WEBVTT 00:00:00.246 --> 00:00:02.974 What is the Higgs? 00:00:03.785 --> 00:00:07.333 Since 1964 we've had this idea 00:00:07.579 --> 00:00:11.030 proposed by Englert, Brout and Higgs 00:00:11.709 --> 00:00:15.287 that empty space is like a medium 00:00:16.117 --> 00:00:19.575 and as particles travel through this medium 00:00:19.852 --> 00:00:21.829 some of them interact with it, 00:00:21.967 --> 00:00:23.906 some of them don't interact with it, 00:00:24.365 --> 00:00:27.213 The ones that do interact with this medium, 00:00:27.305 --> 00:00:28.790 they acquire masses, 00:00:28.898 --> 00:00:31.604 and the ones that pass through it without interacting, 00:00:31.742 --> 00:00:33.557 those are massless particles. 00:00:34.065 --> 00:00:36.421 Let me give you an analogy: 00:00:36.421 --> 00:00:40.047 imagine an infinite field of snow 00:00:40.047 --> 00:00:42.774 extending thoughout all of space, 00:00:43.113 --> 00:00:46.824 flat, featureless, going in all directions, 00:00:47.474 --> 00:00:49.565 maybe the middle of Siberia. 00:00:50.215 --> 00:00:52.448 Now imagine that you're trying to cross 00:00:52.448 --> 00:00:53.859 this field of snow. 00:00:54.105 --> 00:00:56.633 So maybe you're a skier, 00:00:56.633 --> 00:00:58.503 and you skim across the top, 00:00:58.503 --> 00:01:00.233 that's like a particle that a particle that 00:01:00.233 --> 00:01:02.287 does not interact with the Higgs field, 00:01:02.287 --> 00:01:05.869 it does not sink into the snow, it goes very fast, 00:01:05.869 --> 00:01:09.646 that's like a particle with no mass travelling at the speed of light. 00:01:10.996 --> 00:01:13.236 But maybe you've only got snw shoes, 00:01:13.236 --> 00:01:16.964 in that case you sink into the Higgs snow field, 00:01:17.629 --> 00:01:21.078 you've got less speed that the skier, 00:01:21.078 --> 00:01:23.225 less that the speed of light, 00:01:23.225 --> 00:01:25.610 that's like a particle with mass, because you are 00:01:25.610 --> 00:01:28.994 connecting, interacting, with that Higgs snow field. 00:01:29.621 --> 00:01:33.222 And then finally if you've just got boots on, 00:01:33.222 --> 00:01:35.769 then you you sink deeply into the snow, 00:01:35.769 --> 00:01:37.792 you go very very slowly, 00:01:37.792 --> 00:01:40.216 and that's like a particle with a big mass. 00:01:40.585 --> 00:01:44.586 So, think of this Higgs field as being 00:01:44.586 --> 00:01:47.466 like this universal field of snow. 00:01:48.288 --> 00:01:51.727 Now, where does the Higgs boson come in? 00:01:52.416 --> 00:01:55.188 We all know what snow is made out of. 00:01:55.188 --> 00:01:57.249 it's made out of snow flakes. 00:01:57.503 --> 00:02:01.923 In the same way this universal Higgs snow fields, 00:02:01.923 --> 00:02:04.913 is made up out of little quanta, 00:02:04.913 --> 00:02:09.654 those quanta are like snowflakes, that's what we call the Higgs boson. 00:02:13.076 --> 00:02:16.890 The Higgs boson has this job of giving masses 00:02:16.890 --> 00:02:18.990 to all the other elementary particles. 00:02:21.835 --> 00:02:25.414 If you look at the basic equations 00:02:25.414 --> 00:02:29.629 of the Standard Model, as written on my T-shirt, 00:02:30.311 --> 00:02:33.013 they're very symmetric, that way in which 00:02:33.202 --> 00:02:35.681 all the different particles appear is the the same. 00:02:36.206 --> 00:02:39.062 At least on the top two lines there're nothing 00:02:39.062 --> 00:02:42.703 to distinguish particles that have different masses for eaxample. 00:02:44.014 --> 00:02:46.213 But this symmetry has to be broken, 00:02:46.998 --> 00:02:49.038 electrons are lighter than muons, 00:02:49.323 --> 00:02:52.241 the top quark is much much heavier 00:02:52.241 --> 00:02:54.241 than the quarks that make up everyday nuclei. 00:02:54.534 --> 00:02:58.170 So, the top two lines, the symmetric lines, 00:02:58.170 --> 00:03:00.242 cannot be all there is, 00:03:00.242 --> 00:03:02.725 there has to be something to discriminate, 00:03:02.725 --> 00:03:05.389 to distinguish, between the different types of particle. 00:03:06.163 --> 00:03:08.370 And that's the job of the Higgs boson, 00:03:08.370 --> 00:03:11.522 that's the job of the two bottom lines. 00:03:11.522 --> 00:03:15.610 Depending on how those different types of quark 00:03:15.671 --> 00:03:17.887 or the electron and muon, 00:03:17.887 --> 00:03:22.839 depending on how they connect to that Higgs field, 00:03:22.839 --> 00:03:25.649 we believe they get different masses. 00:03:25.649 --> 00:03:28.537 The symmetry between these particles is broken.