The Beginning The Beginning and End of the Universe


The Beginning

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It is a good rule of thumb that, in science,

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the simplest questions are often the hardest to answer.

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Questions like, how did the universe begin?

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In fact, until relatively recently, science simply didn't have the tools

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to begin to answer questions about the origins of the universe.

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But in the last 100 years, a series of breakthroughs have been

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made by men and women who, through observation, determination

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and even sheer good luck, were able to solve this epic cosmic mystery.

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This was real astronomical gold.

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I am going to recreate their most famous discoveries

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and perform their greatest experiments...

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30,000 km/s.

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..that take us from the very biggest objects in the universe

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to the infinitesimally small,

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until I reach the limits of our knowledge by travelling

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back in time to recreate the beginning of the universe.

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The moment one millionth of a second after the universe

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sprang into existence.

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This is a time before matter itself has formed in any way

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that we would recognise it.

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It is as close as we can hope to get to creation,

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to the beginning of time,

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the beginning of the universe itself.

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It is a remarkable fact that science took hundreds of years to come up

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with a theory to explain the origins of the universe.

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All the more surprising, given what a simple

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and fundamental question it is.

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There is something quintessentially human about asking the question,

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where does all of this come from?

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Perhaps because it is a deeper, more fundamental version of

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where I come from?

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Yet, for most of human history, the answers to such an apparently

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simple question could only be attempted by religion.

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It wasn't until the middle of the 20th century that science

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built a coherent and persuasive creation story of its own.

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It was a story based on theory, predictions and observation,

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a story that could finally explain what had happened at the very

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beginning of time, the beginning of the universe itself.

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A little over 100 years ago, if scientists considered the life of

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the universe at all, they considered it eternal, infinite and stable.

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No beginning and no end.

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So even framing the question about the origins of the universe

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was impossible.

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But at the beginning of the 20th century, that began to change.

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New discoveries shook the old certainties

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and paved the way for questions about where the universe came from.

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One observation transformed our idea about

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the true scale of the universe.

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It began with a mystery in the sky.

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By the early part of the 20th century, it was well known

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that our solar system way within a galaxy, the Milky Way.

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Every single star we can see in the sky with the naked eye

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is within our own galaxy and, until the 1920s, all these stars,

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this single galaxy, was the full extent of the entire universe.

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Beyond it was just an empty void.

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But there were some enigmatic objects up there as well,

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just discernible to the naked eye that looked different.

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And one of the most notable is Andromeda.

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You can find Andromeda if you know where to look.

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So, if you start from Cassiopeia, those five stars

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shaped like a sideways letter M, if you move across from the point,

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from the points of the M, slightly up is where you should find it.

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Now, I'm going to use my binoculars to help me in the first instance.

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And if I zoom across...

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Yeah, there it is.

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You can tell it's not a star. I mean, it's basically

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a very faint smudge stuck between those two stars.

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That is it straight up there -

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that is M31, the great Andromeda nebula.

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Now, they were called nebulae, because they had this smudgy,

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sort of wispy, cloudy nature.

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In fact, the word nebula derives from the Latin for cloud.

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These indistinct objects were found scattered throughout the night sky.

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Telescopes revealed many of these nebulae were far more complex

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than simple clouds of interstellar gas.

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They appeared to be vast collections of stars

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and that raised two intriguing possibilities.

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Were these stellar nurseries places where stars were born,

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and therefore residing within our own galaxy, or,

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much more profoundly, were these beautiful, enigmatic objects

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galaxies in their own right sitting way outside the Milky Way?

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The implications of that second possibility were enormous.

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If true, it would instantly

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and utterly transform our idea about the size of the universe.

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Here was an opportunity for an ambitious astronomer to make

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a real name for themselves.

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Perhaps someone with a really big telescope.

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Step forward this man - Edwin Hubble, a man from Missouri,

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although if you had ever met him, you'd never have guessed,

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because he developed this weird persona, a pipe smoking tea drinker

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with a very affected aristocratic English accent.

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Hubble is probably the most famous astronomer ever,

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not least because of his consummate skill at self-promotion,

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but also because of the incredible measurements he would make.

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In Hubble's day, when it came to observations

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and new discoveries, size mattered.

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Today, this is the most powerful optical telescope in the world,

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the GTC, with a primary mirror

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over 10 metres, or 400 inches, in diameter.

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Far bigger than anything Hubble had.

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In September 1923,

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Hubble was working at what was then the biggest telescope

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in the world, the 100-inch Hooker telescope

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at the Mount Wilson Observatory, perched on top of the

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High Sierra mountains overlooking Los Angeles in California.

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He was using the telescope to study one of the most prominent

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nebulae in the sky, the Andromeda nebula.

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The same nebula I looked at earlier, and it was while observing it

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that one very special star caught Hubble's attention,

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one that could reveal the true nature of Andromeda.

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And I am going to use this telescope to look for it now.

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This is the control room of the GTC and, tonight, they've pointed

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the telescope at Andromeda and they are going to take a picture of it.

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It takes about a minute for the exposure

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-to give you a clear enough image?

-That's right.

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Now, the picture is finished, so we're going to open it.

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OK, so, this is Andromeda here.

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That's Andromeda, that's right.

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And now, this is Hubble's original plate.

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Right, now, Hubble's star is down here in this corner.

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Can you find it in your image?

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Yeah, if you take the image and you compare it,

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you will see that we don't see that one.

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What we see is the edge of the galaxy,

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so we have to go a little bit further west...

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-Oh, I see, so all this is just the edge.

-That's the edge.

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-I was assuming it was the centre of the galaxy.

-No, no, no.

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It just goes to show how much more resolution your telescope can get.

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-That's right.

-OK, so, can we see that particular star?

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Yes, in order to find that particular star,

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because it is so faint,

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we have to look for references which are brighter.

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And, in this case, you will see four stars in here,

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which are these four stars.

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-And the star Hubble found will be this one here.

-That's it...

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That tiny star is the one that Hubble found.

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That's amazing.

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And are you able to get a magnitude for that star?

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Yeah, we have to do a little bit of processing on the image,

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but we are able to get it.

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OK. Hubble had found his star.

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He knew it was special,

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because he compared his plate with others taken over previous nights

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and he noticed that his star changed in brightness -

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some nights it was brighter, some nights it was dimmer.

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He realised this is a variable star, and he saw the significance of it.

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He could see that this was real astronomical gold.

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His star was a Cepheid variable.

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In the stellar bestiary,

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Cepheid variable stars hold very special place...

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..because, by studying the way their brightness changes,

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astronomers can calculate how far away they are.

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Hubble's Cepheid was the first to be discovered in a nebula,

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so he knew that, if he could measure its period,

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he would be able to work out its distance from us.

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So, Hubble set about meticulously measuring

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how his star's luminosity varied.

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It's not hard to imagine how exciting

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this must have been for Hubble.

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At his fingertips was the opportunity to resolve

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a fundamental yet simple question -

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was this nebula within the Milky Way or beyond it?

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The answer would reshape our knowledge of the universe.

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Hubble measured the luminosity, or brightness,

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of his star over many nights and plotted this curve here.

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Now, when we measured tonight, we found it had a value of 18.6

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and I know because they measured it last night to be slightly dimmer

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that it falls on this side of the curve.

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But more important is the period,

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the time in days, from peak brightness to peak brightness.

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Hubble measured this to be 31.415 days.

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This is the critical measurement.

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Armed with this and its apparent brightness,

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Hubble calculated the distance to the Andromeda nebula.

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It was immediately apparent that this star is very far away.

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But when Hubble did his calculation, he worked out that it was

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900,000 light years away,

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making this star the most remote object ever recorded.

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It could mean only one thing -

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not only is Andromeda a galaxy in its own right...

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..but it lies well beyond our own Milky Way...

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..and the myriad of other elliptical

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and spiral nebulae were also individual distant galaxies.

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It was a moment in human consciousness when the universe

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had suddenly and dramatically got considerably bigger.

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With this observation, Hubble had redrawn the observable universe.

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It might not have directly challenged

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the idea of a stable universe,

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but it shattered long-held assumptions and opened

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the possibility of other bigger secrets,

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like an origin to the universe.

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Into this profoundly-expanded cosmos strode someone who would,

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without realising it, provide the tools to unlock that secret.

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This guy.

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A story as great as one that explains

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the origins of the universe would somehow feel wrong without involving

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a scientist as great as Albert Einstein.

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And so, of course, it does,

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because it was Einstein who provided the theoretical foundations

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needed to study the universe

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and effectively invent the science of cosmology.

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100 years ago, he proposed his general theory of relativity.

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It turned physics on its head and gave us

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a completely new understanding of the world.

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He proposed that gravity was caused by the warping

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or bending of space-time by massive objects like planets and stars.

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His theories were revolutionary.

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Einstein was a maverick who ignored the conventional

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to follow his own remarkable instincts.

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One of his lecturers once told him,

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"You are a smart boy, Einstein, a very smart boy.

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"But you have one great fault -

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"you do not allow yourself to be told anything."

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Of course, it was this very quality that would allow him

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to change the world of physics and, of course, to mark him out

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as one of the greatest thinkers of the 20th century.

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And in 1917, he took his general theory of relativity

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and applied it to the entire universe.

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By following the logic of his theory,

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he arrived at something rather unsettling -

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the combined attraction of gravity from all

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the matter in the universe would pull every

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object in the cosmos together, beginning slowly

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but gradually accelerating until...

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Gravity would ultimately

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and inevitably lead to the collapse of the universe itself.

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But Einstein believed, like virtually everyone else,

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that the universe was eternal and static and certainly wasn't

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unstable or ever likely to collapse in on itself.

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But his equations appeared to show the opposite.

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In order to prevent the demise of the universe

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and keep everything in balance, he adds this in his equation -

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Lambda, or the Cosmological Constant.

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It is a sort of made-up force of anti-gravity

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that acts against normal gravity itself.

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Now, he had no evidence for this, but it helped ensure

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that his equations described a stable universe.

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Within his grasp was the secret to the origins of the universe.

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Yet Einstein simply couldn't, or wouldn't, bring himself

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to accept the implications of his own equations.

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With hindsight, it seems remarkable that Einstein did this.

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I mean, here was a man who had revolutionised science

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by rejecting conventional wisdom

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and yet, he couldn't bring himself to trust his own theory.

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He felt compelled to massage his equation

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to fit the established view.

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He even admitted that the Cosmological Constant

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was necessary only for the purposes of making a quasi-static

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distribution of matter, basically to keep things the way they were.

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Whatever his reasons, this little character, Lambda,

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would return to haunt him.

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Because, while it prevented Einstein from understanding

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the implications...

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..his ideas opened the way for someone else to propose

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a theory for the origin of the universe.

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He was a young part-time university lecturer of theoretical physics.

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His idea was so radical, it shocked the world of physics

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and split the scientific community.

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He started an argument that wouldn't be resolved for half a century.

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His name was Georges Lemaitre.

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Now, the eagle-eyed might spot the dog collar.

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In fact, he was both a physicist and an ordained priest.

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Of this apparently curious dual role,

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Lemaitre said, "There were two ways of pursuing the truth.

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"I decided to follow both."

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And, using Einstein's theory of relativity,

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he developed his own cosmological models.

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Lemaitre's model described a universe that,

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far from being static, was actually expanding,

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with galaxies hurtling away from one another.

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Furthermore, Lemaitre saw the implications of this.

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Winding back time, he deduced that there had to be a moment

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when the entire universe was squeezed into a tiny volume,

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something he dubbed the primeval atom.

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This was essentially the first description of what became known

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as the big bang theory, the moment of creation of the universe.

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These were revolutionary ideas and so he published them

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in the Annales de la Societe Scientifique de Bruxelles,

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where they were promptly ignored by the scientific community.

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So, he travelled to Brussels to try to gain support for his idea.

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The 1927 Solvay Conference, held here in Brussels, was probably

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the most famous and greatest meeting of minds ever assembled.

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But for our story,

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the most significant meeting didn't happen here.

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It wasn't planned and happened away from the conference.

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It happened here.

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In this park, the unknown Lemaitre approached the most famous,

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the most feted scientist in the world -

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Albert Einstein.

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Here, finally, was his chance to explain his idea about an expanding

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universe to the very person whose theory he had used to derive it.

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You can only imagine Lemaitre's trepidation as he approached.

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If Einstein endorsed his radical idea,

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then surely it would be accepted.

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Surely this brilliant mind, this titan of physics,

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this deeply original thinker, would see the merits of his theory.

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But after a brief discussion,

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Einstein rejected his idea out of hand.

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According to Lemaitre, he said,

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"Vos calculs sont corrects,

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"mais votre physique est abominable."

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As far as Einstein was concerned,

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his maths might have been correct, but his understanding

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of how the real world worked was, well, abominable.

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Once again, Einstein dismissed the idea of a dynamic universe.

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Lemaitre's paper should have ignited science,

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but without the backing of such a huge and influential figure as

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Einstein, his ground-breaking idea was doomed to be quietly forgotten,

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unless some observation or evidence showed up to support

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the idea of an expanding universe.

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Edwin Hubble, here, was riding high after his discovery that

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proved there were galaxies outside of our own.

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He was feted by Hollywood glitterati,

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a guest of honour at the Oscars,

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and, with access to the world's most powerful telescope,

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he was ready for his next challenge.

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He had heard of some unusual observations that many galaxies

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appeared to be moving away from us.

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No-one could understand why this might be.

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So, in 1928, the world's most famous astronomer

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turned his attention to this new cosmic mystery and began to measure

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the speed that these galaxies were moving relative to Earth.

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To measure the velocity that a galaxy was receding from us,

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Hubble use something called redshift.

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Now, it's not a perfect analogy, but the effect is similar to one

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most of us are familiar with in sound -

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the pitch of a car engine as it approaches us is higher,

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because the sound waves are compressed,

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but the pitch drops lower as the car recedes,

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because the sound waves are stretched.

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The effect is similar with light waves.

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As the source of light moves towards us, the observed wavelength

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is squashed towards the violet or blue end of the spectrum.

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But if the source is moving away from us,

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the wavelength is stretched towards the red end of the spectrum,

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or redshifted, in the parlance of astronomers.

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And the greater the velocity the object is receding,

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the greater the redshift.

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With his assistant, Milton Humason, Hubble spent the next year

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carefully measuring the redshift of galaxies.

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And I have got the chance to do the same thing right now

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using this telescope.

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OK, Massimo, have you found a galaxy for me?

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Yes, I found this galaxy.

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So, how far away is this?

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It is approximately 430 megaparsec far.

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So, if you convert that to light years... 430 x 3.26...

0:24:080:24:12

So it's about 1.5 billion light years away.

0:24:120:24:17

-Yeah, yeah.

-OK.

0:24:170:24:19

Hubble needed to measure the average light coming from the galaxy

0:24:210:24:25

in order to get a spectrum, so that he could calculate the redshift.

0:24:250:24:29

Now, Humason did this by exposing a photographic plate

0:24:290:24:33

and it took him a whole week to collect enough light

0:24:330:24:36

to get the spectrum.

0:24:360:24:38

But here at the TNG, the Galileo Telescope, they use instead

0:24:380:24:42

a very sensitive chip that can do this much more quickly.

0:24:420:24:45

How long does it take for you to get a spectrum?

0:24:450:24:49

Approximately 10, 15 minutes.

0:24:490:24:52

So, 10 or 15 minutes' exposure compared with a week

0:24:520:24:55

back in Hubble's time -

0:24:550:24:57

far more powerful than anything they had back then.

0:24:570:25:00

-It's done.

-The spectrum is quite good.

0:25:020:25:05

Ah.

0:25:050:25:07

OK, so this is the raw spectrum that has been taken.

0:25:070:25:10

Is there a particular emission line here that you will

0:25:100:25:13

-use as your reference to measure the redshift?

-Yeah.

0:25:130:25:16

Here, for example, you have an emission line,

0:25:160:25:20

but to obtain real spectra,

0:25:200:25:24

you have to clean it to obtain the final one.

0:25:240:25:29

-Ah, this is the cleaned-up version of that.

-Yes, of that.

0:25:290:25:33

-So this is the actual emission lines from the galaxy...

-Yes.

0:25:330:25:38

And this one below, I guess, is the reference?

0:25:380:25:41

The reference, correct,

0:25:410:25:43

of a galaxy with redshift zero.

0:25:430:25:46

-OK, so one that isn't moving away relative to us.

-Yes.

0:25:460:25:50

And so it is very clear here, if you compare the top one with this one,

0:25:500:25:54

every emission peak is shifted.

0:25:540:25:57

It's shifted in the red.

0:25:570:25:59

The reference line for the sample is H-Alpha,

0:25:590:26:03

and, from these, you can compute the redshift of this galaxy.

0:26:030:26:07

And can you work out from that how fast

0:26:070:26:10

the galaxy is moving away from us?

0:26:100:26:12

In principle, you can obtain this.

0:26:120:26:14

OK, so what is the formula?

0:26:140:26:16

The formula is the difference between the reference wavelength

0:26:160:26:20

and the observed wavelength,

0:26:200:26:22

divided by the reference wavelength and multiplied by C.

0:26:220:26:27

This is the Doppler effect.

0:26:270:26:28

-Let's see if we can do that roughly.

-Yes.

0:26:280:26:30

OK, so this is about...

0:26:300:26:32

7,200, approximate.

0:26:320:26:37

OK.

0:26:370:26:38

Minus 6,563.

0:26:380:26:42

-..63.

-OK.

-Over...

0:26:420:26:44

6,563.

0:26:440:26:46

-And that is the fraction of the speed of light?

-Yes.

0:26:460:26:49

OK, so, I might as well do this.

0:26:490:26:51

I should do it with my calculator, but...

0:26:510:26:54

So...

0:26:540:26:56

OK. So then that we divide by 6,563.

0:27:020:27:06

OK, so it is roughly 0.1 the speed of light.

0:27:060:27:09

So it is about 30,000 km/s, yes?

0:27:110:27:16

-Correct.

-Thank you.

0:27:160:27:17

OK.

0:27:190:27:20

I'm actually quite pleased at my maths here,

0:27:200:27:22

because I was under pressure.

0:27:220:27:24

So, this galaxy is 1.5 billion light years away from the Milky Way

0:27:240:27:30

and, from the redshift,

0:27:300:27:32

we have worked out it is moving away from us

0:27:320:27:35

at 1/10 the speed of light.

0:27:350:27:37

That means it is moving away from us at three...

0:27:370:27:40

At, sorry, 30,000 km/s.

0:27:400:27:44

Boom.

0:27:450:27:47

Science.

0:27:470:27:48

Once he had calculated the speed of the galaxy,

0:27:530:27:56

Hubble then measured how far away it was.

0:27:560:27:58

Once Hubble had both his measurements,

0:28:040:28:07

he could start putting them on a graph of velocity against distance.

0:28:070:28:12

Now, he made 46 different measurements

0:28:120:28:14

and, when he put them on the graph, he noticed a pattern emerging.

0:28:140:28:18

He could draw a line through all these points -

0:28:180:28:21

each one of them is an individual galaxy.

0:28:210:28:23

He noticed a connection between the velocity

0:28:230:28:26

and the distance of a galaxy.

0:28:260:28:28

In fact, the further away it was,

0:28:280:28:31

the faster it was moving away from us.

0:28:310:28:33

In a stable universe, the speeds of galaxies should appear random.

0:28:360:28:40

You wouldn't expect a clear relationship

0:28:420:28:44

between the distance of a galaxy and its velocity.

0:28:440:28:47

Hubble's graph showed that the universe was expanding,

0:28:490:28:53

which has profound implications for the idea

0:28:530:28:56

of a beginning to the universe.

0:28:560:28:58

What this means is that it is not just that the galaxies

0:29:010:29:04

are all speeding away from us and from each other

0:29:040:29:07

but that, if you could wind the clock back,

0:29:070:29:09

there would have been a time when they were all squeezed together

0:29:090:29:12

in the same place.

0:29:120:29:14

Here, finally, was the first observation,

0:29:230:29:25

the first piece of evidence that Lemaitre's idea of a moment

0:29:250:29:29

of creation, of a universe evolving from a Big Bang,

0:29:290:29:33

might be correct.

0:29:330:29:35

Thanks to Hubble's work, Georges Lemaitre,

0:29:510:29:54

the unknown Belgian cleric,

0:29:540:29:56

the theoretician without proper international credentials,

0:29:560:30:00

the man whose physics Einstein called abominable,

0:30:000:30:03

was belatedly rightly recognised for his bold theory.

0:30:030:30:07

Most significantly,

0:30:100:30:12

the biggest name in physics came around to this revolutionary idea.

0:30:120:30:16

In 1931, on a visit to Hubble's observatory,

0:30:190:30:22

Einstein publicly endorsed the Big Bang expanding universe model.

0:30:220:30:28

"The redshifts of distant nebulae

0:30:280:30:30

"has smashed my old construction like a hammer blow," he said.

0:30:300:30:34

Einstein dropped the cosmological constant. He even wrote to Lemaitre,

0:30:340:30:39

"Ever since I introduced the term, I have had a bad conscience.

0:30:390:30:43

"I am unable to believe that such an ugly thing

0:30:430:30:46

"should be realised in nature."

0:30:460:30:49

It must have been quite an absolution for Lemaitre.

0:30:490:30:52

Having been practically cast out into the scientific wilderness,

0:30:520:30:56

he was now firmly at the centre of a cosmological revolution.

0:30:560:31:00

The idea of the Big Bang was finally gaining traction.

0:31:080:31:12

But, despite Einstein's seal of approval,

0:31:140:31:17

and the observations of Hubble,

0:31:170:31:20

the argument was far from over.

0:31:200:31:22

There were still significant objections

0:31:310:31:33

if the idea of a Big Bang was to be widely accepted.

0:31:330:31:36

A scientific theory of creation isn't just about explaining

0:31:360:31:40

the expansion of the universe -

0:31:400:31:42

there were more profound issues to resolve.

0:31:420:31:45

The problem was, the Big Bang raised as many questions as it answered.

0:31:470:31:53

Like, if the universe had erupted from a single point,

0:31:530:31:56

where did all the matter come from?

0:31:560:31:59

To go further, the Big Bang theory needed to explain

0:32:040:32:07

how matter itself had been formed.

0:32:070:32:10

Well, before that could be answered, we need to know

0:32:130:32:16

what the universe is actually made of - the elemental building blocks.

0:32:160:32:19

And working that out took an incredible bit of insight

0:32:190:32:23

by a remarkable woman - Cecilia Payne.

0:32:230:32:26

She studied at Cambridge University, but wasn't awarded a degree,

0:32:260:32:30

because, well, she was a woman.

0:32:300:32:32

So, to continue to her studies,

0:32:320:32:34

she needed to go somewhere more enlightened.

0:32:340:32:36

She left England for America

0:32:360:32:38

and it was there that she revealed the composition of the universe.

0:32:380:32:43

If you were to ask someone what the most common elements were,

0:32:550:32:58

an atmospheric scientist might say nitrogen.

0:32:580:33:01

After all, it makes up more than three quarters of the atmosphere.

0:33:010:33:04

A geologist might say silicon or iron or oxygen...

0:33:040:33:10

which all seems very quaint and Earth-centric

0:33:100:33:13

and really rather parochial.

0:33:130:33:16

So, astronomers thought it better to look at the sun.

0:33:270:33:31

Which makes sense, given that most of what we see

0:33:350:33:38

when we look out into the cosmos is stars.

0:33:380:33:41

The first attempts to analyse the composition of the sun

0:33:460:33:48

were done with a set-up rather like this.

0:33:480:33:51

Well, not exactly like this -

0:33:510:33:53

this is a cutting-edge 21st-century solar telescope.

0:33:530:33:56

But the basic idea was exactly the same.

0:33:560:33:59

The basic idea's very simple.

0:34:080:34:10

The sun's light is reflected off this mirror here,

0:34:100:34:13

up into a second mirror...

0:34:130:34:17

where it bounces off, down through the top of the tower,

0:34:170:34:20

all the way to the bottom, ten storeys down,

0:34:200:34:23

where it's focused and split into a spectrum and analysed.

0:34:230:34:27

This is the control room of the solar telescope.

0:34:450:34:48

The base of the telescope is over there.

0:34:480:34:51

And here, I've got a live feed image of the sun.

0:34:510:34:54

And what I've got up here is a zoomed-in section

0:34:540:34:58

of the spectrum of the light coming from the sun.

0:34:580:35:00

Now, it's in black and white,

0:35:000:35:02

but it actually corresponds to the green part of the spectrum.

0:35:020:35:06

These two thick dark lines correspond to the element iron.

0:35:060:35:10

They tell us there's iron in the sun.

0:35:100:35:13

Now, here I have the spectrum in much more detail,

0:35:130:35:16

and these two lines correspond to these two dips

0:35:160:35:19

in the absorption spectrum

0:35:190:35:21

at very specific wavelengths. This is iron.

0:35:210:35:25

If I look at different parts of the spectrum, I can see other elements.

0:35:250:35:29

This big dip here is hydrogen. These two dips represent oxygen.

0:35:290:35:34

And this dip corresponds to the element magnesium.

0:35:340:35:38

All these dips and lines in the spectrum

0:35:390:35:42

indicate the presence of these elements in the sun's atmosphere.

0:35:420:35:47

Effectively, a fingerprint of the sun's composition.

0:35:470:35:51

To a geologist, these elements are all very familiar.

0:35:530:35:57

It appears, at first glance, that the sun is made of the same stuff

0:35:570:36:00

as the Earth, that the sun is simply a very hot rock.

0:36:000:36:05

And that would have been that

0:36:140:36:16

were it not for the insight of Cecilia Payne.

0:36:160:36:20

She realised that the spectrographs were being affected by processes

0:36:230:36:27

in the sun's atmosphere.

0:36:270:36:28

These would distort the apparent abundance of the elements

0:36:320:36:36

that make up the sun.

0:36:360:36:37

So, she recalculated the relative abundances of the elements

0:36:400:36:43

and discovered that the sun was composed almost entirely

0:36:430:36:47

of just two elements -

0:36:470:36:49

hydrogen and helium.

0:36:490:36:52

All the other elements - carbon, oxygen, sodium, iron -

0:36:520:36:55

that made the sun seem so Earth-like

0:36:550:36:58

amounted to just a tiny fraction of its composition.

0:36:580:37:02

When she first presented this result,

0:37:020:37:04

it was considered impossible.

0:37:040:37:06

In fact, when she wrote up her work,

0:37:060:37:08

she was persuaded to add the comment that these calculated abundances

0:37:080:37:12

of hydrogen and helium were almost certainly not true.

0:37:120:37:17

The idea was only accepted some four years later,

0:37:180:37:22

when the director of a prestigious observatory

0:37:220:37:25

arrived at exactly the same conclusion by different means.

0:37:250:37:31

Ironically, this director was the very same man

0:37:310:37:33

who'd initially dismissed Payne's work as clearly impossible.

0:37:330:37:38

Payne's revelation about the ratio of hydrogen and helium was found

0:37:410:37:46

to be remarkably consistent for almost every star in the galaxy.

0:37:460:37:51

That led to a big conclusion.

0:37:510:37:54

The universe is dominated by just two elements, the simplest

0:37:540:37:57

and lightest elements - hydrogen and helium.

0:37:570:38:01

Together, they make up more than 98% of all the matter in the universe.

0:38:010:38:06

All the other elements that are so important to us -

0:38:060:38:08

like carbon, oxygen, iron - amount to less than 2%.

0:38:080:38:13

So now the challenge for supporters of the Big Bang theory

0:38:160:38:20

was very clear and simple -

0:38:200:38:22

could the Big Bang theory explain the creation

0:38:220:38:26

AND the observed ratios of hydrogen and helium found in the stars?

0:38:260:38:31

But to answer that would require a fundamental shift of emphasis.

0:38:400:38:45

Rather than consider the almost infinite vastness of the universe,

0:38:480:38:53

it was necessary to consider

0:38:530:38:55

the infinitesimally small world of the atom.

0:38:550:38:58

And that required, not an astronomer,

0:38:580:39:01

but an entirely different kind of physicist.

0:39:010:39:04

George Gamow was a Russian nuclear physicist

0:39:040:39:07

and an enthusiastic advocate of the Big Bang idea.

0:39:070:39:12

He turned his attention to the earliest moments of the universe.

0:39:120:39:16

Here, he felt,

0:39:220:39:24

was where the answer to the composition of the universe lay.

0:39:240:39:27

This was when he believed hydrogen and helium were first forged,

0:39:270:39:32

and he proposed it would have happened very soon

0:39:320:39:35

after the birth of the universe.

0:39:350:39:38

He set about building a mathematical model

0:39:380:39:41

of the earliest stages of the universe.

0:39:410:39:45

He was thinking about the universe in terms of seconds and minutes,

0:39:450:39:48

rather than billions of years.

0:39:480:39:51

And he recruited a young protege,

0:39:510:39:54

this chap, Ralph Alpher, to help him.

0:39:540:39:57

After years of hard work, some of which, according to Alpher,

0:39:570:40:00

were aided by hard drinking in a bar,

0:40:000:40:03

they presented their idea.

0:40:030:40:05

By rewinding the universe, it was clear to them that there

0:40:060:40:09

would have been a time when the early universe was incredibly dense

0:40:090:40:13

and phenomenally hot.

0:40:130:40:16

At this stage, which they calculated to be just three minutes

0:40:160:40:19

after the Big Bang, the universe would have been so hot

0:40:190:40:22

that atoms themselves couldn't exist,

0:40:220:40:24

only their constituent parts,

0:40:240:40:26

a kind of superheated primordial soup

0:40:260:40:30

of protons, neutrons and electrons.

0:40:300:40:33

They even gave this soup a name - ylem,

0:40:330:40:35

from an old English word for matter.

0:40:350:40:38

Then came the crucial moment...

0:40:400:40:45

a time when conditions were right for the nuclei

0:40:450:40:48

of the first elements to be forged.

0:40:480:40:50

In a short period of time,

0:40:500:40:52

which they estimated to be less than 15 minutes,

0:40:520:40:55

hydrogen nuclei proton were coming together to form helium,

0:40:550:41:00

in the process of nuclear fusion.

0:41:000:41:02

Moreover, the ratios of hydrogen and helium predicted by their model

0:41:050:41:09

matched that measured in the stars.

0:41:090:41:13

They announced their results in a paper published in 1948.

0:41:160:41:20

However, Gamow added another author to the paper -

0:41:220:41:24

the famous nuclear physicist, Hans Bethe,

0:41:240:41:26

who had nothing to do with the work.

0:41:260:41:28

Gamow added his name for a laugh.

0:41:280:41:30

He thought it made a good science pun,

0:41:300:41:32

because the authors of the paper now read, "Alpher, Bethe and Gamow."

0:41:320:41:38

The young Alpher, however, was less amused to be sharing the credit

0:41:380:41:41

with someone who'd done no work.

0:41:410:41:44

By way of reconciliation, the story goes,

0:41:440:41:47

Gamow produced a bottle of Cointreau for Alpher

0:41:470:41:50

but with the label changed to read, "Ylem."

0:41:500:41:53

The ability to make calculations that explained the origins of matter

0:41:560:42:01

in the first few minutes after a Big Bang was remarkable in itself.

0:42:010:42:06

But there was a very significant prediction

0:42:060:42:09

that emerged from their work.

0:42:090:42:11

A prediction that had the potential to deliver the proof

0:42:110:42:15

that the universe had begun with a Big Bang.

0:42:150:42:19

Alpher continued to study the early evolving universe,

0:42:190:42:22

focusing on what happened next.

0:42:220:42:25

He pictured the universe at this stage as a seething fog

0:42:250:42:28

of free electrons and atomic nuclei.

0:42:280:42:31

Then it dropped to a critical temperature,

0:42:310:42:34

a temperature cool enough for electrons to latch on

0:42:340:42:37

to the nuclei of hydrogen and helium.

0:42:370:42:41

At this precise point,

0:42:410:42:43

light was released to travel freely throughout the universe.

0:42:430:42:47

The first light of creation.

0:42:470:42:49

This might have remained nothing more than an academic curiosity

0:42:570:43:00

had it not been for Alpher's insight.

0:43:000:43:02

You see, he realised that this light from the beginning

0:43:020:43:05

of the universe should still be reaching us now,

0:43:050:43:08

after billions of years.

0:43:080:43:09

Very weak, very faint, but observable in all directions.

0:43:090:43:13

He calculated that the expansion of the universe should be stretching

0:43:130:43:17

the wavelength of this light beyond the range of the visible spectrum

0:43:170:43:21

and should now be arriving as microwave radiation.

0:43:210:43:25

So, find this predicted ancient microwave signature

0:43:280:43:32

and it will prove, not just the theory of the early evolution

0:43:320:43:35

of the universe, but the entire Big Bang theory itself. Simple.

0:43:350:43:40

The problem was, this was the late 1940s

0:43:410:43:44

and no-one had any way of detecting such a weak signal.

0:43:440:43:48

The acid test was quietly forgotten.

0:43:480:43:51

Supporters of the Big Bang now had the prediction

0:43:560:43:59

and observation of an expanding universe.

0:43:590:44:03

And a theory for how elements were forged

0:44:040:44:07

in the first few minutes after the Big Bang.

0:44:070:44:10

But without the clinching evidence for this, the argument over

0:44:130:44:17

whether the Big Bang theory was correct rumbled on.

0:44:170:44:20

The opponents of the Big Bang continually tweaked and adjusted

0:44:240:44:27

their theories to make their idea of an eternal and infinite universe

0:44:270:44:32

fit the new observations.

0:44:320:44:34

The scientific community was still pretty evenly split.

0:44:340:44:39

Conclusive proof of the Big Bang theory would eventually emerge

0:44:400:44:44

some 15 years later.

0:44:440:44:46

It would be revealed quite unexpectedly

0:44:460:44:48

by two young radio engineers.

0:44:480:44:52

In 1964, Arno Penzias and Robert Wilson -

0:44:540:44:58

that's Penzias on the right there -

0:44:580:45:00

discovered something so momentous, it won them the Nobel Prize.

0:45:000:45:04

This telescope is dedicated to study their accidental discovery.

0:45:090:45:14

In 1964, Penzias and Wilson were working at the Bell Laboratories

0:45:150:45:20

in the US where they were given this, a bizarre

0:45:200:45:23

and obsolete piece of kit to play with.

0:45:230:45:26

It looks, for all the world, like an enormous ear trumpet.

0:45:260:45:29

But when they turned their telescope on,

0:45:290:45:33

they found that the sky was saturated with microwave radiation.

0:45:330:45:38

All warm bodies emit microwave radiation,

0:45:400:45:43

whether it's from the atmosphere or from the instrument itself.

0:45:430:45:47

And today's mobile communications flood the sky with it.

0:45:470:45:52

FAINT STATIC

0:45:520:45:57

So, before they could do any useful measurements,

0:45:570:46:00

they had to calibrate their Horn Antenna to see

0:46:000:46:03

if they could reduce this "noise."

0:46:030:46:06

FAINT STATIC

0:46:060:46:09

Even after accounting for the atmosphere

0:46:090:46:11

and their instrumentation -

0:46:110:46:13

of course, there were no mobile phones to worry about back then -

0:46:130:46:16

they were still left with this persistent

0:46:160:46:18

and deeply irritating background noise.

0:46:180:46:20

It was registered on their instruments as a radiation

0:46:200:46:23

with a constant temperature of three degrees above absolute zero,

0:46:230:46:27

a microwave hiss that they couldn't get rid of

0:46:270:46:30

no matter what they tried.

0:46:300:46:32

FAINT STATIC

0:46:340:46:39

Even more annoying for them was the fact that it seemed to be

0:46:390:46:42

everywhere they pointed their celestial ear trumpet.

0:46:420:46:46

They were about to give up when Penzias attended a meeting

0:46:480:46:52

where he casually mentioned this irritant to a colleague.

0:46:520:46:56

A few weeks later, the same colleague phoned him up and said

0:46:560:46:58

he knew of some researchers in Princeton

0:46:580:47:01

who are looking for just such a signal.

0:47:010:47:04

Unwittingly, Penzias and Wilson had stumbled upon

0:47:060:47:10

that predicted radiation - Alpher's burst of light

0:47:100:47:13

from the early evolution of the universe.

0:47:130:47:15

Here, at last, was proof of the Big Bang theory.

0:47:150:47:20

It's quite remarkable to think that this microwave radiation

0:47:310:47:35

has travelled across the furthest reaches of space,

0:47:350:47:37

from 13.8 billion years ago

0:47:370:47:40

when that first light from the Big Bang was released.

0:47:400:47:44

As Penzias himself said, when you go outside,

0:47:440:47:46

you're getting a tiny bit of warmth from the Big Bang on your scalp.

0:47:460:47:51

And, yes, I probably feel it a bit more than most.

0:47:510:47:54

Almost 40 years after Lemaitre first postulated it,

0:47:580:48:02

the idea of the Big Bang had finally entered the scientific mainstream.

0:48:020:48:07

But the discovery of this cosmic microwave background radiation,

0:48:100:48:14

the CMB, and the proof of the Big Bang theory itself,

0:48:140:48:19

isn't the end of our story.

0:48:190:48:21

We've probed back to the first few minutes after the Big Bang.

0:48:280:48:32

And beyond this lies a new frontier of knowledge.

0:48:370:48:40

There are still very big questions to resolve about the beginning

0:49:010:49:04

of the universe, questions like,

0:49:040:49:06

"Where did all the matter itself come from?"

0:49:060:49:09

And "How do you get something from nothing?"

0:49:090:49:12

The answers to these questions lie further back,

0:49:120:49:15

hidden behind the curtain of the CMB.

0:49:150:49:18

Their secrets lie in the primordial universe,

0:49:180:49:21

within the very first second of its existence.

0:49:210:49:25

This is where the edge of our understanding now lies,

0:49:310:49:35

and this is where scientists are focusing their efforts...

0:49:350:49:39

not by looking into the skies,

0:49:390:49:42

but here on the border of Switzerland and France.

0:49:420:49:45

More specifically, at CERN,

0:49:480:49:50

with the largest particle accelerator in the world,

0:49:500:49:53

the Large Hadron Collider, or LHC.

0:49:530:49:57

Now, you might be wondering what a particle accelerator has to do with

0:50:000:50:03

the early universe, because the connection between the two

0:50:030:50:06

is far from obvious.

0:50:060:50:08

The thing to remember is that, when the universe was very young,

0:50:080:50:11

it was much smaller and so all the matter -

0:50:110:50:13

everything that makes up the stars, the galaxies, black holes -

0:50:130:50:16

all had to be confined into a much smaller space.

0:50:160:50:21

At that stage, the universe was phenomenally hot and,

0:50:210:50:24

more significantly, its energy density was very high.

0:50:240:50:28

It was then that the first matter sprang into existence.

0:50:310:50:36

The LHC can't yet replicate that process...

0:50:360:50:40

..but it can allow us to study the properties

0:50:420:50:45

of these fundamental particles.

0:50:450:50:48

Once a year, the LHC stops its normal business of colliding

0:50:480:50:52

beams of protons, and instead uses much more massive particles

0:50:520:50:56

to create collisions with energies more than 80 times greater

0:50:560:51:00

than that produced from two protons.

0:51:000:51:03

They do this by accelerating atoms of lead,

0:51:030:51:07

stripped of all their electrons,

0:51:070:51:09

up to speeds close to that of light,

0:51:090:51:11

and smashing them together.

0:51:110:51:14

And that lets us see something pretty special.

0:51:140:51:17

The collisions are so intense that, for a moment,

0:51:220:51:26

we create something unique -

0:51:260:51:29

a world not of atoms or even neutrons and protons -

0:51:290:51:34

but of quarks and gluons and leptons - exotically named particles

0:51:340:51:39

that came together to form atoms in the first millionth of a second

0:51:390:51:43

after the Big Bang, and have been locked away ever since.

0:51:430:51:49

Down there, underneath that lead shielding, we're recreating a stage

0:51:490:51:54

in the universe's evolution called the quark-gluon plasma.

0:51:540:51:58

Now, this is the moment immediately before the quarks become trapped

0:51:580:52:02

by the gluons to create protons and neutrons,

0:52:020:52:06

which themselves go on to form the nuclei of atoms.

0:52:060:52:09

The phrase we use - grandly -

0:52:090:52:12

is the confinement of the quarks.

0:52:120:52:15

To develop the necessary energy,

0:52:230:52:25

the lead nuclei are passed through a chain of smaller accelerators,

0:52:250:52:30

gradually ramping up the energy until they're finally

0:52:300:52:33

fed into the largest accelerator on Earth, the LHC.

0:52:330:52:38

Now, the maximum energy a beam can achieve is directly related

0:52:380:52:42

to the size of the accelerator,

0:52:420:52:44

and the LHC has a circumference of 27km.

0:52:440:52:48

That means the beams here can achieve an energy

0:52:480:52:51

of 1,000 tera-electronvolts.

0:52:510:52:55

Now, actually, that's less than you might imagine, because

0:52:550:52:58

it's equivalent to the energy that a housefly hits a window pane.

0:52:580:53:03

But the critical difference here

0:53:030:53:05

is that the energy is concentrated,

0:53:050:53:07

it's the energy density that's important.

0:53:070:53:10

The LHC can squeeze all that energy down to a space that's less than

0:53:100:53:14

a trillionth of the size of a single atom.

0:53:140:53:18

This is something that can happen nowhere else in the known universe.

0:53:190:53:24

The two beams of lead nuclei are travelling around the ring

0:53:330:53:37

in opposite directions.

0:53:370:53:38

They're meeting deep underneath this control room at the detector.

0:53:380:53:42

We can see live feed pictures of the detector up on that screen.

0:53:420:53:46

Now, underneath us,

0:53:460:53:47

they're travelling at a speed of 99.9998% the speed of light.

0:53:470:53:53

That means they're covering the full 27km circumference of the ring

0:53:530:53:57

more than 11,000 times per second.

0:53:570:54:01

When the beams reach maximum energy -

0:54:010:54:03

and we can see up there, it says "iron physics stable beams" -

0:54:030:54:06

that means they can be crossed.

0:54:060:54:08

Just like in Ghostbusters.

0:54:080:54:10

At that point, a tiny fraction of the lead nuclei will collide

0:54:100:54:14

and create a super-hot, super-dense fireball

0:54:140:54:18

with a temperature 400,000 times hotter than the centre of the sun,

0:54:180:54:23

and a density that would be equivalent to squeezing

0:54:230:54:26

the whole of Mont Blanc down to the size of a grape.

0:54:260:54:30

That looks like a fantastic image there.

0:54:420:54:46

-Can you tell me what we're seeing?

-It's amazing, actually, isn't it?

0:54:460:54:49

It's literally tens of thousands of particles and antimatter particles

0:54:490:54:54

-flying out - this kind of aftermath of this explosion.

-Right.

0:54:540:54:57

So the coloured particle trails here

0:54:570:55:00

AREN'T the quarks and gluons themselves,

0:55:000:55:03

but evidence of the quark-gluon plasma created by the collision.

0:55:030:55:08

We have to infer its properties from looking at the debris

0:55:080:55:11

that flies out. It's a bit like working out how an aircraft works

0:55:110:55:15

by looking at the debris of a plane crash. That's what we see.

0:55:150:55:19

What I find amazing is, what we're doing here is trying to recreate

0:55:190:55:22

that moment in the early universe where the quarks and gluons

0:55:220:55:27

were all free to float around, cos the energy was so high,

0:55:270:55:30

and then it cooled and they stacked together. You're doing the opposite.

0:55:300:55:33

We're starting with normal matter, smashing it together,

0:55:330:55:36

and going back to that unconfined state, that plasma.

0:55:360:55:41

Yeah. I like to think about it as a time machine.

0:55:410:55:43

We're actually winding back the clock.

0:55:430:55:45

And this is the only way that we can study the properties of free quarks,

0:55:450:55:49

because these quarks have been imprisoned inside particles

0:55:490:55:53

like protons and neutrons for 13.8 billion years.

0:55:530:55:56

That's pretty incredible, isn't it? Finally, after 13.8 billion years,

0:55:560:56:00

you can set these quarks free -

0:56:000:56:01

-even if it's for a fraction of a second.

-Yes.

0:56:010:56:04

While we don't yet know how matter sprang into existence,

0:56:060:56:11

studying these collisions allows us

0:56:110:56:13

to make the first tentative steps towards that discovery.

0:56:130:56:17

What we've just witnessed is the earliest stages of the universe

0:56:190:56:22

that anyone - anywhere - has been able to observe.

0:56:220:56:26

It's the closet we've got to the moment of the Big Bang.

0:56:260:56:30

And, let's face it, it's not bad.

0:56:300:56:33

One millionth of a second after the Big Bang itself.

0:56:330:56:36

Even going this far back in time

0:56:400:56:42

still leaves physics with unanswered questions.

0:56:420:56:45

Beyond this is where some of the deeper mysteries of the universe

0:56:500:56:54

are hiding. How the fundamental forces that bind matter together -

0:56:540:56:59

gravity, electromagnetism and the nuclear forces -

0:56:590:57:02

are connected to each other.

0:57:020:57:04

How the particles that make up matter itself

0:57:040:57:07

condensed out of a fog of energy.

0:57:070:57:10

How mass is generated from the force that binds protons

0:57:100:57:13

and neutrons together.

0:57:130:57:15

And how the universe itself underwent a super-fast expansion

0:57:150:57:20

in one billion-billion- billion-billionth of a second

0:57:200:57:26

to create the structure of the cosmos.

0:57:260:57:28

At the moment, we have no way of observing any of these phenomena.

0:57:300:57:34

This is the realm of abstract theory and speculation.

0:57:360:57:40

If we're ever going to replicate this early stage of the universe's

0:57:440:57:48

evolution, we're going to need to create considerably higher energies.

0:57:480:57:52

Frankly, we're going to need to build a bigger collider.

0:57:520:57:56

And that's a problem. And it's not just one of expense,

0:57:560:57:59

although it would be phenomenally expensive.

0:57:590:58:03

No, it's more one of finding the room to build it.

0:58:030:58:07

Remember when I said the energy's related to the circumference

0:58:090:58:12

of the accelerator? Well, the LHC, down below me,

0:58:120:58:16

has a circumference of 27km.

0:58:160:58:19

It runs beneath the Jura Mountains

0:58:190:58:22

and straddles both France and Switzerland.

0:58:220:58:26

In order to look back and observe the universe at this earliest stage,

0:58:260:58:31

well, we'd need to build an accelerator

0:58:310:58:34

with a circumference larger than the orbit of Pluto.

0:58:340:58:38

Revealing the origin of the universe begs another,

0:58:420:58:45

even more profound question -

0:58:450:58:48

how will it end?

0:58:480:58:50

Next time, I discover whether the universe will end with a bang

0:58:500:58:54

or a whimper.

0:58:540:58:56

Want to discover more about the beginnings of the universe?

0:58:560:59:00

Go to the address below and follow the links to the Open University.

0:59:000:59:05

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