WEBVTT 00:00:00.936 --> 00:00:03.497 What is the Higgs? 00:00:04.191 --> 00:00:07.982 Since 1964 we've had this idea 00:00:08.609 --> 00:00:12.082 proposed by Englert, Brout and Higgs 00:00:12.082 --> 00:00:16.597 that empty space is like a medium 00:00:16.597 --> 00:00:20.582 and as particles travel through this medium 00:00:20.582 --> 00:00:22.742 some of them interact with it, 00:00:22.742 --> 00:00:24.351 some of them don't interact with it, 00:00:24.351 --> 00:00:27.377 The ones that do interact with this medium, 00:00:27.377 --> 00:00:29.096 they acquire masses, 00:00:29.096 --> 00:00:31.863 and the ones that pass through it without interacting, 00:00:31.863 --> 00:00:34.650 those are massless particles. 00:00:34.650 --> 00:00:36.868 Let me give you an analogy: 00:00:36.868 --> 00:00:40.665 imagine an infinite field of snow 00:00:40.665 --> 00:00:43.867 extending thoughout all of space, 00:00:43.867 --> 00:00:47.982 flat, featureless, going in all directions, 00:00:47.982 --> 00:00:50.684 maybe the middle of Siberia. 00:00:50.684 --> 00:00:52.643 Now imagine that you're trying to cross 00:00:52.643 --> 00:00:54.296 this field of snow. 00:00:54.296 --> 00:00:56.356 So maybe you're a skier, 00:00:56.356 --> 00:00:58.762 and you skim across the top, 00:00:58.762 --> 00:01:02.465 that's like a particle that a particle that 00:01:02.465 --> 00:01:04.045 does not interact with the Higgs field, 00:01:04.045 --> 00:01:06.310 it does not sink into the snow, it goes very fast, 00:01:06.310 --> 00:01:11.242 that's like a particle with no mass travelling at the speed of light. 00:01:11.242 --> 00:01:13.712 But maybe you've only got snw shoes, 00:01:13.712 --> 00:01:17.833 in that case you sink into the Higgs snow field, 00:01:17.833 --> 00:01:21.763 you've got less speed that the skier, 00:01:21.763 --> 00:01:23.100 less that the speed of light, 00:01:23.100 --> 00:01:25.663 that's like a particle with mass, because you are 00:01:25.663 --> 00:01:30.109 connecting, interacting, with that Higgs snow field. 00:01:30.109 --> 00:01:33.648 And then finally if you've just got boots on, 00:01:33.648 --> 00:01:35.830 then you you sink deeply into the snow, 00:01:35.830 --> 00:01:37.797 you go very very slowly, 00:01:37.797 --> 00:01:40.799 and that's like a particle with a big mass. 00:01:40.799 --> 00:01:45.350 So, think of this Higgs field as being 00:01:45.350 --> 00:01:48.383 like this universal field of snow. 00:01:48.383 --> 00:01:52.541 Now, where does the Higgs boson come in? 00:01:52.541 --> 00:01:55.710 We all know what snow is made out of. 00:01:55.710 --> 00:01:58.327 it's made out of snow flakes. 00:01:58.327 --> 00:02:02.376 In the same way this universal Higgs snow fields, 00:02:02.376 --> 00:02:04.892 is made up out of little quanta, 00:02:04.892 --> 00:02:11.265 those quanta are like snowflakes, that's what we call the Higgs boson. 00:02:13.499 --> 00:02:16.881 The Higgs boson has this job of giving masses 00:02:16.881 --> 00:02:20.365 to all the other elementary particles. 00:02:23.485 --> 00:02:26.175 If you look at the basic equations 00:02:26.175 --> 00:02:30.715 of the Standard Model, as written on my T-shirt, 00:02:30.715 --> 00:02:33.949 they're very symmetric, that way in which 00:02:33.949 --> 00:02:36.733 all the different particles appear is the the same. 00:02:36.733 --> 00:02:39.268 At least on the top two lines there're nothing 00:02:39.268 --> 00:02:43.277 to distinguish particles that have different masses for eaxample. 00:02:44.132 --> 00:02:47.263 But this symmetry has to be broken, 00:02:47.263 --> 00:02:50.727 electrons are lighter than muons, 00:02:50.727 --> 00:02:54.050 the top quark is much much heavier 00:02:54.050 --> 00:02:56.501 than the quarks that make up everyday nuclei. 00:02:56.501 --> 00:02:59.149 So, the top two lines, the symmetric lines, 00:02:59.149 --> 00:03:01.060 cannot be all there is, 00:03:01.060 --> 00:03:02.592 there has to be something to discriminate, 00:03:02.592 --> 00:03:05.998 to distinguish, between the different types of particle. 00:03:06.530 --> 00:03:09.177 And that's the job of the Higgs boson, 00:03:09.177 --> 00:03:11.618 that's the job of the two bottom lines. 00:03:11.618 --> 00:03:16.216 Depending on how those different types of quark 00:03:16.216 --> 00:03:18.543 or the electron and muon, 00:03:18.543 --> 00:03:23.242 depending on how they connect to that Higgs field, 00:03:23.242 --> 00:03:25.982 we believe they get different masses. 00:03:25.982 --> 99:59:59.999 The symmetry between these particles is broken.