1 00:00:15,547 --> 00:00:17,919 The universe, 2 00:00:17,943 --> 00:00:20,111 rather beautiful, isn't it? 3 00:00:20,729 --> 00:00:23,316 It's quite literally got everything, 4 00:00:23,340 --> 00:00:24,434 from the very big 5 00:00:24,458 --> 00:00:25,656 to the very small. 6 00:00:26,394 --> 00:00:29,026 Sure, there are some less than savory elements in there, 7 00:00:29,050 --> 00:00:32,109 but on the whole, scholars agree that its existence 8 00:00:32,133 --> 00:00:34,208 is probably a good thing. 9 00:00:34,838 --> 00:00:38,607 Such a good thing that an entire field of scientific endeavor 10 00:00:38,631 --> 00:00:40,052 is devoted to its study. 11 00:00:40,857 --> 00:00:43,253 This is known as cosmology. 12 00:00:43,277 --> 00:00:46,214 Cosmologists look at what's out there in space 13 00:00:46,238 --> 00:00:50,263 and piece together the tale of how our universe evolved: 14 00:00:50,287 --> 00:00:51,524 what it's doing now, 15 00:00:51,548 --> 00:00:53,179 what it's going to be doing, 16 00:00:53,203 --> 00:00:55,730 and how it all began in the first place. 17 00:00:55,754 --> 00:01:00,323 It was Edwin Hubble who first noticed that our universe is expanding, 18 00:01:00,347 --> 00:01:04,464 by noting that galaxies seem to be flying further and further apart. 19 00:01:04,938 --> 00:01:07,224 This implied that everything should have started 20 00:01:07,248 --> 00:01:08,868 with the monumental explosion 21 00:01:08,892 --> 00:01:10,462 of an infinitely hot, 22 00:01:10,486 --> 00:01:12,071 infinitely small point. 23 00:01:12,563 --> 00:01:15,369 This idea was jokingly referred to at the time 24 00:01:15,393 --> 00:01:17,304 as the "Big Bang," 25 00:01:17,328 --> 00:01:18,842 but as the evidence piled up, 26 00:01:18,866 --> 00:01:22,705 the notion and the name actually stuck. 27 00:01:22,729 --> 00:01:24,394 We know that after the Big Bang, 28 00:01:24,418 --> 00:01:25,688 the universe cooled down 29 00:01:25,712 --> 00:01:28,647 to form the stars and galaxies that we see today. 30 00:01:29,166 --> 00:01:32,881 Cosmologists have plenty of ideas about how this happened. 31 00:01:32,905 --> 00:01:35,589 But we can also probe the origins of the universe 32 00:01:35,613 --> 00:01:40,662 by recreating the hot, dense conditions that existed at the beginning of time 33 00:01:40,686 --> 00:01:42,071 in the laboratory. 34 00:01:42,718 --> 00:01:45,451 This is done by particle physicists. 35 00:01:46,559 --> 00:01:47,986 Over the past century, 36 00:01:48,010 --> 00:01:50,161 particle physicists have been studying 37 00:01:50,185 --> 00:01:53,198 matter and forces at higher and higher energies. 38 00:01:53,988 --> 00:01:55,583 Firstly with cosmic rays, 39 00:01:55,607 --> 00:01:57,838 and then with particle accelerators, 40 00:01:57,862 --> 00:02:01,966 machines that smash together subatomic particles at great energies. 41 00:02:02,408 --> 00:02:04,510 The greater the energy of the accelerator, 42 00:02:04,534 --> 00:02:07,735 the further back in time they can effectively peek. 43 00:02:08,288 --> 00:02:10,851 Today, things are largely made up of atoms, 44 00:02:10,875 --> 00:02:13,354 but hundreds of seconds after the Big Bang, 45 00:02:13,378 --> 00:02:17,314 it was too hot for electrons to join atomic nuclei to make atoms. 46 00:02:17,842 --> 00:02:22,348 Instead, the universe consisted of a swirling sea of subatomic matter. 47 00:02:22,935 --> 00:02:24,901 A few seconds after the Big Bang, 48 00:02:24,925 --> 00:02:26,185 it was hotter still, 49 00:02:26,209 --> 00:02:28,104 hot enough to overpower the forces 50 00:02:28,128 --> 00:02:30,804 that usually hold protons and neutrons together 51 00:02:30,828 --> 00:02:32,093 in atomic nuclei. 52 00:02:32,816 --> 00:02:35,608 Further back, microseconds after the Big Bang, 53 00:02:35,632 --> 00:02:37,038 and the protons and neutrons 54 00:02:37,062 --> 00:02:39,794 were only just beginning to form from quarks, 55 00:02:39,818 --> 00:02:41,788 one of the fundamental building blocks 56 00:02:41,812 --> 00:02:44,480 of the standard model of particle physics. 57 00:02:44,977 --> 00:02:46,002 Further back still, 58 00:02:46,026 --> 00:02:49,238 and the energy was too great even for the quarks to stick together. 59 00:02:50,018 --> 00:02:53,032 Physicists hope that by going to even greater energies, 60 00:02:53,056 --> 00:02:57,563 they can see back to a time when all the forces were one and the same, 61 00:02:57,587 --> 00:02:59,016 which would make understanding 62 00:02:59,040 --> 00:03:01,271 the origins of the universe a lot easier. 63 00:03:01,710 --> 00:03:05,070 To do that, they'll not only need to build bigger colliders, 64 00:03:05,094 --> 00:03:07,488 but also work hard to combine our knowledge 65 00:03:07,512 --> 00:03:09,169 of the very, very big 66 00:03:09,193 --> 00:03:11,618 with the very, very small 67 00:03:11,642 --> 00:03:14,238 and share these fascinating insights with each other 68 00:03:14,262 --> 00:03:16,083 and with, well, you. 69 00:03:16,707 --> 00:03:18,579 And that's how it should be! 70 00:03:18,603 --> 00:03:22,234 Because, after all, when it comes to our universe, 71 00:03:22,258 --> 00:03:24,350 we're all in this one together.