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Human Universe

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Oldham
Greater Manchester

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Every day, in every town,
there's a moment...

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..when, for the first time, we stare
into the eyes of Mum and Dad

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and are welcomed into
the arms of the universe.

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Every human life has to start
somewhere, a place in space
and time,

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and I started here,
on March the 3rd, 1968,

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in the Royal Oldham Hospital.

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In 1971 we moved here to
the family home in Chadderton -

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it's only about a mile away
from the hospital.

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I stayed here for the next 18 years.

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In 1979 my world expanded a bit
cos I came up the hill to
this school, Hulme Grammar School.

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This was my form room, 3Y,
and that was the end of the universe

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because the girls' school
was through there.

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And it wasn't long before I began to wonder
how my world fitted into the wider cosmos.

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My grandad used to tell me how he
walked up onto this hill

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in the summer of 1927
to see a total solar eclipse.

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And because of that story,
I always wanted to see one, and I
finally got to do it 80 years later.

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And it was a very powerful
experience.

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I didn't know what I'd think.

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he always spoke of
the sky going dark

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and everything going quiet
and the birds stopping singing.

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What I felt was that
I was on a ball of rock.

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I had a very powerful sense that I
was on this... this rocky planet,

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orbiting in the blackness
of space around a star.

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That understanding of where we are
is the culmination of a 400-year
journey of scientific discovery.

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This is the story of how we are
measuring with increasing precision
our place in space and time.

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How we've discovered that we are
an infinitesimal speck in
a possibly infinite universe,

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and, in doing so,
just how valuable we are.

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As far as we know, we humans
are unique in the universe.

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Where are we?

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are we alone?

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Why are we here?

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The only creatures that have
developed the ability to ask
deep questions about the cosmos.

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Human Universe

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Edited By
Sirwaan N

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This curiosity has led us
to a profound change in perspective.

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From believing we were the most
important creatures in all creation...

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..we have uncovered humanity's
true place in the cosmos...

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..and glimpsed our earliest origins.

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a place in space and time

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Ounila Valley
Morocco

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This is the fortified town of
Ait Benhaddou.

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It was built in the 17th century on the
trade route that winds its way north

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across the High Atlas
and into the markets of Marrakech.

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The indigenous Berber people
who built this place

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have been in this part of North
Africa for well over 10,000 years,

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and they're mentioned in Ancient
Egyptian texts and in Greek -

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both Herodotus and Cicero talk of
these people who worship the sun
and the moon.

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In fact, they tell a story of how
they cut off the ears of goats,

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threw them over their houses
in honour of the moon god, Ayyur.

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And the skies are so crystal clear
here that you can see why
they did it.

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Well, not the goat thing,
but worshipped those celestial
objects in the sky.

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High above the village,
the summit affords an unobstructed
view of the heavens.

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The perfect vantage point from
which to ponder your place
in the universe.

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For all of history, or at least,
I imagine for as long as people have
considered such things,

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the Earth has been thought of
as being motionless,
at the centre of the universe.

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And when you think about it,
that's obvious - it doesn't feel
like we're moving,

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and the ground feels solid
beneath our feet,

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the proverbial mountains
move for no-one,

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and the sun, moon and stars
arc across the sky.

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The Earth is motionless at
the centre, and the universe
rotates around it.

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Watching the night sky,

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it's natural to think that
the stars move around us.

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And so, for thousands of years,

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this geocentric view of the universe
was never questioned.

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And it's not just the motion
of the stars -

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Aristotle and the ancient
Greek philosophers thought
about these things in detail.

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They noticed that when you drop
things

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they always fall towards
the centre of the Earth,

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so therefore there must be
something special about the Earth,

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it must be the centre
of the universe.

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These arguments are so persuasive that it
was millennia before they were overturned.

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It was here in Venice that our demotion
from the centre of the universe began.

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Venice
Italy

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Venice was an independent city-state
for well over 1,000 years,

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and by the 15th century it was
the richest city in Europe.

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You see that legacy everywhere -
the buildings are spectacular,

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you can only imagine what it
must have been like in its heyday.

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And that pre-eminence put it at the centre of arguably the greatest
intellectual revolution in the history of human civilisation - the Renaissance.

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The Renaissance was a period when
the rebirth of art and science

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transformed how we saw the world.

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This is the Scuola Grande
di San Rocco,

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and everywhere you look, there is
masterpiece after masterpiece

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from one of the greatest artists
of the Italian Renaissance,
Tintoretto.

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It took him over 20 years, beginning in
the 1560s, to complete this building.

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And it's breathtaking.

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You see scenes from the
Old Testament on the walls,

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scenes from the New Testament.

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And what's striking, apart from the obvious
skill of the painter, is the realism.

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And there - The Last Supper.

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You could almost
walk into that painting,

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you could walk across
that chequered floor,

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up the stairs, turn right and out
through that illuminated doorway.

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In the art of the medieval period
and before,

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you don't see this depiction of
real space, the paintings are flat.

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From the 14th century,

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with the rediscovery
of the geometry of the Greeks,

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then you see a genuine
intellectual shift,

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you see the desire to paint
the world as it really is,

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you see paintings
with perspective and depth.

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And that was a change
in perspective.

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And we got our first hints of our
planet's true place in the cosmos

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when this desire to see
things as they are

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was combined with the city's
most valuable commodity.

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Murano
Venetian Lagoon

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My name is Davide Salvadore

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I was born in Murano.
I live in Murano and I work in Murano

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My family have worked with
glass since 1650

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My father. my grand father
all my family worked with glass

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And I will pass it on to my son

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This, I think, is in my blood

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In Murano, if you are a master glass
blower, you are an important person

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During the Renaissance, these
craftsmen were so valuable to Venice

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that they were barred from leaving
the city on pain of death.

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Murano glass was so prized
because its clarity allowed it

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to be fashioned into optics,
into mirrors and lenses.

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And it was precisely that property that caught the
eye of one of the period's most renowned figures,

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Galileo Galilei.

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Now, in 1609, Galileo came here
to Venice

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to commission lenses
for his new telescope -

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this was the world centre
of glass production -

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and he immediately put
that telescope to good use

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by turning it towards the moon
and sketching what he saw.

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In the 1600s, most people thought
that anything in the heavens

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was perfect, perfectly round,
perfectly smooth,

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but Galileo depicted the lunar
surface as we know it to be today,

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the sunlight bouncing off mountains,
disappearing into valleys,

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its shaded rims of craters.

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Galileo didn't just observe
the moon with his telescope,

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he turned it to the planets

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and also in 1610 he made this series
of sketches of Venus and he noticed

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that, different times of the year,
Venus can appear as a full circle

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in the sky or as a slim crescent
and as everything in-between.

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When Venus is on the other side
of the sun from the Earth,

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we see the whole planet.

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But as it moves around in its orbit,

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less and less sunlight
is seen to strike its surface

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until it crosses the sun
in silhouette.

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The only credible explanation
for these phases of Venus

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is that Venus is a planet,
it's orbiting the sun

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inside the orbit of the Earth,
which is also orbiting the sun.

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So, this is the first confirmation
of a sun-centred solar system.

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Galileo had seen evidence
that the sun, not the Earth,

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was the centre
of the solar system...

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..and began our scientific
exploration of the universe
in earnest.

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'In the last 50 years,

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'we've done more than simply
look out from Earth,

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'we've sent unmanned spacecraft to
every corner of the solar system...'

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No, no, no!

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'..many not much bigger and not much
more advanced than this car.'

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Oops, sorry.

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It's a beautiful
piece of engineering,

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but it's essentially got no brakes.

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'We sent Mariner 10 and Messenger
to Mercury,

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'the closest planet to the sun...'

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It's got no acceleration.

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I don't know what
these sticks do here.

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'..43 missions to Venus...

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'..and 51 to Mars.'

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'But only a handful have made it

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'into the solar system's
outermost reaches.'

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In 1977, a chance alignment of the
planets meant that it was possible,

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at least in principle,
to launch a spacecraft

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to all four of the outer gas giants.

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So, NASA launched two spacecraft,
Voyagers 1 and 2.

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And just 18 months later, they reached
the largest planet in the solar system,

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aptly named after
the Roman king of the gods, Jupiter.

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They explored Saturn.....before separating

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with Voyager 2
going on to visit Uranus.

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And then, in 1989,
after travelling for 12 years...

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..it reached Neptune...

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..the most distant planet
in the solar system.

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Orcas Island
Washington State

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But perhaps the most dramatic
change in perspective

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came on the 21st of December 1968...

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..when we left the Earth
for ourselves

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and set out for another world.

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When you're up flying on a beautiful
day, you're certainly free,

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like a bird, and I just enjoy
the scenery and the solitude of it.

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I've probably got
over 13,000 hours in the air.

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But as a fighter pilot,
one of the things I pride myself in

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is more landings than I have hours.

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Of all the flights
Major General Bill Anders has taken,

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he'll be remembered for the one
he made when he was just 35.

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In the 8th year of
manned flight into space,

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the National Aeronautics and Space Administration prepared men
and equipment for the most advanced manned mission to date.

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Together with Frank Borman
and Jim Lovell,

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Bill climbed aboard the most
powerful machine ever built by man.

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When the rocket ignited,
the giant 5F1 engines

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putting out a total of
7½ million pounds of thrust,

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the racket was unbelievable.

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We have lift-off, lift-off at 7:51am
Eastern Standard Time.

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The sideways forces, as those rockets
gimballed to try to keep us

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pointed straight up,
threw us around in the spacecraft.

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If we hadn't been strapped in,
we'd be bouncing off the walls.

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Within about 30 seconds to a minute,

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we flew out of the noise
and echo from the Earth

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and we knew we were on our way.

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This is Houston,
you're looking good.

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We hear you loud and clear, boys.

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OK, the first stage was very smooth
and this one is smoother.

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The three astronauts had begun the
longest human journey ever attempted.

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I can see the entire Earth
out of the centre window.

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I can see Florida, Cuba,
Central America.

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Over 68 hours and 57 minutes,

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they travelled across 380,000
kilometres of empty space...

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..until suddenly their tiny craft
was plunged into darkness.

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The stars just exploded,
I mean, there were...

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Every star you ever thought about
was visible

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to the degree that it was very
difficult to pick out constellations.

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And yet, as I looked back over my
shoulder, the stars suddenly stopped

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and it was this big, black hole...

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..and that was the moon.

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And I must say, that got the hair on the
back of my neck standing up a little bit.

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On Christmas Eve, 1968,
Apollo 8 entered lunar orbit.

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It was just one crater
on top of another crater

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and no matter how closely you looked,

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you're going to find smaller and
smaller craters on top of the big ones.

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It looked like a battlefield,
it was totally beat up.

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It was as they emerged from behind the
desolate lunar surface for the third time

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that our perception of the Earth
changed for ever.

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When we finally turned around
and were going forward,

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like a car driving on
down the highway,

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we saw for the first time the Earth
come up on the lunar horizon.

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Andres: Oh my god, look at that pictures over threre!

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Andres: There's the Earth commi' up. Wow is that pretty!

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Borman: Hey don't take that, it's not scheduled.

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Andres: You got a color film, Jim?

230
00:24:09,719 --> 00:24:10,719
Andres: Hand me a roll of color, quick, would you?

231
00:24:10,919 --> 00:24:11,919
Andres: Hand me a roll of color, quick, would you?
Lovell: Oh man, that's great! Where is it?

232
00:24:12,119 --> 00:24:13,119
Andres: Hand me a roll of color, quick, would you?
Lovell: Oh man, that's great! Where is it?
Andress: Hurry. Quick

233
00:24:17,400 --> 00:24:21,080
I set the range at infinity,
pointed it at the Earth

234
00:24:21,080 --> 00:24:23,760
and just started clicking away,

235
00:24:23,760 --> 00:24:26,213
changing the F-stop with every click.

236
00:24:26,213 --> 00:24:28,231
Lavell: Got it?
Andres: Yep

237
00:24:28,431 --> 00:24:29,784
Lavell:
Take severall,Take several of 'em
Here,give it to me

238
00:24:29,784 --> 00:24:32,191
Andress: Wait a minute, just let me
get the right setting here now,just calm down
Calm down, Lloveel

239
00:24:34,000 --> 00:24:36,120
The photograph was
the shotgun approach,

240
00:24:36,120 --> 00:24:40,000
figuring one of them was going
to hit, and indeed it did.

241
00:24:51,480 --> 00:24:55,600
The photograph Anders took
is known as Earthrise.

242
00:25:00,080 --> 00:25:03,360
One of THE iconic images
of our time.

243
00:25:18,120 --> 00:25:21,360
After the flight, I've often been
asked what I thought was

244
00:25:21,360 --> 00:25:25,840
the most significant part of
Apollo 8, its biggest contribution,

245
00:25:25,840 --> 00:25:30,800
and I've often said our mission
really was to explore the moon,

246
00:25:30,800 --> 00:25:34,720
but our accomplishment was
that we discovered the Earth.

247
00:25:42,560 --> 00:25:46,000
It was only by looking back
at our planet from afar

248
00:25:46,000 --> 00:25:53,520
that we felt just how small and delicate a part
of the universe our fragile world really is.

249
00:26:00,200 --> 00:26:03,880
When I look up and realise
that the moon is a long way off,

250
00:26:03,880 --> 00:26:07,760
240,000 miles, and sometimes
it's hard to imagine

251
00:26:07,760 --> 00:26:10,640
that we actually zipped
all the way up there

252
00:26:10,640 --> 00:26:14,200
and around it 11 times and back,
in this day and age.

253
00:26:22,000 --> 00:26:25,480
Hundreds of years of exploration
have revealed our planet

254
00:26:25,480 --> 00:26:29,880
to be just one of eight in orbit
around a star we call the sun.

255
00:26:33,960 --> 00:26:37,320
But understanding our place
in the solar system

256
00:26:37,320 --> 00:26:41,600
is only the first step in finding
our place in the universe...

257
00:26:43,960 --> 00:26:48,200
..because far beyond anywhere
we can visit lie the stars.

258
00:26:54,463 --> 00:26:59,852
Bryce Canyon
Utah

259
00:27:02,280 --> 00:27:06,840
Until recently, there was no way of
knowing how distant the stars are.

260
00:27:09,480 --> 00:27:13,760
And so we had no idea of our star's
true place in the heavens.

261
00:27:35,480 --> 00:27:37,760
I've been roping
since I was a little kid.

262
00:27:37,760 --> 00:27:40,080
Now, the older I get,
the more I like roping,

263
00:27:40,080 --> 00:27:42,800
it's a very important part
of the cowboy lifestyle.

264
00:27:46,200 --> 00:27:51,000
The most important skill when you're roping
is accuracy and judging the distance.

265
00:27:51,000 --> 00:27:56,095
You've got to be a real good judge of where the
steer is going to be when you throw your rope.

266
00:28:05,640 --> 00:28:08,400
Because our eyes
are a few inches apart,

267
00:28:08,400 --> 00:28:11,680
each one captures a slightly
different view of the world.

268
00:28:14,360 --> 00:28:20,480
And comparing the differences between the two
images is one of the ways the brain judges distance.

269
00:28:28,680 --> 00:28:30,800
It's a phenomenon known as parallax.

270
00:28:31,920 --> 00:28:36,960
And remarkably, you can use the same effect
to measure the distance to the stars.

271
00:28:39,000 --> 00:28:44,960
Now, the parallax shift of a star in the sky from one
eye to the other is of course imperceptibly small,

272
00:28:44,960 --> 00:28:51,080
but if you could arrange for your head to
be, let's say, 180 million miles in diameter,

273
00:28:51,080 --> 00:28:55,360
then the parallax shift would be
measurable. And you can do that.

274
00:28:55,360 --> 00:28:59,280
Here are two pictures of
a double-star system called 61 Cygni

275
00:28:59,280 --> 00:29:02,720
taken in May and November.

276
00:29:02,720 --> 00:29:06,560
That's when the earth is on
one side of the sun...and the other.

277
00:29:06,560 --> 00:29:09,600
There is your 180 million miles.

278
00:29:09,600 --> 00:29:11,320
And as you can see,

279
00:29:11,320 --> 00:29:14,640
the shift is small...

280
00:29:14,640 --> 00:29:16,040
but noticeable.

281
00:29:24,880 --> 00:29:28,240
Using parallax,
61 Cygni was found to be

282
00:29:28,240 --> 00:29:32,040
104,000 billion kilometres
from earth.

283
00:29:42,960 --> 00:29:46,800
But this technique only works
for our nearest stellar neighbours.

284
00:29:47,920 --> 00:29:51,400
The vast majority of stars
are so much further away

285
00:29:51,400 --> 00:29:55,000
that they exhibit no perceptible
parallax shift at all.

286
00:30:01,520 --> 00:30:04,640
So to go beyond our local
stellar neighbourhood,

287
00:30:04,640 --> 00:30:06,520
a new technique was required.

288
00:30:16,600 --> 00:30:20,760
And it involved measuring the
brightness of the stars themselves.

289
00:30:25,920 --> 00:30:31,360
If you want to use the brightness of a star as seen
from the earth's surface to measure its distance,

290
00:30:31,360 --> 00:30:35,160
then you have to know
how bright the star actually is.

291
00:30:35,160 --> 00:30:38,400
And the first person to work out
how to do that was one of the great

292
00:30:38,400 --> 00:30:43,200
unsung heroes in the history
of astronomy - Henrietta Leavitt.

293
00:30:43,200 --> 00:30:46,960
Leavitt was cataloguing the
brightness of stars from photographs

294
00:30:46,960 --> 00:30:49,880
and she became interested in
a particular kind of star

295
00:30:49,880 --> 00:30:54,320
known as a variable star, which
changes its brightness over time.

296
00:30:54,320 --> 00:30:58,360
So it goes dimmer and brighter,
dimmer and brighter,

297
00:30:58,360 --> 00:31:01,680
over a period of days or weeks
or even months.

298
00:31:03,360 --> 00:31:08,680
She took a special interest in a class
of variable stars called Cepheids.

299
00:31:10,400 --> 00:31:14,520
Now, what Leavitt noticed was that
there is a simple relationship

300
00:31:14,520 --> 00:31:17,920
between the actual brightness
of a Cepheid variable

301
00:31:17,920 --> 00:31:22,320
and the rate of change of
that brightness - its period.

302
00:31:22,320 --> 00:31:26,200
She noticed that,
for the dimmer Cepheid variables,

303
00:31:26,200 --> 00:31:29,680
the rate of change of brightness
is very fast,

304
00:31:29,680 --> 00:31:32,200
whereas for the brightest
of the Cepheids,

305
00:31:32,200 --> 00:31:34,680
the rate of change is slow.

306
00:31:34,680 --> 00:31:41,720
So that means that if you can determine the
distance to just one Cepheid variable by parallax,

307
00:31:41,720 --> 00:31:44,800
then you know the distance
to all of them

308
00:31:44,800 --> 00:31:49,160
just by measuring the rate of change
of the brightness in the sky.

309
00:31:53,480 --> 00:31:57,400
Within a year of the publication
of the paper in 1912,

310
00:31:57,400 --> 00:32:00,320
the size of the Milky Way galaxy
had been measured

311
00:32:00,320 --> 00:32:03,640
and shown to be
100,000 light years across,

312
00:32:03,640 --> 00:32:08,000
with the sun not near the centre,
but close to the edge.

313
00:32:16,680 --> 00:32:21,760
The Milky Way is a disc of
between 200 and 400 billion stars

314
00:32:21,760 --> 00:32:24,560
reaching out in giant spiral arms.

315
00:32:30,080 --> 00:32:32,240
The sun and the solar system

316
00:32:32,240 --> 00:32:34,960
sit within the inner rim
of the Orion arm,

317
00:32:34,960 --> 00:32:38,600
27,000 light years
from the galactic centre,

318
00:32:38,600 --> 00:32:43,280
which they orbit
once every 240 million years.

319
00:32:52,240 --> 00:32:54,040
But as vast as the Milky Way is,

320
00:32:54,040 --> 00:32:57,320
it wasn't long before we found
Cepheid variables

321
00:32:57,320 --> 00:32:59,160
that were far more distant.

322
00:33:00,240 --> 00:33:02,480
Our galaxy wasn't the only one.

323
00:33:07,920 --> 00:33:10,320
Five, four, three

324
00:33:10,320 --> 00:33:12,520
two, one...

325
00:33:12,520 --> 00:33:14,000
and lift-off

326
00:33:14,000 --> 00:33:17,320
of the space shuttle Discovery
with the Hubble Space Telescope,

327
00:33:17,320 --> 00:33:19,320
our window on the universe.

328
00:33:33,840 --> 00:33:35,440
Only 400 years ago,

329
00:33:35,440 --> 00:33:39,520
Galileo used simple glass lenses
to explore the solar system.

330
00:33:42,360 --> 00:33:49,080
Today we use advanced instruments like the
Hubble Space Telescope to explore the universe.

331
00:34:00,520 --> 00:34:02,040
Do you like this, Houston?

332
00:34:03,880 --> 00:34:05,200
Oh, it's not bad.

333
00:34:11,120 --> 00:34:15,480
Hundreds of billions of galaxies
stretching out in every direction

334
00:34:15,480 --> 00:34:18,040
to the edge
of the observable universe

335
00:34:18,040 --> 00:34:20,560
some 46 billion light years away.

336
00:34:33,240 --> 00:34:38,680
We've discovered that the universe is far
grander, far more majestic than anyone suspected

337
00:34:38,680 --> 00:34:41,760
when we first started exploring it
just a few centuries ago.

338
00:34:42,800 --> 00:34:46,240
We've discovered there are
no special places in the universe.

339
00:34:46,240 --> 00:34:49,040
We are not at its centre,

340
00:34:49,040 --> 00:34:52,880
we just orbit around
one of a trillion suns.

341
00:34:52,880 --> 00:34:56,400
Which raises an obvious question -

342
00:34:56,400 --> 00:34:59,200
where did all those stars come from?

343
00:35:07,665 --> 00:35:11,439
Atlas Mountains
Morocco

344
00:35:28,812 --> 00:35:31,507
My name is Souad ait Malik

345
00:35:31,919 --> 00:35:36,770
I'm 19 years old

346
00:35:38,910 --> 00:35:42,969
I am from the village of Ali Oudaoud

347
00:35:43,388 --> 00:35:47,382
I was born here and grew up here

348
00:35:54,720 --> 00:36:00,120
For 51 weeks a year, the 88
households of Souad's tiny village

349
00:36:00,120 --> 00:36:02,160
make up her entire universe.

350
00:36:04,920 --> 00:36:07,160
But this week will be different.

351
00:36:10,760 --> 00:36:14,320
For a few days every year,
thousands of Berber tribespeople

352
00:36:14,320 --> 00:36:18,240
from across the High Atlas
leave their isolated villages

353
00:36:18,240 --> 00:36:20,440
to attend a festival of marriage...

354
00:36:22,360 --> 00:36:24,240
..in the hope of finding a partner

355
00:36:24,240 --> 00:36:27,400
and so beginning a new chapter
in their family history.

356
00:36:31,874 --> 00:36:34,524
This year I'm going to the
marriage festival

357
00:36:34,773 --> 00:36:37,825
If I meet someone, I may marry them.
Why not?

358
00:36:37,825 --> 00:36:42,578
This is the perfect age for me
to get married

359
00:36:50,471 --> 00:36:54,817
So many members of my family got
married at the festival

360
00:36:55,131 --> 00:37:01,256
My first cousin, second cousin and
my grandfather and grandmother

361
00:37:06,840 --> 00:37:11,280
Just as in Souad's family,
for as long as anyone can remember,

362
00:37:11,280 --> 00:37:14,640
each generation of Berber
have returned to this place

363
00:37:14,640 --> 00:37:17,240
to begin the next generation.

364
00:37:29,080 --> 00:37:34,000
Today we can trace our origins much further
back than our immediate family tree,

365
00:37:34,000 --> 00:37:38,000
back in fact further than the origin
of our species here in Africa,

366
00:37:38,000 --> 00:37:40,320
back past the origin
of life on earth

367
00:37:40,320 --> 00:37:42,640
and the formation of earth itself.

368
00:37:42,640 --> 00:37:47,520
Back, in fact, to what appears to be
the beginning of time.

369
00:37:47,520 --> 00:37:54,800
And that didn't require a journey of exploration
in a spaceship, flying off into the unknown.

370
00:37:54,800 --> 00:37:58,160
It just required something
that we all possess -

371
00:37:58,160 --> 00:37:59,920
the human imagination.

372
00:38:19,480 --> 00:38:22,520
Scientists are often described
as being childlike,

373
00:38:22,520 --> 00:38:25,480
and the archetypal example
is Albert Einstein.

374
00:38:25,480 --> 00:38:29,440
I think it means
thinking with simplicity.

375
00:38:32,040 --> 00:38:35,360
Following threads carefully
and tenaciously,

376
00:38:35,360 --> 00:38:37,480
seeing where they lead.

377
00:38:38,760 --> 00:38:41,920
Following the implications
of a thought through,

378
00:38:41,920 --> 00:38:45,560
and asking the question
why, why, why, why?

379
00:38:45,560 --> 00:38:49,640
It's having a mind uncluttered by
the adult affliction of common sense.

380
00:38:52,000 --> 00:38:54,560
Einstein would free his mind
of the everyday

381
00:38:54,560 --> 00:38:57,520
and allow it to wander
through the universe.

382
00:39:00,040 --> 00:39:02,640
He imagined himself
riding on a beam of light.

383
00:39:07,080 --> 00:39:09,000
And, by wondering what he might see,

384
00:39:09,000 --> 00:39:12,320
transformed our understanding
of space and time.

385
00:39:17,720 --> 00:39:23,200
But it was his reimagining of an experiment
dreamt up by Galileo in the 1500s

386
00:39:23,200 --> 00:39:27,000
that laid the foundations
of modern cosmology.

387
00:39:31,560 --> 00:39:35,400
Einstein called it
"the happiest thought of my life".

388
00:39:35,400 --> 00:39:39,440
Which is in itself
an almost childlike sentence,

389
00:39:39,440 --> 00:39:46,720
because following that thought through ultimately led
us to a theory of the origin of the universe itself.

390
00:39:55,400 --> 00:40:01,978
And there's a place where you can see with
your eyes what Einstein saw in his mind.

391
00:40:06,400 --> 00:40:09,840
This is NASA's space power facility
near Cleveland, Ohio,

392
00:40:09,840 --> 00:40:13,600
and it is the world's biggest
vacuum chamber.

393
00:40:13,600 --> 00:40:17,120
It's used to test spacecraft
in the conditions of outer space

394
00:40:17,120 --> 00:40:25,600
and it does that by pumping out the 30 tonnes of air
in this chamber until there are about two grams left.

395
00:40:27,560 --> 00:40:32,000
It's kind of got an eccentric
construction, which is part of its history.

396
00:40:32,000 --> 00:40:39,040
It was built in the 1960s as a nuclear test
facility to test nuclear propulsion systems,

397
00:40:39,040 --> 00:40:41,960
and that meant
that they built it out of aluminium

398
00:40:41,960 --> 00:40:44,520
to make the radiation
easier to deal with.

399
00:40:44,520 --> 00:40:50,520
Aluminium is not the best thing, the strongest
material, to build a vacuum chamber out of,

400
00:40:50,520 --> 00:40:53,440
so they built an outer concrete skin

401
00:40:53,440 --> 00:40:58,120
which is part radiation shielding
and part an external pressure vessel

402
00:40:58,120 --> 00:41:02,480
so this thing can take the force
that's present on the outside

403
00:41:02,480 --> 00:41:06,560
when it's pumped out
to the conditions of outer space.

404
00:41:14,080 --> 00:41:16,040
Galileo's experiment was simple -

405
00:41:16,040 --> 00:41:19,160
he took a heavy object
and a light one

406
00:41:19,160 --> 00:41:23,320
and dropped them at the same time
to see which fell fastest.

407
00:41:37,920 --> 00:41:46,305
Now, in this case, the feathers fell to the ground at a
slower rate than the bowling ball because of air resistance.

408
00:41:49,960 --> 00:41:53,760
So in order to see
the true nature of gravity,

409
00:41:53,760 --> 00:41:55,840
we have to remove the air.

410
00:42:14,320 --> 00:42:20,120
It takes three hours to pump out the
800,000 cubic feet of air from the chamber.

411
00:42:20,120 --> 00:42:23,840
OK, we dropped two millitorr
in the last 30 minutes.

412
00:42:23,840 --> 00:42:27,560
But once it's complete, there's
a near-perfect vacuum inside.

413
00:42:28,600 --> 00:42:33,400
..10% open,
station one, go for drop.

414
00:42:33,400 --> 00:42:37,440
PCB 30-1,
pressure set point at 240 psi.

415
00:42:37,440 --> 00:42:39,120
We are go for drop.

416
00:42:41,080 --> 00:42:44,120
Ten, nine, eight,

417
00:42:44,120 --> 00:42:49,000
seven, six, five, four...

418
00:42:49,000 --> 00:42:52,120
Cameras on. ..Two, one.

419
00:42:52,120 --> 00:42:53,560
Release.

420
00:43:23,080 --> 00:43:26,400
Exact. Look at that.

421
00:43:26,400 --> 00:43:30,720
They came down exactly the same.
Wow! Oh, look, look.

422
00:43:30,720 --> 00:43:33,880
Look how they hit right there.
Holy mackerel!

423
00:43:33,880 --> 00:43:35,200
Exactly.

424
00:43:35,200 --> 00:43:37,240
Exactly the same.

425
00:43:37,240 --> 00:43:39,560
The feathers don't move, nothing.

426
00:43:39,560 --> 00:43:42,840
Look at that,
that's just brilliant!

427
00:43:47,800 --> 00:43:51,080
Isaac Newton would say
that the ball and the feather fall

428
00:43:51,080 --> 00:43:55,000
because there's a force
pulling them down - gravity.

429
00:43:56,240 --> 00:43:59,200
But Einstein imagined the scene
very differently.

430
00:44:00,320 --> 00:44:03,720
The happiest thought of his life
was this.

431
00:44:03,720 --> 00:44:08,200
The reason the bowling ball
and the feather fall together

432
00:44:08,200 --> 00:44:11,160
is because they're not falling.

433
00:44:11,160 --> 00:44:17,520
They're standing still. There is
no force acting on them at all.

434
00:44:21,960 --> 00:44:25,200
He reasoned that if you couldn't see
the background,

435
00:44:25,200 --> 00:44:28,240
there'd be no way of knowing
that the ball and the feathers

436
00:44:28,240 --> 00:44:30,720
were being accelerated
towards the earth.

437
00:44:33,720 --> 00:44:36,280
So he concluded...they weren't.

438
00:44:46,760 --> 00:44:52,280
Instead, Einstein proposed that
the force of gravity is an illusion.

439
00:44:53,600 --> 00:44:56,720
Just as the surface of the earth
isn't flat,

440
00:44:56,720 --> 00:45:00,160
neither, he said,
was the fabric of space.

441
00:45:02,000 --> 00:45:05,000
All objects, like stars and planets,

442
00:45:05,000 --> 00:45:08,960
warp the space and time around them
to produce valleys.

443
00:45:10,600 --> 00:45:14,160
And all objects,
like planets and bowling balls,

444
00:45:14,160 --> 00:45:17,400
move across this curved landscape

445
00:45:17,400 --> 00:45:21,600
giving the appearance
of being diverted by a force.

446
00:45:23,960 --> 00:45:28,000
Einstein called this theory
General Relativity.

447
00:45:31,120 --> 00:45:35,360
Esoteric and strange as Einstein's
theory of gravity seems,

448
00:45:35,360 --> 00:45:38,079
it can be tested.

449
00:45:52,840 --> 00:45:58,920
The Arecibo Observatory in Puerto Rico has the
largest dish of any telescope anywhere in the world...

450
00:46:04,080 --> 00:46:09,400
..enabling it to detect the faintest
radio waves from galaxies far, far away.

451
00:46:15,480 --> 00:46:20,400
When we come back, we should destroy
the shield generator.

452
00:46:40,480 --> 00:46:42,000
Using telescopes like this,

453
00:46:42,000 --> 00:46:46,760
we witness some of the most violent
gravitational events in the cosmos.

454
00:46:52,720 --> 00:46:54,600
The deaths of giant stars.

455
00:47:03,960 --> 00:47:07,480
Entire suns devoured by black holes.

456
00:47:12,000 --> 00:47:17,040
And here at Arecibo, they've studied one of
the most extreme systems in the universe,

457
00:47:17,040 --> 00:47:22,360
a binary pulsar, and measured
the stars' doomed orbits

458
00:47:22,360 --> 00:47:26,360
as they spiral towards each other
to the last millimetre.

459
00:47:27,600 --> 00:47:31,040
These measurements are so precise
that using this telescope

460
00:47:31,040 --> 00:47:40,080
it's found that the radius of the orbits
is decreasing by 1.7 millimetres a day.

461
00:47:40,080 --> 00:47:46,080
That number is precisely the number
calculated using Einstein's theory.

462
00:47:52,640 --> 00:47:56,320
This is why I think that Einstein's
theory of general relativity

463
00:47:56,320 --> 00:48:01,200
is arguably the greatest achievement
of the human intellect.

464
00:48:01,200 --> 00:48:05,840
It is, as far as we can tell,
a precisely accurate description

465
00:48:05,840 --> 00:48:09,000
of everything we look at
in the universe.

466
00:48:11,480 --> 00:48:15,320
But Einstein soon realised
his equations could do far more.

467
00:48:17,600 --> 00:48:21,520
They could rewrite
the most universal of human stories.

468
00:48:45,563 --> 00:48:49,355
Apollo 8
25th December 1968

469
00:48:49,680 --> 00:48:54,320
"In the beginning, God created
the heaven and the earth..."

470
00:48:56,080 --> 00:48:59,600
"..and the earth was
without form and void

471
00:48:59,600 --> 00:49:02,320
"and darkness was upon
the face of the deep."

472
00:49:05,920 --> 00:49:09,680
"And the spirit of God moved upon
the face of the water

473
00:49:09,680 --> 00:49:13,680
"and God said,
'Let there be light'..."

474
00:49:15,480 --> 00:49:17,480
"..and there was light."

475
00:49:32,760 --> 00:49:36,760
Einstein's equations allow you
to predict the shape of space-time

476
00:49:36,760 --> 00:49:39,640
given the distribution
of matter within it.

477
00:49:39,640 --> 00:49:43,560
So if you plug a spherical
blob of matter into his equations -

478
00:49:43,560 --> 00:49:47,720
the sun, let's say - then Einstein's
equations give you a solar system.

479
00:49:47,720 --> 00:49:51,000
They allow you to understand
its past and to predict its future.

480
00:49:51,000 --> 00:49:53,920
And shortly after Einstein
published the theory,

481
00:49:53,920 --> 00:49:55,880
he had another happy thought.

482
00:49:55,880 --> 00:49:58,480
He thought, well, if you can
do that for a solar system,

483
00:49:58,480 --> 00:50:01,200
why can't you do it for a universe?

484
00:50:01,200 --> 00:50:02,880
Think about that for a minute -

485
00:50:02,880 --> 00:50:07,240
understand the past and predict
the future of the entire universe.

486
00:50:07,240 --> 00:50:09,440
Even Einstein thought
he'd gone too far.

487
00:50:11,360 --> 00:50:15,080
Because to do that, you need
to know how matter is distributed

488
00:50:15,080 --> 00:50:19,280
not just around a single star,
but across the whole cosmos.

489
00:50:22,440 --> 00:50:25,880
The simplest thing you can do
is to assume that the universe

490
00:50:25,880 --> 00:50:29,600
is the same everywhere,
there are no special places.

491
00:50:29,600 --> 00:50:32,240
You assume a completely uniform
matter distribution.

492
00:50:32,240 --> 00:50:34,360
And when you do that,

493
00:50:34,360 --> 00:50:37,240
then Einstein's equations
predict something surprising.

494
00:50:37,240 --> 00:50:41,040
They predict that the universe
can't be static,

495
00:50:41,040 --> 00:50:45,280
that the universe is dynamic,
it's constantly changing.

496
00:50:45,280 --> 00:50:48,120
Now, if you have
an expanding universe,

497
00:50:48,120 --> 00:50:51,040
then that implies
that it was smaller in the past,

498
00:50:51,040 --> 00:50:54,440
and ultimately, it implies
that there was a beginning.

499
00:50:54,440 --> 00:50:57,600
The Belgium priest and mathematician
Georges Lemaitre,

500
00:50:57,600 --> 00:51:01,120
who was one of the first to work on
these solutions, put it beautifully.

501
00:51:01,120 --> 00:51:07,362
He said, "The universe must have had
a day without a yesterday."

502
00:51:13,240 --> 00:51:16,840
Einstein's equations describe
the evolution of the universe

503
00:51:16,840 --> 00:51:20,040
all the way back
to its very first moments.

504
00:51:26,480 --> 00:51:29,720
From its adulthood,
with mature stars and galaxies...

505
00:51:33,720 --> 00:51:35,560
..through adolescence...

506
00:51:40,000 --> 00:51:43,680
..to its childhood and the formation
of the first stars.

507
00:51:47,800 --> 00:51:52,720
With every step back in time,
the fabric of space contracts

508
00:51:52,720 --> 00:51:55,000
and the universe gets smaller.

509
00:51:58,800 --> 00:52:01,771
Until 13.8 billion years ago,

510
00:52:01,771 --> 00:52:05,040
it was born... in the big bang.

511
00:52:12,480 --> 00:52:16,560
And perhaps the ultimate triumph
of our exploration of the cosmos

512
00:52:16,560 --> 00:52:18,760
is that in the last few years

513
00:52:18,760 --> 00:52:24,469
we've taken a snapshot
of the universe in its infancy.

514
00:52:32,880 --> 00:52:36,040
Dix, neuf, huit, sept,

515
00:52:36,040 --> 00:52:38,800
six, cinq,

516
00:52:38,800 --> 00:52:42,600
quatre, trois, deux, un...

517
00:52:42,600 --> 00:52:43,920
Go!

518
00:52:45,600 --> 00:52:48,640
On 14th May 2009,

519
00:52:48,640 --> 00:52:54,000
the Planck Satellite was launched
from ESA's spaceport in French Guiana.

520
00:53:12,880 --> 00:53:17,360
Its mission was to travel one and a
half million kilometres into deep space

521
00:53:17,360 --> 00:53:21,000
and there, far from
any interference from earth,

522
00:53:21,000 --> 00:53:23,960
to witness the birth of the cosmos.

523
00:53:30,600 --> 00:53:33,920
For four years,
Planck scoured the heavens,

524
00:53:33,920 --> 00:53:37,640
gathering the oldest light
in the universe -

525
00:53:37,640 --> 00:53:43,200
light that began its journey to earth long
before there were any humans to witness it.

526
00:53:44,320 --> 00:53:47,120
Light that is older than any galaxy,

527
00:53:47,120 --> 00:53:49,880
more ancient than any star.

528
00:53:49,880 --> 00:53:52,920
The cosmic microwave background.

529
00:53:53,920 --> 00:53:56,280
This is the photograph of that light

530
00:53:56,280 --> 00:54:00,000
that was released 380,000 years
after the big bang

531
00:54:00,000 --> 00:54:03,360
and has been journeying
through the cosmos ever since,

532
00:54:03,360 --> 00:54:07,320
for almost the entire history
of the universe.

533
00:54:08,360 --> 00:54:11,200
It really is
the afterglow of the big bang.

534
00:54:17,160 --> 00:54:18,560
In those first moments,

535
00:54:18,560 --> 00:54:22,440
the universe was a fireball
of hot, opaque plasma.

536
00:54:25,320 --> 00:54:28,800
But as it cooled,
the first atoms formed

537
00:54:28,800 --> 00:54:32,520
and the first light was free
to roam through the universe.

538
00:54:37,040 --> 00:54:41,520
And encoded in minute temperature
differences in that light,

539
00:54:41,520 --> 00:54:44,960
is the story
of our earliest origins.

540
00:54:46,640 --> 00:54:51,240
Those tiny variations
in the temperature of this radiation

541
00:54:51,240 --> 00:54:59,320
which correspond to tiny fluctuations in density
in the universe when it was only 380,000 years old

542
00:54:59,320 --> 00:55:01,360
are vitally important,

543
00:55:01,360 --> 00:55:05,400
because these are the seeds
of the galaxies.

544
00:55:05,400 --> 00:55:08,560
Without these slight
density variations,

545
00:55:08,560 --> 00:55:11,920
there would have been nothing
for matter to coalesce around

546
00:55:11,920 --> 00:55:13,960
and we wouldn't exist.

547
00:55:20,560 --> 00:55:23,960
And that makes this, I think,

548
00:55:23,960 --> 00:55:28,480
by far the most remarkable picture
of all time.

549
00:55:37,840 --> 00:55:42,160
So this is our place
in space and time -

550
00:55:42,160 --> 00:55:45,000
13.8 billion years
from the big bang...

551
00:55:49,320 --> 00:55:54,240
..27,000 light years from the centre
of the Milky Way galaxy...

552
00:56:01,840 --> 00:56:06,120
..on a rocky world orbiting
a yellow main sequence star.

553
00:56:22,000 --> 00:56:24,280
Today, the 21st of June,

554
00:56:24,280 --> 00:56:28,560
the earth's northern hemisphere
is tilted towards the sun...

555
00:56:29,720 --> 00:56:32,160
..and here in Poland, people gather

556
00:56:32,160 --> 00:56:35,200
to celebrate the shortest night
of the year.

557
00:56:52,320 --> 00:56:54,440
We've come a long way.

558
00:56:54,440 --> 00:56:58,720
In only 500 years, we've journeyed
to the edge of our solar system

559
00:56:58,720 --> 00:57:01,040
and photographed our home world.

560
00:57:01,040 --> 00:57:02,840
We've counted the galaxies,

561
00:57:02,840 --> 00:57:06,200
we've captured the most ancient
light in the universe

562
00:57:06,200 --> 00:57:08,520
and measured its age,
and in doing so,

563
00:57:08,520 --> 00:57:11,480
we've discovered
that we are just one planet

564
00:57:11,480 --> 00:57:14,800
in orbit around one star
amongst billions,

565
00:57:14,800 --> 00:57:17,400
inside one galaxy amongst trillions,

566
00:57:17,400 --> 00:57:21,800
afloat in a possibly infinite sea
of space-time.

567
00:57:33,440 --> 00:57:36,200
In finding our place
in the universe,

568
00:57:36,200 --> 00:57:41,920
we've come to realise how small
and fragile a part of it we are.

569
00:57:47,240 --> 00:57:51,680
But it's been the most glorious
ascent into insignificance,

570
00:57:51,680 --> 00:57:58,640
because our physical demotion has been the
inevitable consequence of a daring intellectual climb

571
00:57:58,640 --> 00:58:00,560
from being the puppets of the gods

572
00:58:00,560 --> 00:58:03,320
to that most rare
and precious thing,

573
00:58:03,320 --> 00:58:05,600
a scientific civilisation.

574
00:58:05,600 --> 00:58:08,920
The only one we know of
anywhere in the universe

575
00:58:08,920 --> 00:58:13,120
that's been able to comprehend
its true place in nature.

576
00:58:13,120 --> 00:58:16,440
And that is
our greatest achievement.

577
00:58:23,024 --> 00:58:31,886
End