WEBVTT - ATLAS and the LHC 0:00:04.519 --> 0:00:13.119 Technology with tech Stuff from stuff works dot com. Hey there, everybody, 0:00:13.119 --> 0:00:17.040 and welcome to text Stuff. I am your host, Jonathan Strickland. 0:00:17.120 --> 0:00:20.200 I'm a senior writer with how stuff works dot com 0:00:20.239 --> 0:00:22.600 and tech Stuff is the podcast where we look at 0:00:22.640 --> 0:00:27.920 all things technological in existence, try to understand how they 0:00:27.960 --> 0:00:30.800 work and why are they important or are they no 0:00:30.840 --> 0:00:34.640 longer important or were they never important? Today, there's a 0:00:34.800 --> 0:00:37.559 really important one, and in fact, we've done an episode 0:00:37.640 --> 0:00:40.319 about this very topic. Back in two thousand twelve, tech 0:00:40.360 --> 0:00:43.519 Stuff did an episode about the Large Hadron Collider and 0:00:43.560 --> 0:00:47.040 a lot has happened in those five years since that podcast, 0:00:47.080 --> 0:00:49.280 so I thought it would be good to revisit the topic. Plus, 0:00:49.720 --> 0:00:51.839 some of my coworkers had a chance to chat with 0:00:51.880 --> 0:00:56.840 some scientists from the LHC at mog Festen. I'm incredibly 0:00:57.040 --> 0:00:59.840 envious of that and I'm going to include some excerpts 0:00:59.840 --> 0:01:02.200 from those interviews in this episode, and they're pretty awesome. 0:01:02.960 --> 0:01:05.679 So what is the Large Hadron Collider? What is this 0:01:05.959 --> 0:01:09.319 LHC thing? Well, what's a particle accelerator, which means it 0:01:09.440 --> 0:01:14.040 uses forces to accelerate subatomic particles two speeds approaching the 0:01:14.080 --> 0:01:17.880 speed of light. The LHC design allows for two streams 0:01:17.880 --> 0:01:21.399 to accelerate in opposite directions, each looping around the massive 0:01:21.480 --> 0:01:24.800 facility millions of times per second until the two beams 0:01:24.800 --> 0:01:28.319 of particles converge at one of four collision points. They're 0:01:28.360 --> 0:01:31.400 the particles collide with such force that they annihilate each other, 0:01:31.520 --> 0:01:33.600 and we look at the reaction to learn more about 0:01:33.640 --> 0:01:37.800 the fundamental nature of the universe. That's the short version. 0:01:38.200 --> 0:01:41.280 Now let's dive into a longer one. Now, first, what 0:01:41.360 --> 0:01:44.000 the heck is a hadron? Well, technically, it's a particle 0:01:44.000 --> 0:01:49.200 that has made up of quirks, antiquarks, and gluons. Oh, 0:01:49.280 --> 0:01:52.680 our definition has raised the need for more definitions. Alright, 0:01:52.720 --> 0:01:55.000 So a quirk is the sound made by a dirk. 0:01:55.760 --> 0:01:57.840 I'm just kidding. I stole that joke from a book 0:01:57.880 --> 0:02:00.920 called Science Made Stupid, which as a kid I thought 0:02:01.040 --> 0:02:04.880 was the pinnacle of humor. A quirk is actually a 0:02:05.000 --> 0:02:09.320 family of elementary particles that come in different pairs, So 0:02:09.440 --> 0:02:12.160 you could have an up quirk and a down cork. 0:02:12.800 --> 0:02:16.239 These paired quarks have a similar mass but different charges. 0:02:16.680 --> 0:02:19.920 Quirks are bound by the strong nuclear force, which is 0:02:19.919 --> 0:02:23.320 the strongest of the four fundamental forces in the universe, 0:02:23.360 --> 0:02:26.040 and the other three are the weak nuclear force, the 0:02:26.120 --> 0:02:30.320 electro magnetic force, and gravity. While the strong nuclear force 0:02:30.600 --> 0:02:33.560 is the strongest of the four fundamental forces, it also 0:02:33.600 --> 0:02:38.280 operates across the smallest distances, so it's a very strong force, 0:02:38.360 --> 0:02:41.360 but only at distances that are on the subatomic scale. 0:02:42.240 --> 0:02:48.040 An antiquark is the antiparticle component of a cork. Everything 0:02:48.080 --> 0:02:50.960 turns into another. Call for a definition, So an antiparticle 0:02:51.120 --> 0:02:54.799 is one that is identical to a subatomic particle in mass, 0:02:54.840 --> 0:02:58.600 but opposite to it in electric and magnetic properties. When 0:02:58.639 --> 0:03:02.359 these two otherwise idea nicle subatomic particles encounter one another, 0:03:02.400 --> 0:03:06.720 a particle and its antiparticle, they annihilate each other. If 0:03:06.760 --> 0:03:10.200 you've heard about matter and antimatter, it's that concept. When 0:03:10.200 --> 0:03:13.520 our universe formed, for some reason, there was a teen 0:03:13.680 --> 0:03:17.360 c tiny bit more matter than there was anti matter. 0:03:17.639 --> 0:03:20.040 If the two had been equal, they would have annihilated 0:03:20.080 --> 0:03:23.679 each other and we wouldn't have you know, movie theaters 0:03:23.720 --> 0:03:27.920 and caso and stars and stuff. So an antiquark is 0:03:27.960 --> 0:03:32.480 the antiparticle two quarks. But what are gluons. Well, these 0:03:32.520 --> 0:03:37.840 are neutral, massless particles that are forced carrying particles. Sometimes 0:03:37.840 --> 0:03:41.440 they are called messenger particles of the strong nuclear force, 0:03:41.720 --> 0:03:45.600 and there are eight different types of gluons, so you're gluons. 0:03:45.840 --> 0:03:50.040 Quarks and antiquarks are bound together to create certain subatomic 0:03:50.120 --> 0:03:54.560 particles like protons and neutrons. There are lots of them 0:03:54.560 --> 0:03:59.520 in every sub atomic particle, like a countless number of them, 0:03:59.760 --> 0:04:03.760 and number is constantly changing. Within a proton, for example, 0:04:04.120 --> 0:04:09.120 there's a shorthand and somewhat misleading statement that protons are 0:04:09.120 --> 0:04:12.760 made up of two up quarks and one down quirk. 0:04:13.080 --> 0:04:16.080 But that sounds like there's just three quarks and a proton. 0:04:16.560 --> 0:04:19.599 Nothing can be further from the truth. There are zillions 0:04:19.640 --> 0:04:23.720 of quarks inside a proton. The shorthand actually means there 0:04:23.760 --> 0:04:27.320 are two more up quarks, then there are up anti 0:04:27.360 --> 0:04:31.600 quarks and one more down quirk than down anti quarks. 0:04:31.960 --> 0:04:34.599 So it's sort of a microcosm of a well, I 0:04:34.600 --> 0:04:38.040 guess the macro cosm of the cosmos itself. Remember when 0:04:38.040 --> 0:04:40.200 I said there were you know, if there were equal 0:04:40.240 --> 0:04:43.560 amounts matter and anti matter, everything would be annihilated. Well, 0:04:43.600 --> 0:04:48.200 there you go. Theoretical physicist Matt Strassler has a great 0:04:48.279 --> 0:04:51.480 article about this that makes it easier to understand and 0:04:51.560 --> 0:04:54.520 in that article. He explains that a proton consists of 0:04:54.560 --> 0:04:59.000 these uncountable elementary particles with gluon's moving around at near 0:04:59.080 --> 0:05:02.960 the speed of light, sometimes appearing or disappearing. And he says, 0:05:03.040 --> 0:05:07.040 your hydrogen atom, which consists of a relatively stationary proton 0:05:07.120 --> 0:05:10.400 as the nucleus and a single electron zipping around it 0:05:10.520 --> 0:05:14.240 speeds far below the speed of light, is a peaceful 0:05:14.360 --> 0:05:18.000 example of balance compared to what's going on inside of 0:05:18.040 --> 0:05:21.080 a proton. And then he uses this analogy which I 0:05:21.120 --> 0:05:24.640 love so much I have to quote it directly. He says, 0:05:25.320 --> 0:05:29.040 in short, atoms are too protons as a pod to 0:05:29.080 --> 0:05:32.080 do in a delicate ballet is to a dance floor 0:05:32.200 --> 0:05:35.560 crowded with drunk twenty something's bouncing and flailing to a 0:05:35.680 --> 0:05:41.440 dj That that image really works for me. Particle accelerators 0:05:41.480 --> 0:05:45.800 like the LHC smash open subatomic particles like protons to 0:05:45.920 --> 0:05:49.480 study these elementary particles and their behaviors, as well as 0:05:49.520 --> 0:05:52.400 to suss out the fundamental secrets of the universe. So 0:05:52.440 --> 0:05:55.160 I started off this whole rabbit hole by asking the 0:05:55.279 --> 0:05:58.920 question what is a hadron? Well, hadrons include not only protons, 0:05:58.960 --> 0:06:04.000 but also neutron, pion plus articles, kon plus articles, and 0:06:04.360 --> 0:06:07.599 other stuff that's more exotic than your basic atomic science 0:06:07.600 --> 0:06:11.720 class typically covers. The commonality between all of these particles 0:06:11.760 --> 0:06:15.280 is that they are made up of some combination of quarks, antiquarks, 0:06:15.320 --> 0:06:18.560 and gluons, and the nature of that combination determines what 0:06:18.720 --> 0:06:22.080 sort of particles they are and thus their physical properties. 0:06:22.320 --> 0:06:24.960 The Large Hadron Collider's mission is to smash these sorts 0:06:24.960 --> 0:06:28.839 of particles apart, violently and at great speeds. All right, 0:06:28.920 --> 0:06:31.640 so let's look at some history of how the LHC 0:06:31.960 --> 0:06:34.120 came to be, and then we'll look at how it 0:06:34.240 --> 0:06:39.080 do what it do. In n four, the European Committee 0:06:39.080 --> 0:06:43.080 for Future Accelerators met with CERN to discuss a new 0:06:43.120 --> 0:06:48.120 particle accelerator facility. And CERTAIN is an amazing organization. You 0:06:48.160 --> 0:06:52.000 may recall that Tim berners Lee, who is credited as 0:06:52.040 --> 0:06:55.919 being the father of the Worldwide Web, he created that 0:06:56.000 --> 0:06:58.799 first web page for CERN. He was working for CERN. 0:06:59.360 --> 0:07:04.000 So CERTAIN has had a very important role in technology 0:07:04.040 --> 0:07:06.599 for years, and it's gone well outside of just the 0:07:06.640 --> 0:07:09.520 realm of particle physics. And I can't believe I used 0:07:09.520 --> 0:07:15.000 the sentence just the realm of particle physics. So this 0:07:15.480 --> 0:07:19.640 new facility they started to talk about was an idea 0:07:19.680 --> 0:07:23.840 for a new collider. The event's name itself was the 0:07:23.920 --> 0:07:27.280 Large Hadron Collider in the l EP Tunnel. That was 0:07:27.320 --> 0:07:29.320 what they called it, the Large Hadron Collider in the 0:07:29.480 --> 0:07:32.680 l EP Tunnel. L EP is an acronym for the 0:07:32.800 --> 0:07:37.120 Large Electron Positron Collider. I'm sure you know. An electron 0:07:37.240 --> 0:07:40.920 is the negatively charged subatomic particle that typically orbits an 0:07:40.920 --> 0:07:44.800 atomic nucleus. It's also the basis for electricity, but you've 0:07:44.840 --> 0:07:47.680 heard me talk about that enough recently, I'm sure. A 0:07:47.840 --> 0:07:51.960 positron is a subatomic particle that has the same mass 0:07:52.200 --> 0:07:54.680 as an electron, but has a positive charge, not a 0:07:54.720 --> 0:07:58.080 negative one. The magnitude of that charge is numerically the 0:07:58.160 --> 0:08:01.800 same as an electrons negative charge, except we're talking positive 0:08:01.840 --> 0:08:05.520 instead of negative with positrons. It is therefore the antiparticle 0:08:05.880 --> 0:08:10.520 to an electron. Unlike protons, which are a type of hadron, 0:08:10.960 --> 0:08:15.080 electrons and positrons are fundamental particles that cannot be split 0:08:15.160 --> 0:08:19.480 into any smaller particles. They interact through the weak nuclear force, 0:08:19.600 --> 0:08:22.120 not the strong nuclear force. This puts them in a 0:08:22.160 --> 0:08:26.720 category of subatomic particles called leptons. This also includes stuff 0:08:26.760 --> 0:08:32.760 like muons, electron neutrinos, and various antiparticles. The Large Electron 0:08:32.880 --> 0:08:37.600 Positron Collider became the largest electron positron accelerator ever built. 0:08:38.160 --> 0:08:41.840 Planning for the twenty seven kilometer circumference tunnel began back 0:08:41.880 --> 0:08:46.720 in nineteen eighty three and construction ended in nineteen Digging 0:08:46.760 --> 0:08:50.600 the tunnel took three years, using three tunnel boring machines. 0:08:50.720 --> 0:08:53.800 You know, we talked about those in that Elon Musk 0:08:53.880 --> 0:08:57.360 episode about the hyperloop and the boring company. Those tunnel 0:08:57.360 --> 0:09:01.360 digging devices are pretty slow. A snail is faster. The 0:09:01.559 --> 0:09:05.080 l EP itself was commissioned in July nine, with the 0:09:05.120 --> 0:09:09.080 first beams circulating on Bastille Day of that year. That's 0:09:09.360 --> 0:09:12.640 July fourteenth, in case you aren't up on your French history. 0:09:13.000 --> 0:09:18.160 The first collisions allowed scientists to produce and observe z bosons. 0:09:19.080 --> 0:09:21.840 So now we have another question. One the sam hill 0:09:21.920 --> 0:09:24.680 is a boson? Well, at first I thought a boson 0:09:24.840 --> 0:09:26.680 was the sailor who was in charge of equipment and 0:09:26.720 --> 0:09:28.600 crew aboard a ship. But as it turns out, that's 0:09:28.600 --> 0:09:32.120 a bow sun, which is actually spelled like boat swain, 0:09:32.600 --> 0:09:34.760 and that has nothing to do with particle physics, unless 0:09:34.760 --> 0:09:40.040 you're talking about very tiny boats, Noah. Boson is another 0:09:40.080 --> 0:09:42.720 type of sub atomic particle that has a spin that 0:09:42.760 --> 0:09:45.960 has a quantum number of either zero or an integral number. 0:09:46.160 --> 0:09:48.320 Does that clear it up all right? Well, this might 0:09:48.360 --> 0:09:52.800 be more helpful. According to Einstein's work, all particles in 0:09:52.880 --> 0:09:58.280 existence fall into two broad categories. They are either fermions 0:09:58.679 --> 0:10:01.800 or they are boson. This is all based off of math. 0:10:01.880 --> 0:10:04.760 By the way, Einstein's math only really works if this 0:10:04.840 --> 0:10:08.480 supposition holds true, and so far it seems to be so. 0:10:09.480 --> 0:10:12.760 Bosons include particles that can all do the same thing 0:10:12.840 --> 0:10:15.920 at the same time. For example, a photon is a 0:10:15.960 --> 0:10:19.120 type of boson. You can make photons line up in 0:10:19.120 --> 0:10:22.160 a specific direction in a specific phase, and you can 0:10:22.200 --> 0:10:25.040 create a laser beam with a precise wavelength of color. 0:10:25.360 --> 0:10:28.400 All the photons within that laser beam are behaving in 0:10:28.440 --> 0:10:32.840 the exact same way. Fermions cannot do the same thing 0:10:32.880 --> 0:10:36.400 in the same place. Electrons are a type of fermion. 0:10:36.720 --> 0:10:39.640 They cannot orbit an atom in exactly the same way. 0:10:39.679 --> 0:10:43.000 You can't have two electrons orbiting the atom exactly the 0:10:43.080 --> 0:10:47.479 same way. Fermions include charged leptons such as the electrons 0:10:47.559 --> 0:10:51.319 and positrons I just talked about. Bosons include the force 0:10:51.400 --> 0:10:55.439 carrying particles as well as the Higgs particle. More about 0:10:55.440 --> 0:10:58.920 the Higgs boson in a little bit. Okay, so the 0:10:59.000 --> 0:11:02.760 Z bosons and the W bosons are responsible for the 0:11:02.800 --> 0:11:06.640 weak nuclear force. Later, the l e P was souped 0:11:06.720 --> 0:11:09.560 up so that they could produce pairs of W bosons. 0:11:09.960 --> 0:11:13.000 For eleven years, scientists use the l e P to 0:11:13.160 --> 0:11:17.079 learn more about these mysterious particles, producing them in the millions. 0:11:17.600 --> 0:11:20.920 On November two, two thousand, the l EP shut down 0:11:20.960 --> 0:11:23.840 for the last time, to be dismantled. In its place 0:11:24.160 --> 0:11:27.600 would be the Large Hadron Collider. While the l EP 0:11:27.720 --> 0:11:30.200 project was still in action, other groups were forming to 0:11:30.240 --> 0:11:32.880 create the teams and facilities that would be attached to 0:11:32.960 --> 0:11:36.600 the l h C. One of those was Atlas A 0:11:36.800 --> 0:11:40.439 t l A S. Atlas is a detector that captures 0:11:40.480 --> 0:11:44.520 information from proton proton collisions. It would become one of 0:11:44.760 --> 0:11:48.600 four collision detectors along the path of the LHC. It 0:11:48.920 --> 0:11:52.000 and the CMS detector are the biggest of the experiments 0:11:52.080 --> 0:11:56.160 running on the Large Hadron Collider. There's also alice A, 0:11:56.480 --> 0:12:00.000 l I C E and l h C B detectors 0:12:00.280 --> 0:12:03.160 that look at more specific phenomena. They sit in big 0:12:03.240 --> 0:12:08.040 caverns along the LHC ring underground, but in this timeline 0:12:08.040 --> 0:12:10.959 we're talking about, they were still just ideas. At that point, 0:12:11.000 --> 0:12:13.520 the LHC itself had not yet been approved and the 0:12:13.679 --> 0:12:16.640 l e P was still in operation. The CERN Council 0:12:16.679 --> 0:12:21.439 would approve the LHC project in December nine. In October, 0:12:23.000 --> 0:12:27.160 the project leaders published the LHC Conceptual Design Report, which 0:12:27.160 --> 0:12:31.440 included the idea of these four detectors and their arrangement 0:12:31.520 --> 0:12:35.800 around the perimeter of the LHC ring. CMS and ATLAS 0:12:35.800 --> 0:12:40.080 would both get official approval in January. The following month, 0:12:40.120 --> 0:12:43.040 ALICE would get the nod That happened on Valentine's Day, 0:12:44.280 --> 0:12:49.800 Happy Valentine's Day. Alice. LHC B would be approved on September. 0:12:51.520 --> 0:12:54.840 There are other experiments connected to the LHC with scientific 0:12:54.880 --> 0:12:58.400 instruments that are near the big detectors and that look 0:12:58.440 --> 0:13:01.320 at specific phenomena, but the four detectors are what most 0:13:01.320 --> 0:13:04.040 people are familiar with if they know anything about the LHC. 0:13:04.240 --> 0:13:08.440 That is two years after the LP shut down, so 0:13:08.559 --> 0:13:12.760 this would be two thousand two. The ATLAS cavern was completed. 0:13:13.120 --> 0:13:16.760 Atlas is the largest in volume of all the detectors 0:13:16.840 --> 0:13:19.160 I mentioned earlier. We had a team of producers meet 0:13:19.200 --> 0:13:22.080 with scientists who work with the large hadron colliders, specifically 0:13:22.120 --> 0:13:26.079 with the Atlas project. One of those scientists is Stephen Goldfarb. 0:13:26.320 --> 0:13:30.080 Here's how he explained Atlas's role in the LHC SO. 0:13:30.200 --> 0:13:34.360 Atlas is is one of four large detectors that sits 0:13:34.360 --> 0:13:38.200 at the collision points on large hadron collider. Large hadron 0:13:38.240 --> 0:13:41.520 collider brings protons around and accelerates them and has them 0:13:41.520 --> 0:13:46.280 collide at four different places. You surround those places with detectors. 0:13:46.720 --> 0:13:50.680 Atlas is the largest in volume of these detectors. It's 0:13:50.679 --> 0:13:54.360 about a half of a football field in length to 0:13:54.400 --> 0:13:57.160 give you an idea of the size, and packed full 0:13:57.200 --> 0:13:59.920 of sophisticated equipment. It's one of the most complex devide 0:14:00.200 --> 0:14:03.160 is I think ever constructed. About a hundred more than 0:14:03.160 --> 0:14:06.320 a hundred million different channels of information come out of 0:14:06.360 --> 0:14:11.679 this thing. Its rule is if if you like an analogy. 0:14:11.720 --> 0:14:17.280 Is perhaps the strongest lens on a microscope that's ever 0:14:17.320 --> 0:14:20.400 been built. It's to look into nature and to try 0:14:20.440 --> 0:14:22.880 to understand what we're made out of what are the 0:14:22.880 --> 0:14:27.760 fundamental components of of of matter and then to understand 0:14:27.800 --> 0:14:31.320 the rules around that. And we're making some big steps forward, 0:14:31.880 --> 0:14:34.760 but we still have some major questions to try to answer. 0:14:35.560 --> 0:14:37.720 Now we've got a lot more to say about the LHC, 0:14:38.240 --> 0:14:40.800 but before we dive into the rest of it, let's 0:14:40.800 --> 0:14:50.760 take a quick break to thank our sponsor. We're back now. 0:14:50.880 --> 0:14:54.640 These detectors have to capture information coming from a sub 0:14:54.640 --> 0:14:58.320 atomic scale. Those collisions often will create situations that will 0:14:58.320 --> 0:15:00.800 blip out of existence in just just a moment a 0:15:00.880 --> 0:15:03.560 fraction of a second, so the measurements have to be 0:15:03.680 --> 0:15:08.120 not only precise, but also happen faster than I can 0:15:08.280 --> 0:15:12.200 even imagine. That also means that every observation generates an 0:15:12.360 --> 0:15:15.920 enormous amount of data. So the challenges with the LHC 0:15:16.080 --> 0:15:18.600 aren't just with the physics of getting streams of sub 0:15:18.680 --> 0:15:21.880 atomic particles accelerated to near the speed of light and 0:15:21.880 --> 0:15:24.480 then making them smash together. It's also a lot of 0:15:24.520 --> 0:15:28.080 sorting and analyzing data to find meaningful information hidden in 0:15:28.080 --> 0:15:32.440 those collisions. So it's a monumental amount of work. Back 0:15:32.440 --> 0:15:35.600 to the timeline, the CMS team finished the cavern for 0:15:35.640 --> 0:15:39.040 their detector in two thousand five. Two years later, the 0:15:39.160 --> 0:15:43.040 last of the LHC's super conducting magnets were locked into place. 0:15:43.520 --> 0:15:46.440 Those would be dipole magnets, and this particular one was 0:15:46.480 --> 0:15:50.800 dipole magnet number one thousand, two hundred thirty two. After 0:15:50.800 --> 0:15:53.240 each magnet made the journey down that through the shaft 0:15:53.320 --> 0:15:56.160 to the level of the tunnel one feet below the surface, 0:15:56.480 --> 0:15:58.800 they were loaded into a special vehicle that would take 0:15:58.840 --> 0:16:03.040 them to their destination at a blistering three kilometers per hour. 0:16:03.200 --> 0:16:04.880 You had to go super slow so that you don't 0:16:05.120 --> 0:16:10.080 end up damaging these delicate and enormous pieces of machinery. 0:16:10.480 --> 0:16:14.480 These magnets are are huge. The LHC wasn't ready to 0:16:14.600 --> 0:16:18.400 begin warming up until two thousand eight. At ten a 0:16:18.640 --> 0:16:22.480 m September two thousand eight, the LHC fired a beam 0:16:22.480 --> 0:16:25.880 of protons around the ring for the first time. Unfortunately, 0:16:25.960 --> 0:16:28.880 on September nine, two thousand eight, a fault in the 0:16:28.920 --> 0:16:32.920 electrical bus connection between a dipole and a quadruple caused 0:16:32.920 --> 0:16:37.160 some mechanical damage and released some liquid helium from the system. 0:16:37.160 --> 0:16:40.240 This set work on the LHC back by about a year. 0:16:40.560 --> 0:16:44.280 On April thirty, two thousand nine, the final replacement magnet, 0:16:44.360 --> 0:16:48.240 the fifty third replacement magnet, was lowered down to complete 0:16:48.240 --> 0:16:51.240 the repair work from the September two thousand eight accident. 0:16:52.480 --> 0:16:56.120 November two thousand nine saw particle beams again traveling down 0:16:56.160 --> 0:17:00.800 the LHC path. The LHC conducted collision experiments through November 0:17:00.880 --> 0:17:04.160 and into December two thousand nine. It then shut down 0:17:04.200 --> 0:17:07.240 for the winter, which the LHC does every year in 0:17:07.320 --> 0:17:10.720 order to conserve some energy. And during those first collision experiments, 0:17:10.760 --> 0:17:13.640 scientists were working with collisions on the scale of two 0:17:13.680 --> 0:17:17.919 point three six t e V. T e V stands 0:17:17.920 --> 0:17:21.160 for terra electron volts. An electron volt is a unit 0:17:21.200 --> 0:17:24.280 of energy equal to one point six time ten to 0:17:24.480 --> 0:17:28.960 the power of negative nineteen jewels. It's equal to the 0:17:29.080 --> 0:17:32.400 charge of a single electron moving across an electric potential 0:17:32.440 --> 0:17:36.040 difference of one vault, which you know that sounds like 0:17:36.080 --> 0:17:38.399 a lot, and on a sub atomic scale it is. 0:17:38.880 --> 0:17:41.080 But to give you an idea of what kind of 0:17:41.160 --> 0:17:43.680 energy we're talking about, a mosquito flapping its wings is 0:17:43.680 --> 0:17:47.320 the kinetic energy equivalent of about one terra electron voult, 0:17:47.640 --> 0:17:50.359 so two point three six tera electron volts on the 0:17:50.359 --> 0:17:55.639 macro scale is incredibly tiny. November two thousand nine also 0:17:55.720 --> 0:17:57.480 saw one of the stories that got a lot of 0:17:57.480 --> 0:18:00.280 circulation in the early days of the LHC, which was 0:18:00.320 --> 0:18:04.080 the system shut down due to a bread eating bird. Now, 0:18:04.080 --> 0:18:06.200 the way the story was reported was that the power 0:18:06.240 --> 0:18:09.400 supply to the LHC got frazzled, and when engineers went 0:18:09.440 --> 0:18:12.600 to check where these connections might have shorted out to 0:18:12.640 --> 0:18:15.359 see what the problem was, they found a bird eating 0:18:15.400 --> 0:18:19.640 bread over a power circuit. Crumbs supposedly caused the problem. 0:18:19.680 --> 0:18:22.800 According to CERN, however, this wasn't necessarily the problem. It 0:18:22.920 --> 0:18:25.360 might have contributed to the issue, but they don't really know. 0:18:25.560 --> 0:18:28.600 The truth of the matter was that the power site, uh, 0:18:28.640 --> 0:18:31.240 there were some feathers, there was some bread, and that 0:18:31.320 --> 0:18:33.760 was about all they could really say for sure. Power 0:18:33.920 --> 0:18:37.879 was restored and the LHC experienced only a minor delay. 0:18:38.359 --> 0:18:42.160 In February, the LHC began to circulate beams in preparation 0:18:42.240 --> 0:18:45.359 for more collision experiments in the spring, culminating in two 0:18:45.600 --> 0:18:49.600 three point five terra electron volt proton beams circulating by March. 0:18:50.960 --> 0:18:54.520 This eventually allowed ATLAS to capture information from seven terra 0:18:54.640 --> 0:18:58.560 electron volt center of mass energy collisions for the first time. 0:19:00.000 --> 0:19:04.600 Skip ahead to December, when researchers at the LHC had 0:19:04.600 --> 0:19:07.199 begun to tune into data that could potentially prove the 0:19:07.240 --> 0:19:12.760 existence of the at that time purely hypothetical Higgs Boson particle. 0:19:13.280 --> 0:19:17.680 The Higgs boson is a particle that explains why mass exists, 0:19:18.520 --> 0:19:21.400 as in, why does matter have mass? To dive into 0:19:21.440 --> 0:19:24.160 more detail about this would require someone far better versed 0:19:24.200 --> 0:19:27.240 in quantum mechanics than i am. In two thousand twelve, 0:19:27.440 --> 0:19:31.600 on July four, scientists that the CMS and ATLAS detectors 0:19:31.640 --> 0:19:34.879 confirmed the discovery of a particle consistent with the Higgs 0:19:34.920 --> 0:19:39.760 Boson hypothesis. Atlas scientist Kate Shaw talks about that experience 0:19:40.280 --> 0:19:43.880 so well. The classic story with Atlas is of course 0:19:43.920 --> 0:19:47.040 the discovery of the Higgs boson. So this is really 0:19:47.040 --> 0:19:49.760 one of our miles staying discoveries we've made. And this 0:19:49.840 --> 0:19:53.080 is a long story of over fifty years of fifty 0:19:53.160 --> 0:19:56.160 years old. So it began with us trying to describe 0:19:56.200 --> 0:19:59.480 the universe. There was a big problem where we didn't 0:19:59.560 --> 0:20:02.639 understand why some particles had mass and other ones didn't. 0:20:03.200 --> 0:20:06.119 And so some theorists at the time, including Peter Hicks 0:20:06.760 --> 0:20:10.920 Um made a prediction of a way that these particles 0:20:10.960 --> 0:20:14.160 can have mass, and they said, if it's true, then 0:20:14.200 --> 0:20:16.480 there should be this thing called a h exsposon. Now 0:20:16.600 --> 0:20:19.520 at the time they said, don't even try to look 0:20:19.600 --> 0:20:22.520 for this because it's too difficult, it's too rare, you'll 0:20:22.560 --> 0:20:25.920 never find it. Do not invest in, you know, accelerators 0:20:25.960 --> 0:20:29.000 to do this. But fifty years later, we have the 0:20:29.040 --> 0:20:35.359 technology and know how to make these fantastic particle accelerators, 0:20:35.480 --> 0:20:38.639 and we've been able to find the Higgs boson. We 0:20:38.680 --> 0:20:40.959 found it in two thousand and twelve. And that's a 0:20:40.960 --> 0:20:44.960 fantastic thing that these things were just were predicted fifty 0:20:45.040 --> 0:20:48.239 years ago, and only now are we actually able to 0:20:48.320 --> 0:20:53.040 find and prove these theorists correct. In February, the LHC 0:20:53.320 --> 0:20:55.800 ended its first run of experiments and shut down to 0:20:55.880 --> 0:20:59.280 undergo adjustments for more powerful experiments in the future. The 0:20:59.480 --> 0:21:03.679 estimated downtime was that approximately two years. On June three, 0:21:03.720 --> 0:21:07.879 two thousand fifteen, the LHC came back online, conducting collisions 0:21:07.880 --> 0:21:10.920 at an energy level of thirteen terror electron volts, much 0:21:10.960 --> 0:21:14.880 greater than any particle accelerator ever before. Now I've talked 0:21:14.920 --> 0:21:17.879 about what's going on generally speaking with the LHC, but 0:21:17.960 --> 0:21:21.200 how does it work specifically. For one thing, all those 0:21:21.240 --> 0:21:24.720 magnets have to be really efficient. To maximize efficiency, the 0:21:24.840 --> 0:21:28.080 LHC uses liquid helium to cool components to just a 0:21:28.200 --> 0:21:34.160 hair above absolute zero kelvin. Zero kelvin represents zero molecular movement. 0:21:34.280 --> 0:21:38.280 The molecular movement is essentially heat, so we're talking very 0:21:38.400 --> 0:21:44.280 very very cold here, colder than space. Even had that temperature, 0:21:45.080 --> 0:21:48.520 you can get super conductivity, in which a conductor is 0:21:48.640 --> 0:21:52.320 perfectly efficient and loses no energy as heat. There's no 0:21:52.480 --> 0:21:56.239 resistance in a superconductor. This is why power allages are 0:21:56.240 --> 0:21:58.720 a really big problem for the LHC. The power goes 0:21:58.760 --> 0:22:01.080 out and the system begins to warm up as liquid 0:22:01.080 --> 0:22:04.679 helium stop stops circulating through the system. If it heats 0:22:04.720 --> 0:22:08.000 up enough, it loses its super conductivity, and you have 0:22:08.080 --> 0:22:10.400 to wait until you've cooled it back down to that 0:22:10.560 --> 0:22:13.520 hair above absolute zero before you can begin again. They 0:22:13.520 --> 0:22:16.760 actually use liquid nitrogen to cool it down a certain amount, 0:22:17.160 --> 0:22:20.000 but liquid nitrogen isn't cold enough, so that's why they 0:22:20.040 --> 0:22:23.000 have to go to liquid helium. After it's been cooled down. 0:22:23.040 --> 0:22:27.920 To a certain threshold. So here's how getting those collisions 0:22:27.960 --> 0:22:32.440 to happen works. First, you start with some hydrogen atoms. 0:22:32.480 --> 0:22:35.480 The standard hydrogen atom consists of a single proton and 0:22:35.520 --> 0:22:40.000 a single electron that's orbiting that proton nucleus. Then you 0:22:40.080 --> 0:22:43.320 strip the electron away from the hydrogen atom. That leaves 0:22:43.320 --> 0:22:47.919 you with protons, those positively charged sub atomic particles. The 0:22:47.960 --> 0:22:51.280 protons enter the line act two L I N A 0:22:51.440 --> 0:22:54.760 C two. This is a machine that organizes protons into 0:22:54.800 --> 0:22:58.560 beams and fires them into an accelerator called the PS booster. 0:22:59.359 --> 0:23:03.640 The PS booster uses radio frequency cavities to accelerate the protons, 0:23:03.640 --> 0:23:06.320 so it's an electric field that pushes the protons to 0:23:06.480 --> 0:23:11.679 increasingly higher speeds. Because you've got a charged particle, you 0:23:11.720 --> 0:23:15.239 can use the opposite charge to pull the particle toward it, 0:23:15.480 --> 0:23:18.760 or a similar charge to push the particle away. So 0:23:19.080 --> 0:23:23.639 you just use that to increase the speed of that 0:23:23.720 --> 0:23:27.360 particle as it travels around this particular part of the accelerator. 0:23:28.520 --> 0:23:30.840 Magnets are there to make sure the protons stay on 0:23:30.840 --> 0:23:33.000 the right path. The magnetic fields kind of act as 0:23:33.000 --> 0:23:36.600 bumper rails for the protons. When these beams hit the 0:23:36.600 --> 0:23:39.760 correct energy level as determined by the experiment. They pass 0:23:39.880 --> 0:23:43.240 from the PS booster into another accelerator called the super 0:23:43.320 --> 0:23:47.520 Proton syncotron, which I was pretty sure was a Decepticon 0:23:47.680 --> 0:23:50.919 robot in one of those Michael Bay movies. The beams 0:23:50.920 --> 0:23:54.440 continue to accelerate and the protons separate into bunches. So 0:23:55.000 --> 0:23:58.040 think of groups of protons traveling a circular path, picking 0:23:58.119 --> 0:24:01.480 up speed constantly with other packs of protons right in 0:24:01.560 --> 0:24:04.240 front and right behind them, and each bunch is pretty big. 0:24:04.320 --> 0:24:07.440 I'm talking one point one times ten to the eleventh 0:24:07.520 --> 0:24:11.120 power of protons with two thousand, eight hundred eight bunches 0:24:11.200 --> 0:24:14.800 per beam. Once this beam hits the next threshold and 0:24:14.880 --> 0:24:18.760 energy levels, the SPS then injects it into the actual 0:24:19.200 --> 0:24:22.720 l h C. The beams divide into two. One beam 0:24:22.760 --> 0:24:26.600 travels around the kilometer circumference clockwise and the other one 0:24:26.640 --> 0:24:28.760 goes witter shans, which, as you all know, is my 0:24:28.800 --> 0:24:33.000 favorite synonym for counter clockwise. Now I'll talk more about 0:24:33.040 --> 0:24:35.560 how this works and what comes out of it in 0:24:35.600 --> 0:24:38.159 just a second, but first let's take another quick break 0:24:38.320 --> 0:24:48.280 to thank our sponsor. Alright, So those two beams, which 0:24:48.320 --> 0:24:51.719