0:00:03 > 0:00:08In the beginning, the universe was a bit of a let down, really.
0:00:09 > 0:00:11For millions of years after the Big Bang,
0:00:11 > 0:00:14things were actually rather boring.
0:00:15 > 0:00:18It's just this...soup.
0:00:21 > 0:00:23The Big Bang was not the moment of creation.
0:00:25 > 0:00:30The real moment of creation came 100 million years later.
0:00:30 > 0:00:33There was this magical, if you like, metaphysical moment.
0:00:35 > 0:00:36The cosmic dawn.
0:00:38 > 0:00:40The moment of first light.
0:00:40 > 0:00:43It's the moment the first stars were born...
0:00:45 > 0:00:49The first stars are fundamental to how the universe evolved.
0:00:51 > 0:00:53They're like the rock stars in the universe.
0:00:53 > 0:00:55They live fast and die young.
0:00:55 > 0:00:59..the moment that lit up the universe...
0:00:59 > 0:01:01For the first time in cosmic history,
0:01:01 > 0:01:04the universe really is getting interesting.
0:01:04 > 0:01:09..and began forging the ingredients that made you, me
0:01:09 > 0:01:11and everything around us.
0:01:11 > 0:01:16It was the starting point that led to the appearance of life.
0:01:17 > 0:01:20Astronomers are now trying to witness
0:01:20 > 0:01:22and understand this moment of creation.
0:01:23 > 0:01:27I guess what we're trying to achieve is to see the beginning of things.
0:01:27 > 0:01:29THUNDERCLAP
0:01:33 > 0:01:37We are dealing with a scientific version of the story of Genesis.
0:01:40 > 0:01:41Let there be light!
0:02:03 > 0:02:07This is the Murchison country, Mid West, Western Australia.
0:02:08 > 0:02:12It's the ancestral home of our people, the Yamaji.
0:02:12 > 0:02:17It's very remote and the night skies are something special.
0:02:27 > 0:02:29I like how it's flickering there.
0:02:29 > 0:02:31It's like, if you come...
0:02:32 > 0:02:36Our people like to tell stories and paint pictures -
0:02:36 > 0:02:39stories about the land, about the stars,
0:02:39 > 0:02:41about how things got here.
0:02:41 > 0:02:45And there's Venus, beautiful and bright too. Look at that.
0:02:45 > 0:02:49Sometimes it's the morning star, sometimes it's the evening star.
0:02:49 > 0:02:52That's in a story from the Kouri people, over in the east,
0:02:52 > 0:02:57that when Venus comes this way, they say hello to us
0:02:57 > 0:02:59and then, we say hello to them.
0:02:59 > 0:03:00- When it goes back?- Yes.
0:03:00 > 0:03:02Oh, nice, that's a nice thought.
0:03:02 > 0:03:06Many people tell stories about creation and how we got here.
0:03:08 > 0:03:12This is Steven Tingay. He's an astronomer.
0:03:12 > 0:03:14- That's Orion. - That's Orion's Belt.
0:03:14 > 0:03:17It's just dark enough to see the saucepan, the three stars.
0:03:17 > 0:03:19That's that one over there.
0:03:19 > 0:03:22He knows a lot about the stars,
0:03:22 > 0:03:24but he didn't know about the emu in the sky.
0:03:28 > 0:03:34The emu in the sky tells a story about our ancestors,
0:03:34 > 0:03:38how they used to gather food
0:03:38 > 0:03:42and that emu in the sky
0:03:42 > 0:03:47would tell them the right time to go out hunting.
0:03:47 > 0:03:49It's all about collecting our bush tucker.
0:03:49 > 0:03:54When you see the emu's laying, that's the time -
0:03:54 > 0:03:57and then, when the emu is standing, that's the season over.
0:04:00 > 0:04:03I've been looking at the night sky since I was six years old
0:04:03 > 0:04:07and looking at the Milky Way for decades,
0:04:07 > 0:04:09and never, ever saw it.
0:04:09 > 0:04:12I forget who it was that pointed it out and said well, you know,
0:04:12 > 0:04:16there's the emu's head, neck, body and I've just gone...
0:04:16 > 0:04:18whoa!
0:04:18 > 0:04:20That's been there all the time that I've been looking at it
0:04:20 > 0:04:22and I've never seen it.
0:04:22 > 0:04:25It was mind-blowing.
0:04:25 > 0:04:28Steven's looking for more discoveries in the sky.
0:04:28 > 0:04:33He's trying to put together his own story about how we got here,
0:04:33 > 0:04:37the scientific story of our creation.
0:04:37 > 0:04:42He's built himself a giant radio telescope out here on our land,
0:04:42 > 0:04:45to tune into something no human has ever seen -
0:04:45 > 0:04:48the moment the first stars were born,
0:04:48 > 0:04:51the first light was made,
0:04:51 > 0:04:53and the first stuff that made all of us.
0:04:55 > 0:04:58Some people call it the moment of creation.
0:05:00 > 0:05:02This may be our land,
0:05:02 > 0:05:05but it's a story about every single one of us.
0:05:05 > 0:05:07THUNDERCLAP
0:05:09 > 0:05:12Steven Tingay is not alone.
0:05:12 > 0:05:16Here at Harvard, Avi Loeb is also hoping to build up
0:05:16 > 0:05:21a complete picture of the life story of the universe...
0:05:26 > 0:05:29..to assemble a cosmic photo album
0:05:29 > 0:05:33that traces our story right back to the beginning of time.
0:05:36 > 0:05:39Our cosmic family book.
0:05:44 > 0:05:48That's an image of the earth from the moon, a quite beautiful image.
0:05:48 > 0:05:51This is our home and, of course,
0:05:51 > 0:05:53we would like to trace our cosmic roots
0:05:53 > 0:05:57all the way back to where we started.
0:06:01 > 0:06:04We have some brilliant pictures of our universe
0:06:04 > 0:06:08as it is today - as an adult.
0:06:08 > 0:06:11Our solar system,
0:06:11 > 0:06:14our Milky Way galaxy
0:06:14 > 0:06:16and our galactic neighbours.
0:06:20 > 0:06:24And if we go to the very beginning of the album,
0:06:24 > 0:06:30we also have one picture of the universe as a newborn baby.
0:06:32 > 0:06:33Where it all began.
0:06:37 > 0:06:41It's called the cosmic microwave background.
0:06:42 > 0:06:46This is an image of the infant universe,
0:06:46 > 0:06:49and that image shows us the conditions
0:06:49 > 0:06:51in the very early universe.
0:06:52 > 0:06:55The picture tells us without doubt
0:06:55 > 0:06:59that our story started with a hot, dense and bright beginning.
0:07:04 > 0:07:06The Big Bang,
0:07:06 > 0:07:11often credited as being the moment of creation.
0:07:11 > 0:07:17The Big Bang arranged the initial conditions of the universe.
0:07:17 > 0:07:19Early on, the universe was very bright.
0:07:19 > 0:07:22The temperature of radiation was very high,
0:07:22 > 0:07:26much higher than we find at the centres of stars nowadays,
0:07:26 > 0:07:29but as the universe expanded, it cooled off.
0:07:30 > 0:07:36And as it cooled, the universe became darker and darker.
0:07:36 > 0:07:38The lights went out
0:07:38 > 0:07:44and our universe was nothing more than a vast black fog of hydrogen.
0:07:46 > 0:07:48Welcome to the dark ages.
0:07:51 > 0:07:53Several million years after the Big Bang,
0:07:53 > 0:07:57the universe was dark and boring,
0:07:57 > 0:08:03filled with cold hydrogen atoms floating through space.
0:08:03 > 0:08:06All the things we treasure did not exist.
0:08:08 > 0:08:10The Big Bang was not the moment of creation.
0:08:11 > 0:08:14The Big Bang gets all the credit,
0:08:14 > 0:08:18but in reality, it merely set the stage.
0:08:18 > 0:08:23It created space and time, a brief flash of light and some fog,
0:08:23 > 0:08:26but nothing that you and I would recognise
0:08:26 > 0:08:28as our present day universe...
0:08:29 > 0:08:33..and it left us with the longest interval in history -
0:08:33 > 0:08:35the dark ages.
0:08:37 > 0:08:40Then, we get to the dark ages.
0:08:40 > 0:08:42We don't have photos of those.
0:08:42 > 0:08:46These are the missing pages in our photo album.
0:08:49 > 0:08:54The dark ages are the last great frontier in our cosmic history.
0:08:55 > 0:08:59The universe, the cosmic photo album.
0:09:01 > 0:09:03Yeah, that's worth a blow-up.
0:09:07 > 0:09:10I guess this is the famous cosmic dark ages.
0:09:12 > 0:09:17Astronomers are desperate to fill in the missing pages,
0:09:17 > 0:09:19the childhood years of our universe...
0:09:20 > 0:09:22It's still blank.
0:09:22 > 0:09:25..to see the moment of transformation,
0:09:25 > 0:09:29when the dark fog gave way to a universe of light...
0:09:29 > 0:09:32These are the bits that we want to fill in.
0:09:32 > 0:09:33How dark is it?
0:09:35 > 0:09:38..to see the first stars in the cosmic dawn,
0:09:38 > 0:09:41the real moment of creation.
0:09:42 > 0:09:45The first star probably formed about here.
0:09:45 > 0:09:48Somewhere in these pages.
0:09:52 > 0:09:56To reach this moment in our cosmic history,
0:09:56 > 0:10:00astronomers have devised some extraordinary techniques.
0:10:08 > 0:10:11At the Edinburgh Royal Observatory,
0:10:11 > 0:10:14Jim Dunlop and Ross McClure
0:10:14 > 0:10:18are trying to see the cosmic dawn by tunnelling deep into space.
0:10:22 > 0:10:25What we're trying to achieve is see the beginning of things,
0:10:25 > 0:10:29see when the first structures in the universe formed -
0:10:29 > 0:10:31first stars, first galaxies.
0:10:32 > 0:10:37And to do that, they have been using the Hubble space telescope
0:10:37 > 0:10:41to take one of the most important pictures ever.
0:10:41 > 0:10:43We're looking at an ordinary patch of sky,
0:10:43 > 0:10:46in this case, a little bit to the right of Orion,
0:10:46 > 0:10:50but it's a tiny, tiny area, smaller than my fingernail.
0:10:50 > 0:10:53It looks blank to the human eye.
0:10:53 > 0:10:55It may look blank with the naked eye,
0:10:55 > 0:10:58but Hubble is allowing Jim and Ross
0:10:58 > 0:11:02to tunnel deeper into the distant universe than ever before,
0:11:02 > 0:11:06in their search for ancient light from the cosmic dawn.
0:11:14 > 0:11:18We're trying to look back as far as we can,
0:11:18 > 0:11:20to the beginning of time,
0:11:20 > 0:11:22as close to the Big Bang as we can manage.
0:11:23 > 0:11:28Here we have Orion, a constellation that many people will recognise,
0:11:28 > 0:11:30and we're zooming in, tunnelling in.
0:11:31 > 0:11:33To collect the faint light
0:11:33 > 0:11:36from the most distant objects in the universe,
0:11:36 > 0:11:40they use what may be the longest exposure in cosmic history.
0:11:42 > 0:11:45During the course of 650 orbits,
0:11:45 > 0:11:50they pointed Hubble at the same tiny thumbnail patch of dark sky
0:11:50 > 0:11:52for 100 hours.
0:11:52 > 0:11:56So we go deeper, tunnelling into deep space
0:11:56 > 0:11:58and then we start to see very faint galaxies appear.
0:12:00 > 0:12:02As they tunnel,
0:12:02 > 0:12:05they are reaching further back in time,
0:12:05 > 0:12:07because the further away something is,
0:12:07 > 0:12:11the longer its light has taken to reach us.
0:12:11 > 0:12:14And what we see of a distant object
0:12:14 > 0:12:17is how it looked in the distant past.
0:12:20 > 0:12:23One of the simplest ways to look at it is to realise
0:12:23 > 0:12:27that even the sun is seen as it was eight minutes ago.
0:12:28 > 0:12:30So, if the sun disappeared,
0:12:30 > 0:12:35we wouldn't know for eight minutes and if Jupiter disappeared,
0:12:35 > 0:12:38we wouldn't know for about an hour, or something like that.
0:12:38 > 0:12:42What's really staggering is that once you get to the nearest galaxy,
0:12:42 > 0:12:44that delay is already several million years.
0:12:46 > 0:12:51Which means that we're seeing these galaxies as they were
0:12:51 > 0:12:54millions of years in the past.
0:12:54 > 0:12:57Deeper down the tunnel,
0:12:57 > 0:12:59there are galaxies that we see as they were
0:12:59 > 0:13:02many billions of years ago.
0:13:02 > 0:13:05And here, we start to come into this image of what's called
0:13:05 > 0:13:09the Hubble ultra deep field and these galaxies now,
0:13:09 > 0:13:13we're seeing back to within a billion years or so of the Big Bang.
0:13:22 > 0:13:27This here is the deepest ever image of the night sky ever taken.
0:13:29 > 0:13:33The deepest image shows the oldest things -
0:13:33 > 0:13:37galaxies that formed less than a billion years after the Big Bang.
0:13:40 > 0:13:44That tiny - if you like - borehole that we've made into the sky,
0:13:44 > 0:13:47it is a window into a very different time.
0:13:49 > 0:13:54For three months, Jim and Ross had exclusive first access,
0:13:54 > 0:13:56looking through this window in time...
0:13:56 > 0:13:59We were the first people to look at this data.
0:13:59 > 0:14:02..and they set about analysing the ancient light
0:14:02 > 0:14:05for signs of the earliest stars and galaxies.
0:14:05 > 0:14:07There was this one object in there,
0:14:07 > 0:14:08from the thousands that were in that image,
0:14:08 > 0:14:12that we identified as being potentially the most...
0:14:12 > 0:14:15the most distant object that ever had been seen by anyone.
0:14:16 > 0:14:19This one here is the most distant of all.
0:14:20 > 0:14:24This is zoomed in. It's just literally a faint blob
0:14:24 > 0:14:26and there's only a few photons of light
0:14:26 > 0:14:29being collected to see this object, which we're seeing
0:14:29 > 0:14:32only 500 million years after the Big Bang.
0:14:35 > 0:14:40This faint blob turned out to be an entire galaxy.
0:14:43 > 0:14:45You see, it's not a star, it's not point-like.
0:14:45 > 0:14:49You can see it's slightly extended, which proves it's a galaxy -
0:14:49 > 0:14:52I think about 20 times smaller than our Milky Way.
0:14:52 > 0:14:55But that's about all we have on this galaxy.
0:14:55 > 0:14:58We can't even measure its colour very well.
0:14:58 > 0:15:02It's only just detected by Hubble in its very reddest wavelength.
0:15:03 > 0:15:06It's an excitement, to be the first person to ever look at that image
0:15:06 > 0:15:08and from that image,
0:15:08 > 0:15:11to see this object that nobody's ever seen before.
0:15:14 > 0:15:18And until the next generation of telescopes come online,
0:15:18 > 0:15:22it's as far away as we can possibly see.
0:15:25 > 0:15:27This was, interestingly,
0:15:27 > 0:15:30the most distant object you could see with Hubble.
0:15:30 > 0:15:34Hubble's incapable of seeing any further than this object.
0:15:34 > 0:15:38I guess it also means no-one's going to pip you for the next few years?
0:15:38 > 0:15:39Correct.
0:15:41 > 0:15:44- We are the record holders for a few more years.- Yeah.
0:15:49 > 0:15:55Ross and Jim have identified the earliest galaxy ever found.
0:15:55 > 0:15:59It was born more than 13 billion years ago.
0:15:59 > 0:16:01You can do the sticking, since you've got young kids,
0:16:01 > 0:16:03so you're used to this stuff.
0:16:03 > 0:16:06It's a picture that takes us right to the edge of the dark ages.
0:16:06 > 0:16:08Which way up is it?
0:16:08 > 0:16:11We've filled one more page in the cosmic album,
0:16:11 > 0:16:15taken one step closer to creation,
0:16:15 > 0:16:16but for now, that's the limit.
0:16:20 > 0:16:22Using this method,
0:16:22 > 0:16:26the cosmic dawn and the very first stars
0:16:26 > 0:16:29still remain tantalisingly out of reach.
0:16:38 > 0:16:41But it is only one method.
0:16:41 > 0:16:45What if even older objects could be found elsewhere in the universe?
0:16:48 > 0:16:51At Siding Spring Observatory, in Australia,
0:16:51 > 0:16:57Stefan Keller is also searching for the first stars and the cosmic dawn,
0:16:57 > 0:17:01but not by staring across the entire universe.
0:17:01 > 0:17:06He's looking much closer to home for some very unusual stars.
0:17:08 > 0:17:13The star we are most familiar with is, of course, our own sun.
0:17:16 > 0:17:18Here we are on top of a mountain,
0:17:18 > 0:17:21catching the last rays of the sun,
0:17:21 > 0:17:24and the sun is very special for us,
0:17:24 > 0:17:28but it's a very average sort of star.
0:17:28 > 0:17:33It's been around for about 4.6 billion years,
0:17:33 > 0:17:36a third of the lifetime of the universe.
0:17:37 > 0:17:40That may sound a long time,
0:17:40 > 0:17:44but it's pretty typical for stars in our galaxy.
0:17:49 > 0:17:53And among the 200 billion stars of the Milky Way,
0:17:53 > 0:17:57Stefan is searching to see if any truly ancient stars
0:17:57 > 0:18:01may have survived since the very beginning.
0:18:02 > 0:18:07What we are looking for are those very rare stars
0:18:07 > 0:18:10that are amongst the oldest stars that are out there.
0:18:10 > 0:18:15But spotting a truly ancient star is no easy task,
0:18:15 > 0:18:18when all you have to go on is a pinprick of light.
0:18:19 > 0:18:23The light is all that we have to work with.
0:18:23 > 0:18:28We need special ways of dissecting the starlight that is coming to us,
0:18:28 > 0:18:33so that we can understand where they've come from, how old they are.
0:18:33 > 0:18:37When we decode that, we can uniquely identify
0:18:37 > 0:18:41some of the older stars that remain with us today.
0:18:41 > 0:18:45The secret to spotting an extremely old star
0:18:45 > 0:18:47is to see what it's made of.
0:18:53 > 0:18:57It's all down to a process of cosmic recycling.
0:19:00 > 0:19:03Stars are fundamental to life,
0:19:03 > 0:19:05because they're the furnaces
0:19:05 > 0:19:11that have created everything that we need on earth.
0:19:11 > 0:19:15The rocks that we see have been formed inside a stellar interior
0:19:15 > 0:19:18and then thrown back out into the universe.
0:19:18 > 0:19:21The gold and the silver in the rings on my finger,
0:19:21 > 0:19:23they've all been made in a supernova.
0:19:23 > 0:19:25There's no other place in the universe
0:19:25 > 0:19:27that you can create elements like that.
0:19:29 > 0:19:33After a lifetime forging elements as heavy as iron,
0:19:33 > 0:19:36a star will eventually run out of fuel.
0:19:43 > 0:19:47Many then explode in a massive supernova,
0:19:47 > 0:19:51spewing out a cloud of debris into interstellar space.
0:19:57 > 0:20:03This rich cloud is then recycled into the next generation of stars.
0:20:06 > 0:20:12Again and again and again, this cosmic recycling is taking place.
0:20:12 > 0:20:14In a star like the sun,
0:20:14 > 0:20:19there have been about a thousand generations of stars before it.
0:20:20 > 0:20:24Each generation has a richer and richer composition
0:20:24 > 0:20:27of heavier and heavier elements,
0:20:27 > 0:20:32and particularly noticeable is the build-up of iron.
0:20:32 > 0:20:36So, the amount of iron is an arrow of time.
0:20:36 > 0:20:39It shows us how old the star is.
0:20:45 > 0:20:49If you want to find a very old star
0:20:49 > 0:20:52from the beginning of the recycling process,
0:20:52 > 0:20:55you need to find one with very little iron.
0:20:56 > 0:21:00The way to do that is to look for a specific
0:21:00 > 0:21:03but minute variation in colour,
0:21:03 > 0:21:07something that Stefan's robotic Skymapper telescope
0:21:07 > 0:21:09is carefully designed to spot.
0:21:16 > 0:21:20So, our sun has a particular yellow colour.
0:21:20 > 0:21:23If we then looked at a star of similar temperature,
0:21:23 > 0:21:25but which was much older,
0:21:25 > 0:21:28it would have an ever so slightly different colour.
0:21:28 > 0:21:33It's slightly bluer and so, by looking for stars
0:21:33 > 0:21:35that are ever so slightly bluer,
0:21:35 > 0:21:39we can zero in on the needle in the haystack
0:21:39 > 0:21:44and we can do that at a rate of about 100,000 stars per hour.
0:21:46 > 0:21:51Each night, Skymapper captures the light from nearly a million stars.
0:21:51 > 0:21:55It automatically analyses the colour of each one
0:21:55 > 0:21:58and arranges them for Stefan according to iron content.
0:22:03 > 0:22:08So, we see in most stars, like the sun, have quite a lot of iron,
0:22:08 > 0:22:10but then there's this tail of objects
0:22:10 > 0:22:14that don't have much iron in them at all,
0:22:14 > 0:22:17and they're the potential needles in the haystack.
0:22:20 > 0:22:26And in 2013, Skymapper presented Stefan with one particular star
0:22:26 > 0:22:28that looked quite unlike any other.
0:22:29 > 0:22:36Here you see 100 or so ordinary stars scattered around the field
0:22:36 > 0:22:41and in the centre is the star that we discovered.
0:22:41 > 0:22:44The initial reading from Skymapper
0:22:44 > 0:22:49suggested that this star had an incredibly low iron content.
0:22:49 > 0:22:53At first, we thought we must have done something wrong here,
0:22:53 > 0:22:56but we confirmed it the next night
0:22:56 > 0:22:59and that's when things really got exciting.
0:23:01 > 0:23:05The next step was to take a much closer look
0:23:05 > 0:23:06with a much bigger telescope.
0:23:11 > 0:23:16We were lucky enough to find some telescope time over in Chile
0:23:16 > 0:23:20and we stared at this one star the entire night,
0:23:20 > 0:23:23building up a very detailed spectrum of the star.
0:23:24 > 0:23:26There were a number of things that we saw
0:23:26 > 0:23:29that we just hadn't ever seen before.
0:23:30 > 0:23:35With enough light, it's possible to make a detailed spectrum
0:23:35 > 0:23:38that can reveal the precise ingredients of a star.
0:23:40 > 0:23:43What we see here is the spectrum of light
0:23:43 > 0:23:45from a star that's similar to the sun.
0:23:45 > 0:23:48This is like a fingerprint from the star
0:23:48 > 0:23:53and it tells us how much iron, magnesium and calcium
0:23:53 > 0:23:55is inside that star.
0:23:55 > 0:23:59And you can see that there's quite a lot of lines here.
0:23:59 > 0:24:04In the case of our star, which is up the top here, all we see
0:24:04 > 0:24:08are the lines of hydrogen
0:24:08 > 0:24:11and a little bit here, which is carbon.
0:24:11 > 0:24:15And so, it's quite a different recipe and indeed,
0:24:15 > 0:24:19we just don't see any iron detectable in this star
0:24:19 > 0:24:22and we knew that we were onto something very exciting,
0:24:22 > 0:24:25because we had never seen a star like this before.
0:24:27 > 0:24:30A star with no detectable iron
0:24:30 > 0:24:35must have been made very early in the process of cosmic recycling.
0:24:38 > 0:24:42It's been around for 13.6 billion years.
0:24:43 > 0:24:46It's a very pristine star.
0:24:46 > 0:24:48It formed very early on in the history of the universe,
0:24:48 > 0:24:52before much stellar recycling had taken place.
0:24:52 > 0:24:56Stefan had discovered the oldest star ever seen.
0:24:56 > 0:25:01It's been burning for 13.6 billion years.
0:25:01 > 0:25:04Could it be a remnant from the cosmic dawn?
0:25:06 > 0:25:10In fact, what we're able to do with this star is,
0:25:10 > 0:25:12for the first time,
0:25:12 > 0:25:16say that there was only one star that preceded it.
0:25:23 > 0:25:27Stefan's star had to have been formed from the exploding debris
0:25:27 > 0:25:32of one of the very first stars of the cosmic dawn.
0:25:32 > 0:25:33Remarkably,
0:25:33 > 0:25:38it is from only the second generation of stars ever made.
0:25:46 > 0:25:48Stefan's discovery takes us
0:25:48 > 0:25:52further back towards the dark ages than ever before.
0:25:52 > 0:25:57His star is even older than Jim and Ross's blobby galaxy
0:25:57 > 0:26:02and amazingly, it's right here in our own galaxy.
0:26:03 > 0:26:05Ah, here we are!
0:26:05 > 0:26:08That looks like the right spot.
0:26:08 > 0:26:13This is a star that predates the Milky Way galaxy itself.
0:26:13 > 0:26:16But we must go even further,
0:26:16 > 0:26:18because even before this
0:26:18 > 0:26:22came the very first stars of the cosmic dawn -
0:26:22 > 0:26:26stars that lie beyond the reach of any telescope,
0:26:26 > 0:26:28that we may never see directly.
0:26:41 > 0:26:45So, how can we know what ended the dark ages -
0:26:45 > 0:26:50how light and structure emerged in the very first stars?
0:26:50 > 0:26:54What if we could visualise building them from scratch,
0:26:54 > 0:26:55by going right back to
0:26:55 > 0:26:59the individual atoms of that hydrogen fog?
0:27:02 > 0:27:05If you go back to the this time of the dark ages,
0:27:05 > 0:27:07the universe looked completely different.
0:27:09 > 0:27:13If you had a human observer translated back in time,
0:27:13 > 0:27:17you would see a completely dark, boring, featureless universe -
0:27:17 > 0:27:20an utterly alien place, it would appear to us.
0:27:26 > 0:27:29It was a universe without any light.
0:27:29 > 0:27:31There were no stars, no galaxies.
0:27:32 > 0:27:35Just a collection of lone hydrogen atoms
0:27:35 > 0:27:37and the odd bit of helium,
0:27:37 > 0:27:41spread out in a diffuse fog.
0:27:43 > 0:27:46Hydrogen would be in its most primitive state -
0:27:46 > 0:27:48single hydrogen atoms.
0:27:48 > 0:27:51Basically, we would have, say,
0:27:51 > 0:27:55a volume of the size of my stretched-out arms
0:27:55 > 0:28:00and in this volume, you would basically have one hydrogen atom.
0:28:00 > 0:28:06So diffuse, that if a hydrogen atom was the size of a ping-pong ball,
0:28:06 > 0:28:10the next closest one would be almost halfway to the moon.
0:28:12 > 0:28:14So, we have this very diffuse universe.
0:28:14 > 0:28:16How do we get stars out of this?
0:28:17 > 0:28:22Volker Bromm decided the only way to get a picture of the first star
0:28:22 > 0:28:25was to build one from scratch,
0:28:25 > 0:28:27one hydrogen atom at a time.
0:28:28 > 0:28:31It was time to forget the telescopes
0:28:31 > 0:28:34and bring on the supercomputer.
0:28:34 > 0:28:38We can input into the supercomputers all the laws of physics -
0:28:38 > 0:28:40from, as we say, first principle.
0:28:40 > 0:28:42We can put in the initial conditions,
0:28:42 > 0:28:45because initial conditions is what we see here.
0:28:45 > 0:28:46There are no missing pieces.
0:28:46 > 0:28:48We have all the laws of physics
0:28:48 > 0:28:51that describe the behaviour of these basic ingredients
0:28:51 > 0:28:55and at that point, we set up the computer and then we let it go.
0:29:45 > 0:29:49The scale of the calculation seems impossible -
0:29:49 > 0:29:55to model the behaviour of vast clouds of primordial hydrogen gas,
0:29:55 > 0:29:58trillions of hydrogen atoms,
0:29:58 > 0:30:00one interaction at a time,
0:30:00 > 0:30:02and to ask the question...
0:30:03 > 0:30:04..will they form a star?
0:30:06 > 0:30:08At first, you might think this is hopeless.
0:30:08 > 0:30:10How do we get things like stars out of this?
0:30:10 > 0:30:14But what really then kicks in is the force of gravity
0:30:14 > 0:30:17and the force of gravity has an infinite reach.
0:30:17 > 0:30:20It reaches over vast stretches of the universe -
0:30:20 > 0:30:24millions of light years, so the force of gravity is a very patient force.
0:30:25 > 0:30:30Crucially, the distribution of matter wasn't completely even.
0:30:30 > 0:30:34Tiny fluctuations left over from the Big Bang
0:30:34 > 0:30:38meant some regions were slightly more dense than others...
0:30:39 > 0:30:42..allowing gravity to work its magic.
0:30:47 > 0:30:50Gravity would very, very slowly act
0:30:50 > 0:30:53to clump matter together.
0:30:56 > 0:31:01Certain regions of space, where the density of primordial stuff
0:31:01 > 0:31:03is larger than the rest.
0:31:06 > 0:31:08And then, what would happen is millions of years,
0:31:08 > 0:31:11millions of years would create and attract more and more material.
0:31:14 > 0:31:19Eventually, gravity could pull such a vast collection of atoms
0:31:19 > 0:31:22so incredibly close together,
0:31:22 > 0:31:24under such extreme pressure
0:31:24 > 0:31:28that it would trigger nuclear fusion
0:31:28 > 0:31:30and a star could be born.
0:31:36 > 0:31:40But Volker's supercomputer simulations revealed a problem.
0:31:41 > 0:31:45Something was stopping the first stars from sparking into life.
0:31:46 > 0:31:50Gravity may be pulling the gas atoms closer together,
0:31:50 > 0:31:53but there's another force trying to push them apart.
0:31:56 > 0:31:59This comes together and you compress gas,
0:31:59 > 0:32:02then it also is heated up and at some point,
0:32:02 > 0:32:04the heat will basically have random motion -
0:32:04 > 0:32:08and the random motion will basically prevent gravity
0:32:08 > 0:32:11from condensing the gas any further.
0:32:13 > 0:32:16The more the gravity squeezes inwards,
0:32:16 > 0:32:19the more the gas heats up and pushes outwards.
0:32:20 > 0:32:21It's a stalemate.
0:32:23 > 0:32:26Later stars overcome this problem
0:32:26 > 0:32:30because they come from a cloud enriched by heavier elements
0:32:30 > 0:32:33that can readily absorb some of the heat,
0:32:33 > 0:32:35letting gravity win the fight
0:32:35 > 0:32:38and squeeze the gas beyond the point of no return.
0:32:40 > 0:32:42But with no heavy elements,
0:32:42 > 0:32:46how could the primordial gas get past the stalemate?
0:32:47 > 0:32:50And then, the important question is, can this gas,
0:32:50 > 0:32:53this primordial gas, can this get rid of the heat?
0:32:58 > 0:33:01Volker realised there had to be
0:33:01 > 0:33:04something else in the primordial gas,
0:33:04 > 0:33:06or the universe would have got stuck.
0:33:07 > 0:33:10What tipped the balance in favour of gravity
0:33:10 > 0:33:14were a few chance encounters between the hydrogen atoms.
0:33:17 > 0:33:19Very rarely, something very dramatic happened.
0:33:19 > 0:33:23You have the two hydrogen atoms and they meet
0:33:23 > 0:33:26and they form hydrogen molecules.
0:33:27 > 0:33:31And crucially, a pair like this are able to absorb
0:33:31 > 0:33:35a tiny bit of heat in a way that a lone atom can't.
0:33:37 > 0:33:42This is the key process for the entire end of the cosmic dark ages.
0:33:42 > 0:33:45The gas can cool, gravity can take over
0:33:45 > 0:33:47and eventually create conditions
0:33:47 > 0:33:50that are so extreme, in terms of temperature and density,
0:33:50 > 0:33:53that you can trigger nuclear fusion
0:33:53 > 0:33:56and can eventually form, out of this material, stars.
0:33:59 > 0:34:03MUSIC: Lacrimosa by Zbigniew Preisner
0:34:13 > 0:34:16The first star is born.
0:34:17 > 0:34:21The first light of the universe is created.
0:34:26 > 0:34:29The gas has collapsed for millions of years
0:34:29 > 0:34:30into the centre of the system
0:34:30 > 0:34:33and now, for the first time in cosmic history,
0:34:33 > 0:34:36we see the moment of first light -
0:34:36 > 0:34:38the moment that the first star formed.
0:34:42 > 0:34:47What Volker discovered about these first stars was a revelation.
0:34:48 > 0:34:51Big surprise was that the first stars that formed
0:34:51 > 0:34:55were very different from stars that form in the present-day universe.
0:34:55 > 0:35:00Because these stars were made purely from the primordial gas
0:35:00 > 0:35:02with no heavier elements,
0:35:02 > 0:35:04they must have been huge.
0:35:06 > 0:35:09What we found is that in the early universe,
0:35:09 > 0:35:11stars are much more massive -
0:35:11 > 0:35:13maybe even 100 times more massive than the sun.
0:35:39 > 0:35:42After 100 million years,
0:35:42 > 0:35:46this was how the dark ages finally came to an end.
0:35:55 > 0:35:58The first stars were giants,
0:35:58 > 0:36:01100 times or more the mass of the sun.
0:36:02 > 0:36:04That has dramatic consequences,
0:36:04 > 0:36:07because massive stars have a very different life -
0:36:07 > 0:36:09a much more violent life
0:36:09 > 0:36:12than the kind of low mass star that the sun is.
0:36:13 > 0:36:15They would be 20 times hotter...
0:36:19 > 0:36:21..shining ultraviolet blue...
0:36:24 > 0:36:27..10 million times more luminous than the sun.
0:36:46 > 0:36:49Although we may never see them for real,
0:36:49 > 0:36:53Volker's model has given us an image of these first stars.
0:36:53 > 0:36:55The one picture that really captures
0:36:55 > 0:36:59this metaphysical moment of first light, it would be like this -
0:36:59 > 0:37:03a supercomputer frame that shows the very first star.
0:37:03 > 0:37:06It's an image from the childhood of the universe.
0:37:06 > 0:37:11An image of the first light from the first ever star.
0:37:11 > 0:37:15Let's patch it in just at the end of the cosmic dark ages,
0:37:15 > 0:37:17because this is when it happened.
0:37:17 > 0:37:19It shows the moment when,
0:37:19 > 0:37:22from the impenetrable fog of the dark ages,
0:37:22 > 0:37:26light finally dawned on the universe
0:37:26 > 0:37:29and of course, it wasn't just one star.
0:37:32 > 0:37:34ORCHESTRA TUNES UP
0:37:36 > 0:37:39It had been a long time coming,
0:37:39 > 0:37:42but after 100 million years of nothing,
0:37:42 > 0:37:45the show had finally started.
0:37:48 > 0:37:49CONDUCTOR TAPS BATON
0:37:50 > 0:37:53ORCHESTRA PLAYS
0:38:01 > 0:38:04The dark ages of the universe ended almost abruptly.
0:38:07 > 0:38:11It was the same pattern across the universe.
0:38:12 > 0:38:16Soon after the first star formed, a few million years later,
0:38:16 > 0:38:20another star formed somewhere else and then the process accelerated.
0:38:23 > 0:38:26After 100 million years of darkness,
0:38:26 > 0:38:29lights were coming on across the universe.
0:38:31 > 0:38:34It grew up exponentially.
0:38:34 > 0:38:37Very quickly, within tens of millions of years,
0:38:37 > 0:38:40there were plenty of stars filling up the universe.
0:38:40 > 0:38:44That was the era that so many astronomers had searched for...
0:38:45 > 0:38:47..the cosmic dawn.
0:39:04 > 0:39:07The cosmic dawn would have been spectacular.
0:39:13 > 0:39:17New galaxies were forming out of darkness.
0:39:19 > 0:39:24This age of enlightenment was a very dynamic period of time.
0:39:30 > 0:39:34And it wasn't just light that was created during the cosmic dawn.
0:39:36 > 0:39:42The cosmic dawn is the beginning of complexity in the universe
0:39:42 > 0:39:44that led to our existence.
0:39:48 > 0:39:51The birth of these great furnaces also triggered
0:39:51 > 0:39:55the forging of the more useful ingredients of the universe.
0:39:58 > 0:40:00Obviously, I think it's interesting.
0:40:00 > 0:40:03For the first time, new elements are being made.
0:40:04 > 0:40:07They take hydrogen, turn it into helium.
0:40:07 > 0:40:11Helium gets combined to make carbon
0:40:11 > 0:40:14and we go to oxygen and silicon.
0:40:14 > 0:40:16Deep in their hearts,
0:40:16 > 0:40:20the first giant stars began a transformation of matter,
0:40:20 > 0:40:24producing the heavy elements necessary for life.
0:40:25 > 0:40:30And their huge size had another important consequence.
0:40:30 > 0:40:33They burnt through their fuel incredibly quickly.
0:40:38 > 0:40:41They can only live for a very short time, only a few million years.
0:40:41 > 0:40:43That's really nothing.
0:40:43 > 0:40:46You might say they're like the rock stars in the universe.
0:40:46 > 0:40:48They live fast and die young.
0:40:48 > 0:40:52And so, by the time you make another one over here,
0:40:52 > 0:40:55this one may already be ready to die.
0:41:07 > 0:41:12When they died, they died in a unique type of supernova -
0:41:12 > 0:41:14a hypernova...
0:41:16 > 0:41:20..the biggest explosion ever in the universe.
0:41:28 > 0:41:30Stars were appearing and disappearing.
0:41:32 > 0:41:36It's like fireworks, it's very dynamic.
0:41:37 > 0:41:43These were the very first events that spewed out the heavy elements
0:41:43 > 0:41:47and led to the formation of the second generation of stars.
0:41:49 > 0:41:54And so began the process of stellar recycling,
0:41:54 > 0:41:59that after about a thousand generations of birth and death,
0:41:59 > 0:42:02led eventually to our own sun being formed.
0:42:06 > 0:42:09It had been a long time coming,
0:42:09 > 0:42:12but the birth of the first stars
0:42:12 > 0:42:16was the catalyst that triggered the transformation of the universe.
0:42:20 > 0:42:24For the first time, stars were made,
0:42:24 > 0:42:26light was produced
0:42:26 > 0:42:28and heavy elements were forged.
0:42:30 > 0:42:35And yet, it would still appear an utterly alien universe,
0:42:35 > 0:42:39because the dramatic events of the cosmic dawn
0:42:39 > 0:42:43were still shrouded behind a veil of fog
0:42:43 > 0:42:46and for hundreds of millions of years,
0:42:46 > 0:42:48the universe was opaque.
0:42:52 > 0:42:57How, then, did our universe go from something so alien and opaque
0:42:57 > 0:42:59to what we see today?
0:42:59 > 0:43:04It's a transformation that wouldn't be complete while the fog survived.
0:43:12 > 0:43:15Those first stars? Very bright.
0:43:15 > 0:43:18You know, they could be a million times as bright as our own sun,
0:43:18 > 0:43:21giving off tons and tons of light.
0:43:21 > 0:43:23But the light's not getting very far yet.
0:43:23 > 0:43:27Actually, most of it gets sort of stopped by all this fog of hydrogen.
0:43:29 > 0:43:32Atoms of neutral hydrogen still fill the space
0:43:32 > 0:43:35between the giant first stars,
0:43:35 > 0:43:38so even if we could see that far away,
0:43:38 > 0:43:42we might never be able to see them through the fog.
0:43:43 > 0:43:47As the light leaves the surface of the star and travels outward,
0:43:47 > 0:43:50it gets stopped and so, it couldn't get to us yet,
0:43:50 > 0:43:53so the universe at this point is still opaque.
0:43:57 > 0:43:58But somehow,
0:43:58 > 0:44:03the universe transformed from opaque to transparent.
0:44:06 > 0:44:10Tom Abel is trying to work out what happened to the fog.
0:44:16 > 0:44:19Like Volker, he uses supercomputer simulation
0:44:19 > 0:44:23to try and model these first stars and the fog,
0:44:23 > 0:44:27and to work out how the universe became transparent.
0:44:30 > 0:44:33What we'd like to do is try and predict the past.
0:44:35 > 0:44:39What we have here is one of the first stars forming.
0:44:39 > 0:44:43There's a whole filament of gas, that was all that hydrogen gas.
0:44:43 > 0:44:47Now see, everything that gets blue here gets really hot.
0:44:47 > 0:44:50That's the ultraviolet radiation from this star affecting
0:44:50 > 0:44:54everything up to thousands of light years away from that star.
0:44:56 > 0:44:59These giants were so hot
0:44:59 > 0:45:02that most of the light they gave out was ultraviolet
0:45:02 > 0:45:07and it would have had a drastic effect on thick fog.
0:45:07 > 0:45:11It's so strong, it can blast the electrons out of the hydrogen atoms.
0:45:14 > 0:45:18The radiation that they give off as it's trying to escape
0:45:18 > 0:45:20ionises hydrogen gas,
0:45:20 > 0:45:23but as a consequence, you actually make things transparent.
0:45:25 > 0:45:28Radiation hits the fog,
0:45:28 > 0:45:31fog gets transparent.
0:45:31 > 0:45:34Now, my boundary to the fog is further away.
0:45:34 > 0:45:38Radiation in the next little bit can go a little further,
0:45:38 > 0:45:39so I make these bubbles.
0:45:45 > 0:45:49Each star created a clearing in the fog around itself,
0:45:49 > 0:45:52blowing a bubble of transparent space.
0:45:56 > 0:46:00The simplest way to think about it is some Swiss cheese.
0:46:00 > 0:46:05As their light travels out, it changes the cheese.
0:46:05 > 0:46:09Our air bubbles are growing and we make ever larger ones.
0:46:09 > 0:46:11In this way of thinking about it,
0:46:11 > 0:46:13at the end, we end up with no cheese at all,
0:46:13 > 0:46:16or the bubbles are so big
0:46:16 > 0:46:20that the light from those objects really travels freely.
0:46:24 > 0:46:28Tom has modelled an entire chunk of the universe,
0:46:28 > 0:46:31revealing how it gradually became transparent
0:46:31 > 0:46:34during this epoch of re-ionisation.
0:46:35 > 0:46:39What we have here is actually the large scale now,
0:46:39 > 0:46:43and every little dot that you see in here represents a galaxy
0:46:43 > 0:46:46and that galaxy has massive stars inside of it.
0:46:46 > 0:46:48They put out ultraviolet radiation
0:46:48 > 0:46:52and it makes progressively more of the universe
0:46:52 > 0:46:54more and more transparent.
0:46:54 > 0:46:56You just look, there are some regions
0:46:56 > 0:46:59you can see further and further into the queue
0:46:59 > 0:47:02and you see how all these individual bubbles coalesce,
0:47:02 > 0:47:05and you get sort of long path lines, like you can see here,
0:47:05 > 0:47:09where you can look deep down already and we're not even complete yet.
0:47:09 > 0:47:13Some parts of the universe are still neutral and opaque.
0:47:14 > 0:47:16But there it goes, and the whole fog lifts
0:47:16 > 0:47:19and all the galaxies are revealed.
0:47:27 > 0:47:32Re-ionisation would be completed somewhere in these pages.
0:47:32 > 0:47:35Tom's models offer an explanation
0:47:35 > 0:47:39for how our universe finally became transparent.
0:47:39 > 0:47:42Shall we glue it in? Maybe with a light glue?
0:47:42 > 0:47:43TOM LAUGHS
0:47:43 > 0:47:46In case we have to correct it.
0:47:46 > 0:47:47It's the last piece
0:47:47 > 0:47:50in our theoretical jigsaw of the cosmic dawn.
0:48:02 > 0:48:04After half a billion years,
0:48:04 > 0:48:08the universe had gone through an astonishing transformation.
0:48:10 > 0:48:14From a dark, featureless sea of fog,
0:48:14 > 0:48:16the first stars were born.
0:48:20 > 0:48:24They triggered a rollercoaster of creation.
0:48:26 > 0:48:28Light was generated,
0:48:28 > 0:48:30matter was transformed
0:48:30 > 0:48:33and vast bubbles of fog were cleared.
0:48:35 > 0:48:38And at the climax of the cosmic dawn,
0:48:38 > 0:48:40the curtain was lifted
0:48:40 > 0:48:45to reveal a universe that was now transparent.
0:48:46 > 0:48:51Finally, here was a universe that we recognise...
0:48:52 > 0:48:54..our universe.
0:48:58 > 0:49:00At least, that's the theory.
0:49:00 > 0:49:04But back in the real world, how can we check?
0:49:06 > 0:49:08We can't see the first stars for real.
0:49:08 > 0:49:10They're all dead.
0:49:10 > 0:49:13And even if we could look back that far,
0:49:13 > 0:49:16they'd be hidden in the fog.
0:49:16 > 0:49:19However, all is not lost,
0:49:19 > 0:49:23because the first stars left behind ghosts -
0:49:23 > 0:49:25the bubbles in the fog.
0:49:25 > 0:49:27RADIO RETUNES
0:49:27 > 0:49:30MUSIC: First Light by Django Django
0:49:30 > 0:49:33And these ghosts may offer one last chance
0:49:33 > 0:49:36to make contact with the first stars of the cosmic dawn...
0:49:38 > 0:49:39RADIO RETUNES
0:49:41 > 0:49:46..because the hydrogen fog was transmitting a radio signal.
0:49:47 > 0:49:51MUSIC: First Light by My Morning Jacket
0:49:51 > 0:49:54# First light tonight
0:49:55 > 0:49:58# First light tomorrow
0:50:00 > 0:50:05# First light this morning First light this evening
0:50:05 > 0:50:06# First light tonight... #
0:50:06 > 0:50:11Steven Tingay is trying to tune in to Radio Hydrogen.
0:50:12 > 0:50:15In the early universe, in the first billion years,
0:50:15 > 0:50:18there were vast amounts of hydrogen
0:50:18 > 0:50:23and each one of those hydrogen atoms can randomly give off a radio wave.
0:50:23 > 0:50:27And so, we can tune our telescope to that radio frequency
0:50:27 > 0:50:30and then, we're tuning in to the hydrogen gas.
0:50:30 > 0:50:33# Been looking back
0:50:34 > 0:50:37# Down through the ages
0:50:39 > 0:50:44# First I was an ancient Then I was an infant
0:50:44 > 0:50:46# Now I am alive. #
0:50:47 > 0:50:51Trouble is, once the radio waves reach Planet Earth,
0:50:51 > 0:50:55that particular band of radio is rather crowded.
0:50:57 > 0:51:02Hydrogen gas produces the radio waves at a very specific frequency.
0:51:02 > 0:51:07That's similar to sort of FM radio, by the time they get to us.
0:51:07 > 0:51:10So it means that we've got to build our telescopes
0:51:10 > 0:51:13in areas where there's no human interference,
0:51:13 > 0:51:17so you can't have FM radio, you can't have TV.
0:51:17 > 0:51:19You can't have mobile phones,
0:51:19 > 0:51:22traffic on the road, or anything like that.
0:51:22 > 0:51:26# First light this evening First light this morning
0:51:26 > 0:51:30# First light tonight. #
0:51:31 > 0:51:35It's worth it, because hidden in this radio signal
0:51:35 > 0:51:41could be the only message we'll ever get from the cosmic dawn.
0:51:41 > 0:51:42Distance is the only cure,
0:51:42 > 0:51:45so we need to be in the middle of nowhere, basically.
0:51:45 > 0:51:48So, Steven's heading out to Murchison country,
0:51:48 > 0:51:50in Western Australia.
0:51:50 > 0:51:53It's about the size of the Netherlands,
0:51:53 > 0:51:56but with less than 150 residents...
0:51:56 > 0:51:59RADIO SIGNAL GOES FUZZY
0:51:59 > 0:52:03..and amongst the worst radio, TV and phone reception
0:52:03 > 0:52:05anywhere on the planet.
0:52:05 > 0:52:06RADIO STATIC
0:52:09 > 0:52:10The perfect place for
0:52:10 > 0:52:15one of the strangest-looking telescopes you'll ever see.
0:52:29 > 0:52:32This is Steven's telescope...
0:52:33 > 0:52:36..hundreds of miles from the nearest town.
0:52:36 > 0:52:41The Murchison Widefield Array, or MWA.
0:52:42 > 0:52:472,000 antennas spread over more than a square kilometre,
0:52:47 > 0:52:51all tuned into the radio signal from the cosmic dawn.
0:52:53 > 0:52:55So, what we've got here are the antennas.
0:52:55 > 0:52:59We have a cluster of 16 of them here,
0:52:59 > 0:53:03so you can build a lot of antennas and get a very sensitive telescope.
0:53:09 > 0:53:14Sensitive enough to receive radio waves from the primordial fog
0:53:14 > 0:53:18that had been travelling more than 13 billion light years.
0:53:24 > 0:53:26And handily for Steven,
0:53:26 > 0:53:30the radio waves are only transmitted by the opaque fog,
0:53:30 > 0:53:32not by the transparent bubbles.
0:53:36 > 0:53:40So, that gas outside the bubble produces the radio waves.
0:53:40 > 0:53:42No radio waves from the bubble.
0:53:43 > 0:53:46And so, for us, we're sort of looking for this Swiss cheese
0:53:46 > 0:53:51pattern of bubbles and holes in the hydrogen gas distribution.
0:54:03 > 0:54:07So, although it's not possible to see the first stars,
0:54:07 > 0:54:10it should be possible, with this radio set,
0:54:10 > 0:54:12to find clues about them
0:54:12 > 0:54:15from the way they cleared the hydrogen fog.
0:54:18 > 0:54:20We don't actually see the stars themselves.
0:54:20 > 0:54:23We see the effect of the star on its environment.
0:54:25 > 0:54:29Each atom only emits a tiny signal,
0:54:29 > 0:54:31but there was a lot of gas,
0:54:31 > 0:54:35and it all adds up to a signal that Steven is close to detecting.
0:54:44 > 0:54:48This is an actual image made from the MWA data.
0:54:48 > 0:54:52This is a patch of the sky that's around about 30 degrees across,
0:54:52 > 0:54:55so it's quite a big chunk of sky.
0:54:55 > 0:54:58So, we're looking through our atmosphere,
0:54:58 > 0:55:00we're looking through our galaxy,
0:55:00 > 0:55:03we're looking through most of the universe.
0:55:03 > 0:55:07If you look carefully down here, you can see many, many specks
0:55:07 > 0:55:09and these are all galaxies or quasars
0:55:09 > 0:55:12millions, billions of light years away,
0:55:12 > 0:55:17so we need to remove each of these signals, one by one,
0:55:17 > 0:55:19in order to peel back those layers
0:55:19 > 0:55:24and hopefully, what we're left with is just the signature of the gas
0:55:24 > 0:55:27and the first stars forming, 13 billion years ago.
0:55:34 > 0:55:39This signature will be our first direct contact
0:55:39 > 0:55:42with the very first stars of the universe.
0:55:42 > 0:55:46It will take us right back to the moment of creation
0:55:46 > 0:55:50and provide our first glimpse of the cosmic dawn.
0:55:57 > 0:55:59It's incredible to think that in this very image,
0:55:59 > 0:56:01that I'm looking at right now,
0:56:01 > 0:56:03that signal exists.
0:56:03 > 0:56:09What's really special for me is being able to look at this
0:56:09 > 0:56:12while sort of sitting in an ancient landscape,
0:56:12 > 0:56:14where we've actually built the telescope
0:56:14 > 0:56:17and collected the data from these signals
0:56:17 > 0:56:20that have traversed billions of light years throughout the universe,
0:56:20 > 0:56:24so it's just astonishing on a number of different levels for me.
0:56:27 > 0:56:30But this is just the beginning.
0:56:30 > 0:56:34Once Steven has tuned in to the first stars,
0:56:34 > 0:56:38he's going to fill this entire landscape with antennas
0:56:38 > 0:56:42to make a much bigger, more precise radio,
0:56:42 > 0:56:47that will let him map the early universe as never before.
0:56:49 > 0:56:51We want to build a much bigger telescope -
0:56:51 > 0:56:53100 times bigger -
0:56:53 > 0:56:57and this will dissect the first billion years of the universe,
0:56:57 > 0:56:59step by step,
0:56:59 > 0:57:02and watch the evolution of the first stars and galaxies
0:57:02 > 0:57:04forming in a great deal of detail.
0:57:18 > 0:57:20We are all curious where we came from.
0:57:21 > 0:57:26If one opens the first chapter of Genesis, in the Bible,
0:57:26 > 0:57:30the Old Testament, one finds a version of this story -
0:57:30 > 0:57:35how the universe started and how we humans came to live in it.
0:57:37 > 0:57:39Some bits of this story are right.
0:57:40 > 0:57:42There was a beginning in time.
0:57:43 > 0:57:46Light came into existence from darkness.
0:57:47 > 0:57:49Life was created.
0:57:52 > 0:57:55But other parts of the story are wrong.
0:57:55 > 0:57:59Some things are out of context and mixed up
0:57:59 > 0:58:02and there are some missing elements.
0:58:02 > 0:58:06If I had to give a grade to this early version of the story,
0:58:06 > 0:58:08I would give it a B+.
0:58:11 > 0:58:13We are now at a special time
0:58:13 > 0:58:17that allows us to explore this question scientifically.
0:58:19 > 0:58:21We are able to peer deep into space
0:58:21 > 0:58:25and see those very early sources of light
0:58:25 > 0:58:28that tell us how we came into existence.
0:58:32 > 0:58:34And of course, with modern technology,
0:58:34 > 0:58:37we are hoping to get the story much more accurate -
0:58:37 > 0:58:39to the level of an A+.