14 Minutes of Mind-Blowing Space Facts! | With Astrophysicist Brian Cox — Transcript

Full transcript

1. 0:00there are 2 trillion galaxies  in the observable universe
2. 0:03you need to know that the Milky Way  galaxy has got 200 billion stars
3. 0:07most of those stars now we  know have planetary systems
4. 0:11we estimate there are something like 20
5. 0:13billion earth-like planets or  potentially earth-like  planets
6. 0:17in the Milky Way galaxy alone. so if you're asking  questions about what is my place in the universe
7. 0:22you need to know those things first of all.  it's a framework within which you can think.
8. 0:33I've been doing some work on black holes and  there's progress being made on that now which
9. 0:38I think is profound and exciting. so they are  stars at the end of their life Bigger Than The
10. 0:44Sun more massive than the Sun but they run out  of their fuel and they start to collapse because
11. 0:49gravity squashes them and if they're sufficiently  massive then there's nothing that can stop the
12. 0:54collapse and so they collapse as far as we know to  a point and essentially an infinitely dense point,
13. 1:02but they collapse to such an extent that there's  a region around it where from which light can't
14. 1:08escape. so nothing can escape and that that's a  black hole they they're surrounded this region
15. 1:15where if you fall in It's called The Event  Horizon and if you go across that Horizon
16. 1:20then you are going to the center there's one way  of thinking about it which is quite cool which is
17. 1:25that uh the time and space sort of flip is one  way to think about it so in the same way that
18. 1:30we are going into the future now so we're going  to tomorrow there's nothing we can do about it we
19. 1:36are going to tomorrow um in the same way if you  fall in across the Event Horizon of a black hole
20. 1:42you are going to the middle The Singularity it's  called so that's that's your future every line
21. 1:48of your future points to the center of the  black hole. we have now got photographs of
22. 1:54them so we have two photographs which are radio  telescope photographs one of the the one in the
23. 1:59center of our Galaxy which is a little one it's  called Sagittarius A star so it's about 6 million
24. 2:05times the mass of the Sun and they took a photo  of one in the Galaxy m87. 55 million light years
25. 2:11away that thing is around 6 billion times the mass  of the Sun so if you took our sun we you can fit
26. 2:18a million Earths inside and collapsed it down to  make a black hole it would form a black hole when
27. 2:23it shrunk. so you squash it down till it's about  2 miles and then that would form a black hole.
28. 2:306 billion times the mass of the Sun means you  multiply that by 6 billion so these things
29. 2:36that the so called Schwarzschild radius  is larger than our solar system. so what
30. 2:41what you're seeing there is the emission  from the material that's swelling around
31. 2:45it it's called the accretion disc so you have  material that's orbiting very fast emitting a
32. 2:51lot of radiation and that's what you see.  it's a flat disc by the way think Saturn's
33. 2:55rings so this material is very flat but what  you're seeing in that photograph is the light
34. 3:01rays being bent around the black hole from  that flat disc so that was a prediction uh
35. 3:07from Einstein's theory basically published it  in 1915. and you can predict that that's one
36. 3:12what one should look like and then just about  was at 4 years ago now maybe five years ago,
37. 3:17for the first time in history we get an image  of one and it looks like the prediction.
38. 3:28in science at the moment space science we have  this debate a lot actually because of course
39. 3:33um space probes like curiosity that's on Mars at  the moment that's really cheap compared to sending
40. 3:39people to Mars and so quite often the scientists  who want to find out about the worlds will say
41. 3:45well we should spend it on robots we shouldn't  spend it on people I think crude space exploration
42. 3:50is in in some ways I mean it's clearly true at  the moment that humans can do more than robots
43. 3:57so we can explore the place better it's about  living and working off the planet which I think
44. 4:05is quite a persuasive argument actually we we've  already industrialized near Earth orbit so it's
45. 4:11already a multi-billion dollar industry you know  communication satellites and weather satellites
46. 4:15GPS whatever you we're already up there and so  learning to live and work in space is I think a
47. 4:21natural extension of our of our civilization plus  the fact if you talk to Elon or Jeff Bezos they
48. 4:28point out that the amount of resources available  just slightly above our heads is vest and so I I
49. 4:34remember I talked to Jeff Bas actually once and  he he thinks really simply and he said know for
50. 4:40example in the asteroid belt there's enough  metal I think to build a skyscraper what is
51. 4:46it something like 800 stories tall and cover the  Earth in it right if you want. now we don't want to
52. 4:52do that but his point was that that the energy  from the Sun is all up there the resources are
53. 4:58up there so you could almost imagine trying to  Zone the Earth residential at some point in the
54. 5:03future to protect the planet and do your heavy  industry off the planet for example and these
55. 5:08sound it sounds like science fiction except that  now SpaceX and Blue Origin those people have got
56. 5:14reusable Rockets so suddenly the economics become  sensible. I think expansion is good and I think we
57. 5:21will expand and I think we will expand outwards  because there's not much room left on this planet
58. 5:26to expand that's a whole different idea it's not about Gathering scientific information it's
59. 5:32about a frontier and all the benefits that  come from operating as a civilization on a
60. 5:38frontier which we have lost on the earth because  there is no Frontier left and so I like that idea
61. 5:51so there there is no other planet we can  go to other than Mars you can't go to Jupiter
62. 5:56or Saturn you can't go to Mercury or Venus so  if we want to go go somewhere and expand our
63. 6:00civilization it has to be Mars and everything's  there that you need it's interesting actually
64. 6:05because we know something about the history of Mars  now quite a lot about the history of Mars and
65. 6:10it's certainly clear that there was water  almost certainly oceans rivers so and that
66. 6:17water is almost certainly still there so there's  certainly ice there may even be pockets of liquid
67. 6:22water below the surface somewhere so um couple  that with all the the minerals and the resources
68. 6:28that we know are there and you have everything  you need so that's the thing about Mars it's
69. 6:32quite nice relative to everywhere else other than  the earth you can't go to Venus you'd just melt
70. 6:39it's what is it 400 and something degrees and  uh 90 atmospheric pressure so Mars is quite nice
71. 6:55I think there must be a um even in the  solar system I would not be surprised if we
72. 7:03find microbes on mars or on some of the moons  of Jupiter or Saturn where there's liquid water
73. 7:10and the reason is if you think about the reason I  think that and it's a guess is because if you look
74. 7:16at the history of life on Earth so Earth formed  there was no life it was a ball of rock and almost
75. 7:22as soon as it cooled down we see evidence of life  so certainly 3.8 billion years ago possibly even
76. 7:29further back than that we see evidence of life  on Earth. so somewhere along the line geochemistry
77. 7:37active geochemistry became biochemistry on Earth.  and we have some idea you know that that if you
78. 7:44get gradients of temperature and acid and alkaline  and the conditions that are naturally present
79. 7:51on the surface of oceans, then complex carbon  chemistry spontaneously happens. so we have a
80. 7:59we know that life almost certainly we know that  life began on Earth I mean the other option is
81. 8:04it came from space or something like that but it  probably didn't right probably began on Earth um
82. 8:10so that means that at least here that happened  and that we know that the conditions that led to
83. 8:16the origin of life on Earth were present on Mars  3.8 4 billion years ago and we know that they're
84. 8:22present on Europa today so I don't see that  there's anything special life is just chemistry
85. 8:29the idea that geochemistry becomes biochemistry  is not fanciful because it happened here so I
86. 8:35think that given the same conditions it would  be surprising to me if the same thing didn't
87. 8:40happen in that life begins to test that is one  of the great frontiers of science now it's one
88. 8:48of the great challenges which is why another  reason we're interested in Mars because we
89. 8:52know those conditions were there we know there  were what's called hydrothermal vent systems
90. 8:56on the floors of oceans on Mars 3.8 or 4  billion years ago so it would be good to
91. 9:03know what I've said is right and the way we  find out is to find life or evidence of past life.
92. 9:15you know that there's a thing there's a  theory called the Grand Tack Theory so it's very
93. 9:22hard to explain the evolution of our solar system  when you do computer models of solar systems you
94. 9:28don't tend to get four Rock planets to close to  the Sun and four big gas giants further out and
95. 9:33one of the current best theories and this I say  this because it shows you how looky we might be
96. 9:38is that Jupiter they tend to form these big gas  giants and migrate inwards towards the star so
97. 9:44in almost all the computer simulations just  because you got this big gas giant orbiting
98. 9:49in all the dust around the star they tend  to drop inwards and it looks like Jupiter
99. 9:54did that so it looks like it formed and came in  and came in almost to where Mars orbits today
100. 10:00and and cleared out the region around Mars  actually which is maybe the reason Mars is so
101. 10:04small compared to the other to Venus and Earth but  then Saturn was coming in as well and uh in the
102. 10:12computer models the interaction between Jupiter  and Saturn stops Jupiter coming in before it gets
103. 10:18to the Earth and they both get dragged out again  and so to where they are today oh wow and so that
104. 10:24and that that seems to be it's one of the best  theories for the evolution of our solar system.
105. 10:29so what are the chances you know the the chances  of that are so minuscule tiny so that's the thing
106. 10:38I think about these rocky planets you in order  to get a civilization on them I think you need
107. 10:45I guess you need quite unusual solar systems and  that would be a guess and you need quite unusual
108. 10:51stability on the planet for for billions of years  and that's why I think we might be quite lucky.
109. 11:04an answer would be uh we are small finite beings  right which are just clusters of atoms as we said
110. 11:13before they're very rare but we understand roughly  how they how they came to be and we have a a
111. 11:20limited amount of time not actually unfortunately  but because of the laws of nature the laws of
112. 11:27nature forbid us to be Immortal immortality  is ruled out by the laws of physics but also
113. 11:35what's interesting about if you look at the basic  physics of the universe going from The Big Bang to
114. 11:40where we are today then the physics is driven by  the fact that the Universe began in an extremely
115. 11:47ordered state so it was a very highly ordered  system and it is tending towards a more disordered
116. 11:54system at the moment and that's called the second  law of thermodynamics. what we strongly suspect and
117. 12:02and I would say no uh is that in that process of  going from order to disorder complexity emerges
118. 12:11naturally for a brief period of time so it's a  natural part of the evolution of the universe that
119. 12:18you get a period in time when there's complexity  in the universe so stars and planets and galaxies
120. 12:23and life and civilizations but they are they  exist because the universe is decaying not in
121. 12:30spite of the fact the universe is decaying so our  existence in that sort of picture is necessarily
122. 12:38finite and necessarily time limited and it is a  remarkable thing that that complexity has got so
123. 12:44far that there are things in the universe that can  think and feel and explore it. and I think that is
124. 12:51the answer if you want an answer to the meaning of  it all is that that you are part of the universe
125. 12:57because of the way the laws of nature work you  are allowed to exist but you're allowed to exist
126. 13:03for a temporary for a small amount of time in a  possibly infinite Universe what more do you want
127. 13:10you know when I when I see people who go I want  I want more than that I want more you know must
128. 13:15there must be more to it what do you mean the  ingredients in our bodies were assembled in the
129. 13:20hearts of long dead stars over billions of years  and have assembled themselves spontaneously into
130. 13:26temporary structures that can think can feel and  explore and then those structures will Decay away
131. 13:32again at some point and in the very far future  there'll be no structures left so so there we are
132. 13:37we exist in this little window when we can observe  This Magnificent Universe why do you want any more