1 00:00:00,936 --> 00:00:03,497 What is the Higgs? 2 00:00:04,191 --> 00:00:07,982 Since 1964 we've had this idea 3 00:00:08,609 --> 00:00:12,082 proposed by Englert, Brout and Higgs 4 00:00:12,082 --> 00:00:16,597 that empty space is like a medium 5 00:00:16,597 --> 00:00:20,582 and as particles travel through this medium 6 00:00:20,582 --> 00:00:22,742 some of them interact with it, 7 00:00:22,742 --> 00:00:24,351 some of them don't interact with it, 8 00:00:24,351 --> 00:00:27,377 The ones that do interact with this medium, 9 00:00:27,377 --> 00:00:29,096 they acquire masses, 10 00:00:29,096 --> 00:00:31,863 and the ones that pass through it without interacting, 11 00:00:31,863 --> 00:00:34,650 those are massless particles. 12 00:00:34,650 --> 00:00:36,868 Let me give you an analogy: 13 00:00:36,868 --> 00:00:40,665 imagine an infinite field of snow 14 00:00:40,665 --> 00:00:43,867 extending thoughout all of space, 15 00:00:43,867 --> 00:00:47,982 flat, featureless, going in all directions, 16 00:00:47,982 --> 00:00:50,684 maybe the middle of Siberia. 17 00:00:50,684 --> 00:00:52,643 Now imagine that you're trying to cross 18 00:00:52,643 --> 00:00:54,296 this field of snow. 19 00:00:54,296 --> 00:00:56,356 So maybe you're a skier, 20 00:00:56,356 --> 00:00:58,762 and you skim across the top, 21 00:00:58,762 --> 00:01:02,465 that's like a particle that a particle that 22 00:01:02,465 --> 00:01:04,045 does not interact with the Higgs field, 23 00:01:04,045 --> 00:01:06,310 it does not sink into the snow, it goes very fast, 24 00:01:06,310 --> 00:01:11,242 that's like a particle with no mass travelling at the speed of light. 25 00:01:11,242 --> 00:01:13,712 But maybe you've only got snw shoes, 26 00:01:13,712 --> 00:01:17,833 in that case you sink into the Higgs snow field, 27 00:01:17,833 --> 00:01:21,763 you've got less speed that the skier, 28 00:01:21,763 --> 00:01:23,100 less that the speed of light, 29 00:01:23,100 --> 00:01:25,663 that's like a particle with mass, because you are 30 00:01:25,663 --> 00:01:30,109 connecting, interacting, with that Higgs snow field. 31 00:01:30,109 --> 00:01:33,648 And then finally if you've just got boots on, 32 00:01:33,648 --> 00:01:35,830 then you you sink deeply into the snow, 33 00:01:35,830 --> 00:01:37,797 you go very very slowly, 34 00:01:37,797 --> 00:01:40,799 and that's like a particle with a big mass. 35 00:01:40,799 --> 00:01:45,350 So, think of this Higgs field as being 36 00:01:45,350 --> 00:01:48,383 like this universal field of snow. 37 00:01:48,383 --> 00:01:52,541 Now, where does the Higgs boson come in? 38 00:01:52,541 --> 00:01:55,710 We all know what snow is made out of. 39 00:01:55,710 --> 00:01:58,327 it's made out of snow flakes. 40 00:01:58,327 --> 00:02:02,376 In the same way this universal Higgs snow fields, 41 00:02:02,376 --> 00:02:04,892 is made up out of little quanta, 42 00:02:04,892 --> 00:02:11,265 those quanta are like snowflakes, that's what we call the Higgs boson. 43 00:02:13,499 --> 00:02:16,881 The Higgs boson has this job of giving masses 44 00:02:16,881 --> 00:02:20,365 to all the other elementary particles. 45 00:02:23,485 --> 00:02:26,175 If you look at the basic equations 46 00:02:26,175 --> 00:02:30,715 of the Standard Model, as written on my T-shirt, 47 00:02:30,715 --> 00:02:33,949 they're very symmetric, that way in which 48 00:02:33,949 --> 00:02:36,733 all the different particles appear is the the same. 49 00:02:36,733 --> 00:02:39,268 At least on the top two lines there're nothing 50 00:02:39,268 --> 00:02:43,277 to distinguish particles that have different masses for eaxample. 51 00:02:44,132 --> 00:02:47,263 But this symmetry has to be broken, 52 00:02:47,263 --> 00:02:50,727 electrons are lighter than muons, 53 00:02:50,727 --> 00:02:54,050 the top quark is much much heavier 54 00:02:54,050 --> 00:02:56,501 than the quarks that make up everyday nuclei. 55 00:02:56,501 --> 00:02:59,149 So, the top two lines, the symmetric lines, 56 00:02:59,149 --> 00:03:01,060 cannot be all there is, 57 00:03:01,060 --> 00:03:02,592 there has to be something to discriminate, 58 00:03:02,592 --> 00:03:05,998 to distinguish, between the different types of particle. 59 00:03:06,530 --> 00:03:09,177 And that's the job of the Higgs boson, 60 00:03:09,177 --> 00:03:11,618 that's the job of the two bottom lines. 61 00:03:11,618 --> 00:03:16,216 Depending on how those different types of quark 62 00:03:16,216 --> 00:03:18,543 or the electron and muon, 63 00:03:18,543 --> 00:03:23,242 depending on how they connect to that Higgs field, 64 00:03:23,242 --> 00:03:25,982 we believe they get different masses. 65 00:03:25,982 --> 99:59:59,999 The symmetry between these particles is broken.