WEBVTT 00:00:08.460 --> 00:00:11.310 It is one of the most important announcement in the past decades. 00:00:14.610 --> 00:00:19.980 It confirms essentially most of what has been done in physics. 00:00:20.150 --> 00:00:25.320 This year prizes is about something very small that makes all the difference. 00:00:25.500 --> 00:00:27.730 I am rather surprised it has happened in my lifetime. 00:00:32.820 --> 00:00:39.060 At CERN's foundation in 1954, the world of particle physics was a very different one. 00:00:39.710 --> 00:00:44.210 Scientists were trying to come to grips with the plenty of particles observed in Nature. 00:00:44.511 --> 00:00:51.061 They lacked of an overall framework to explain the basic constitution of matter and the forces that act upon them. 00:00:51.761 --> 00:00:55.411 This framework would later become known as the Standard Model. 00:00:56.771 --> 00:01:02.500 By the end of the decade CERN physicists were already providing insight into the weak interaction, 00:01:02.500 --> 00:01:05.360 a force without which the Sun would not shine. 00:01:07.790 --> 00:01:14.360 The 1960s we saw the birth of electro-weak theory, which unifies the weak and electromagnetic forces. 00:01:15.760 --> 00:01:21.210 A vital part of this is a mechanism that accounts for the vastly different ranges of theses forces, 00:01:21.210 --> 00:01:23.320 as well as for particle masses. 00:01:23.721 --> 00:01:28.811 These were beautiful concepts but they needed experimental evidences to back them up. 00:01:30.300 --> 00:01:36.760 Particle physicists embarked on a global search for the carriers of the weak forces, W and Z bosons, 00:01:36.760 --> 00:01:39.800 whose existence would prove the theorists were right. 00:01:42.510 --> 00:01:47.440 A major breakthrough came in 1973 with the discovery at the PS. 00:01:49.490 --> 00:01:56.760 The Gargamelle experiment identified weak neutron currents, tell tale science of the existence of Z bosons. 00:01:57.501 --> 00:02:02.241 This ground break result brought the first evidence for the electro-weak theory. 00:02:03.200 --> 00:02:09.780 Our physicist were on the right track, but direct detection of weak bosons would take another decade. 00:02:11.300 --> 00:02:15.500 In 1976, CERN brought the SPS on stream. 00:02:16.260 --> 00:02:19.990 Larger and more powerful than CERN's previous accelerators, 00:02:19.990 --> 00:02:23.940 the SPS would go on to collide protons with anti-protons. 00:02:24.760 --> 00:02:29.880 By 1983 SPS experiments had seen W and Z bosons. 00:02:31.340 --> 00:02:37.750 Their long way to discovery led to the Nobel Prize for CERN's Carlo Rubia and Simon Van der Meer. 00:02:37.920 --> 00:02:43.940 "This discovery of the W and Z is not the end, it is the beginning." 00:02:43.940 --> 00:02:51.480 The next step begun when LEP, the 27 km large electron-positron collider, was switched on, in 1989. 00:02:51.740 --> 00:02:55.260 It was designed to study weak bosons in detail. 00:03:00.780 --> 00:03:04.760 The LEP collaborations soon had their first major result. 00:03:04.760 --> 00:03:09.220 By measuring the decays of Z bosons, they found that Nature has three, 00:03:09.220 --> 00:03:12.540 and only three, families of matter particles. 00:03:12.560 --> 00:03:16.560 Everything we see in the Universe is made of the lightest family. 00:03:19.220 --> 00:03:25.580 During its 11 years of operation, LEP placed electro-weak theory on solid experimental ground. 00:03:25.730 --> 00:03:31.780 The Standard Model was almost complete, but what accounted for the mass of particles? 00:03:31.860 --> 00:03:34.650 There was one last missing piece of the puzzle to 00:03:34.661 --> 00:03:39.730 uncover: the physical manifestation of the Brout-Englert-Higgs mechanism. 00:03:39.730 --> 00:03:42.730 A particle called the Higgs boson. 00:03:43.730 --> 00:03:48.400 Its discovery was in sight. With the construction of Large Hadron Collider, 00:03:48.400 --> 00:03:53.220 CERN would take its first steps into a new century of discovery . 00:03:56.490 --> 00:03:58.820 "Today is a special day." 00:03:59.240 --> 00:04:06.810 On the 4th of July 2012, the CMS and Atlas collaborations announced the discovery of Higgs bosons. 00:04:07.510 --> 00:04:11.280 "Theses results are the outcome of the ingenui division 00:04:11.281 --> 00:04:17.141 and painstaking work of our community from accelerator to detector instrumentation, computing and physics." 00:04:17.730 --> 00:04:25.760 "We have observed the new bosons with mass of 125.3 plus minus 0.6 GeV, at 4.97 deviations." 00:04:30.981 --> 00:04:35.991 It was the final evidence the world has been waiting for, heating headlines around the world, 00:04:36.000 --> 00:04:43.200 winning the Noble Prize for Peter Higgs and François Englert and cementing CERN's pivotal role in the development of the Standard Model. 00:04:49.730 --> 00:04:55.910 The Higgs boson completes the Standard Model, but many questions about our Universe remain unanswered, 00:04:55.910 --> 00:05:02.780 mysteries that will captivate future generations of scientists and lead them to untold discoveries.