0:00:00.246,0:00:02.974 What is the Higgs? 0:00:03.785,0:00:07.333 Since 1964 we've had this idea 0:00:07.579,0:00:11.030 proposed by Englert, Brout and Higgs 0:00:11.709,0:00:15.287 that empty space is like a medium 0:00:16.117,0:00:19.575 and as particles travel through this medium 0:00:19.852,0:00:21.829 some of them interact with it, 0:00:21.967,0:00:23.906 some of them don't interact with it, 0:00:24.365,0:00:27.213 The ones that do interact with this medium, 0:00:27.305,0:00:28.790 they acquire masses, 0:00:28.898,0:00:31.604 and the ones that pass through it without interacting, 0:00:31.742,0:00:33.557 those are massless particles. 0:00:34.065,0:00:36.421 Let me give you an analogy: 0:00:36.421,0:00:40.047 imagine an infinite field of snow 0:00:40.047,0:00:42.774 extending thoughout all of space, 0:00:43.113,0:00:46.824 flat, featureless, going in all directions, 0:00:47.474,0:00:49.565 maybe the middle of Siberia. 0:00:50.215,0:00:52.448 Now imagine that you're trying to cross 0:00:52.448,0:00:53.859 this field of snow. 0:00:54.105,0:00:56.633 So maybe you're a skier, 0:00:56.633,0:00:58.503 and you skim across the top, 0:00:58.503,0:01:00.233 that's like a particle that a particle that 0:01:00.233,0:01:02.287 does not interact with the Higgs field, 0:01:02.287,0:01:05.869 it does not sink into the snow, it goes very fast, 0:01:05.869,0:01:09.646 that's like a particle with no mass travelling at the speed of light. 0:01:10.996,0:01:13.236 But maybe you've only got snw shoes, 0:01:13.236,0:01:16.964 in that case you sink into the Higgs snow field, 0:01:17.629,0:01:21.078 you've got less speed that the skier, 0:01:21.078,0:01:23.225 less that the speed of light, 0:01:23.225,0:01:25.610 that's like a particle with mass, because you are 0:01:25.610,0:01:28.994 connecting, interacting, with that Higgs snow field. 0:01:29.621,0:01:33.222 And then finally if you've just got boots on, 0:01:33.222,0:01:35.769 then you you sink deeply into the snow, 0:01:35.769,0:01:37.792 you go very very slowly, 0:01:37.792,0:01:40.216 and that's like a particle with a big mass. 0:01:40.585,0:01:44.586 So, think of this Higgs field as being 0:01:44.586,0:01:47.466 like this universal field of snow. 0:01:48.288,0:01:51.727 Now, where does the Higgs boson come in? 0:01:52.416,0:01:55.188 We all know what snow is made out of. 0:01:55.188,0:01:57.249 it's made out of snow flakes. 0:01:57.503,0:02:01.923 In the same way this universal Higgs snow fields, 0:02:01.923,0:02:04.913 is made up out of little quanta, 0:02:04.913,0:02:09.654 those quanta are like snowflakes, that's what we call the Higgs boson. 0:02:13.076,0:02:16.890 The Higgs boson has this job of giving masses 0:02:16.890,0:02:18.990 to all the other elementary particles. 0:02:21.835,0:02:25.414 If you look at the basic equations 0:02:25.414,0:02:29.629 of the Standard Model, as written on my T-shirt, 0:02:30.311,0:02:33.013 they're very symmetric, that way in which 0:02:33.202,0:02:35.681 all the different particles appear is the the same. 0:02:36.206,0:02:39.062 At least on the top two lines there're nothing 0:02:39.062,0:02:42.703 to distinguish particles that have different masses for eaxample. 0:02:44.014,0:02:46.213 But this symmetry has to be broken, 0:02:46.998,0:02:49.038 electrons are lighter than muons, 0:02:49.323,0:02:52.241 the top quark is much much heavier 0:02:52.241,0:02:54.241 than the quarks that make up everyday nuclei. 0:02:54.534,0:02:58.170 So, the top two lines, the symmetric lines, 0:02:58.170,0:03:00.242 cannot be all there is, 0:03:00.242,0:03:02.725 there has to be something to discriminate, 0:03:02.725,0:03:05.389 to distinguish, between the different types of particle. 0:03:06.163,0:03:08.370 And that's the job of the Higgs boson, 0:03:08.370,0:03:11.522 that's the job of the two bottom lines. 0:03:11.522,0:03:15.610 Depending on how those different types of quark 0:03:15.671,0:03:17.887 or the electron and muon, 0:03:17.887,0:03:22.839 depending on how they connect to that Higgs field, 0:03:22.839,0:03:25.649 we believe they get different masses. 0:03:25.649,0:03:28.537 The symmetry between these particles is broken.