1 00:00:00,246 --> 00:00:02,697 What is the Higgs? 2 00:00:03,785 --> 00:00:07,333 Since 1964 we've had this idea 3 00:00:07,579 --> 00:00:08,738 proposed by Englert, Brout and Higgs 4 99:59:59,999 --> 99:59:59,999 that empty space is like a medium 5 99:59:59,999 --> 99:59:59,999 and as particles travel through this medium 6 99:59:59,999 --> 99:59:59,999 some of them interact with it, 7 99:59:59,999 --> 99:59:59,999 some of them don't interact with it, 8 99:59:59,999 --> 99:59:59,999 The ones that do interact with this medium, 9 99:59:59,999 --> 99:59:59,999 they acquire masses, 10 99:59:59,999 --> 99:59:59,999 and the ones that pass through it without interacting, 11 99:59:59,999 --> 99:59:59,999 those are massless particles. 12 99:59:59,999 --> 99:59:59,999 Let me give you an analogy: 13 99:59:59,999 --> 99:59:59,999 imagine an infinite field of snow 14 99:59:59,999 --> 99:59:59,999 extending thoughout all of space, 15 99:59:59,999 --> 99:59:59,999 flat, featureless, going in all directions, 16 99:59:59,999 --> 99:59:59,999 maybe the middle of Siberia. 17 99:59:59,999 --> 99:59:59,999 Now imagine that you're trying to cross 18 99:59:59,999 --> 99:59:59,999 this field of snow. 19 99:59:59,999 --> 99:59:59,999 So maybe you're a skier, 20 99:59:59,999 --> 99:59:59,999 and you skim across the top, 21 99:59:59,999 --> 99:59:59,999 that's like a particle that a particle that 22 99:59:59,999 --> 99:59:59,999 does not interact with the Higgs field, 23 99:59:59,999 --> 99:59:59,999 it does not sink into the snow, it goes very fast, 24 99:59:59,999 --> 99:59:59,999 that's like a particle with no mass travelling at the speed of light. 25 99:59:59,999 --> 99:59:59,999 But maybe you've only got snw shoes, 26 99:59:59,999 --> 99:59:59,999 in that case you sink into the Higgs snow field, 27 99:59:59,999 --> 99:59:59,999 you've got less speed that the skier, 28 99:59:59,999 --> 99:59:59,999 less that the speed of light, 29 99:59:59,999 --> 99:59:59,999 that's like a particle with mass, because you are 30 99:59:59,999 --> 99:59:59,999 connecting, interacting, with that Higgs snow field. 31 99:59:59,999 --> 99:59:59,999 And then finally if you've just got boots on, 32 99:59:59,999 --> 99:59:59,999 then you you sink deeply into the snow, 33 99:59:59,999 --> 99:59:59,999 you go very very slowly, 34 99:59:59,999 --> 99:59:59,999 and that's like a particle with a big mass. 35 99:59:59,999 --> 99:59:59,999 So, think of this Higgs field as being 36 99:59:59,999 --> 99:59:59,999 like this universal field of snow. 37 99:59:59,999 --> 99:59:59,999 Now, where does the Higgs boson come in? 38 99:59:59,999 --> 99:59:59,999 We all know what snow is made out of. 39 99:59:59,999 --> 99:59:59,999 it's made out of snow flakes. 40 99:59:59,999 --> 99:59:59,999 In the same way this universal Higgs snow fields, 41 99:59:59,999 --> 99:59:59,999 is made up out of little quanta, 42 99:59:59,999 --> 99:59:59,999 those quanta are like snowflakes, that's what we call the Higgs boson. 43 99:59:59,999 --> 99:59:59,999 The Higgs boson has this job of giving masses 44 99:59:59,999 --> 99:59:59,999 to all the other elementary particles. 45 99:59:59,999 --> 99:59:59,999 If you look at the basic equations 46 99:59:59,999 --> 99:59:59,999 of the Standard Model, as written on my T-shirt, 47 99:59:59,999 --> 99:59:59,999 they're very symmetric, that way in which 48 99:59:59,999 --> 99:59:59,999 all the different particles appear is the the same. 49 99:59:59,999 --> 99:59:59,999 At least on the top two lines there're nothing 50 99:59:59,999 --> 99:59:59,999 to distinguish particles that have different masses for eaxample. 51 99:59:59,999 --> 99:59:59,999 But this symmetry has to be broken, 52 99:59:59,999 --> 99:59:59,999 electrons are lighter than muons, 53 99:59:59,999 --> 99:59:59,999 the top quark is much much heavier 54 99:59:59,999 --> 99:59:59,999 than the quarks that make up everyday nuclei. 55 99:59:59,999 --> 99:59:59,999 So, the top two lines, the symmetric lines, 56 99:59:59,999 --> 99:59:59,999 cannot be all there is, 57 99:59:59,999 --> 99:59:59,999 there has to be something to discriminate, 58 99:59:59,999 --> 99:59:59,999 to distinguish, between the different types of particle. 59 99:59:59,999 --> 99:59:59,999 And that's the job of the Higgs boson, 60 99:59:59,999 --> 99:59:59,999 that's the job of the two bottom lines. 61 99:59:59,999 --> 99:59:59,999 Depending on how those different types of quark 62 99:59:59,999 --> 99:59:59,999 or the electron and muon, 63 99:59:59,999 --> 99:59:59,999 depending on how they connect to that Higgs field, 64 99:59:59,999 --> 99:59:59,999 we believe they get different masses. 65 99:59:59,999 --> 99:59:59,999 The symmetry between these particles is broken.