0:00:03.351,0:00:04.466 What is the Higgs? 9:59:59.000,9:59:59.000 Since 1964 we've had this idea 9:59:59.000,9:59:59.000 proposed by Englert, Brout and Higgs 9:59:59.000,9:59:59.000 that empty space is like a medium 9:59:59.000,9:59:59.000 and as particles travel through this medium 9:59:59.000,9:59:59.000 some of them interact with it, 9:59:59.000,9:59:59.000 some of them don't interact with it, 9:59:59.000,9:59:59.000 The ones that do interact with this medium, 9:59:59.000,9:59:59.000 they acquire masses, 9:59:59.000,9:59:59.000 and the ones that pass through it without interacting, 9:59:59.000,9:59:59.000 those are massless particles. 9:59:59.000,9:59:59.000 Let me give you an analogy: 9:59:59.000,9:59:59.000 imagine an infinite field of snow 9:59:59.000,9:59:59.000 extending thoughout all of space, 9:59:59.000,9:59:59.000 flat, featureless, going in all directions, 9:59:59.000,9:59:59.000 maybe the middle of Siberia. 9:59:59.000,9:59:59.000 Now imagine that you're trying to cross 9:59:59.000,9:59:59.000 this field of snow. 9:59:59.000,9:59:59.000 So maybe you're a skier, 9:59:59.000,9:59:59.000 and you skim across the top, 9:59:59.000,9:59:59.000 that's like a particle that a particle that 9:59:59.000,9:59:59.000 does not interact with the Higgs field, 9:59:59.000,9:59:59.000 it does not sink into the snow, it goes very fast, 9:59:59.000,9:59:59.000 that's like a particle with no mass travelling at the speed of light. 9:59:59.000,9:59:59.000 But maybe you've only got snw shoes, 9:59:59.000,9:59:59.000 in that case you sink into the Higgs snow field, 9:59:59.000,9:59:59.000 you've got less speed that the skier, 9:59:59.000,9:59:59.000 less that the speed of light, 9:59:59.000,9:59:59.000 that's like a particle with mass, because you are 9:59:59.000,9:59:59.000 connecting, interacting, with that Higgs snow field. 9:59:59.000,9:59:59.000 And then finally if you've just got boots on, 9:59:59.000,9:59:59.000 then you you sink deeply into the snow, 9:59:59.000,9:59:59.000 you go very very slowly, 9:59:59.000,9:59:59.000 and that's like a particle with a big mass. 9:59:59.000,9:59:59.000 So, think of this Higgs field as being 9:59:59.000,9:59:59.000 like this universal field of snow. 9:59:59.000,9:59:59.000 Now, where does the Higgs boson come in? 9:59:59.000,9:59:59.000 We all know what snow is made out of. 9:59:59.000,9:59:59.000 it's made out of snow flakes. 9:59:59.000,9:59:59.000 In the same way this universal Higgs snow fields, 9:59:59.000,9:59:59.000 is made up out of little quanta, 9:59:59.000,9:59:59.000 those quanta are like snowflakes, that's what we call the Higgs boson. 9:59:59.000,9:59:59.000 The Higgs boson has this job of giving masses 9:59:59.000,9:59:59.000 to all the other elementary particles. 9:59:59.000,9:59:59.000 If you look at the basic equations 9:59:59.000,9:59:59.000 of the Standard Model, as written on my T-shirt, 9:59:59.000,9:59:59.000 they're very symmetric, that way in which 9:59:59.000,9:59:59.000 all the different particles appear is the the same. 9:59:59.000,9:59:59.000 At least on the top two lines there're nothing 9:59:59.000,9:59:59.000 to distinguish particles that have different masses for eaxample. 9:59:59.000,9:59:59.000 But this symmetry has to be broken, 9:59:59.000,9:59:59.000 electrons are lighter than muons, 9:59:59.000,9:59:59.000 the top quark is much much heavier 9:59:59.000,9:59:59.000 than the quarks that make up everyday nuclei. 9:59:59.000,9:59:59.000 So, the top two lines, the symmetric lines, 9:59:59.000,9:59:59.000 cannot be all there is, 9:59:59.000,9:59:59.000 there has to be something to discriminate, 9:59:59.000,9:59:59.000 to distinguish, between the different types of particle. 9:59:59.000,9:59:59.000 And that's the job of the Higgs boson, 9:59:59.000,9:59:59.000 that's the job of the two bottom lines. 9:59:59.000,9:59:59.000 Depending on how those different types of quark 9:59:59.000,9:59:59.000 or the electron and muon, 9:59:59.000,9:59:59.000 depending on how they connect to that Higgs field, 9:59:59.000,9:59:59.000 that Higgs boson, 9:59:59.000,9:59:59.000 we believe they get different masses. 9:59:59.000,9:59:59.000 The symmetry between these particles is broken.