0:00:07 > 0:00:09It is a good rule of thumb that, in science,
0:00:09 > 0:00:13the simplest questions are often the hardest to answer.
0:00:16 > 0:00:19Questions like, how did the universe begin?
0:00:21 > 0:00:26In fact, until relatively recently, science simply didn't have the tools
0:00:26 > 0:00:29to begin to answer questions about the origins of the universe.
0:00:31 > 0:00:34But in the last 100 years, a series of breakthroughs have been
0:00:34 > 0:00:39made by men and women who, through observation, determination
0:00:39 > 0:00:46and even sheer good luck, were able to solve this epic cosmic mystery.
0:00:46 > 0:00:48This was real astronomical gold.
0:00:48 > 0:00:51I am going to recreate their most famous discoveries
0:00:51 > 0:00:53and perform their greatest experiments...
0:00:53 > 0:00:5630,000 km/s.
0:00:56 > 0:01:00..that take us from the very biggest objects in the universe
0:01:00 > 0:01:02to the infinitesimally small,
0:01:02 > 0:01:06until I reach the limits of our knowledge by travelling
0:01:06 > 0:01:10back in time to recreate the beginning of the universe.
0:01:10 > 0:01:14The moment one millionth of a second after the universe
0:01:14 > 0:01:16sprang into existence.
0:01:16 > 0:01:19This is a time before matter itself has formed in any way
0:01:19 > 0:01:21that we would recognise it.
0:01:21 > 0:01:25It is as close as we can hope to get to creation,
0:01:25 > 0:01:28to the beginning of time,
0:01:28 > 0:01:30the beginning of the universe itself.
0:01:55 > 0:01:59It is a remarkable fact that science took hundreds of years to come up
0:01:59 > 0:02:02with a theory to explain the origins of the universe.
0:02:05 > 0:02:07All the more surprising, given what a simple
0:02:07 > 0:02:09and fundamental question it is.
0:02:11 > 0:02:15There is something quintessentially human about asking the question,
0:02:15 > 0:02:17where does all of this come from?
0:02:17 > 0:02:20Perhaps because it is a deeper, more fundamental version of
0:02:20 > 0:02:22where I come from?
0:02:29 > 0:02:33Yet, for most of human history, the answers to such an apparently
0:02:33 > 0:02:37simple question could only be attempted by religion.
0:02:39 > 0:02:42It wasn't until the middle of the 20th century that science
0:02:42 > 0:02:47built a coherent and persuasive creation story of its own.
0:02:47 > 0:02:51It was a story based on theory, predictions and observation,
0:02:51 > 0:02:55a story that could finally explain what had happened at the very
0:02:55 > 0:02:58beginning of time, the beginning of the universe itself.
0:03:03 > 0:03:07A little over 100 years ago, if scientists considered the life of
0:03:07 > 0:03:12the universe at all, they considered it eternal, infinite and stable.
0:03:13 > 0:03:15No beginning and no end.
0:03:17 > 0:03:21So even framing the question about the origins of the universe
0:03:21 > 0:03:22was impossible.
0:03:24 > 0:03:28But at the beginning of the 20th century, that began to change.
0:03:31 > 0:03:33New discoveries shook the old certainties
0:03:33 > 0:03:38and paved the way for questions about where the universe came from.
0:03:42 > 0:03:45One observation transformed our idea about
0:03:45 > 0:03:47the true scale of the universe.
0:03:50 > 0:03:53It began with a mystery in the sky.
0:04:00 > 0:04:03By the early part of the 20th century, it was well known
0:04:03 > 0:04:09that our solar system way within a galaxy, the Milky Way.
0:04:09 > 0:04:12Every single star we can see in the sky with the naked eye
0:04:12 > 0:04:17is within our own galaxy and, until the 1920s, all these stars,
0:04:17 > 0:04:22this single galaxy, was the full extent of the entire universe.
0:04:22 > 0:04:24Beyond it was just an empty void.
0:04:26 > 0:04:30But there were some enigmatic objects up there as well,
0:04:30 > 0:04:33just discernible to the naked eye that looked different.
0:04:35 > 0:04:38And one of the most notable is Andromeda.
0:04:41 > 0:04:44You can find Andromeda if you know where to look.
0:04:44 > 0:04:47So, if you start from Cassiopeia, those five stars
0:04:47 > 0:04:52shaped like a sideways letter M, if you move across from the point,
0:04:52 > 0:04:56from the points of the M, slightly up is where you should find it.
0:04:56 > 0:05:01Now, I'm going to use my binoculars to help me in the first instance.
0:05:01 > 0:05:04And if I zoom across...
0:05:04 > 0:05:06Yeah, there it is.
0:05:06 > 0:05:10You can tell it's not a star. I mean, it's basically
0:05:10 > 0:05:14a very faint smudge stuck between those two stars.
0:05:14 > 0:05:16That is it straight up there -
0:05:16 > 0:05:19that is M31, the great Andromeda nebula.
0:05:19 > 0:05:23Now, they were called nebulae, because they had this smudgy,
0:05:23 > 0:05:25sort of wispy, cloudy nature.
0:05:25 > 0:05:28In fact, the word nebula derives from the Latin for cloud.
0:05:33 > 0:05:37These indistinct objects were found scattered throughout the night sky.
0:05:44 > 0:05:48Telescopes revealed many of these nebulae were far more complex
0:05:48 > 0:05:51than simple clouds of interstellar gas.
0:05:55 > 0:05:58They appeared to be vast collections of stars
0:05:58 > 0:06:02and that raised two intriguing possibilities.
0:06:02 > 0:06:06Were these stellar nurseries places where stars were born,
0:06:06 > 0:06:09and therefore residing within our own galaxy, or,
0:06:09 > 0:06:13much more profoundly, were these beautiful, enigmatic objects
0:06:13 > 0:06:18galaxies in their own right sitting way outside the Milky Way?
0:06:21 > 0:06:24The implications of that second possibility were enormous.
0:06:25 > 0:06:27If true, it would instantly
0:06:27 > 0:06:32and utterly transform our idea about the size of the universe.
0:06:42 > 0:06:46Here was an opportunity for an ambitious astronomer to make
0:06:46 > 0:06:49a real name for themselves.
0:06:49 > 0:06:52Perhaps someone with a really big telescope.
0:07:11 > 0:07:16Step forward this man - Edwin Hubble, a man from Missouri,
0:07:16 > 0:07:19although if you had ever met him, you'd never have guessed,
0:07:19 > 0:07:23because he developed this weird persona, a pipe smoking tea drinker
0:07:23 > 0:07:28with a very affected aristocratic English accent.
0:07:28 > 0:07:32Hubble is probably the most famous astronomer ever,
0:07:32 > 0:07:36not least because of his consummate skill at self-promotion,
0:07:36 > 0:07:39but also because of the incredible measurements he would make.
0:07:41 > 0:07:44In Hubble's day, when it came to observations
0:07:44 > 0:07:47and new discoveries, size mattered.
0:07:52 > 0:07:57Today, this is the most powerful optical telescope in the world,
0:07:57 > 0:08:01the GTC, with a primary mirror
0:08:01 > 0:08:05over 10 metres, or 400 inches, in diameter.
0:08:07 > 0:08:09Far bigger than anything Hubble had.
0:08:11 > 0:08:13In September 1923,
0:08:13 > 0:08:16Hubble was working at what was then the biggest telescope
0:08:16 > 0:08:18in the world, the 100-inch Hooker telescope
0:08:18 > 0:08:21at the Mount Wilson Observatory, perched on top of the
0:08:21 > 0:08:25High Sierra mountains overlooking Los Angeles in California.
0:08:25 > 0:08:28He was using the telescope to study one of the most prominent
0:08:28 > 0:08:31nebulae in the sky, the Andromeda nebula.
0:08:34 > 0:08:38The same nebula I looked at earlier, and it was while observing it
0:08:38 > 0:08:42that one very special star caught Hubble's attention,
0:08:42 > 0:08:45one that could reveal the true nature of Andromeda.
0:08:47 > 0:08:50And I am going to use this telescope to look for it now.
0:08:55 > 0:08:58This is the control room of the GTC and, tonight, they've pointed
0:08:58 > 0:09:02the telescope at Andromeda and they are going to take a picture of it.
0:09:02 > 0:09:04It takes about a minute for the exposure
0:09:04 > 0:09:07- to give you a clear enough image? - That's right.
0:09:07 > 0:09:10Now, the picture is finished, so we're going to open it.
0:09:12 > 0:09:14OK, so, this is Andromeda here.
0:09:14 > 0:09:16That's Andromeda, that's right.
0:09:16 > 0:09:20And now, this is Hubble's original plate.
0:09:20 > 0:09:24Right, now, Hubble's star is down here in this corner.
0:09:25 > 0:09:27Can you find it in your image?
0:09:27 > 0:09:30Yeah, if you take the image and you compare it,
0:09:30 > 0:09:32you will see that we don't see that one.
0:09:32 > 0:09:34What we see is the edge of the galaxy,
0:09:34 > 0:09:36so we have to go a little bit further west...
0:09:36 > 0:09:39- Oh, I see, so all this is just the edge.- That's the edge.
0:09:39 > 0:09:43- I was assuming it was the centre of the galaxy.- No, no, no.
0:09:43 > 0:09:46It just goes to show how much more resolution your telescope can get.
0:09:46 > 0:09:49- That's right.- OK, so, can we see that particular star?
0:09:49 > 0:09:51Yes, in order to find that particular star,
0:09:51 > 0:09:52because it is so faint,
0:09:52 > 0:09:55we have to look for references which are brighter.
0:09:55 > 0:09:59And, in this case, you will see four stars in here,
0:09:59 > 0:10:01which are these four stars.
0:10:01 > 0:10:05- And the star Hubble found will be this one here.- That's it...
0:10:05 > 0:10:09That tiny star is the one that Hubble found.
0:10:09 > 0:10:10That's amazing.
0:10:10 > 0:10:13And are you able to get a magnitude for that star?
0:10:13 > 0:10:16Yeah, we have to do a little bit of processing on the image,
0:10:16 > 0:10:18but we are able to get it.
0:10:18 > 0:10:21OK. Hubble had found his star.
0:10:21 > 0:10:22He knew it was special,
0:10:22 > 0:10:26because he compared his plate with others taken over previous nights
0:10:26 > 0:10:30and he noticed that his star changed in brightness -
0:10:30 > 0:10:33some nights it was brighter, some nights it was dimmer.
0:10:33 > 0:10:38He realised this is a variable star, and he saw the significance of it.
0:10:38 > 0:10:42He could see that this was real astronomical gold.
0:10:44 > 0:10:46His star was a Cepheid variable.
0:10:46 > 0:10:48In the stellar bestiary,
0:10:48 > 0:10:52Cepheid variable stars hold very special place...
0:10:54 > 0:10:57..because, by studying the way their brightness changes,
0:10:57 > 0:11:00astronomers can calculate how far away they are.
0:11:02 > 0:11:06Hubble's Cepheid was the first to be discovered in a nebula,
0:11:06 > 0:11:08so he knew that, if he could measure its period,
0:11:08 > 0:11:12he would be able to work out its distance from us.
0:11:13 > 0:11:16So, Hubble set about meticulously measuring
0:11:16 > 0:11:18how his star's luminosity varied.
0:11:20 > 0:11:23It's not hard to imagine how exciting
0:11:23 > 0:11:24this must have been for Hubble.
0:11:24 > 0:11:28At his fingertips was the opportunity to resolve
0:11:28 > 0:11:31a fundamental yet simple question -
0:11:31 > 0:11:35was this nebula within the Milky Way or beyond it?
0:11:35 > 0:11:39The answer would reshape our knowledge of the universe.
0:11:41 > 0:11:44Hubble measured the luminosity, or brightness,
0:11:44 > 0:11:48of his star over many nights and plotted this curve here.
0:11:48 > 0:11:52Now, when we measured tonight, we found it had a value of 18.6
0:11:52 > 0:11:56and I know because they measured it last night to be slightly dimmer
0:11:56 > 0:12:00that it falls on this side of the curve.
0:12:00 > 0:12:02But more important is the period,
0:12:02 > 0:12:07the time in days, from peak brightness to peak brightness.
0:12:07 > 0:12:12Hubble measured this to be 31.415 days.
0:12:12 > 0:12:14This is the critical measurement.
0:12:17 > 0:12:20Armed with this and its apparent brightness,
0:12:20 > 0:12:23Hubble calculated the distance to the Andromeda nebula.
0:12:25 > 0:12:30It was immediately apparent that this star is very far away.
0:12:30 > 0:12:33But when Hubble did his calculation, he worked out that it was
0:12:33 > 0:12:36900,000 light years away,
0:12:36 > 0:12:40making this star the most remote object ever recorded.
0:12:42 > 0:12:44It could mean only one thing -
0:12:44 > 0:12:47not only is Andromeda a galaxy in its own right...
0:12:49 > 0:12:52..but it lies well beyond our own Milky Way...
0:12:54 > 0:12:56..and the myriad of other elliptical
0:12:56 > 0:13:01and spiral nebulae were also individual distant galaxies.
0:13:03 > 0:13:06It was a moment in human consciousness when the universe
0:13:06 > 0:13:10had suddenly and dramatically got considerably bigger.
0:13:10 > 0:13:14With this observation, Hubble had redrawn the observable universe.
0:13:14 > 0:13:17It might not have directly challenged
0:13:17 > 0:13:19the idea of a stable universe,
0:13:19 > 0:13:23but it shattered long-held assumptions and opened
0:13:23 > 0:13:26the possibility of other bigger secrets,
0:13:26 > 0:13:29like an origin to the universe.
0:13:29 > 0:13:33Into this profoundly-expanded cosmos strode someone who would,
0:13:33 > 0:13:37without realising it, provide the tools to unlock that secret.
0:13:39 > 0:13:40This guy.
0:13:52 > 0:13:54A story as great as one that explains
0:13:54 > 0:13:58the origins of the universe would somehow feel wrong without involving
0:13:58 > 0:14:01a scientist as great as Albert Einstein.
0:14:01 > 0:14:03And so, of course, it does,
0:14:03 > 0:14:07because it was Einstein who provided the theoretical foundations
0:14:07 > 0:14:09needed to study the universe
0:14:09 > 0:14:13and effectively invent the science of cosmology.
0:14:16 > 0:14:21100 years ago, he proposed his general theory of relativity.
0:14:21 > 0:14:23It turned physics on its head and gave us
0:14:23 > 0:14:26a completely new understanding of the world.
0:14:30 > 0:14:34He proposed that gravity was caused by the warping
0:14:34 > 0:14:39or bending of space-time by massive objects like planets and stars.
0:14:43 > 0:14:46His theories were revolutionary.
0:14:46 > 0:14:49Einstein was a maverick who ignored the conventional
0:14:49 > 0:14:51to follow his own remarkable instincts.
0:14:55 > 0:14:57One of his lecturers once told him,
0:14:57 > 0:15:00"You are a smart boy, Einstein, a very smart boy.
0:15:00 > 0:15:02"But you have one great fault -
0:15:02 > 0:15:06"you do not allow yourself to be told anything."
0:15:06 > 0:15:09Of course, it was this very quality that would allow him
0:15:09 > 0:15:13to change the world of physics and, of course, to mark him out
0:15:13 > 0:15:16as one of the greatest thinkers of the 20th century.
0:15:19 > 0:15:23And in 1917, he took his general theory of relativity
0:15:23 > 0:15:26and applied it to the entire universe.
0:15:28 > 0:15:30By following the logic of his theory,
0:15:30 > 0:15:33he arrived at something rather unsettling -
0:15:33 > 0:15:36the combined attraction of gravity from all
0:15:36 > 0:15:40the matter in the universe would pull every
0:15:40 > 0:15:44object in the cosmos together, beginning slowly
0:15:44 > 0:15:47but gradually accelerating until...
0:15:49 > 0:15:50Gravity would ultimately
0:15:50 > 0:15:55and inevitably lead to the collapse of the universe itself.
0:15:57 > 0:16:01But Einstein believed, like virtually everyone else,
0:16:01 > 0:16:05that the universe was eternal and static and certainly wasn't
0:16:05 > 0:16:08unstable or ever likely to collapse in on itself.
0:16:16 > 0:16:19But his equations appeared to show the opposite.
0:16:20 > 0:16:23In order to prevent the demise of the universe
0:16:23 > 0:16:27and keep everything in balance, he adds this in his equation -
0:16:27 > 0:16:30Lambda, or the Cosmological Constant.
0:16:30 > 0:16:33It is a sort of made-up force of anti-gravity
0:16:33 > 0:16:37that acts against normal gravity itself.
0:16:37 > 0:16:40Now, he had no evidence for this, but it helped ensure
0:16:40 > 0:16:43that his equations described a stable universe.
0:16:46 > 0:16:50Within his grasp was the secret to the origins of the universe.
0:16:52 > 0:16:56Yet Einstein simply couldn't, or wouldn't, bring himself
0:16:56 > 0:16:59to accept the implications of his own equations.
0:17:01 > 0:17:04With hindsight, it seems remarkable that Einstein did this.
0:17:04 > 0:17:08I mean, here was a man who had revolutionised science
0:17:08 > 0:17:10by rejecting conventional wisdom
0:17:10 > 0:17:14and yet, he couldn't bring himself to trust his own theory.
0:17:14 > 0:17:18He felt compelled to massage his equation
0:17:18 > 0:17:20to fit the established view.
0:17:20 > 0:17:22He even admitted that the Cosmological Constant
0:17:22 > 0:17:27was necessary only for the purposes of making a quasi-static
0:17:27 > 0:17:32distribution of matter, basically to keep things the way they were.
0:17:32 > 0:17:35Whatever his reasons, this little character, Lambda,
0:17:35 > 0:17:37would return to haunt him.
0:17:41 > 0:17:44Because, while it prevented Einstein from understanding
0:17:44 > 0:17:45the implications...
0:17:48 > 0:17:51..his ideas opened the way for someone else to propose
0:17:51 > 0:17:54a theory for the origin of the universe.
0:17:59 > 0:18:04He was a young part-time university lecturer of theoretical physics.
0:18:06 > 0:18:09His idea was so radical, it shocked the world of physics
0:18:09 > 0:18:12and split the scientific community.
0:18:12 > 0:18:16He started an argument that wouldn't be resolved for half a century.
0:18:16 > 0:18:18His name was Georges Lemaitre.
0:18:21 > 0:18:24Now, the eagle-eyed might spot the dog collar.
0:18:24 > 0:18:28In fact, he was both a physicist and an ordained priest.
0:18:28 > 0:18:30Of this apparently curious dual role,
0:18:30 > 0:18:34Lemaitre said, "There were two ways of pursuing the truth.
0:18:34 > 0:18:36"I decided to follow both."
0:18:36 > 0:18:39And, using Einstein's theory of relativity,
0:18:39 > 0:18:41he developed his own cosmological models.
0:18:43 > 0:18:46Lemaitre's model described a universe that,
0:18:46 > 0:18:49far from being static, was actually expanding,
0:18:49 > 0:18:52with galaxies hurtling away from one another.
0:18:56 > 0:19:00Furthermore, Lemaitre saw the implications of this.
0:19:00 > 0:19:03Winding back time, he deduced that there had to be a moment
0:19:03 > 0:19:08when the entire universe was squeezed into a tiny volume,
0:19:08 > 0:19:10something he dubbed the primeval atom.
0:19:13 > 0:19:17This was essentially the first description of what became known
0:19:17 > 0:19:21as the big bang theory, the moment of creation of the universe.
0:19:27 > 0:19:31These were revolutionary ideas and so he published them
0:19:31 > 0:19:35in the Annales de la Societe Scientifique de Bruxelles,
0:19:35 > 0:19:39where they were promptly ignored by the scientific community.
0:19:41 > 0:19:45So, he travelled to Brussels to try to gain support for his idea.
0:19:49 > 0:19:54The 1927 Solvay Conference, held here in Brussels, was probably
0:19:54 > 0:19:58the most famous and greatest meeting of minds ever assembled.
0:20:01 > 0:20:02But for our story,
0:20:02 > 0:20:05the most significant meeting didn't happen here.
0:20:05 > 0:20:08It wasn't planned and happened away from the conference.
0:20:10 > 0:20:12It happened here.
0:20:14 > 0:20:18In this park, the unknown Lemaitre approached the most famous,
0:20:18 > 0:20:21the most feted scientist in the world -
0:20:21 > 0:20:22Albert Einstein.
0:20:25 > 0:20:29Here, finally, was his chance to explain his idea about an expanding
0:20:29 > 0:20:34universe to the very person whose theory he had used to derive it.
0:20:34 > 0:20:38You can only imagine Lemaitre's trepidation as he approached.
0:20:38 > 0:20:41If Einstein endorsed his radical idea,
0:20:41 > 0:20:43then surely it would be accepted.
0:20:43 > 0:20:47Surely this brilliant mind, this titan of physics,
0:20:47 > 0:20:51this deeply original thinker, would see the merits of his theory.
0:20:52 > 0:20:55But after a brief discussion,
0:20:55 > 0:20:58Einstein rejected his idea out of hand.
0:20:58 > 0:20:59According to Lemaitre, he said,
0:20:59 > 0:21:02"Vos calculs sont corrects,
0:21:02 > 0:21:05"mais votre physique est abominable."
0:21:05 > 0:21:06As far as Einstein was concerned,
0:21:06 > 0:21:09his maths might have been correct, but his understanding
0:21:09 > 0:21:13of how the real world worked was, well, abominable.
0:21:16 > 0:21:20Once again, Einstein dismissed the idea of a dynamic universe.
0:21:25 > 0:21:28Lemaitre's paper should have ignited science,
0:21:28 > 0:21:31but without the backing of such a huge and influential figure as
0:21:31 > 0:21:37Einstein, his ground-breaking idea was doomed to be quietly forgotten,
0:21:37 > 0:21:42unless some observation or evidence showed up to support
0:21:42 > 0:21:44the idea of an expanding universe.
0:21:52 > 0:21:55Edwin Hubble, here, was riding high after his discovery that
0:21:55 > 0:21:58proved there were galaxies outside of our own.
0:21:58 > 0:22:01He was feted by Hollywood glitterati,
0:22:01 > 0:22:03a guest of honour at the Oscars,
0:22:03 > 0:22:05and, with access to the world's most powerful telescope,
0:22:05 > 0:22:07he was ready for his next challenge.
0:22:13 > 0:22:17He had heard of some unusual observations that many galaxies
0:22:17 > 0:22:19appeared to be moving away from us.
0:22:21 > 0:22:24No-one could understand why this might be.
0:22:27 > 0:22:30So, in 1928, the world's most famous astronomer
0:22:30 > 0:22:35turned his attention to this new cosmic mystery and began to measure
0:22:35 > 0:22:39the speed that these galaxies were moving relative to Earth.
0:22:44 > 0:22:47To measure the velocity that a galaxy was receding from us,
0:22:47 > 0:22:50Hubble use something called redshift.
0:22:50 > 0:22:54Now, it's not a perfect analogy, but the effect is similar to one
0:22:54 > 0:22:56most of us are familiar with in sound -
0:22:56 > 0:23:00the pitch of a car engine as it approaches us is higher,
0:23:00 > 0:23:02because the sound waves are compressed,
0:23:02 > 0:23:06but the pitch drops lower as the car recedes,
0:23:06 > 0:23:08because the sound waves are stretched.
0:23:11 > 0:23:13The effect is similar with light waves.
0:23:13 > 0:23:17As the source of light moves towards us, the observed wavelength
0:23:17 > 0:23:21is squashed towards the violet or blue end of the spectrum.
0:23:21 > 0:23:23But if the source is moving away from us,
0:23:23 > 0:23:27the wavelength is stretched towards the red end of the spectrum,
0:23:27 > 0:23:30or redshifted, in the parlance of astronomers.
0:23:30 > 0:23:33And the greater the velocity the object is receding,
0:23:33 > 0:23:35the greater the redshift.
0:23:39 > 0:23:43With his assistant, Milton Humason, Hubble spent the next year
0:23:43 > 0:23:46carefully measuring the redshift of galaxies.
0:23:47 > 0:23:50And I have got the chance to do the same thing right now
0:23:50 > 0:23:52using this telescope.
0:23:55 > 0:23:59OK, Massimo, have you found a galaxy for me?
0:23:59 > 0:24:01Yes, I found this galaxy.
0:24:01 > 0:24:03So, how far away is this?
0:24:03 > 0:24:08It is approximately 430 megaparsec far.
0:24:08 > 0:24:12So, if you convert that to light years... 430 x 3.26...
0:24:12 > 0:24:17So it's about 1.5 billion light years away.
0:24:17 > 0:24:19- Yeah, yeah.- OK.
0:24:21 > 0:24:25Hubble needed to measure the average light coming from the galaxy
0:24:25 > 0:24:29in order to get a spectrum, so that he could calculate the redshift.
0:24:29 > 0:24:33Now, Humason did this by exposing a photographic plate
0:24:33 > 0:24:36and it took him a whole week to collect enough light
0:24:36 > 0:24:38to get the spectrum.
0:24:38 > 0:24:42But here at the TNG, the Galileo Telescope, they use instead
0:24:42 > 0:24:45a very sensitive chip that can do this much more quickly.
0:24:45 > 0:24:49How long does it take for you to get a spectrum?
0:24:49 > 0:24:52Approximately 10, 15 minutes.
0:24:52 > 0:24:55So, 10 or 15 minutes' exposure compared with a week
0:24:55 > 0:24:57back in Hubble's time -
0:24:57 > 0:25:00far more powerful than anything they had back then.
0:25:02 > 0:25:05- It's done. - The spectrum is quite good.
0:25:05 > 0:25:07Ah.
0:25:07 > 0:25:10OK, so this is the raw spectrum that has been taken.
0:25:10 > 0:25:13Is there a particular emission line here that you will
0:25:13 > 0:25:16- use as your reference to measure the redshift?- Yeah.
0:25:16 > 0:25:20Here, for example, you have an emission line,
0:25:20 > 0:25:24but to obtain real spectra,
0:25:24 > 0:25:29you have to clean it to obtain the final one.
0:25:29 > 0:25:33- Ah, this is the cleaned-up version of that.- Yes, of that.
0:25:33 > 0:25:38- So this is the actual emission lines from the galaxy...- Yes.
0:25:38 > 0:25:41And this one below, I guess, is the reference?
0:25:41 > 0:25:43The reference, correct,
0:25:43 > 0:25:46of a galaxy with redshift zero.
0:25:46 > 0:25:50- OK, so one that isn't moving away relative to us.- Yes.
0:25:50 > 0:25:54And so it is very clear here, if you compare the top one with this one,
0:25:54 > 0:25:57every emission peak is shifted.
0:25:57 > 0:25:59It's shifted in the red.
0:25:59 > 0:26:03The reference line for the sample is H-Alpha,
0:26:03 > 0:26:07and, from these, you can compute the redshift of this galaxy.
0:26:07 > 0:26:10And can you work out from that how fast
0:26:10 > 0:26:12the galaxy is moving away from us?
0:26:12 > 0:26:14In principle, you can obtain this.
0:26:14 > 0:26:16OK, so what is the formula?
0:26:16 > 0:26:20The formula is the difference between the reference wavelength
0:26:20 > 0:26:22and the observed wavelength,
0:26:22 > 0:26:27divided by the reference wavelength and multiplied by C.
0:26:27 > 0:26:28This is the Doppler effect.
0:26:28 > 0:26:30- Let's see if we can do that roughly. - Yes.
0:26:30 > 0:26:32OK, so this is about...
0:26:32 > 0:26:377,200, approximate.
0:26:37 > 0:26:38OK.
0:26:38 > 0:26:42Minus 6,563.
0:26:42 > 0:26:44- ..63.- OK.- Over...
0:26:44 > 0:26:466,563.
0:26:46 > 0:26:49- And that is the fraction of the speed of light?- Yes.
0:26:49 > 0:26:51OK, so, I might as well do this.
0:26:51 > 0:26:54I should do it with my calculator, but...
0:26:54 > 0:26:56So...
0:27:02 > 0:27:06OK. So then that we divide by 6,563.
0:27:06 > 0:27:09OK, so it is roughly 0.1 the speed of light.
0:27:11 > 0:27:16So it is about 30,000 km/s, yes?
0:27:16 > 0:27:17- Correct.- Thank you.
0:27:19 > 0:27:20OK.
0:27:20 > 0:27:22I'm actually quite pleased at my maths here,
0:27:22 > 0:27:24because I was under pressure.
0:27:24 > 0:27:30So, this galaxy is 1.5 billion light years away from the Milky Way
0:27:30 > 0:27:32and, from the redshift,
0:27:32 > 0:27:35we have worked out it is moving away from us
0:27:35 > 0:27:37at 1/10 the speed of light.
0:27:37 > 0:27:40That means it is moving away from us at three...
0:27:40 > 0:27:44At, sorry, 30,000 km/s.
0:27:45 > 0:27:47Boom.
0:27:47 > 0:27:48Science.
0:27:53 > 0:27:56Once he had calculated the speed of the galaxy,
0:27:56 > 0:27:58Hubble then measured how far away it was.
0:28:04 > 0:28:07Once Hubble had both his measurements,
0:28:07 > 0:28:12he could start putting them on a graph of velocity against distance.
0:28:12 > 0:28:14Now, he made 46 different measurements
0:28:14 > 0:28:18and, when he put them on the graph, he noticed a pattern emerging.
0:28:18 > 0:28:21He could draw a line through all these points -
0:28:21 > 0:28:23each one of them is an individual galaxy.
0:28:23 > 0:28:26He noticed a connection between the velocity
0:28:26 > 0:28:28and the distance of a galaxy.
0:28:28 > 0:28:31In fact, the further away it was,
0:28:31 > 0:28:33the faster it was moving away from us.
0:28:36 > 0:28:40In a stable universe, the speeds of galaxies should appear random.
0:28:42 > 0:28:44You wouldn't expect a clear relationship
0:28:44 > 0:28:47between the distance of a galaxy and its velocity.
0:28:49 > 0:28:53Hubble's graph showed that the universe was expanding,
0:28:53 > 0:28:56which has profound implications for the idea
0:28:56 > 0:28:58of a beginning to the universe.
0:29:01 > 0:29:04What this means is that it is not just that the galaxies
0:29:04 > 0:29:07are all speeding away from us and from each other
0:29:07 > 0:29:09but that, if you could wind the clock back,
0:29:09 > 0:29:12there would have been a time when they were all squeezed together
0:29:12 > 0:29:14in the same place.
0:29:23 > 0:29:25Here, finally, was the first observation,
0:29:25 > 0:29:29the first piece of evidence that Lemaitre's idea of a moment
0:29:29 > 0:29:33of creation, of a universe evolving from a Big Bang,
0:29:33 > 0:29:35might be correct.
0:29:51 > 0:29:54Thanks to Hubble's work, Georges Lemaitre,
0:29:54 > 0:29:56the unknown Belgian cleric,
0:29:56 > 0:30:00the theoretician without proper international credentials,
0:30:00 > 0:30:03the man whose physics Einstein called abominable,
0:30:03 > 0:30:07was belatedly rightly recognised for his bold theory.
0:30:10 > 0:30:12Most significantly,
0:30:12 > 0:30:16the biggest name in physics came around to this revolutionary idea.
0:30:19 > 0:30:22In 1931, on a visit to Hubble's observatory,
0:30:22 > 0:30:28Einstein publicly endorsed the Big Bang expanding universe model.
0:30:28 > 0:30:30"The redshifts of distant nebulae
0:30:30 > 0:30:34"has smashed my old construction like a hammer blow," he said.
0:30:34 > 0:30:39Einstein dropped the cosmological constant. He even wrote to Lemaitre,
0:30:39 > 0:30:43"Ever since I introduced the term, I have had a bad conscience.
0:30:43 > 0:30:46"I am unable to believe that such an ugly thing
0:30:46 > 0:30:49"should be realised in nature."
0:30:49 > 0:30:52It must have been quite an absolution for Lemaitre.
0:30:52 > 0:30:56Having been practically cast out into the scientific wilderness,
0:30:56 > 0:31:00he was now firmly at the centre of a cosmological revolution.
0:31:08 > 0:31:12The idea of the Big Bang was finally gaining traction.
0:31:14 > 0:31:17But, despite Einstein's seal of approval,
0:31:17 > 0:31:20and the observations of Hubble,
0:31:20 > 0:31:22the argument was far from over.
0:31:31 > 0:31:33There were still significant objections
0:31:33 > 0:31:36if the idea of a Big Bang was to be widely accepted.
0:31:36 > 0:31:40A scientific theory of creation isn't just about explaining
0:31:40 > 0:31:42the expansion of the universe -
0:31:42 > 0:31:45there were more profound issues to resolve.
0:31:47 > 0:31:53The problem was, the Big Bang raised as many questions as it answered.
0:31:53 > 0:31:56Like, if the universe had erupted from a single point,
0:31:56 > 0:31:59where did all the matter come from?
0:32:04 > 0:32:07To go further, the Big Bang theory needed to explain
0:32:07 > 0:32:10how matter itself had been formed.
0:32:13 > 0:32:16Well, before that could be answered, we need to know
0:32:16 > 0:32:19what the universe is actually made of - the elemental building blocks.
0:32:19 > 0:32:23And working that out took an incredible bit of insight
0:32:23 > 0:32:26by a remarkable woman - Cecilia Payne.
0:32:26 > 0:32:30She studied at Cambridge University, but wasn't awarded a degree,
0:32:30 > 0:32:32because, well, she was a woman.
0:32:32 > 0:32:34So, to continue to her studies,
0:32:34 > 0:32:36she needed to go somewhere more enlightened.
0:32:36 > 0:32:38She left England for America
0:32:38 > 0:32:43and it was there that she revealed the composition of the universe.
0:32:55 > 0:32:58If you were to ask someone what the most common elements were,
0:32:58 > 0:33:01an atmospheric scientist might say nitrogen.
0:33:01 > 0:33:04After all, it makes up more than three quarters of the atmosphere.
0:33:04 > 0:33:10A geologist might say silicon or iron or oxygen...
0:33:10 > 0:33:13which all seems very quaint and Earth-centric
0:33:13 > 0:33:16and really rather parochial.
0:33:27 > 0:33:31So, astronomers thought it better to look at the sun.
0:33:35 > 0:33:38Which makes sense, given that most of what we see
0:33:38 > 0:33:41when we look out into the cosmos is stars.
0:33:46 > 0:33:48The first attempts to analyse the composition of the sun
0:33:48 > 0:33:51were done with a set-up rather like this.
0:33:51 > 0:33:53Well, not exactly like this -
0:33:53 > 0:33:56this is a cutting-edge 21st-century solar telescope.
0:33:56 > 0:33:59But the basic idea was exactly the same.
0:34:08 > 0:34:10The basic idea's very simple.
0:34:10 > 0:34:13The sun's light is reflected off this mirror here,
0:34:13 > 0:34:17up into a second mirror...
0:34:17 > 0:34:20where it bounces off, down through the top of the tower,
0:34:20 > 0:34:23all the way to the bottom, ten storeys down,
0:34:23 > 0:34:27where it's focused and split into a spectrum and analysed.
0:34:45 > 0:34:48This is the control room of the solar telescope.
0:34:48 > 0:34:51The base of the telescope is over there.
0:34:51 > 0:34:54And here, I've got a live feed image of the sun.
0:34:54 > 0:34:58And what I've got up here is a zoomed-in section
0:34:58 > 0:35:00of the spectrum of the light coming from the sun.
0:35:00 > 0:35:02Now, it's in black and white,
0:35:02 > 0:35:06but it actually corresponds to the green part of the spectrum.
0:35:06 > 0:35:10These two thick dark lines correspond to the element iron.
0:35:10 > 0:35:13They tell us there's iron in the sun.
0:35:13 > 0:35:16Now, here I have the spectrum in much more detail,
0:35:16 > 0:35:19and these two lines correspond to these two dips
0:35:19 > 0:35:21in the absorption spectrum
0:35:21 > 0:35:25at very specific wavelengths. This is iron.
0:35:25 > 0:35:29If I look at different parts of the spectrum, I can see other elements.
0:35:29 > 0:35:34This big dip here is hydrogen. These two dips represent oxygen.
0:35:34 > 0:35:38And this dip corresponds to the element magnesium.
0:35:39 > 0:35:42All these dips and lines in the spectrum
0:35:42 > 0:35:47indicate the presence of these elements in the sun's atmosphere.
0:35:47 > 0:35:51Effectively, a fingerprint of the sun's composition.
0:35:53 > 0:35:57To a geologist, these elements are all very familiar.
0:35:57 > 0:36:00It appears, at first glance, that the sun is made of the same stuff
0:36:00 > 0:36:05as the Earth, that the sun is simply a very hot rock.
0:36:14 > 0:36:16And that would have been that
0:36:16 > 0:36:20were it not for the insight of Cecilia Payne.
0:36:23 > 0:36:27She realised that the spectrographs were being affected by processes
0:36:27 > 0:36:28in the sun's atmosphere.
0:36:32 > 0:36:36These would distort the apparent abundance of the elements
0:36:36 > 0:36:37that make up the sun.
0:36:40 > 0:36:43So, she recalculated the relative abundances of the elements
0:36:43 > 0:36:47and discovered that the sun was composed almost entirely
0:36:47 > 0:36:49of just two elements -
0:36:49 > 0:36:52hydrogen and helium.
0:36:52 > 0:36:55All the other elements - carbon, oxygen, sodium, iron -
0:36:55 > 0:36:58that made the sun seem so Earth-like
0:36:58 > 0:37:02amounted to just a tiny fraction of its composition.
0:37:02 > 0:37:04When she first presented this result,
0:37:04 > 0:37:06it was considered impossible.
0:37:06 > 0:37:08In fact, when she wrote up her work,
0:37:08 > 0:37:12she was persuaded to add the comment that these calculated abundances
0:37:12 > 0:37:17of hydrogen and helium were almost certainly not true.
0:37:18 > 0:37:22The idea was only accepted some four years later,
0:37:22 > 0:37:25when the director of a prestigious observatory
0:37:25 > 0:37:31arrived at exactly the same conclusion by different means.
0:37:31 > 0:37:33Ironically, this director was the very same man
0:37:33 > 0:37:38who'd initially dismissed Payne's work as clearly impossible.
0:37:41 > 0:37:46Payne's revelation about the ratio of hydrogen and helium was found
0:37:46 > 0:37:51to be remarkably consistent for almost every star in the galaxy.
0:37:51 > 0:37:54That led to a big conclusion.
0:37:54 > 0:37:57The universe is dominated by just two elements, the simplest
0:37:57 > 0:38:01and lightest elements - hydrogen and helium.
0:38:01 > 0:38:06Together, they make up more than 98% of all the matter in the universe.
0:38:06 > 0:38:08All the other elements that are so important to us -
0:38:08 > 0:38:13like carbon, oxygen, iron - amount to less than 2%.
0:38:16 > 0:38:20So now the challenge for supporters of the Big Bang theory
0:38:20 > 0:38:22was very clear and simple -
0:38:22 > 0:38:26could the Big Bang theory explain the creation
0:38:26 > 0:38:31AND the observed ratios of hydrogen and helium found in the stars?
0:38:40 > 0:38:45But to answer that would require a fundamental shift of emphasis.
0:38:48 > 0:38:53Rather than consider the almost infinite vastness of the universe,
0:38:53 > 0:38:55it was necessary to consider
0:38:55 > 0:38:58the infinitesimally small world of the atom.
0:38:58 > 0:39:01And that required, not an astronomer,
0:39:01 > 0:39:04but an entirely different kind of physicist.
0:39:04 > 0:39:07George Gamow was a Russian nuclear physicist
0:39:07 > 0:39:12and an enthusiastic advocate of the Big Bang idea.
0:39:12 > 0:39:16He turned his attention to the earliest moments of the universe.
0:39:22 > 0:39:24Here, he felt,
0:39:24 > 0:39:27was where the answer to the composition of the universe lay.
0:39:27 > 0:39:32This was when he believed hydrogen and helium were first forged,
0:39:32 > 0:39:35and he proposed it would have happened very soon
0:39:35 > 0:39:38after the birth of the universe.
0:39:38 > 0:39:41He set about building a mathematical model
0:39:41 > 0:39:45of the earliest stages of the universe.
0:39:45 > 0:39:48He was thinking about the universe in terms of seconds and minutes,
0:39:48 > 0:39:51rather than billions of years.
0:39:51 > 0:39:54And he recruited a young protege,
0:39:54 > 0:39:57this chap, Ralph Alpher, to help him.
0:39:57 > 0:40:00After years of hard work, some of which, according to Alpher,
0:40:00 > 0:40:03were aided by hard drinking in a bar,
0:40:03 > 0:40:05they presented their idea.
0:40:06 > 0:40:09By rewinding the universe, it was clear to them that there
0:40:09 > 0:40:13would have been a time when the early universe was incredibly dense
0:40:13 > 0:40:16and phenomenally hot.
0:40:16 > 0:40:19At this stage, which they calculated to be just three minutes
0:40:19 > 0:40:22after the Big Bang, the universe would have been so hot
0:40:22 > 0:40:24that atoms themselves couldn't exist,
0:40:24 > 0:40:26only their constituent parts,
0:40:26 > 0:40:30a kind of superheated primordial soup
0:40:30 > 0:40:33of protons, neutrons and electrons.
0:40:33 > 0:40:35They even gave this soup a name - ylem,
0:40:35 > 0:40:38from an old English word for matter.
0:40:40 > 0:40:45Then came the crucial moment...
0:40:45 > 0:40:48a time when conditions were right for the nuclei
0:40:48 > 0:40:50of the first elements to be forged.
0:40:50 > 0:40:52In a short period of time,
0:40:52 > 0:40:55which they estimated to be less than 15 minutes,
0:40:55 > 0:41:00hydrogen nuclei proton were coming together to form helium,
0:41:00 > 0:41:02in the process of nuclear fusion.
0:41:05 > 0:41:09Moreover, the ratios of hydrogen and helium predicted by their model
0:41:09 > 0:41:13matched that measured in the stars.
0:41:16 > 0:41:20They announced their results in a paper published in 1948.
0:41:22 > 0:41:24However, Gamow added another author to the paper -
0:41:24 > 0:41:26the famous nuclear physicist, Hans Bethe,
0:41:26 > 0:41:28who had nothing to do with the work.
0:41:28 > 0:41:30Gamow added his name for a laugh.
0:41:30 > 0:41:32He thought it made a good science pun,
0:41:32 > 0:41:38because the authors of the paper now read, "Alpher, Bethe and Gamow."
0:41:38 > 0:41:41The young Alpher, however, was less amused to be sharing the credit
0:41:41 > 0:41:44with someone who'd done no work.
0:41:44 > 0:41:47By way of reconciliation, the story goes,
0:41:47 > 0:41:50Gamow produced a bottle of Cointreau for Alpher
0:41:50 > 0:41:53but with the label changed to read, "Ylem."
0:41:56 > 0:42:01The ability to make calculations that explained the origins of matter
0:42:01 > 0:42:06in the first few minutes after a Big Bang was remarkable in itself.
0:42:06 > 0:42:09But there was a very significant prediction
0:42:09 > 0:42:11that emerged from their work.
0:42:11 > 0:42:15A prediction that had the potential to deliver the proof
0:42:15 > 0:42:19that the universe had begun with a Big Bang.
0:42:19 > 0:42:22Alpher continued to study the early evolving universe,
0:42:22 > 0:42:25focusing on what happened next.
0:42:25 > 0:42:28He pictured the universe at this stage as a seething fog
0:42:28 > 0:42:31of free electrons and atomic nuclei.
0:42:31 > 0:42:34Then it dropped to a critical temperature,
0:42:34 > 0:42:37a temperature cool enough for electrons to latch on
0:42:37 > 0:42:41to the nuclei of hydrogen and helium.
0:42:41 > 0:42:43At this precise point,
0:42:43 > 0:42:47light was released to travel freely throughout the universe.
0:42:47 > 0:42:49The first light of creation.
0:42:57 > 0:43:00This might have remained nothing more than an academic curiosity
0:43:00 > 0:43:02had it not been for Alpher's insight.
0:43:02 > 0:43:05You see, he realised that this light from the beginning
0:43:05 > 0:43:08of the universe should still be reaching us now,
0:43:08 > 0:43:09after billions of years.
0:43:09 > 0:43:13Very weak, very faint, but observable in all directions.
0:43:13 > 0:43:17He calculated that the expansion of the universe should be stretching
0:43:17 > 0:43:21the wavelength of this light beyond the range of the visible spectrum
0:43:21 > 0:43:25and should now be arriving as microwave radiation.
0:43:28 > 0:43:32So, find this predicted ancient microwave signature
0:43:32 > 0:43:35and it will prove, not just the theory of the early evolution
0:43:35 > 0:43:40of the universe, but the entire Big Bang theory itself. Simple.
0:43:41 > 0:43:44The problem was, this was the late 1940s
0:43:44 > 0:43:48and no-one had any way of detecting such a weak signal.
0:43:48 > 0:43:51The acid test was quietly forgotten.
0:43:56 > 0:43:59Supporters of the Big Bang now had the prediction
0:43:59 > 0:44:03and observation of an expanding universe.
0:44:04 > 0:44:07And a theory for how elements were forged
0:44:07 > 0:44:10in the first few minutes after the Big Bang.
0:44:13 > 0:44:17But without the clinching evidence for this, the argument over
0:44:17 > 0:44:20whether the Big Bang theory was correct rumbled on.
0:44:24 > 0:44:27The opponents of the Big Bang continually tweaked and adjusted
0:44:27 > 0:44:32their theories to make their idea of an eternal and infinite universe
0:44:32 > 0:44:34fit the new observations.
0:44:34 > 0:44:39The scientific community was still pretty evenly split.
0:44:40 > 0:44:44Conclusive proof of the Big Bang theory would eventually emerge
0:44:44 > 0:44:46some 15 years later.
0:44:46 > 0:44:48It would be revealed quite unexpectedly
0:44:48 > 0:44:52by two young radio engineers.
0:44:54 > 0:44:58In 1964, Arno Penzias and Robert Wilson -
0:44:58 > 0:45:00that's Penzias on the right there -
0:45:00 > 0:45:04discovered something so momentous, it won them the Nobel Prize.
0:45:09 > 0:45:14This telescope is dedicated to study their accidental discovery.
0:45:15 > 0:45:20In 1964, Penzias and Wilson were working at the Bell Laboratories
0:45:20 > 0:45:23in the US where they were given this, a bizarre
0:45:23 > 0:45:26and obsolete piece of kit to play with.
0:45:26 > 0:45:29It looks, for all the world, like an enormous ear trumpet.
0:45:29 > 0:45:33But when they turned their telescope on,
0:45:33 > 0:45:38they found that the sky was saturated with microwave radiation.
0:45:40 > 0:45:43All warm bodies emit microwave radiation,
0:45:43 > 0:45:47whether it's from the atmosphere or from the instrument itself.
0:45:47 > 0:45:52And today's mobile communications flood the sky with it.
0:45:52 > 0:45:57FAINT STATIC
0:45:57 > 0:46:00So, before they could do any useful measurements,
0:46:00 > 0:46:03they had to calibrate their Horn Antenna to see
0:46:03 > 0:46:06if they could reduce this "noise."
0:46:06 > 0:46:09FAINT STATIC
0:46:09 > 0:46:11Even after accounting for the atmosphere
0:46:11 > 0:46:13and their instrumentation -
0:46:13 > 0:46:16of course, there were no mobile phones to worry about back then -
0:46:16 > 0:46:18they were still left with this persistent
0:46:18 > 0:46:20and deeply irritating background noise.
0:46:20 > 0:46:23It was registered on their instruments as a radiation
0:46:23 > 0:46:27with a constant temperature of three degrees above absolute zero,
0:46:27 > 0:46:30a microwave hiss that they couldn't get rid of
0:46:30 > 0:46:32no matter what they tried.
0:46:34 > 0:46:39FAINT STATIC
0:46:39 > 0:46:42Even more annoying for them was the fact that it seemed to be
0:46:42 > 0:46:46everywhere they pointed their celestial ear trumpet.
0:46:48 > 0:46:52They were about to give up when Penzias attended a meeting
0:46:52 > 0:46:56where he casually mentioned this irritant to a colleague.
0:46:56 > 0:46:58A few weeks later, the same colleague phoned him up and said
0:46:58 > 0:47:01he knew of some researchers in Princeton
0:47:01 > 0:47:04who are looking for just such a signal.
0:47:06 > 0:47:10Unwittingly, Penzias and Wilson had stumbled upon
0:47:10 > 0:47:13that predicted radiation - Alpher's burst of light
0:47:13 > 0:47:15from the early evolution of the universe.
0:47:15 > 0:47:20Here, at last, was proof of the Big Bang theory.
0:47:31 > 0:47:35It's quite remarkable to think that this microwave radiation
0:47:35 > 0:47:37has travelled across the furthest reaches of space,
0:47:37 > 0:47:40from 13.8 billion years ago
0:47:40 > 0:47:44when that first light from the Big Bang was released.
0:47:44 > 0:47:46As Penzias himself said, when you go outside,
0:47:46 > 0:47:51you're getting a tiny bit of warmth from the Big Bang on your scalp.
0:47:51 > 0:47:54And, yes, I probably feel it a bit more than most.
0:47:58 > 0:48:02Almost 40 years after Lemaitre first postulated it,
0:48:02 > 0:48:07the idea of the Big Bang had finally entered the scientific mainstream.
0:48:10 > 0:48:14But the discovery of this cosmic microwave background radiation,
0:48:14 > 0:48:19the CMB, and the proof of the Big Bang theory itself,
0:48:19 > 0:48:21isn't the end of our story.
0:48:28 > 0:48:32We've probed back to the first few minutes after the Big Bang.
0:48:37 > 0:48:40And beyond this lies a new frontier of knowledge.
0:49:01 > 0:49:04There are still very big questions to resolve about the beginning
0:49:04 > 0:49:06of the universe, questions like,
0:49:06 > 0:49:09"Where did all the matter itself come from?"
0:49:09 > 0:49:12And "How do you get something from nothing?"
0:49:12 > 0:49:15The answers to these questions lie further back,
0:49:15 > 0:49:18hidden behind the curtain of the CMB.
0:49:18 > 0:49:21Their secrets lie in the primordial universe,
0:49:21 > 0:49:25within the very first second of its existence.
0:49:31 > 0:49:35This is where the edge of our understanding now lies,
0:49:35 > 0:49:39and this is where scientists are focusing their efforts...
0:49:39 > 0:49:42not by looking into the skies,
0:49:42 > 0:49:45but here on the border of Switzerland and France.
0:49:48 > 0:49:50More specifically, at CERN,
0:49:50 > 0:49:53with the largest particle accelerator in the world,
0:49:53 > 0:49:57the Large Hadron Collider, or LHC.
0:50:00 > 0:50:03Now, you might be wondering what a particle accelerator has to do with
0:50:03 > 0:50:06the early universe, because the connection between the two
0:50:06 > 0:50:08is far from obvious.
0:50:08 > 0:50:11The thing to remember is that, when the universe was very young,
0:50:11 > 0:50:13it was much smaller and so all the matter -
0:50:13 > 0:50:16everything that makes up the stars, the galaxies, black holes -
0:50:16 > 0:50:21all had to be confined into a much smaller space.
0:50:21 > 0:50:24At that stage, the universe was phenomenally hot and,
0:50:24 > 0:50:28more significantly, its energy density was very high.
0:50:31 > 0:50:36It was then that the first matter sprang into existence.
0:50:36 > 0:50:40The LHC can't yet replicate that process...
0:50:42 > 0:50:45..but it can allow us to study the properties
0:50:45 > 0:50:48of these fundamental particles.
0:50:48 > 0:50:52Once a year, the LHC stops its normal business of colliding
0:50:52 > 0:50:56beams of protons, and instead uses much more massive particles
0:50:56 > 0:51:00to create collisions with energies more than 80 times greater
0:51:00 > 0:51:03than that produced from two protons.
0:51:03 > 0:51:07They do this by accelerating atoms of lead,
0:51:07 > 0:51:09stripped of all their electrons,
0:51:09 > 0:51:11up to speeds close to that of light,
0:51:11 > 0:51:14and smashing them together.
0:51:14 > 0:51:17And that lets us see something pretty special.
0:51:22 > 0:51:26The collisions are so intense that, for a moment,
0:51:26 > 0:51:29we create something unique -
0:51:29 > 0:51:34a world not of atoms or even neutrons and protons -
0:51:34 > 0:51:39but of quarks and gluons and leptons - exotically named particles
0:51:39 > 0:51:43that came together to form atoms in the first millionth of a second
0:51:43 > 0:51:49after the Big Bang, and have been locked away ever since.
0:51:49 > 0:51:54Down there, underneath that lead shielding, we're recreating a stage
0:51:54 > 0:51:58in the universe's evolution called the quark-gluon plasma.
0:51:58 > 0:52:02Now, this is the moment immediately before the quarks become trapped
0:52:02 > 0:52:06by the gluons to create protons and neutrons,
0:52:06 > 0:52:09which themselves go on to form the nuclei of atoms.
0:52:09 > 0:52:12The phrase we use - grandly -
0:52:12 > 0:52:15is the confinement of the quarks.
0:52:23 > 0:52:25To develop the necessary energy,
0:52:25 > 0:52:30the lead nuclei are passed through a chain of smaller accelerators,
0:52:30 > 0:52:33gradually ramping up the energy until they're finally
0:52:33 > 0:52:38fed into the largest accelerator on Earth, the LHC.
0:52:38 > 0:52:42Now, the maximum energy a beam can achieve is directly related
0:52:42 > 0:52:44to the size of the accelerator,
0:52:44 > 0:52:48and the LHC has a circumference of 27km.
0:52:48 > 0:52:51That means the beams here can achieve an energy
0:52:51 > 0:52:55of 1,000 tera-electronvolts.
0:52:55 > 0:52:58Now, actually, that's less than you might imagine, because
0:52:58 > 0:53:03it's equivalent to the energy that a housefly hits a window pane.
0:53:03 > 0:53:05But the critical difference here
0:53:05 > 0:53:07is that the energy is concentrated,
0:53:07 > 0:53:10it's the energy density that's important.
0:53:10 > 0:53:14The LHC can squeeze all that energy down to a space that's less than
0:53:14 > 0:53:18a trillionth of the size of a single atom.
0:53:19 > 0:53:24This is something that can happen nowhere else in the known universe.
0:53:33 > 0:53:37The two beams of lead nuclei are travelling around the ring
0:53:37 > 0:53:38in opposite directions.
0:53:38 > 0:53:42They're meeting deep underneath this control room at the detector.
0:53:42 > 0:53:46We can see live feed pictures of the detector up on that screen.
0:53:46 > 0:53:47Now, underneath us,
0:53:47 > 0:53:53they're travelling at a speed of 99.9998% the speed of light.
0:53:53 > 0:53:57That means they're covering the full 27km circumference of the ring
0:53:57 > 0:54:01more than 11,000 times per second.
0:54:01 > 0:54:03When the beams reach maximum energy -
0:54:03 > 0:54:06and we can see up there, it says "iron physics stable beams" -
0:54:06 > 0:54:08that means they can be crossed.
0:54:08 > 0:54:10Just like in Ghostbusters.
0:54:10 > 0:54:14At that point, a tiny fraction of the lead nuclei will collide
0:54:14 > 0:54:18and create a super-hot, super-dense fireball
0:54:18 > 0:54:23with a temperature 400,000 times hotter than the centre of the sun,
0:54:23 > 0:54:26and a density that would be equivalent to squeezing
0:54:26 > 0:54:30the whole of Mont Blanc down to the size of a grape.
0:54:42 > 0:54:46That looks like a fantastic image there.
0:54:46 > 0:54:49- Can you tell me what we're seeing? - It's amazing, actually, isn't it?
0:54:49 > 0:54:54It's literally tens of thousands of particles and antimatter particles
0:54:54 > 0:54:57- flying out - this kind of aftermath of this explosion.- Right.
0:54:57 > 0:55:00So the coloured particle trails here
0:55:00 > 0:55:03AREN'T the quarks and gluons themselves,
0:55:03 > 0:55:08but evidence of the quark-gluon plasma created by the collision.
0:55:08 > 0:55:11We have to infer its properties from looking at the debris
0:55:11 > 0:55:15that flies out. It's a bit like working out how an aircraft works
0:55:15 > 0:55:19by looking at the debris of a plane crash. That's what we see.
0:55:19 > 0:55:22What I find amazing is, what we're doing here is trying to recreate
0:55:22 > 0:55:27that moment in the early universe where the quarks and gluons
0:55:27 > 0:55:30were all free to float around, cos the energy was so high,
0:55:30 > 0:55:33and then it cooled and they stacked together. You're doing the opposite.
0:55:33 > 0:55:36We're starting with normal matter, smashing it together,
0:55:36 > 0:55:41and going back to that unconfined state, that plasma.
0:55:41 > 0:55:43Yeah. I like to think about it as a time machine.
0:55:43 > 0:55:45We're actually winding back the clock.
0:55:45 > 0:55:49And this is the only way that we can study the properties of free quarks,
0:55:49 > 0:55:53because these quarks have been imprisoned inside particles
0:55:53 > 0:55:56like protons and neutrons for 13.8 billion years.
0:55:56 > 0:56:00That's pretty incredible, isn't it? Finally, after 13.8 billion years,
0:56:00 > 0:56:01you can set these quarks free -
0:56:01 > 0:56:04- even if it's for a fraction of a second.- Yes.
0:56:06 > 0:56:11While we don't yet know how matter sprang into existence,
0:56:11 > 0:56:13studying these collisions allows us
0:56:13 > 0:56:17to make the first tentative steps towards that discovery.
0:56:19 > 0:56:22What we've just witnessed is the earliest stages of the universe
0:56:22 > 0:56:26that anyone - anywhere - has been able to observe.
0:56:26 > 0:56:30It's the closet we've got to the moment of the Big Bang.
0:56:30 > 0:56:33And, let's face it, it's not bad.
0:56:33 > 0:56:36One millionth of a second after the Big Bang itself.
0:56:40 > 0:56:42Even going this far back in time
0:56:42 > 0:56:45still leaves physics with unanswered questions.
0:56:50 > 0:56:54Beyond this is where some of the deeper mysteries of the universe
0:56:54 > 0:56:59are hiding. How the fundamental forces that bind matter together -
0:56:59 > 0:57:02gravity, electromagnetism and the nuclear forces -
0:57:02 > 0:57:04are connected to each other.
0:57:04 > 0:57:07How the particles that make up matter itself
0:57:07 > 0:57:10condensed out of a fog of energy.
0:57:10 > 0:57:13How mass is generated from the force that binds protons
0:57:13 > 0:57:15and neutrons together.
0:57:15 > 0:57:20And how the universe itself underwent a super-fast expansion
0:57:20 > 0:57:26in one billion-billion- billion-billionth of a second
0:57:26 > 0:57:28to create the structure of the cosmos.
0:57:30 > 0:57:34At the moment, we have no way of observing any of these phenomena.
0:57:36 > 0:57:40This is the realm of abstract theory and speculation.
0:57:44 > 0:57:48If we're ever going to replicate this early stage of the universe's
0:57:48 > 0:57:52evolution, we're going to need to create considerably higher energies.
0:57:52 > 0:57:56Frankly, we're going to need to build a bigger collider.
0:57:56 > 0:57:59And that's a problem. And it's not just one of expense,
0:57:59 > 0:58:03although it would be phenomenally expensive.
0:58:03 > 0:58:07No, it's more one of finding the room to build it.
0:58:09 > 0:58:12Remember when I said the energy's related to the circumference
0:58:12 > 0:58:16of the accelerator? Well, the LHC, down below me,
0:58:16 > 0:58:19has a circumference of 27km.
0:58:19 > 0:58:22It runs beneath the Jura Mountains
0:58:22 > 0:58:26and straddles both France and Switzerland.
0:58:26 > 0:58:31In order to look back and observe the universe at this earliest stage,
0:58:31 > 0:58:34well, we'd need to build an accelerator
0:58:34 > 0:58:38with a circumference larger than the orbit of Pluto.
0:58:42 > 0:58:45Revealing the origin of the universe begs another,
0:58:45 > 0:58:48even more profound question -
0:58:48 > 0:58:50how will it end?
0:58:50 > 0:58:54Next time, I discover whether the universe will end with a bang
0:58:54 > 0:58:56or a whimper.
0:58:56 > 0:59:00Want to discover more about the beginnings of the universe?
0:59:00 > 0:59:05Go to the address below and follow the links to the Open University.