Inside CERN Horizon


Inside CERN

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Five days ago, hundreds of the world's brainiest people

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descended on a hotel in Chicago.

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Good morning, ladies and gentlemen.

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They have come to hear news from particle physicists

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working at CERN.

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Last year, researchers there had started running

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the Large Hadron Collider at the highest energy ever...

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..and a rumour quickly emerged.

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They were on the brink of a huge discovery.

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We started hearing these mysterious noises

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about something going on at CERN.

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This may be what I have been spending an entire lifetime

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waiting for.

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A strange bump on a graph suggested that they might have discovered

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a brand-new particle...

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..that could revolutionise physics...

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Right here, right now at CERN, in 2016,

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is THE most exciting time and place in the history of science.

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If you want, really, to change the conditions of humanity,

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then you need breakthroughs.

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..and could change our understanding of how everything works.

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The discovery of a new particle may mean a complete rethinking

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of the conceptual basis of the physics world.

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For the last eight months,

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it looked like the universe was about to be turned upside down...

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..and Horizon has been inside CERN following the story.

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I doubt that it will be named after me,

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but I can think of it like this, that it might be!

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There was a short circuit on a circuit-breaker developed

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which arced and damaged the nearby equipment.

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Two teams of physicists...

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..one massive machine...

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and a dream.

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Was the bump was just a glitch in the data,

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or the biggest physics discovery in over a century?

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A Nobel prize is possible.

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Bonjour. Bienvenue a CERN.

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This is the European Organization for Nuclear Research - CERN.

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CERN is home to half of the world's particle physicists...

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..and the biggest particle-hunting machine that has ever been built.

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The Large Hadron Collider, or LHC.

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Inside this pipe, two beams of protons

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are sent hurtling around a 27km loop

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before being smashed together

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to create subatomic particles.

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In November 2015, researchers here got

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a tantalising glimpse of what they thought might be

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a brand-new particle.

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A particle that could transform our understanding

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of how the universe works.

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Now they're trying to find it.

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The Large Hadron Collider has been hunting for particles since 2009...

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..and it's the job of British physicist Mike Lamont

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to keep it running.

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Today, it's having one of its off days.

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This is not a cock-up.

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We stop because,

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as you can see,

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there's a huge amount of stuff down here -

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big systems, cooling, ventilation,

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cryogenics, etc,

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and this stuff needs a bit of periodic tender loving care.

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With over 4,000 miles of cabling and 100,000 processor cores,

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the LHC is one of the most complicated machines in the world.

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She is not a simple beast to operate,

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and a lot of time we spend wrestling it under control.

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We need very powerful magnets to bend the beam around in a circle,

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so basically, these are superconducting magnets,

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they're cooled with superfluid helium at 1.9K.

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The fact that this actually works at all

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is a real testament to an awful lot of hard work, modern technology,

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planning, precision on a completely remarkable scale.

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With the hunt on for a potential new particle,

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Mike and his team are trying to run the LHC

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at its highest ever energy,

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and it's making their job more challenging than usual.

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We had a very interesting month,

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with a number of fairly major technical problems,

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including the famous weasel,

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which took us out for about six days,

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but from now on, after this maintenance period,

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it's pedal to the metal for two or three months.

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To try and find new particles,

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the LHC does something that was once completely out of our grasp.

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It recreates the conditions that existed just after the Big Bang.

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The Big Bang was an explosion that happened

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at the beginning of the universe, when all matter was created.

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So, this is the year zero, and if we draw a line...

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From this point, the universe expanded,

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getting cooler, its energy dispersing.

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..to where we are in the universe now, where humans exist,

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that's 14 billion years.

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We know that when the universe was 9 billion years old,

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the sun was formed,

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and over 8 billion years before that,

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the first stars were born,

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but the LHC is able to look even further back in time

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to when all that existed were the fundamental building blocks

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of the universe - particles.

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So, in a way, the Large Hadron Collider

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is like a time machine,

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trying to create the conditions that happened

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just in the few millionths of a second after the Big Bang

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to see what particles existed when the energy density

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of the universe was really, really high.

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To do this, the LHC makes use of

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one the most famous scientific discoveries ever made.

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What we're doing is using the very high energy of the protons

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in the collision using Einstein's equation E = mc2...

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..which tells us that mass and energy are equivalent,

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so we have protons and they're going round and round the LHC,

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and we have one set of protons going round this way

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and we have another set of protons

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which are going around in the opposite direction,

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getting faster and faster, closer to the speed of light,

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and more and more energetic.

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Then we get one proton beam

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and the other proton beam

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going at the highest energies,

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and then we smash them together.

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At the moment of collision,

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the energy is converted into mass

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in the form of thousands of particles.

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Although most will be ones we already know about,

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the hope is that undiscovered particles might also be created

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that could help explain some of the mysteries

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of how the universe was formed.

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SHE BLOWS

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But creating particles is just the beginning.

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Detecting them requires

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some of the most sophisticated machines in the world.

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I come into the cavern hundreds of times in a year

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and every time I walk in,

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my jaw still drops a little bit when I see ATLAS.

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We built this thing. We REALLY built this thing.

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Dave Charlton runs the snappily named

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A Toroidal Large Hadron Collider Apparatus, known as ATLAS.

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It's the largest particle detector on the LHC circuit.

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The collisions take place right in the centre of the experiment,

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about 30 metres away from where we're standing.

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ATLAS has seven different detecting systems

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arranged in layers around the collision point.

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They're poised to capture evidence of the particles

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that have been produced.

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Dave hopes that ATLAS will lead the hunt for the potential new particle,

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but he's not the only one

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with a giant particle detector at his disposal.

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There's another massive detector on the LHC circuit -

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the Compact Muon Solenoid.

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CMS.

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It's run by Italian physicist Tiziano Camporesi.

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The croissant has become something almost associated to me

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because I've grown into the habit of bringing croissants every morning

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to the crew which is working at the experiment.

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So now, if I show up without croissants,

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they are disappointed.

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No, actually, I like this... I like this habit.

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You know, when you have a ritual,

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you don't want to change it because it will bring bad luck.

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Tiziano's machine, CMS, is very similar to Dave's.

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CMS is big. It's a 14,000-tonne object...

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..which basically is five storeys high

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and something like 26 metres long.

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But ATLAS is slightly bigger.

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Look at the size of it. As you can see,

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it's really a huge experiment.

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25 metres high, 45 metres long.

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These detectors are purposefully designed

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to do the same thing in two different ways.

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You could see it as an oversized camera,

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something like a 100-megapixel camera.

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Nowadays, a digital camera might be 25 megapixels, 25 million channels,

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but we're able to read out our 100 million channels

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40 million times a second.

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The idea is that new particles

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will be seen by both detectors independently.

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It can help ensure their findings are valid,

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but that doesn't stop both teams

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wanting to be first to make a discovery.

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We understand that there is some healthy competition

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between us and ATLAS, so we are convinced that CMS is better.

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HE CHUCKLES

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There IS a rivalry between the experiments.

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We don't want to lose.

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If CMS and ATLAS detect a new particle,

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it could be the most important physics discovery in over 100 years.

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Ah, you've made it! Come on in. We can talk about some physics.

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It's going to be fun.

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By the beginning of the 20th century,

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particle physicists like Professor Jim Gates

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had ascertained that milk, bowls, glasses -

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in fact, everything we see around us -

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is made from atoms...

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..and that atoms themselves are made of even smaller subatomic particles.

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From the 1950s, hundreds of particles were discovered...

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There was this strange quark -

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and this was not the order in which they were discovered -

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and then the top quark...

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and the most familiar particle of them all, the electron.

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All of our electronics come from this.

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And so we kept discovering particles -

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neutrino, gluon...

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But the influx of new particles did little to help explain

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how the universe really behaved.

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So, this is the state of knowledge about particles

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in the 1950s, '60s and '70s.

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It was a zoo of particles jumbled about -

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confusion, no order.

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It was only by studying their characteristics

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that physicists could begin to understand

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how these particles worked together.

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It turned out that the electron, in fact, has another particle

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very similar to it called the muon.

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This family of particles was called the leptons

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and they were soon joined by another - the quarks.

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Quarks are really important,

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because they are what you need to construct protons and neutrons.

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And now, with protons, neutrons and the electron,

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you can construct atoms.

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From atoms, you can construct cells, molecules, compounds

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and, ultimately, us -

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so these guys are really, really important.

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This group are the known as the fermions -

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they're particles that make matter -

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but you can't build a universe with fermions alone.

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They're held in patterns

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and interact through particles known as force carriers.

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One of them is the photon, the particle of light.

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It is the carrier of the electromagnetic force -

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so, we're going to put that up here.

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Then there are other forces in nature beside the electromagnetism -

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there's a weak nuclear force.

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It has carriers - we call them the W and the Z particle.

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This family is completed by the gluons

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that hold matter together inside an atom,

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and the Higgs, responsible for giving the other particles mass.

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And now we have the modern Standard Model,

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born around 1973,

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where the fermions are all sitting here divided into two families

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of quarks and leptons,

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and these guys are the force carriers.

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It is the best-tested, most tested piece of science

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that has ever been constructed.

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It literally explains tens of thousands of observational facts.

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It is just an amazing triumph

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that almost nobody has ever heard of, outside of physics.

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The Standard Model has served as a map to our understanding

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of the particles in the world around us for over 40 years...

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..but physicists have hoped, for almost as long,

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that it's not the end of the story -

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that other particles will also exist

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that could help explain

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some of the more troublesome mysteries of the universe.

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The problem is finding them.

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I'm not going to disturb these guys.

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These guys are doing serious work!

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Fixing the chair, yeah! Fixing the chair!

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THEY LAUGH

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At CERN, it takes hundreds of researchers

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writing millions of lines of computer code

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to scour collisions for signs of new particles.

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This thing is a raw image,

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as they come in, basically unfiltered,

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from the collisions which are happening 100 metres below ground,

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under our feet.

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What makes the job even harder is that undiscovered particles

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will only exist at very high energies

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like those inside the LHC -

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and almost as soon as they're created, they decay

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into the stable particles that we're familiar with.

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So, I'd like to change this 60...

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Let's say... Make it 1, or...?

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So the teams aren't looking for the particles themselves,

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but for the trails they leave behind.

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This is detective work,

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because, basically, you are seeing fragments of the disintegration,

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you are trying to understand from the behaviour of the fragments

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how the particle was to start with.

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It's a task for some of the brightest minds in physics

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working around the clock.

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What we really like is a young brain, I have to tell you!

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Because, I mean, these guys are amazing.

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I lived through that, I know what it means -

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once you become in my position,

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the level of stress becomes a different one.

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Towards the end of last year,

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it looked like all the hard work would pay off.

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28-year-old Dr Livia Soffi is an analyst for CMS.

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She was once a European artistic roller-skating champion.

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I really like to relax, to stay a little bit under the sun

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without staying in the office.

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I really like the lake,

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because when I was younger, I used to go to the sea -

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now we cannot go to the sea,

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but we have the lake, it is nice, as well.

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Then we can take an ice cream -

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there is an Italian ice cream place close to here,

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so it's very nice.

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Last November, Livia found something unexpected in the data

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coming from the CMS detector.

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What she saw was a mysterious bump on a graph.

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So, basically, the idea is that if you do not have anything new,

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you will see the dashed line,

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and if the solid line, here, the observation,

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is inside these two bands,

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this means that everything is quiet,

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then the fluctuation is not interesting.

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When the fluctuation goes outside the bands,

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this means that your expectation and what you observe

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are not so compatible.

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It might not look like much,

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but the bump indicates that,

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at the energy of 750 giga-electronvolts,

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the LHC is producing unexpected bursts of photons.

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We have two possibilities.

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Either our detector is not working - but this is not the case,

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because we know that it is well performing -

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or we have observed something.

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I have never seen something like this in my life.

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This could be evidence of a brand-new particle.

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A particle that disappears into a pair of photons

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almost as soon as it's created.

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And what made the bump even more exciting

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was that it wasn't just seen in CMS.

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James Beacham is an analyst at the other detector, ATLAS.

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To my mind, right here, right now at CERN, in 2016,

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is THE most important time and place in the history of science,

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because we have just pushed forward, as a species,

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into an energy regime where we have never been.

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No-one's ever looked here.

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APPLAUSE

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On the 15th of December, both ATLAS and CMS

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presented their findings.

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We, of course, observed a little bump at 750 GeV...

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It was in this seminar that the science community learnt

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that the mysterious bump was being seen

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by both the CMS and ATLAS detectors.

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It was an extremely exciting seminar that we had here at CERN,

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and, to me, watching, you know,

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and then, suddenly, he shows this little thing,

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and I'm like, "This is very intriguing."

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The implications of such a little bump,

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if it turns into, potentially, a new particle, are super-huge.

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This is completely uncharted territory.

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The excitement quickly spread out into the physics world.

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Within weeks, 300 papers had been written by theorists

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trying to determine what this potential particle might be.

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When the result was announced,

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the whole theory group was just crazy -

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crazy with discussion,

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crazy to understand what it was...

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Er... That's it!

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This was the moment, it seemed.

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We started hearing these mysterious noises

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about something going on at CERN,

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and it had a very prosaic name - the 750 GeV bump.

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It sounds like a dance, to me.

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I thought it was a joke - but then I began to look more carefully,

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thinking that, "Oh, my goodness, this may be

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"what I have been spending an entire lifetime waiting for."

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By the beginning of this year,

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the race was on for ATLAS and CMS to gather more collision data

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to see if the mysterious bump would reappear,

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or if it was simply a statistical fluctuation.

0:22:490:22:52

The fact that the two experiments

0:22:540:22:55

seem to see a hint of something in the same place is fascinating,

0:22:550:22:59

but the statistics are too low with the current data sample

0:22:590:23:01

to get too excited.

0:23:010:23:03

It's more potential excitement, at this stage,

0:23:030:23:05

for the experimentalists

0:23:050:23:07

rather than cast-iron established excitement.

0:23:070:23:10

For the bump to be confirmed as a new particle,

0:23:120:23:15

the two teams work independently,

0:23:150:23:17

both trying to collect enough data

0:23:170:23:19

to reach a level of statistical certainty known as 5-sigma.

0:23:190:23:23

I mean, to give you a feel for the scale of the statistics

0:23:250:23:27

for the Higgs discovery,

0:23:270:23:29

we had a few tens of events

0:23:290:23:31

that were identified as being signal-like Higgs events,

0:23:310:23:34

but we had looked in a million billion events.

0:23:340:23:39

So, that's the complexity of the science that we do.

0:23:390:23:42

It's really...

0:23:420:23:43

I mean, people talk about a needle in a haystack,

0:23:430:23:46

but it's a needle in a haystack of haystacks of haystacks!

0:23:460:23:48

A grain of sand in an ocean.

0:23:480:23:50

It's a huge task,

0:23:510:23:53

but with the physics world desperate for news,

0:23:530:23:56

the teams have just three months

0:23:560:23:57

to announce if they really have found a brand-new particle.

0:23:570:24:01

The big thing is our conference in Chicago.

0:24:020:24:06

The first week of August. By that time, we should have...

0:24:060:24:10

..I think at least doubled the data which we took last year.

0:24:120:24:17

As you know...

0:24:170:24:18

MUSIC: A Kind of Magic by Queen plays in background

0:24:180:24:22

This is specific to our experiment.

0:24:220:24:25

You have to realise that the guy who designed our architecture here

0:24:250:24:31

for taking data, he is a Queen fan,

0:24:310:24:35

so all of the change of states of the machines,

0:24:350:24:39

or of the experiments, are basically announced

0:24:390:24:42

by a snippet of a Queen song.

0:24:420:24:44

Everybody has become aware of the meaning and of the Queen songs!

0:24:440:24:50

"It's a kind of magic" means that you have managed to start the run.

0:24:500:24:53

The last time particle physicists were this excited, prizes were won.

0:25:020:25:07

This is the Nobel medal which I received in 2013.

0:25:110:25:16

I think it had something to do with some work I did in...

0:25:160:25:22

When was it? 1964.

0:25:220:25:25

Make way, please.

0:25:280:25:30

On the 4th of July, 2012,

0:25:320:25:35

Peter Higgs arrived at CERN for an announcement.

0:25:350:25:38

On the day itself, I found myself

0:25:390:25:43

being besieged by crowds of physicists

0:25:430:25:46

who had more or less camped out overnight

0:25:460:25:49

in the hope of getting into the lecture theatre,

0:25:490:25:52

which was really already fully booked.

0:25:520:25:56

So good morning...

0:25:570:25:59

Fabiola Gianotti, who is now Director-General of CERN,

0:25:590:26:03

was part of a team from ATLAS.

0:26:030:26:05

The atmosphere was absolutely amazing,

0:26:070:26:10

it was a big, big emotion.

0:26:100:26:12

So you can see here some beautiful events,

0:26:120:26:15

selected by our pic search.

0:26:150:26:17

We were working days and nights,

0:26:170:26:20

nourished and pushed only by adrenaline,

0:26:200:26:23

because we didn't have the time to sleep, to eat - it was fantastic.

0:26:230:26:27

So this channel has a tiny rate...

0:26:270:26:30

At this conference, CMS and ATLAS confirmed that they had found

0:26:300:26:34

a particle predicted by Peter nearly half a century earlier.

0:26:340:26:40

..extremely clean, except one big spike here, in this hadron here.

0:26:400:26:46

An excess, with a local significance of 5.0 sigma,

0:26:460:26:50

at a mass of 126.5 GeV - thank you.

0:26:500:26:54

It was 48 years from the time that the theory was formulated

0:27:010:27:05

as something which might be useful in particle physics,

0:27:050:27:09

to the discovery of the particle.

0:27:090:27:11

So it was a long wait.

0:27:110:27:13

I think we have it. Do you agree?

0:27:150:27:18

LAUGHTER AND APPLAUSE

0:27:180:27:21

Everybody cheered and got up, it was rather like the end of

0:27:210:27:25

a football match, rather than a scientific seminar.

0:27:250:27:28

Then I went into hiding again and had some lunch and escaped.

0:27:340:27:38

Fly home before anybody else tried to capture me.

0:27:380:27:41

The Higgs boson was the final piece needed

0:27:440:27:47

to complete the maths of the Standard Model.

0:27:470:27:49

But an unpredicted new particle, like the 750 GeV bump,

0:27:530:27:57

could be even more significant.

0:27:570:27:59

If the bump which has been seen recently is genuine,

0:28:010:28:06

that is opening up a new era.

0:28:060:28:09

So it's very exciting.

0:28:090:28:10

The hope was that if it really is a new particle,

0:28:140:28:18

the bump could help physicists answer some of life's big questions.

0:28:180:28:23

Like, "How stable is our universe?

0:28:250:28:28

"Does it have hidden extra dimensions?"

0:28:280:28:31

And an old bugbear - "What is the universe actually made of?"

0:28:330:28:38

In the 1930s, evidence emerged that the luminous matter,

0:28:420:28:47

the matter which forms the stars, it cannot be sufficient

0:28:470:28:52

to justify the dynamics of what we observe in the sky.

0:28:520:28:56

There should be something else that gives a gravitational pull.

0:28:560:29:00

Physicists faced the rather disturbing realisation that

0:29:010:29:06

they don't really know what makes up most of the universe.

0:29:060:29:09

So 95% of what is around in our universe

0:29:120:29:16

is not the ordinary matter that we are used with,

0:29:160:29:20

and that the Standard Model explains.

0:29:200:29:23

This is very frustrating for particle physicists,

0:29:240:29:27

but particle physicists always look on the bright side,

0:29:270:29:31

and they see that there is an opportunity.

0:29:310:29:33

This unidentified stuff has been called "dark matter"

0:29:370:29:42

and "dark energy".

0:29:420:29:44

And the bump could bring us a step closer

0:29:440:29:46

to finding out what it actually is.

0:29:460:29:48

The 750 GeV particle cannot be the dark matter,

0:29:550:29:59

because we know that it decays very quickly into two photons,

0:29:590:30:03

meaning that if it were around in the cosmos, it would have

0:30:030:30:07

disappeared very quickly, so we know that it cannot be.

0:30:070:30:10

However, there has been speculations that the 750

0:30:100:30:14

must be part of a bigger family.

0:30:140:30:18

Inside this family,

0:30:180:30:19

there could be one particle

0:30:190:30:21

that plays the role of the dark matter.

0:30:210:30:24

So, even if the 750 is not dark matter,

0:30:240:30:27

it could be related to the particle giving rise to the dark matter.

0:30:270:30:30

This may have a lot of implications

0:30:300:30:32

in understanding the structure of the universe,

0:30:320:30:36

understanding how this dark matter was formed

0:30:360:30:39

and understanding its role in the universe.

0:30:390:30:43

A new particle could well have a profound effect.

0:30:460:30:49

But first, they had to find it.

0:30:500:30:53

It's the middle of May at CERN.

0:31:010:31:03

And with just over two months until the important summer conference,

0:31:040:31:08

the mission to gather data continues.

0:31:080:31:10

So we are just getting ready to go to work.

0:31:130:31:15

My boyfriend is hiding.

0:31:150:31:16

SHE LAUGHS

0:31:160:31:19

You can come out.

0:31:190:31:20

If he wants to.

0:31:210:31:23

The LHC has been providing an unprecedented amount of collisions

0:31:260:31:30

for the teams on the detectors.

0:31:300:31:32

We had the longest fill in the history of the LHC.

0:31:320:31:37

And this happened over the weekend, so basically,

0:31:370:31:40

starting from Friday and then continuing through Saturday.

0:31:400:31:45

Dr Magda Chelstowska is part of the ATLAS team,

0:31:460:31:49

and it's her job to clean up and format the data as it's collected.

0:31:490:31:53

I think of myself as a person who gives birth to the data.

0:31:560:32:01

So I feel that it is my child, it is my kid.

0:32:010:32:05

Because I prepare the data and I polish it and massage it

0:32:050:32:09

and make it into something which then can go out and be on its own.

0:32:090:32:15

The race is on to see which team will be first to gather

0:32:150:32:18

enough data to find out if the bump is back.

0:32:180:32:21

When we know that we are very close to making

0:32:210:32:25

a major breakthrough in physics,

0:32:250:32:29

we of course want to do it as soon as possible,

0:32:290:32:32

because we don't want the experiment on the other side to beat us to it.

0:32:320:32:37

ATLAS and CMS are working blind, accumulating and processing the data

0:32:400:32:44

without actually being able to see what it's showing.

0:32:440:32:48

It means the two teams can't influence either their own

0:32:500:32:53

or the other's results.

0:32:530:32:55

THEY CHUCKLE

0:32:550:32:57

And with a discovery of this potential significance, for ATLAS,

0:32:570:33:00

it is up to Dr Marco Delmastro to make sure nothing is left to chance.

0:33:000:33:05

It's always difficult to see whether this excess is a new particle

0:33:050:33:10

or not, because nature is behaving in a sort of stochastical way.

0:33:100:33:14

We will be spending days and nights, basically,

0:33:160:33:19

going through all the stuff,

0:33:190:33:21

from the current that we measure inside the detector

0:33:210:33:25

to the piece of software that transforms current to energy,

0:33:250:33:28

and then tell us where the things are in the detector

0:33:280:33:31

and how they are constructed, to the very end.

0:33:310:33:34

In the back of my head, there is always a small devil

0:33:350:33:38

sitting on my shoulder, saying,

0:33:380:33:40

"Are you sure you checked everything?

0:33:400:33:42

"Are you sure that there is nothing wrong in what you're doing?"

0:33:420:33:46

That is my worry, and still is my worry, so yeah,

0:33:470:33:51

I think it is going to stay there for a while.

0:33:510:33:54

As the teams crunch the data,

0:34:030:34:05

speculation about what the new particle might be is rife.

0:34:050:34:10

Jim Gates hopes it could prove a theory known as supersymmetry.

0:34:130:34:16

He has been studying this idea for nearly 40 years.

0:34:190:34:24

For a long time, the idea of supersymmetry was pooh-poohed.

0:34:240:34:27

In fact, I remember all throughout graduate school,

0:34:270:34:30

I had colleagues working on other things that were considered

0:34:300:34:32

"good physics", and there I was in the corner,

0:34:320:34:35

the only student in my team working on this supersymmetrical stuff.

0:34:350:34:39

The idea of supersymmetry was born when physicists started

0:34:410:34:45

questioning why the Standard Model wasn't mathematically more balanced.

0:34:450:34:50

So here is the triumph of the study of the standard models.

0:34:500:34:54

And many of us who were studying physics then looked at this,

0:34:540:34:57

and we noticed that there is a lack of balance here, a lack of symmetry.

0:34:570:35:02

To make this obvious, let me put some lines on the table.

0:35:020:35:05

And you can see that there are

0:35:080:35:11

two quadrants here that are empty.

0:35:110:35:14

Physicists are very sensitive to the lack of symmetry or balance.

0:35:140:35:18

And we can ask the question,

0:35:180:35:21

"What would the world look like if it were balanced?"

0:35:210:35:23

And we ask the question with mathematics.

0:35:230:35:26

Supersymmetrists found that the Standard Model

0:35:270:35:30

could be given balance if a mirror image

0:35:300:35:33

of each of the particles also existed.

0:35:330:35:37

They were called "superpartners" or "sparticles".

0:35:380:35:42

So if the universe is supersymmetric,

0:35:450:35:47

there must be another particle

0:35:470:35:49

on this side that we call the selectron.

0:35:490:35:52

And also, that has to occur for its neutrino,

0:35:520:35:55

which we would call a sneutrino.

0:35:550:35:58

For the muon, there's another particle called the smuon.

0:35:590:36:02

We physicists, when we make great triumphs, are so happy

0:36:040:36:08

that we get giddy, so we name things in a silly manner.

0:36:080:36:12

The idea is deceptively simple.

0:36:120:36:15

Each ordinary matter particle

0:36:150:36:17

has an undiscovered supersymmetric force partner.

0:36:170:36:21

And each force particle,

0:36:210:36:23

an undiscovered supersymmetric matter partner.

0:36:230:36:27

Once we've made this change we are looking at

0:36:290:36:32

not the Standard Model but a supersymmetric extension

0:36:320:36:36

of the Standard Model, where we get a balance on both sides -

0:36:360:36:40

there's a balance of the superpartners

0:36:400:36:42

to the ordinary matter...

0:36:420:36:44

There's a balance for the super force carriers

0:36:440:36:46

to the ordinary force carriers.

0:36:460:36:49

And this is what we've been wondering about for

0:36:490:36:51

over 30 years -

0:36:510:36:53

is it just mass or is it the universe we look at?

0:36:530:36:56

Devotees of supersymmetry believe that their theory solves

0:36:580:37:02

one of the most worrying mysteries of our universe.

0:37:020:37:05

At the smallest scales, the universe is in a constant state of flux...

0:37:070:37:13

seething with particles popping in and out of existence.

0:37:130:37:17

The best way to understand it is to try to understand

0:37:190:37:22

something about what's going on inside of a teapot.

0:37:220:37:25

We can see the water is boiling, there's bubbles coming out,

0:37:250:37:28

some are big, they explode, they disappear.

0:37:280:37:30

So if you imagine that this surface is the universe,

0:37:300:37:33

the bubbles popping in and out are actually virtual particles,

0:37:330:37:36

they're virtual electrons and photons -

0:37:360:37:38

all the particles that make up our universe,

0:37:380:37:40

they pop into existence and then they disappear.

0:37:400:37:43

This state of chaos is known as the quantum vacuum.

0:37:480:37:52

And Jim thinks that without supersymmetry,

0:37:530:37:57

it might make the universe unstable.

0:37:570:37:59

I'm going to use a set of quarters to represent our universe.

0:38:020:38:05

And...with a little bit of work I can get it to balance.

0:38:070:38:10

With the particles of the Standard Model, there's actually

0:38:100:38:13

a preponderance of one type of particle over the other.

0:38:130:38:16

And now let's follow what happens

0:38:160:38:19

if you let this preponderance work for a while.

0:38:190:38:23

It's as if you are pressing on the stack of coins,

0:38:230:38:25

but because of the preponderance

0:38:250:38:27

you are always pressing in one direction.

0:38:270:38:29

And what you find is that we are very close to being

0:38:290:38:32

in a situation where the universe might collapse.

0:38:320:38:35

Now, supersymmetry can help solve this problem.

0:38:370:38:40

So, if you have particles - all the ones we know about,

0:38:440:38:47

as well as the sparticles - they press, but they press

0:38:470:38:51

in opposite directions.

0:38:510:38:53

And our universe is a much more stable place.

0:38:530:38:57

And I know I would sleep much more quietly at night

0:38:570:39:00

knowing I live in a stable universe.

0:39:000:39:02

The problem is that in 30 years of research...

0:39:060:39:10

no sparticle has ever been found.

0:39:100:39:12

But is that finally about to change?

0:39:130:39:15

The 750 GeV bump might actually be one of these particles

0:39:170:39:22

that we've predicted by the mathematics of supersymmetry.

0:39:220:39:25

And if that's the case, it becomes the herald for supersymmetry.

0:39:250:39:29

For me it will mean several things. Emotionally it will be a great high.

0:39:290:39:33

I have been a supporter of the idea of supersymmetry

0:39:330:39:36

since I was 25 years old, first learning theoretical physics.

0:39:360:39:41

The dream was to find a magical piece of mathematics.

0:39:420:39:47

Simultaneously, an accurate description of something in nature.

0:39:470:39:51

It will be a source of intense joy.

0:39:510:39:53

With the hopes of theoretical physicists around the world

0:40:140:40:17

at stake, the pressure is on the LHC to keep providing collisions.

0:40:170:40:23

But running this machine at such high energy...

0:40:240:40:27

..is putting a huge strain on all its systems.

0:40:280:40:31

When it's running well, it runs well,

0:40:340:40:37

but there are a lot of things that can go wrong and do go wrong.

0:40:370:40:40

So it can get quite stressful.

0:40:400:40:42

Today, one of the accelerators that provides the LHC with protons,

0:40:440:40:48

the Proton Synchrotron - or PS -

0:40:480:40:52

has broken down.

0:40:520:40:54

This is one of the veritable workhorses of CERN,

0:40:540:40:56

and really is like the beating heart of the complex,

0:40:560:41:01

and at the moment the line is flat.

0:41:010:41:03

So we are in some of the oldest parts of CERN here.

0:41:050:41:09

The PS has been with us since 1959,

0:41:090:41:11

so there's some really old kit around here.

0:41:110:41:14

And...this beast here is what we call the rotating machine,

0:41:190:41:23

if you like, it's a kind of temporary energy storage system

0:41:230:41:26

which we use to power and de-power the PS machine,

0:41:260:41:31

the main bending magnets of the PS.

0:41:310:41:33

It was retired a few years ago, it was pressed back into service

0:41:330:41:38

because we've had a problem with the new version.

0:41:380:41:41

Unfortunately, last week a problem developed on this -

0:41:410:41:45

there was a short-circuit on a circuit breaker

0:41:450:41:48

developed downstairs, which arced and damaged the circuit breaker

0:41:480:41:53

and some nearby equipment.

0:41:530:41:55

Thanks to the failure of this near-50-year-old power supply,

0:41:580:42:02

the world's most expensive science experiment is just an empty pipe.

0:42:020:42:07

There's a huge experimental community on the LHC out there

0:42:100:42:13

really looking forward to getting as much data as they can this year.

0:42:130:42:16

And of course, there's a lot of pressure to get the complex

0:42:160:42:18

back up and running properly.

0:42:180:42:20

I still can't believe it says 1967 on there, actually.

0:42:210:42:25

If the LHC isn't running again soon, the worry for the experimentalists

0:42:270:42:32

is that they won't be ready for the August conference.

0:42:320:42:35

Another day that it's not coming in,

0:42:360:42:38

it's a bit frustrating. I like to wake up in the morning

0:42:380:42:41

to see how much data we took...

0:42:410:42:43

..overnight. But lately I haven't had any good mornings!

0:42:450:42:49

In the very beginning, there was a loss of 1.7 inverse picobarns

0:42:530:42:57

because of a problem. And then at the end of the run...

0:42:570:43:00

But the teams are determined to find a way around the problem.

0:43:000:43:04

So, we are considering suppressing our technical stops.

0:43:050:43:11

Which basically will put us on track for our goals of achieving

0:43:110:43:18

basically something like three times the statistics

0:43:180:43:22

which we have accumulated last year...

0:43:220:43:25

in time for the summer conference in Chicago.

0:43:250:43:29

At the University of Maryland near Washington, DC,

0:43:410:43:45

Professor Raman Sundrum has great expectations

0:43:450:43:48

about what the bump might be.

0:43:480:43:50

His hope is that it could be

0:43:520:43:53

a hypothetical particle that has near mythical status.

0:43:530:43:57

A force carrier particle of gravity -

0:44:000:44:04

known as an extra-dimensional graviton.

0:44:040:44:07

The discovery of a graviton could help solve a puzzle

0:44:090:44:13

that has baffled physicists for a long, long time.

0:44:130:44:17

Gravity seems strong, it seems like it's the first force that,

0:44:170:44:20

you know, cavemen would have known about, right?

0:44:200:44:23

It's the thing that dominates most of our lives,

0:44:230:44:25

just being pulled down to the Earth.

0:44:250:44:27

But we can sort of see why physicists

0:44:270:44:29

think that gravity is in fact the weakest force.

0:44:290:44:32

And a quick way to demonstrate that is to just take a simple object,

0:44:320:44:35

like a paperclip.

0:44:350:44:37

Watch gravity act on it.

0:44:370:44:38

But we can act on this paperclip with this magnet,

0:44:390:44:43

which seems much smaller, and perhaps much weaker than the Earth.

0:44:430:44:47

The entire gravitational pull of the planet can be easily overcome...

0:44:480:44:53

..with just a small magnet.

0:44:550:44:56

If you work this out you actually find that electromagnetism is

0:44:580:45:02

by far and away stronger than the force of gravity.

0:45:020:45:07

It's basically one followed by about 30 zeros times stronger than

0:45:070:45:11

the force of gravity.

0:45:110:45:14

That's how weak gravity is to a physicist.

0:45:140:45:16

Raman believes there is one mind-blowing way

0:45:180:45:20

to explain this puzzle -

0:45:200:45:23

the existence of a tiny, invisible extra dimension in our universe.

0:45:230:45:29

We're used to living in three dimensions of space -

0:45:310:45:34

we can travel forwards and backwards, left and right,

0:45:340:45:37

and up and down.

0:45:370:45:39

If you just look at the vast expanse of the grass,

0:45:390:45:42

it looks fairly flat,

0:45:420:45:44

and so you'd say, effectively, for my purposes, it's two-dimensional.

0:45:440:45:48

But if you're small, you can go places humans can't.

0:45:490:45:53

And the grass looks rather different.

0:45:550:45:57

From the bug's point of view, the grass

0:45:590:46:00

does not look that two-dimensional. Doesn't look that flat.

0:46:000:46:04

If it really gets in there, it can go up and down these clovers,

0:46:040:46:07

or up and down a blade of grass,

0:46:070:46:09

so it's really in there with the third dimension,

0:46:090:46:12

the vertical dimension.

0:46:120:46:13

The grass looks 2D to humans because we're so big,

0:46:130:46:17

and perhaps the same applies to our apparently 3D universe.

0:46:170:46:21

It might be that for human-size creatures like us,

0:46:230:46:26

we live in something that looks effectively three-dimensional.

0:46:260:46:30

And yet, there's another dimension -

0:46:300:46:32

a very small dimension that's sort of hidden to the naked eye.

0:46:320:46:35

But if you are a microscopic, subatomic particle,

0:46:350:46:39

you might be a little bit like that bug.

0:46:390:46:41

If an invisible extra dimension exists, it could mean

0:46:420:46:46

that gravity appears weak because we're only seeing

0:46:460:46:49

part of its strength. The rest is hidden - in the extra dimension.

0:46:490:46:54

And the discovery of a graviton in the LHC

0:46:560:47:00

could help prove this extraordinary theory.

0:47:000:47:02

That's part of what the LHC is doing when it collides protons.

0:47:060:47:09

The collision is incredibly energetic and that energy provides

0:47:090:47:14

the kind of quantum mechanical magnifying glass for these particles

0:47:140:47:20

to look inside the extra dimension and report back in an indirect way.

0:47:200:47:24

If it is a graviton, then that has very great significance.

0:47:250:47:30

It's the middle of June at CERN.

0:47:400:47:43

For the last four weeks, the LHC has been running so well

0:47:430:47:47

that the team from ATLAS have finally gathered enough data

0:47:470:47:51

to see if the bump is back.

0:47:510:47:53

The machine has been working over the clock and produced

0:47:560:47:59

a lot of collisions and now we have almost as much data as we got

0:47:590:48:04

in 2015, so it's kind of exciting times because the day has arrived

0:48:040:48:10

to look at this data and to see if there's something there or not.

0:48:100:48:15

I am VERY optimistic!

0:48:150:48:17

Well, last time, I was actually quite pessimistic

0:48:170:48:21

cos I didn't think that we would get enough data at this point,

0:48:210:48:25

so now my optimism is going up and up with each day!

0:48:250:48:30

My gut feeling - I...

0:48:300:48:33

Oh, I'm really oscillating, I would say, and, erm...

0:48:330:48:38

Yeah, I still hope there is something there.

0:48:380:48:43

The results will be revealed in an ATLAS team meeting.

0:48:470:48:51

You have to stay outside.

0:48:520:48:55

The secrecy is because ATLAS have beaten CMS to it

0:49:040:49:08

and they don't want them to know their conclusions.

0:49:080:49:11

An hour later, Marco and the team are out. The results are clear.

0:49:170:49:22

750 is here, so you will expect to see a bump somewhere here.

0:49:240:49:29

The data is the data, so unless we made

0:49:290:49:31

a very bad mistake in processing the data,

0:49:310:49:35

you can see by eye that there is no evident excess there.

0:49:350:49:39

It's very flat. There is no bump there.

0:49:390:49:42

Data that we have looked at from this year,

0:49:450:49:48

we haven't seen anything yet, which is a bit disappointing,

0:49:480:49:51

to be honest, but that's actually how most of our searches turn out.

0:49:510:49:57

We don't allow ourselves to hope, but, of course,

0:49:570:50:00

we are humans and we were probably

0:50:000:50:02

unconsciously hoping for something more and we're not seeing it.

0:50:020:50:07

It might simply mean there was a fluctuation

0:50:070:50:10

of the background noise in 2015 that has gone away,

0:50:100:50:13

so it's a bit disappointing, honestly,

0:50:130:50:16

and, of course, we are not in the position

0:50:160:50:19

to draw a definitive conclusion,

0:50:190:50:21

but, yeah, it could have been a more exciting day.

0:50:210:50:25

The only hope for the bump

0:50:260:50:28

is that it's been found by the other team, CMS.

0:50:280:50:32

They don't know about the ATLAS results and, three days later,

0:50:340:50:39

they're ready to look at their data.

0:50:390:50:42

I am very excited.

0:50:440:50:47

At least in my life, working life,

0:50:470:50:49

it's the most exciting moment.

0:50:490:50:51

So now we're going to open the reports.

0:50:570:51:01

And there's nothing.

0:51:020:51:05

So, no bump.

0:51:060:51:08

Nothing is there.

0:51:100:51:11

We just see something that is compatible with the expectations.

0:51:110:51:16

There was just... There have been many times in the past.

0:51:170:51:20

It will happen in the future.

0:51:200:51:22

Too bad. Of course, you are hopeful that somebody finds something

0:51:220:51:25

cos that's basically why we do the job,

0:51:250:51:28

but it basically tells everybody now that we don't need to be excited

0:51:280:51:32

because the fluctuation we saw for the moment is gone

0:51:320:51:36

and now we have to wait for the rest of the data.

0:51:360:51:41

So, I'm looking at it and, er...

0:51:430:51:47

And...

0:51:490:51:51

there is nothing.

0:51:510:51:54

The results are shared with the rest of the team at the weekly meeting.

0:51:570:52:01

Can you hear me?

0:52:040:52:06

The 750 bump now doesn't look very healthy, put it like this.

0:52:070:52:14

So, I'm going to report on the status of the analysis.

0:52:140:52:21

I would give it 95% probability that it was fluctuation

0:52:230:52:30

and in fact we always said that and we tried to keep very cool about it.

0:52:300:52:35

Obviously, I would have preferred that nature had surprised us

0:52:350:52:40

because it was a real surprise, this 750 thing.

0:52:400:52:44

On the other hand, if this thing had been real, it would have really

0:52:440:52:47

meant a complete change of the way we interpret nature,

0:52:470:52:53

so it has always been in the back of my mind

0:52:530:52:56

that this thing could be a fluctuation.

0:52:560:53:00

We got permission to look at data over the weekend

0:53:000:53:04

and now if we look at data,

0:53:040:53:05

what we can see is the observed 750 is not confirmed.

0:53:050:53:11

But in the next months, we'll get four times more statistics

0:53:110:53:14

so by that time, one will be able to tell for sure.

0:53:140:53:19

It's the 5th of August.

0:53:480:53:50

Tiziano and Dave are in Chicago for the conference.

0:53:500:53:54

The time has come for them to share the results of their hunt

0:54:020:54:05

for the 750 GEV bump with the rest of the physics world.

0:54:050:54:10

It's a great pleasure to be here today to talk about the first half

0:54:150:54:18

of the highlights from the LHC and the way we've organised this...

0:54:180:54:22

Further data has confirmed what the teams feared.

0:54:220:54:25

But then, as you will have heard,

0:54:250:54:27

we were looking at the 2016 data

0:54:270:54:29

and I'm afraid to say in the 2016 data,

0:54:290:54:31

there is no clustering around the 730-750 GEV region

0:54:310:54:36

and so there's about four times more data and so, from this,

0:54:360:54:39

we have to conclude that the 2015 excess

0:54:390:54:41

was most likely a statistical fluctuation.

0:54:410:54:44

The dream of the 750 GEV bump is over.

0:54:440:54:48

It would have been a revolution.

0:54:500:54:51

Yep, we would have broken the Standard Model of particle physics.

0:54:510:54:55

It would have sent a lot of theories back to the drawing board.

0:54:550:54:59

The bump was just a fluctuation in the data.

0:55:010:55:05

That it was seen by both detectors was a highly unlikely coincidence.

0:55:050:55:10

The bump was a cruel statistical fluke.

0:55:100:55:14

It's simply the kind of thing which can happen because basically

0:55:140:55:20

when we're dealing with statistics, it's like,

0:55:200:55:22

you know, flipping a coin five to ten times,

0:55:220:55:26

you can always get heads.

0:55:260:55:27

And the disappointing news

0:55:290:55:31

quickly reaches the rest of the physics world.

0:55:310:55:34

We'd have vastly preferred that it WAS there because it would have

0:55:360:55:40

definitely heralded a much richer particle physics

0:55:400:55:44

that would play out, guaranteed, in the next few years.

0:55:440:55:47

Scientists are human and so we have feelings just like everyone else.

0:55:470:55:51

I guess, in my case, I would say disappointment

0:55:510:55:54

but not discouragement, and so we have to look a little bit harder.

0:55:540:55:58

The 750 GEV bump didn't live up to anyone's hopes.

0:56:010:56:05

But the quest to understand the mysteries

0:56:080:56:11

of the particle world are far from over.

0:56:110:56:13

Back at CERN, the hunt for particles goes on

0:56:180:56:21

and they're certainly not giving up.

0:56:210:56:24

We are clever beings.

0:56:270:56:29

Human beings are clever beings, so our intrinsic wish

0:56:290:56:34

and our intrinsic duty and right

0:56:340:56:36

is really to be intelligent, clever beings.

0:56:360:56:40

Today, the LHC is operating at the highest capacity it's ever achieved.

0:56:400:56:46

The machine is performing exceptionally well at the moment.

0:56:480:56:52

We really are somewhere where we didn't expect to be.

0:56:520:56:55

Things aren't breaking down very often and we're sitting there

0:56:550:56:58

for 24 hours at a time with stable beams continually producing

0:56:580:57:03

these high rates of collisions to the experiments

0:57:030:57:06

and nothing's going wrong.

0:57:060:57:08

These bottles have come from ATLAS and CMS. We had a small celebration.

0:57:080:57:12

We actually reached design luminosity a couple of weeks ago.

0:57:120:57:15

This was actually a quite profound achievement for the LHC.

0:57:150:57:19

The Large Hadron Collider is the most ambitious

0:57:190:57:22

scientific experiment ever undertaken.

0:57:220:57:25

For now, it's holding on to its secrets,

0:57:250:57:28

but the teams working there

0:57:280:57:30

still hope that they will be the ones to unlock them.

0:57:300:57:34

One day. Oh, there's a huge amount more in the LHC.

0:57:340:57:38

We've barely started the journey at this point, clearly.

0:57:380:57:41

We have another 20 years of data-taking

0:57:410:57:44

and we will have huge, huge data samples

0:57:440:57:47

and lots of sensitivity to new particles if they're there.

0:57:470:57:51

I'm excited about the future.

0:57:510:57:53

The one thing where I would not be ready to bet

0:57:530:57:56

is whether the discovery's going to happen in the next six months,

0:57:560:57:59

the next three years or the next ten years.

0:57:590:58:02

It all depends on how kind nature is going to be with us.

0:58:020:58:06

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