,121 --> 00:51:53,801
even a fleeting thought,

655
00:51:53,801 --> 00:51:59,161
all information needs to be embodied
in some form of physical system.

656
00:52:01,641 --> 00:52:05,721
Amazingly, the reason
we understand the true connection

657
00:52:05,721 --> 00:52:10,881
between information and reality
is because of Maxwell's demon.

658
00:52:13,641 --> 00:52:17,801
Remember, it seemed like
the demon could use information

659
00:52:17,801 --> 00:52:23,281
to create order in a box of air that
started out completely disordered.

660
00:52:23,281 --> 00:52:26,801
Moreover, it could do this
without expending any effort.

661
00:52:28,841 --> 00:52:32,201
Information seemed to be able
to break the laws of physics.

662
00:52:33,481 --> 00:52:36,881
Well, that's not true - it can't.

663
00:52:43,041 --> 00:52:48,081
The reason why Maxwell's demon can't
get energy for free lies here -

664
00:52:48,081 --> 00:52:49,921
in his head.

665
00:52:56,081 --> 00:52:58,041
What was discovered was this -

666
00:52:58,041 --> 00:53:01,281
the demon really is using
nothing more than information

667
00:53:01,281 --> 00:53:03,361
to create useful energy.

668
00:53:03,361 --> 00:53:06,641
But this doesn't mean that he's
getting something for nothing.

669
00:53:06,641 --> 00:53:09,161
Remember how the demon works?

670
00:53:09,161 --> 00:53:13,041
He spots a fast-moving molecule
on one side of the box,

671
00:53:13,041 --> 00:53:16,281
opens a partition and lets it
through to the other side.

672
00:53:16,281 --> 00:53:20,481
But each time he does that,
he has to store information

673
00:53:20,481 --> 00:53:23,881
about that molecule's
speed in his memory.

674
00:53:25,281 --> 00:53:29,521
Soon his memory will fill up
and then he can only continue

675
00:53:29,521 --> 00:53:32,641
if he starts deleting information.

676
00:53:32,641 --> 00:53:37,321
Crucially this deletion would
require him to expend energy.

677
00:53:38,721 --> 00:53:43,601
The demon needs to keep a record
of which molecules are moving where

678
00:53:43,601 --> 00:53:47,641
and if the record-keeping
device is only finite size,

679
00:53:47,641 --> 00:53:50,081
at some point the demon is
going to have to erase it.

680
00:53:50,081 --> 00:53:51,921
That's an irreversible process

681
00:53:51,921 --> 00:53:54,401
that increases
the entropy of the universe.

682
00:53:54,401 --> 00:53:56,481
Its the erasure of information

683
00:53:56,481 --> 00:53:58,641
that increases entropy
once and for all.

684
00:54:01,641 --> 00:54:03,081
What was discovered

685
00:54:03,081 --> 00:54:06,721
is that there's a certain,
specific minimum amount of energy,

686
00:54:06,721 --> 00:54:08,841
known as the Landauer limit,

687
00:54:08,841 --> 00:54:13,121
that's required to delete
one bit of information.

688
00:54:14,441 --> 00:54:19,281
It's tiny, less than a trillion
trillionth of the amount of energy

689
00:54:19,281 --> 00:54:22,481
in a gram of sugar, but it's real.

690
00:54:22,481 --> 00:54:26,281
It's a part of the fundamental
fabric of the universe.

691
00:54:33,561 --> 00:54:37,321
Amazingly, we can now
do real experiments

692
00:54:37,321 --> 00:54:39,561
that test aspects of Maxwell's idea.

693
00:54:40,601 --> 00:54:44,681
By using lasers
and tiny particles of dust,

694
00:54:44,681 --> 00:54:47,321
scientists around the world
have explored the relationship

695
00:54:47,321 --> 00:54:52,001
between information and energy
with incredible accuracy.

696
00:54:53,721 --> 00:54:57,841
Maxwell's thought experiment,
dreamt up in the age of steam,

697
00:54:57,841 --> 00:55:01,921
still remains at the cutting edge
of scientific research today.

698
00:55:07,401 --> 00:55:12,001
Maxwell's demon links together
two of the most important concepts

699
00:55:12,001 --> 00:55:16,281
in science - the study of energy
and the study of information

700
00:55:16,281 --> 00:55:19,881
and shows that the two
are profoundly linked.

701
00:55:19,881 --> 00:55:22,441
What we now know
is that information,

702
00:55:22,441 --> 00:55:25,321
far from being some
abstract concept,

703
00:55:25,321 --> 00:55:29,441
obeys the same laws of physics
as everything else in the universe.

704
00:55:38,161 --> 00:55:41,401
Information is not
just an abstraction,

705
00:55:41,401 --> 00:55:45,281
just a mathematical thing or formula
that you write on the paper.

706
00:55:45,281 --> 00:55:47,641
Information is actually
carried by something.

707
00:55:47,641 --> 00:55:50,321
So it is encoded onto something -

708
00:55:50,321 --> 00:55:53,801
a stone, a book, a CD.

709
00:55:53,801 --> 00:55:56,761
Whatever it is, there is a carrier
where the information is on.

710
00:55:56,761 --> 00:56:01,401
That means that information behaves
according to those laws of physics.

711
00:56:01,401 --> 00:56:04,321
So it cannot break
the laws of physics.

712
00:56:10,001 --> 00:56:14,081
What humanity has learnt
over the last few millennia

713
00:56:14,081 --> 00:56:18,241
is that information can never
be divorced from the physical world.

714
00:56:24,081 --> 00:56:25,721
But this is not a hindrance.

715
00:56:25,721 --> 00:56:31,001
What makes information so powerful
is the fact it can be stored

716
00:56:31,001 --> 00:56:34,241
in any physical system we choose.

717
00:56:35,521 --> 00:56:38,721
From using stone and clay
to allow information

718
00:56:38,721 --> 00:56:41,121
to be preserved over eons

719
00:56:41,121 --> 00:56:45,041
to using electricity and light
so it can be sent quickly,

720
00:56:45,041 --> 00:56:49,881
the medium that stores information
gives it unique properties.

721
00:56:54,521 --> 00:56:58,601
Today, scientists are exploring new
ways of manipulating information,

722
00:56:58,601 --> 00:57:03,201
using everything from DNA
to quantum particles.

723
00:57:03,201 --> 00:57:07,441
They hope that this work will
usher in a new information age,

724
00:57:07,441 --> 00:57:10,841
every bit as transformative
as the last.

725
00:57:13,521 --> 00:57:17,641
What we now know is that we are just
at the beginning of our journey

726
00:57:17,641 --> 00:57:20,681
to unlock the power of information.

727
00:57:36,801 --> 00:57:40,281
It's always been clear
that creating physical order -

728
00:57:40,281 --> 00:57:43,521
the structures we see around us -
has a cost.

729
00:57:43,521 --> 00:57:47,641
We need to do work
to expend energy to build them.

730
00:57:47,641 --> 00:57:51,481
But in the last few years, we've
learnt that ordering information,

731
00:57:51,481 --> 00:57:55,601
creating the invisible, digital
structures of the modern world,

732
00:57:55,601 --> 00:57:58,281
also has an inescapable cost.

733
00:57:58,281 --> 00:58:01,881
As abstract and ethereal
as information seems,

734
00:58:01,881 --> 00:58:06,001
we now know it must always be
embodied in a physical system.

735
00:58:06,001 --> 00:58:09,441
I find this an incredibly
exciting idea.

736
00:58:09,441 --> 00:58:14,721
Think about it this way - a lump of
clay can be used to write a poem on.

737
00:58:14,721 --> 00:58:18,961
Molecules of air can carry
the sound of a symphony.

738
00:58:18,961 --> 00:58:22,681
And a single photon
is like a paint brush.

739
00:58:22,681 --> 00:58:25,241
Every aspect of
the physical universe

740
00:58:25,241 --> 00:58:27,641
can be thought of as a blank canvas,

741
00:58:27,641 --> 00:58:32,561
which we can use to build
beauty, structure and order.

742
00:58:46,121 --> 00:58:51,681
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