[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:19.40,0:00:23.69,Default,,0000,0000,0000,,I have a slight problem,\Nbut the show's going on.
Dialogue: 0,0:00:26.39,0:00:28.10,Default,,0000,0000,0000,,My blood's red.
Dialogue: 0,0:00:28.71,0:00:30.55,Default,,0000,0000,0000,,Is Viennese blood red?
Dialogue: 0,0:00:30.89,0:00:32.28,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:00:32.28,0:00:33.89,Default,,0000,0000,0000,,I suspect it is.
Dialogue: 0,0:00:36.74,0:00:38.58,Default,,0000,0000,0000,,Why is blood red?
Dialogue: 0,0:00:40.34,0:00:42.84,Default,,0000,0000,0000,,Does anybody know? Can you tell me?
Dialogue: 0,0:00:42.84,0:00:43.89,Default,,0000,0000,0000,,(Audience) It's iron.
Dialogue: 0,0:00:43.89,0:00:45.93,Default,,0000,0000,0000,,It's iron, yes.
Dialogue: 0,0:00:45.93,0:00:49.46,Default,,0000,0000,0000,,It's iron in the hemoglobin,\Nin our bloodstream,
Dialogue: 0,0:00:49.88,0:00:51.64,Default,,0000,0000,0000,,that makes the blood red.
Dialogue: 0,0:00:52.43,0:00:54.38,Default,,0000,0000,0000,,Iron is one of the chemical elements,
Dialogue: 0,0:00:54.38,0:00:56.48,Default,,0000,0000,0000,,and I'm going to talk\Nabout that in a moment.
Dialogue: 0,0:00:56.48,0:00:57.66,Default,,0000,0000,0000,,But, just first ...
Dialogue: 0,0:00:58.40,0:01:00.26,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:01:00.26,0:01:01.65,Default,,0000,0000,0000,,... tomato ketchup.
Dialogue: 0,0:01:02.20,0:01:04.67,Default,,0000,0000,0000,,We'll hear more about tomatoes later.
Dialogue: 0,0:01:04.67,0:01:07.11,Default,,0000,0000,0000,,(Laughter) (Applause)
Dialogue: 0,0:01:12.72,0:01:16.18,Default,,0000,0000,0000,,Back to the chemical elements and iron.
Dialogue: 0,0:01:16.59,0:01:19.32,Default,,0000,0000,0000,,It is, indeed, \None of the chemical elements,
Dialogue: 0,0:01:19.32,0:01:23.14,Default,,0000,0000,0000,,and even if you're not a chemist,\Nyou probably know of some others.
Dialogue: 0,0:01:25.95,0:01:29.21,Default,,0000,0000,0000,,An answer given by a student in an exam.
Dialogue: 0,0:01:29.21,0:01:32.13,Default,,0000,0000,0000,,[H2O is hot water and CO2 is cold water.]
Dialogue: 0,0:01:32.13,0:01:34.41,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:01:38.60,0:01:41.44,Default,,0000,0000,0000,,So, you know what H2O is?
Dialogue: 0,0:01:42.13,0:01:45.46,Default,,0000,0000,0000,,(Audience) Water.\NJocelyn Burnell: Water. CO2?
Dialogue: 0,0:01:45.46,0:01:47.66,Default,,0000,0000,0000,,(Audience) Carbon dioxide.\NJB: Carbon dioxide.
Dialogue: 0,0:01:47.66,0:01:51.23,Default,,0000,0000,0000,,So, we've got here\Nanother three chemical elements:
Dialogue: 0,0:01:51.23,0:01:54.05,Default,,0000,0000,0000,,hydrogen, oxygen, and carbon.
Dialogue: 0,0:01:54.85,0:01:57.28,Default,,0000,0000,0000,,And while we're dealing\Nwith student exam questions,
Dialogue: 0,0:01:57.28,0:01:59.28,Default,,0000,0000,0000,,here's another one about water:
Dialogue: 0,0:02:00.00,0:02:02.24,Default,,0000,0000,0000,,Water is composed of two gins ...
Dialogue: 0,0:02:02.24,0:02:04.73,Default,,0000,0000,0000,,[Water is composed of two gins,\NOxygin and Hydrogin.]
Dialogue: 0,0:02:04.73,0:02:07.21,Default,,0000,0000,0000,,[Oxygin is pure gin.\NHydrogin is water and gin.]
Dialogue: 0,0:02:07.21,0:02:09.17,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:02:14.72,0:02:19.21,Default,,0000,0000,0000,,These answers come from\Nthe United States of America, but ...
Dialogue: 0,0:02:19.21,0:02:21.99,Default,,0000,0000,0000,,(Laughter) (Applause)
Dialogue: 0,0:02:26.26,0:02:30.56,Default,,0000,0000,0000,,It's a wonderful resource of all sorts\Nof amazing things that come true.
Dialogue: 0,0:02:32.98,0:02:36.44,Default,,0000,0000,0000,,Maybe some of you\Nrecall seeing a diagram like this
Dialogue: 0,0:02:36.44,0:02:38.93,Default,,0000,0000,0000,,in school chemistry laboratories.
Dialogue: 0,0:02:39.49,0:02:41.77,Default,,0000,0000,0000,,You can see it in other places, too,
Dialogue: 0,0:02:41.77,0:02:46.64,Default,,0000,0000,0000,,even these days on tea towels,\Nmugs, bags, pens.
Dialogue: 0,0:02:47.72,0:02:53.23,Default,,0000,0000,0000,,It's a tabulation of the 100 plus\Nchemical elements that we know about.
Dialogue: 0,0:02:55.09,0:02:57.63,Default,,0000,0000,0000,,In Oxford, where I come from,
Dialogue: 0,0:02:58.13,0:03:00.95,Default,,0000,0000,0000,,we have it on taxis and buses, as well -
Dialogue: 0,0:03:00.95,0:03:02.77,Default,,0000,0000,0000,,but that's Oxford.
Dialogue: 0,0:03:02.77,0:03:04.60,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:03:06.24,0:03:10.57,Default,,0000,0000,0000,,Now, in our bodies, there's clearly\Niron in the bloodstream,
Dialogue: 0,0:03:10.57,0:03:15.58,Default,,0000,0000,0000,,there's also hydrogen and oxygen\Nbecause we're two-thirds water.
Dialogue: 0,0:03:15.96,0:03:19.97,Default,,0000,0000,0000,,There's carbon in our tissues,\Ncalcium in our bones.
Dialogue: 0,0:03:22.78,0:03:26.24,Default,,0000,0000,0000,,I'm going to focus on the iron\Nbecause this is a short talk.
Dialogue: 0,0:03:27.77,0:03:32.38,Default,,0000,0000,0000,,Where did that iron, and, indeed,\Nwhere did those other things come from?
Dialogue: 0,0:03:32.38,0:03:34.72,Default,,0000,0000,0000,,How did it get into our bodies?
Dialogue: 0,0:03:35.15,0:03:37.44,Default,,0000,0000,0000,,It's not in the air ... much.
Dialogue: 0,0:03:38.54,0:03:42.45,Default,,0000,0000,0000,,It's come through what we've eaten:\Nplants and animals.
Dialogue: 0,0:03:44.01,0:03:48.08,Default,,0000,0000,0000,,How did the iron\Nget into the plants and animals?
Dialogue: 0,0:03:49.53,0:03:51.35,Default,,0000,0000,0000,,Well, it came from the earth.
Dialogue: 0,0:03:51.81,0:03:53.67,Default,,0000,0000,0000,,How did it get into the earth?
Dialogue: 0,0:03:53.67,0:03:56.04,Default,,0000,0000,0000,,Where did it come from before that?
Dialogue: 0,0:03:57.98,0:03:59.89,Default,,0000,0000,0000,,What I am going to be telling you about
Dialogue: 0,0:03:59.89,0:04:04.23,Default,,0000,0000,0000,,is how the stars have created\Nthe chemical elements -
Dialogue: 0,0:04:04.23,0:04:09.61,Default,,0000,0000,0000,,the key ingredients of life:\Noxygen, carbon, calcium, iron -
Dialogue: 0,0:04:10.10,0:04:12.30,Default,,0000,0000,0000,,with particular emphasis on the iron.
Dialogue: 0,0:04:14.08,0:04:18.46,Default,,0000,0000,0000,,Stars are formed in some\Nof the dark spots of the galaxy,
Dialogue: 0,0:04:18.46,0:04:19.95,Default,,0000,0000,0000,,the dark patches.
Dialogue: 0,0:04:20.38,0:04:23.60,Default,,0000,0000,0000,,There are particles\Nof gas and dust milling around,
Dialogue: 0,0:04:23.97,0:04:25.67,Default,,0000,0000,0000,,by chance as a little knot,
Dialogue: 0,0:04:25.67,0:04:28.44,Default,,0000,0000,0000,,it's got extra gravity,\Npulls in some more,
Dialogue: 0,0:04:28.44,0:04:30.99,Default,,0000,0000,0000,,puts up the gravity, pulls in more.
Dialogue: 0,0:04:30.99,0:04:33.62,Default,,0000,0000,0000,,And over some millions of years,
Dialogue: 0,0:04:33.62,0:04:38.72,Default,,0000,0000,0000,,this little knot grows into\Nwhat's going to be a full-blown star.
Dialogue: 0,0:04:39.83,0:04:43.46,Default,,0000,0000,0000,,When the temperature\Nin the middle of this lump
Dialogue: 0,0:04:43.46,0:04:46.10,Default,,0000,0000,0000,,reaches about 10 million degrees,
Dialogue: 0,0:04:46.10,0:04:48.38,Default,,0000,0000,0000,,nuclear reactions start,
Dialogue: 0,0:04:48.38,0:04:53.95,Default,,0000,0000,0000,,and, in particular, a nuclear reaction\Nof hydrogen being converted to helium.
Dialogue: 0,0:04:54.72,0:04:58.35,Default,,0000,0000,0000,,And there's some energy to spare,\Nand it comes out of starlight.
Dialogue: 0,0:04:59.92,0:05:02.07,Default,,0000,0000,0000,,Our sun's busy doing that:
Dialogue: 0,0:05:02.07,0:05:07.68,Default,,0000,0000,0000,,our sun is burning about 600 million\Ntons of hydrogen every second.
Dialogue: 0,0:05:08.53,0:05:11.38,Default,,0000,0000,0000,,It's done that for 5 billion years.
Dialogue: 0,0:05:11.38,0:05:15.05,Default,,0000,0000,0000,,It'll do it for about\Nanother 5 billion years.
Dialogue: 0,0:05:15.70,0:05:21.54,Default,,0000,0000,0000,,And shortly after that, it will end,\Nand it's actually no use for this story.
Dialogue: 0,0:05:21.54,0:05:23.58,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:05:23.58,0:05:27.15,Default,,0000,0000,0000,,We have to focus\Non a very small minority of stars,
Dialogue: 0,0:05:27.15,0:05:29.29,Default,,0000,0000,0000,,the extremely massive ones,
Dialogue: 0,0:05:29.29,0:05:33.34,Default,,0000,0000,0000,,10, 20, 30 times the size of our sun.
Dialogue: 0,0:05:34.44,0:05:36.71,Default,,0000,0000,0000,,Examples of these that you might know:
Dialogue: 0,0:05:36.71,0:05:42.52,Default,,0000,0000,0000,,the Pleiades - which is in the winter sky\Nnear the constellation of Orion,
Dialogue: 0,0:05:42.52,0:05:43.73,Default,,0000,0000,0000,,and Betelgeuse -
Dialogue: 0,0:05:43.73,0:05:48.77,Default,,0000,0000,0000,,which is the reddish star,\Ntop left in the constellation of Orion.
Dialogue: 0,0:05:49.90,0:05:53.94,Default,,0000,0000,0000,,These big stars not only convert\Nhydrogen to helium,
Dialogue: 0,0:05:53.94,0:05:55.44,Default,,0000,0000,0000,,but then the helium to carbon,
Dialogue: 0,0:05:55.44,0:05:59.51,Default,,0000,0000,0000,,and work their way\Nacross the periodic table
Dialogue: 0,0:05:59.51,0:06:02.81,Default,,0000,0000,0000,,till they end up with iron\Nin the center of the core.
Dialogue: 0,0:06:03.36,0:06:07.63,Default,,0000,0000,0000,,And this is the first place\Nthat we have iron in the universe -
Dialogue: 0,0:06:08.07,0:06:10.05,Default,,0000,0000,0000,,in the cores of some stars.
Dialogue: 0,0:06:11.66,0:06:16.26,Default,,0000,0000,0000,,Not very useful to us\Nif it's in the cores of stars.
Dialogue: 0,0:06:17.59,0:06:23.51,Default,,0000,0000,0000,,But star death, dramatic star death,\Ncomes to the rescue.
Dialogue: 0,0:06:25.48,0:06:30.43,Default,,0000,0000,0000,,A pair of photographs here:\Na "before" and an "after."
Dialogue: 0,0:06:31.22,0:06:34.88,Default,,0000,0000,0000,,We're looking at\Na southern hemisphere object
Dialogue: 0,0:06:34.88,0:06:37.61,Default,,0000,0000,0000,,called the Large Magellanic Cloud.
Dialogue: 0,0:06:38.03,0:06:42.20,Default,,0000,0000,0000,,It's a small galaxy,\Nexternal to ours, but quite nearby.
Dialogue: 0,0:06:42.73,0:06:46.32,Default,,0000,0000,0000,,We're seeing up top left\Na glowing mass of gas,
Dialogue: 0,0:06:47.23,0:06:49.26,Default,,0000,0000,0000,,quite a lot of pink hydrogen gas,
Dialogue: 0,0:06:49.76,0:06:51.90,Default,,0000,0000,0000,,millions of little stars,
Dialogue: 0,0:06:52.35,0:06:55.63,Default,,0000,0000,0000,,and one of them, bottom right,\Npicked out with an arrow.
Dialogue: 0,0:06:57.15,0:06:59.96,Default,,0000,0000,0000,,For those of you\Nwho are not astrophysicists,
Dialogue: 0,0:07:00.39,0:07:03.48,Default,,0000,0000,0000,,the arrow's added after the photo's taken.
Dialogue: 0,0:07:03.48,0:07:05.72,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:07:07.74,0:07:13.54,Default,,0000,0000,0000,,But, this inconspicuous star\Nthat we had to pick out with an arrow
Dialogue: 0,0:07:13.54,0:07:14.88,Default,,0000,0000,0000,,becomes this,
Dialogue: 0,0:07:15.77,0:07:19.81,Default,,0000,0000,0000,,and you don't need an arrow\Nto see that thing in the bottom right.
Dialogue: 0,0:07:20.87,0:07:24.35,Default,,0000,0000,0000,,The star has exploded catastrophically.
Dialogue: 0,0:07:24.93,0:07:26.100,Default,,0000,0000,0000,,It was one of these big stars
Dialogue: 0,0:07:26.100,0:07:30.18,Default,,0000,0000,0000,,like the ones in the Pleiades,\Nor Betelgeuse.
Dialogue: 0,0:07:30.18,0:07:34.18,Default,,0000,0000,0000,,It's gone all the way through\Nthe various chemical elements.
Dialogue: 0,0:07:34.18,0:07:37.76,Default,,0000,0000,0000,,It's got this range of onion shells\Nwith iron in the middle
Dialogue: 0,0:07:37.76,0:07:40.36,Default,,0000,0000,0000,,and the other chemical\Nelements outside it,
Dialogue: 0,0:07:41.12,0:07:43.24,Default,,0000,0000,0000,,and it has exploded.
Dialogue: 0,0:07:44.49,0:07:47.99,Default,,0000,0000,0000,,The physics of the explosion\Nis quite complicated,
Dialogue: 0,0:07:47.99,0:07:50.39,Default,,0000,0000,0000,,so I'm not going to go\Ninto the details of that,
Dialogue: 0,0:07:50.39,0:07:52.97,Default,,0000,0000,0000,,but it is a catastrophic explosion.
Dialogue: 0,0:07:53.87,0:07:56.66,Default,,0000,0000,0000,,We used to assume\Nit was totally catastrophic.
Dialogue: 0,0:07:56.66,0:08:01.05,Default,,0000,0000,0000,,We now know that the pulsars\Nthat Vlad mentioned in his introduction
Dialogue: 0,0:08:01.05,0:08:04.57,Default,,0000,0000,0000,,are formed from the cores\Nof these exploding stars.
Dialogue: 0,0:08:04.57,0:08:10.02,Default,,0000,0000,0000,,But 95% of the star\Nis skooshed out into space,
Dialogue: 0,0:08:11.38,0:08:14.90,Default,,0000,0000,0000,,which means that being\Nfanned out across space
Dialogue: 0,0:08:15.44,0:08:19.62,Default,,0000,0000,0000,,are useful chemical elements\Nthat were inside the star:
Dialogue: 0,0:08:19.62,0:08:23.72,Default,,0000,0000,0000,,oxygen, calcium, carbon, iron,
Dialogue: 0,0:08:24.61,0:08:30.27,Default,,0000,0000,0000,,spread out, made available\Nby the catastrophic terminal explosion
Dialogue: 0,0:08:30.27,0:08:32.22,Default,,0000,0000,0000,,of this particular star.
Dialogue: 0,0:08:35.17,0:08:41.39,Default,,0000,0000,0000,,Now, getting from there to us\Nis quite a long story,
Dialogue: 0,0:08:41.93,0:08:44.63,Default,,0000,0000,0000,,and I'm going to do this bit by mime.
Dialogue: 0,0:08:45.91,0:08:48.29,Default,,0000,0000,0000,,You've probably got some sense
Dialogue: 0,0:08:48.29,0:08:52.24,Default,,0000,0000,0000,,that physics professors\Nhave a slightly dubious reputation.
Dialogue: 0,0:08:52.24,0:08:53.19,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:08:53.19,0:08:56.33,Default,,0000,0000,0000,,The female ones are utterly nuts!
Dialogue: 0,0:08:56.76,0:08:58.85,Default,,0000,0000,0000,,And I'm just about to prove it!
Dialogue: 0,0:08:58.85,0:09:00.77,Default,,0000,0000,0000,,(Applause)
Dialogue: 0,0:09:05.32,0:09:07.80,Default,,0000,0000,0000,,So, this stage is the Milky Way -
Dialogue: 0,0:09:07.80,0:09:09.17,Default,,0000,0000,0000,,our galaxy,
Dialogue: 0,0:09:09.61,0:09:13.58,Default,,0000,0000,0000,,and this is a story\Nthat involves all the Milky Way.
Dialogue: 0,0:09:15.00,0:09:18.78,Default,,0000,0000,0000,,Over here in the Milky Way\Nis one of these dark clouds
Dialogue: 0,0:09:18.78,0:09:21.23,Default,,0000,0000,0000,,where stars sometimes form,
Dialogue: 0,0:09:21.80,0:09:25.70,Default,,0000,0000,0000,,particles of gas, molecules,\Ndust milling around.
Dialogue: 0,0:09:27.15,0:09:29.24,Default,,0000,0000,0000,,By chance, there's a little knot,
Dialogue: 0,0:09:29.24,0:09:34.16,Default,,0000,0000,0000,,it has extra gravity, it pulls in\Nsome more bits of dust and gas,
Dialogue: 0,0:09:34.16,0:09:36.45,Default,,0000,0000,0000,,puts up the mass, puts up the gravity,
Dialogue: 0,0:09:36.45,0:09:38.29,Default,,0000,0000,0000,,pulls in some more bits.
Dialogue: 0,0:09:39.59,0:09:44.08,Default,,0000,0000,0000,,To save time, folks, this is going to be\None of these very massive stars,
Dialogue: 0,0:09:44.08,0:09:46.95,Default,,0000,0000,0000,,otherwise we're here for a long time.
Dialogue: 0,0:09:47.99,0:09:51.26,Default,,0000,0000,0000,,So, this gradually grows, gradually grows.
Dialogue: 0,0:09:52.26,0:09:54.72,Default,,0000,0000,0000,,And at the point when it's grown so much
Dialogue: 0,0:09:54.72,0:09:59.27,Default,,0000,0000,0000,,that the temperature in the middle\Nhas reached about 10 million degrees,
Dialogue: 0,0:09:59.27,0:10:02.58,Default,,0000,0000,0000,,it starts its sequence\Nof nuclear reactions,
Dialogue: 0,0:10:03.03,0:10:07.11,Default,,0000,0000,0000,,and it burns, converts hydrogen to helium.
Dialogue: 0,0:10:07.11,0:10:08.80,Default,,0000,0000,0000,,Brrrr!
Dialogue: 0,0:10:10.18,0:10:13.32,Default,,0000,0000,0000,,Then it starts to run out\Nof hydrogen in its core.
Dialogue: 0,0:10:13.96,0:10:16.47,Default,,0000,0000,0000,,So it starts converting helium to carbon.
Dialogue: 0,0:10:16.47,0:10:17.47,Default,,0000,0000,0000,,Brrrr!
Dialogue: 0,0:10:18.57,0:10:20.22,Default,,0000,0000,0000,,That doesn't last as long.
Dialogue: 0,0:10:20.22,0:10:22.27,Default,,0000,0000,0000,,Then it runs out of helium in its core,
Dialogue: 0,0:10:22.27,0:10:26.23,Default,,0000,0000,0000,,so it converts carbon\Nto oxygen, oxygen ...
Dialogue: 0,0:10:26.23,0:10:28.41,Default,,0000,0000,0000,,Brrr! Brr! Brr! Brr!
Dialogue: 0,0:10:28.41,0:10:29.71,Default,,0000,0000,0000,,Boom!
Dialogue: 0,0:10:29.71,0:10:31.87,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:10:32.71,0:10:38.12,Default,,0000,0000,0000,,And millions and millions\Nand millions of tons of stuff, gas,
Dialogue: 0,0:10:38.12,0:10:41.36,Default,,0000,0000,0000,,fan out from this explosion site
Dialogue: 0,0:10:42.20,0:10:44.13,Default,,0000,0000,0000,,in one part of our Milky Way.
Dialogue: 0,0:10:46.62,0:10:49.15,Default,,0000,0000,0000,,It percolates, slowly,
Dialogue: 0,0:10:49.15,0:10:52.60,Default,,0000,0000,0000,,but we've got eons, there's no rush.
Dialogue: 0,0:10:52.60,0:10:54.14,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:10:54.14,0:10:55.72,Default,,0000,0000,0000,,It can travel,
Dialogue: 0,0:10:55.72,0:10:59.03,Default,,0000,0000,0000,,and it does travel,\Ngradually, in all directions,
Dialogue: 0,0:10:59.03,0:11:01.02,Default,,0000,0000,0000,,but we're interested in this bit.
Dialogue: 0,0:11:02.34,0:11:04.22,Default,,0000,0000,0000,,And some comes over here
Dialogue: 0,0:11:05.04,0:11:07.58,Default,,0000,0000,0000,,to where there is another\Nof these dark clouds
Dialogue: 0,0:11:07.58,0:11:10.48,Default,,0000,0000,0000,,with particles of gas\Nand dust milling around.
Dialogue: 0,0:11:11.25,0:11:15.05,Default,,0000,0000,0000,,And some of the material\Nfrom that distant explosion
Dialogue: 0,0:11:15.05,0:11:16.82,Default,,0000,0000,0000,,finds its way over here,
Dialogue: 0,0:11:17.22,0:11:21.74,Default,,0000,0000,0000,,and that material is rich\Nin carbon and calcium
Dialogue: 0,0:11:21.74,0:11:24.48,Default,,0000,0000,0000,,and iron and oxygen, and so on.
Dialogue: 0,0:11:24.48,0:11:26.42,Default,,0000,0000,0000,,So it joins this cloud,
Dialogue: 0,0:11:26.42,0:11:30.16,Default,,0000,0000,0000,,and by chance a little knot forms,\Nit's got extra gravity,
Dialogue: 0,0:11:30.16,0:11:34.12,Default,,0000,0000,0000,,pulls in some more particles,\Nputs up the mass, puts up the gravity,
Dialogue: 0,0:11:34.12,0:11:35.83,Default,,0000,0000,0000,,pulls in some more particles,
Dialogue: 0,0:11:35.83,0:11:38.35,Default,,0000,0000,0000,,puts up the mass, puts up the gravity,
Dialogue: 0,0:11:38.35,0:11:41.17,Default,,0000,0000,0000,,and over a million years,\N10 million years,
Dialogue: 0,0:11:41.17,0:11:43.05,Default,,0000,0000,0000,,it grows and grows and grows.
Dialogue: 0,0:11:44.03,0:11:47.07,Default,,0000,0000,0000,,And once again,\NI have to crave your indulgence,
Dialogue: 0,0:11:47.07,0:11:50.23,Default,,0000,0000,0000,,could this also be\None of these big stars?--
Dialogue: 0,0:11:50.74,0:11:52.98,Default,,0000,0000,0000,,otherwise we're here all night.
Dialogue: 0,0:11:53.72,0:11:56.03,Default,,0000,0000,0000,,So this big star grows,
Dialogue: 0,0:11:56.03,0:12:01.10,Default,,0000,0000,0000,,and the nuclear reactions start,\Nand it burns, converts hydrogen to helium.
Dialogue: 0,0:12:01.10,0:12:02.20,Default,,0000,0000,0000,,Brrrr!
Dialogue: 0,0:12:02.67,0:12:05.03,Default,,0000,0000,0000,,Runs out of hydrogen, burns helium. Brrrr!
Dialogue: 0,0:12:05.03,0:12:06.62,Default,,0000,0000,0000,,Runs out of helium, burns carbon.
Dialogue: 0,0:12:06.62,0:12:08.96,Default,,0000,0000,0000,,Brrr! Brr! Brr! Brr! Boom!
Dialogue: 0,0:12:08.96,0:12:10.39,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:12:10.39,0:12:12.60,Default,,0000,0000,0000,,Now, you know the next bit of the story.
Dialogue: 0,0:12:12.60,0:12:17.08,Default,,0000,0000,0000,,Millions and millions and millions\Nof tons of stuff fan out across space,
Dialogue: 0,0:12:17.81,0:12:20.99,Default,,0000,0000,0000,,and some of it makes its way over here
Dialogue: 0,0:12:21.67,0:12:25.70,Default,,0000,0000,0000,,to another dark part\Nof the galaxy - the Milky Way -
Dialogue: 0,0:12:26.60,0:12:29.65,Default,,0000,0000,0000,,where there's a star beginning to form.
Dialogue: 0,0:12:30.26,0:12:32.65,Default,,0000,0000,0000,,The material that comes from there
Dialogue: 0,0:12:33.19,0:12:38.08,Default,,0000,0000,0000,,is doubly enriched in carbon\Nand calcium and iron, and so on,
Dialogue: 0,0:12:38.08,0:12:40.86,Default,,0000,0000,0000,,because of the stuff\Nthat that star generated,
Dialogue: 0,0:12:40.86,0:12:43.43,Default,,0000,0000,0000,,plus the stuff it got\Nfrom that star, as well.
Dialogue: 0,0:12:44.19,0:12:49.02,Default,,0000,0000,0000,,So, what's arriving here\Nis double dose carbon,
Dialogue: 0,0:12:49.02,0:12:51.12,Default,,0000,0000,0000,,calcium, iron, and so on.
Dialogue: 0,0:12:51.65,0:12:57.30,Default,,0000,0000,0000,,And here in this cloud,\Na star called the Sun is forming,
Dialogue: 0,0:12:57.80,0:12:59.14,Default,,0000,0000,0000,,and it's made from the stuff
Dialogue: 0,0:12:59.14,0:13:01.47,Default,,0000,0000,0000,,that happens to be\Nin this patch of the galaxy,
Dialogue: 0,0:13:01.47,0:13:03.93,Default,,0000,0000,0000,,plus the stuff that's come from that star,
Dialogue: 0,0:13:03.93,0:13:06.32,Default,,0000,0000,0000,,plus the stuff\Nthat's come direct from there,
Dialogue: 0,0:13:06.32,0:13:09.22,Default,,0000,0000,0000,,and maybe from some other\Nexploding stars, as well.
Dialogue: 0,0:13:09.72,0:13:13.07,Default,,0000,0000,0000,,Our sun is a third-generation star.
Dialogue: 0,0:13:13.60,0:13:16.67,Default,,0000,0000,0000,,Our star is a late-forming star,
Dialogue: 0,0:13:17.20,0:13:19.19,Default,,0000,0000,0000,,and it has to be
Dialogue: 0,0:13:19.72,0:13:21.40,Default,,0000,0000,0000,,or we wouldn't be here.
Dialogue: 0,0:13:22.42,0:13:28.15,Default,,0000,0000,0000,,We can only exist close to a young star
Dialogue: 0,0:13:28.15,0:13:31.82,Default,,0000,0000,0000,,that's been enriched\Nby previous solar cycles.
Dialogue: 0,0:13:33.02,0:13:34.68,Default,,0000,0000,0000,,So, the sun forms,
Dialogue: 0,0:13:35.05,0:13:37.30,Default,,0000,0000,0000,,some of the material is left over.
Dialogue: 0,0:13:38.76,0:13:41.34,Default,,0000,0000,0000,,You've perhaps seen pictures \Nof the planet Saturn
Dialogue: 0,0:13:41.34,0:13:43.34,Default,,0000,0000,0000,,with its rings around it.
Dialogue: 0,0:13:43.34,0:13:45.40,Default,,0000,0000,0000,,This is a giant version of that.
Dialogue: 0,0:13:45.99,0:13:47.62,Default,,0000,0000,0000,,So you've got a sun
Dialogue: 0,0:13:48.09,0:13:51.19,Default,,0000,0000,0000,,and some of the debris\Nin a giant ring around it.
Dialogue: 0,0:13:52.43,0:13:54.08,Default,,0000,0000,0000,,Let's focus on the debris -
Dialogue: 0,0:13:54.64,0:13:56.33,Default,,0000,0000,0000,,little bits going around.
Dialogue: 0,0:13:56.33,0:13:59.04,Default,,0000,0000,0000,,Little bits occasionally collide\Nwith other bits,
Dialogue: 0,0:13:59.04,0:14:02.13,Default,,0000,0000,0000,,and they go around\Nand collide with other bits
Dialogue: 0,0:14:02.13,0:14:03.89,Default,,0000,0000,0000,,and go around.
Dialogue: 0,0:14:03.89,0:14:07.72,Default,,0000,0000,0000,,And ultimately, you end up with planets
Dialogue: 0,0:14:08.35,0:14:11.05,Default,,0000,0000,0000,,and the ring, the rest\Nof the ring has disappeared.
Dialogue: 0,0:14:11.64,0:14:14.58,Default,,0000,0000,0000,,The planets are made\Nof the same stuff as the sun,
Dialogue: 0,0:14:14.58,0:14:17.20,Default,,0000,0000,0000,,which, you remember,\Nis made of the stuff that was here,
Dialogue: 0,0:14:17.20,0:14:19.32,Default,,0000,0000,0000,,plus stuff from there,\Nplus stuff from there.
Dialogue: 0,0:14:21.76,0:14:23.53,Default,,0000,0000,0000,,It makes eight planets,
Dialogue: 0,0:14:24.18,0:14:26.06,Default,,0000,0000,0000,,not Pluto.
Dialogue: 0,0:14:26.06,0:14:28.06,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:14:28.90,0:14:31.12,Default,,0000,0000,0000,,Pluto was grabbed later.
Dialogue: 0,0:14:31.62,0:14:35.10,Default,,0000,0000,0000,,You can think of Pluto\Nas an adopted child, if you wish.
Dialogue: 0,0:14:35.60,0:14:37.46,Default,,0000,0000,0000,,The rest are birth children.
Dialogue: 0,0:14:38.80,0:14:43.09,Default,,0000,0000,0000,,So, these planets are basically\Nmade of the same stuff as the sun,
Dialogue: 0,0:14:44.04,0:14:47.06,Default,,0000,0000,0000,,which is made up of stuff that was here,
Dialogue: 0,0:14:47.06,0:14:52.60,Default,,0000,0000,0000,,plus debris from exploding stars\Nactually all over our galaxy.
Dialogue: 0,0:14:52.60,0:14:55.27,Default,,0000,0000,0000,,It's not that we can say,\N"It was that one and that one."
Dialogue: 0,0:14:55.27,0:14:57.70,Default,,0000,0000,0000,,It's that one and that one\Nand that one and that one
Dialogue: 0,0:14:57.70,0:15:00.19,Default,,0000,0000,0000,,and that one and that one\Nand that one and that one -
Dialogue: 0,0:15:00.61,0:15:03.78,Default,,0000,0000,0000,,doubly enriched with all\Nthese useful chemical elements.
Dialogue: 0,0:15:04.40,0:15:07.52,Default,,0000,0000,0000,,And the planets, likewise,\Nare of the same stuff.
Dialogue: 0,0:15:08.28,0:15:09.58,Default,,0000,0000,0000,,There has been some change
Dialogue: 0,0:15:09.58,0:15:12.76,Default,,0000,0000,0000,,in that the planets\Nclosest to the sun got hot,
Dialogue: 0,0:15:12.76,0:15:16.57,Default,,0000,0000,0000,,and the material that most easily\Nevaporates has boiled off.
Dialogue: 0,0:15:17.15,0:15:20.86,Default,,0000,0000,0000,,Further out, you can see\Nthe original composition rather better.
Dialogue: 0,0:15:21.64,0:15:24.10,Default,,0000,0000,0000,,But that's broadly what has happened.
Dialogue: 0,0:15:24.78,0:15:30.94,Default,,0000,0000,0000,,So we who eat the plants and the animals\Nthat absorb elements from the earth,
Dialogue: 0,0:15:31.76,0:15:34.58,Default,,0000,0000,0000,,we are made\Nof the same stuff as the earth,
Dialogue: 0,0:15:35.12,0:15:37.66,Default,,0000,0000,0000,,and the earth is made\Nof the same stuff as the sun,
Dialogue: 0,0:15:38.46,0:15:41.52,Default,,0000,0000,0000,,which is made up\Nof the rest of the galaxy.
Dialogue: 0,0:15:42.82,0:15:48.16,Default,,0000,0000,0000,,So, iron was created\Nin those very massive stars,
Dialogue: 0,0:15:48.16,0:15:52.14,Default,,0000,0000,0000,,ones that went through\Nlots of nuclear reactions.
Dialogue: 0,0:15:53.11,0:15:55.44,Default,,0000,0000,0000,,And that iron was made available
Dialogue: 0,0:15:55.44,0:15:59.36,Default,,0000,0000,0000,,by the catastrophic death\Nof those big stars.
Dialogue: 0,0:15:59.86,0:16:02.42,Default,,0000,0000,0000,,So there's life and death already.
Dialogue: 0,0:16:04.18,0:16:07.69,Default,,0000,0000,0000,,If it wasn't for those stars,\Nparticularly the ones that had died,
Dialogue: 0,0:16:07.69,0:16:09.54,Default,,0000,0000,0000,,we would not be here.
Dialogue: 0,0:16:10.63,0:16:14.24,Default,,0000,0000,0000,,And we're intimately and ultimately
Dialogue: 0,0:16:14.24,0:16:15.86,Default,,0000,0000,0000,,children of the stars,
Dialogue: 0,0:16:16.75,0:16:19.62,Default,,0000,0000,0000,,to such an extent that, actually,
Dialogue: 0,0:16:19.98,0:16:22.14,Default,,0000,0000,0000,,we are stars.
Dialogue: 0,0:16:22.85,0:16:24.26,Default,,0000,0000,0000,,Thank you.
Dialogue: 0,0:16:24.26,0:16:26.60,Default,,0000,0000,0000,,(Applause)