0:00:00.936,0:00:03.497 What is the Higgs? 0:00:04.191,0:00:07.982 Since 1964 we've had this idea 0:00:08.609,0:00:12.082 proposed by Englert, Brout and Higgs 0:00:12.082,0:00:16.597 that empty space is like a medium 0:00:16.597,0:00:20.582 and as particles travel through this medium 0:00:20.582,0:00:22.742 some of them interact with it, 0:00:22.742,0:00:24.351 some of them don't interact with it, 0:00:24.351,0:00:27.377 The ones that do interact with this medium, 0:00:27.377,0:00:29.096 they acquire masses, 0:00:29.096,0:00:31.863 and the ones that pass through it without interacting, 0:00:31.863,0:00:34.650 those are massless particles. 0:00:34.650,0:00:36.868 Let me give you an analogy: 0:00:36.868,0:00:40.665 imagine an infinite field of snow 0:00:40.665,0:00:43.867 extending thoughout all of space, 0:00:43.867,0:00:47.982 flat, featureless, going in all directions, 0:00:47.982,0:00:50.684 maybe the middle of Siberia. 0:00:50.684,0:00:52.643 Now imagine that you're trying to cross 0:00:52.643,0:00:54.296 this field of snow. 0:00:54.296,0:00:56.356 So maybe you're a skier, 0:00:56.356,0:00:58.762 and you skim across the top, 0:00:58.762,0:01:02.465 that's like a particle that a particle that 0:01:02.465,0:01:04.045 does not interact with the Higgs field, 0:01:04.045,0:01:06.310 it does not sink into the snow, it goes very fast, 0:01:06.310,0:01:11.242 that's like a particle with no mass travelling at the speed of light. 0:01:11.242,0:01:13.712 But maybe you've only got snw shoes, 0:01:13.712,0:01:17.833 in that case you sink into the Higgs snow field, 0:01:17.833,0:01:21.763 you've got less speed that the skier, 0:01:21.763,0:01:23.100 less that the speed of light, 0:01:23.100,0:01:25.663 that's like a particle with mass, because you are 0:01:25.663,0:01:30.109 connecting, interacting, with that Higgs snow field. 0:01:30.109,0:01:33.648 And then finally if you've just got boots on, 0:01:33.648,0:01:35.830 then you you sink deeply into the snow, 0:01:35.830,0:01:37.797 you go very very slowly, 0:01:37.797,0:01:40.799 and that's like a particle with a big mass. 0:01:40.799,0:01:45.350 So, think of this Higgs field as being 0:01:45.350,0:01:48.383 like this universal field of snow. 0:01:48.383,0:01:52.541 Now, where does the Higgs boson come in? 0:01:52.541,0:01:55.710 We all know what snow is made out of. 0:01:55.710,0:01:58.327 it's made out of snow flakes. 0:01:58.327,0:02:02.376 In the same way this universal Higgs snow fields, 0:02:02.376,0:02:04.892 is made up out of little quanta, 0:02:04.892,0:02:11.265 those quanta are like snowflakes, that's what we call the Higgs boson. 0:02:13.499,0:02:16.881 The Higgs boson has this job of giving masses 0:02:16.881,0:02:20.365 to all the other elementary particles. 0:02:23.485,0:02:26.175 If you look at the basic equations 0:02:26.175,0:02:30.715 of the Standard Model, as written on my T-shirt, 0:02:30.715,0:02:33.949 they're very symmetric, that way in which 0:02:33.949,0:02:36.733 all the different particles appear is the the same. 0:02:36.733,0:02:39.268 At least on the top two lines there're nothing 0:02:39.268,0:02:43.277 to distinguish particles that have different masses for eaxample. 0:02:44.132,0:02:47.263 But this symmetry has to be broken, 0:02:47.263,0:02:50.727 electrons are lighter than muons, 0:02:50.727,0:02:54.050 the top quark is much much heavier 0:02:54.050,0:02:56.501 than the quarks that make up everyday nuclei. 0:02:56.501,0:02:59.149 So, the top two lines, the symmetric lines, 0:02:59.149,0:03:01.060 cannot be all there is, 0:03:01.060,0:03:02.592 there has to be something to discriminate, 0:03:02.592,0:03:05.998 to distinguish, between the different types of particle. 0:03:06.530,0:03:09.177 And that's the job of the Higgs boson, 0:03:09.177,0:03:11.618 that's the job of the two bottom lines. 0:03:11.618,0:03:16.216 Depending on how those different types of quark 0:03:16.216,0:03:18.543 or the electron and muon, 0:03:18.543,0:03:23.242 depending on how they connect to that Higgs field, 0:03:23.242,0:03:25.982 we believe they get different masses. 0:03:25.982,9:59:59.000 The symmetry between these particles is broken.