TEDGlobal 2005
Martin Rees: Is this our final century?
Filmed:
Readability: 5
2,914,928 views
Speaking as both an astronomer and "a concerned member of the human race," Sir Martin Rees examines our planet and its future from a cosmic perspective. He urges action to prevent dark consequences from our scientific and technological development.
Martin Rees - Astrophysicist
Lord Martin Rees, one of the world's most eminent astronomers, is an emeritus professor of cosmology and astrophysics at the University of Cambridge and the UK's Astronomer Royal. He is one of our key thinkers on the future of humanity in the cosmos. Full bio
Lord Martin Rees, one of the world's most eminent astronomers, is an emeritus professor of cosmology and astrophysics at the University of Cambridge and the UK's Astronomer Royal. He is one of our key thinkers on the future of humanity in the cosmos. Full bio
Double-click the English transcript below to play the video.
00:24
If you take 10,000 people at random, 9,999 have something in common:
0
0
6000
00:30
their interests in business lie on or near the Earth's surface.
1
6000
5000
00:35
The odd one out is an astronomer, and I am one of that strange breed.
2
11000
4000
00:39
(Laughter)
3
15000
1000
00:40
My talk will be in two parts. I'll talk first as an astronomer,
4
16000
5000
00:45
and then as a worried member of the human race.
5
21000
4000
00:49
But let's start off by remembering that Darwin showed
6
25000
5000
00:54
how we're the outcome of four billion years of evolution.
7
30000
4000
00:58
And what we try to do in astronomy and cosmology
8
34000
3000
01:01
is to go back before Darwin's simple beginning,
9
37000
3000
01:04
to set our Earth in a cosmic context.
10
40000
4000
01:08
And let me just run through a few slides.
11
44000
3000
01:11
This was the impact that happened last week on a comet.
12
47000
4000
01:16
If they'd sent a nuke, it would have been rather more spectacular
13
52000
2000
01:18
than what actually happened last Monday.
14
54000
2000
01:21
So that's another project for NASA.
15
57000
2000
01:23
That's Mars from the European Mars Express, and at New Year.
16
59000
5000
01:28
This artist's impression turned into reality
17
64000
5000
01:33
when a parachute landed on Titan, Saturn's giant moon.
18
69000
4000
01:37
It landed on the surface. This is pictures taken on the way down.
19
73000
4000
01:41
That looks like a coastline.
20
77000
1000
01:42
It is indeed, but the ocean is liquid methane --
21
78000
3000
01:45
the temperature minus 170 degrees centigrade.
22
81000
5000
01:50
If we go beyond our solar system,
23
86000
2000
01:52
we've learned that the stars aren't twinkly points of light.
24
88000
4000
01:56
Each one is like a sun with a retinue of planets orbiting around it.
25
92000
4000
02:01
And we can see places where stars are forming,
26
97000
3000
02:04
like the Eagle Nebula. We see stars dying.
27
100000
3000
02:07
In six billion years, the sun will look like that.
28
103000
3000
02:10
And some stars die spectacularly in a supernova explosion,
29
106000
4000
02:14
leaving remnants like that.
30
110000
2000
02:16
On a still bigger scale, we see entire galaxies of stars.
31
112000
4000
02:20
We see entire ecosystems where gas is being recycled.
32
116000
3000
02:23
And to the cosmologist,
33
119000
2000
02:25
these galaxies are just the atoms, as it were, of the large-scale universe.
34
121000
6000
02:31
This picture shows a patch of sky
35
127000
3000
02:34
so small that it would take about 100 patches like it
36
130000
3000
02:37
to cover the full moon in the sky.
37
133000
2000
02:40
Through a small telescope, this would look quite blank,
38
136000
2000
02:42
but you see here hundreds of little, faint smudges.
39
138000
4000
02:46
Each is a galaxy, fully like ours or Andromeda,
40
142000
4000
02:50
which looks so small and faint because its light
41
146000
2000
02:52
has taken 10 billion light-years to get to us.
42
148000
3000
02:56
The stars in those galaxies probably don't have planets around them.
43
152000
4000
03:01
There's scant chance of life there -- that's because there's been no time
44
157000
3000
03:04
for the nuclear fusion in stars to make silicon and carbon and iron,
45
160000
6000
03:10
the building blocks of planets and of life.
46
166000
3000
03:14
We believe that all of this emerged from a Big Bang --
47
170000
5000
03:20
a hot, dense state. So how did that amorphous Big Bang
48
176000
4000
03:24
turn into our complex cosmos?
49
180000
2000
03:26
I'm going to show you a movie simulation
50
182000
3000
03:29
16 powers of 10 faster than real time,
51
185000
2000
03:31
which shows a patch of the universe where the expansions have subtracted out.
52
187000
4000
03:35
But you see, as time goes on in gigayears at the bottom,
53
191000
4000
03:39
you will see structures evolve as gravity feeds
54
195000
3000
03:42
on small, dense irregularities, and structures develop.
55
198000
4000
03:46
And we'll end up after 13 billion years
56
202000
2000
03:48
with something looking rather like our own universe.
57
204000
4000
03:55
And we compare simulated universes like that --
58
211000
3000
03:58
I'll show you a better simulation at the end of my talk --
59
214000
2000
04:00
with what we actually see in the sky.
60
216000
4000
04:04
Well, we can trace things back to the earlier stages of the Big Bang,
61
220000
6000
04:10
but we still don't know what banged and why it banged.
62
226000
4000
04:14
That's a challenge for 21st-century science.
63
230000
3000
04:19
If my research group had a logo, it would be this picture here:
64
235000
3000
04:22
an ouroboros, where you see the micro-world on the left --
65
238000
4000
04:27
the world of the quantum -- and on the right
66
243000
3000
04:30
the large-scale universe of planets, stars and galaxies.
67
246000
5000
04:35
We know our universes are united though --
68
251000
2000
04:37
links between left and right.
69
253000
2000
04:39
The everyday world is determined by atoms,
70
255000
2000
04:41
how they stick together to make molecules.
71
257000
2000
04:43
Stars are fueled by how the nuclei in those atoms react together.
72
259000
6000
04:49
And, as we've learned in the last few years, galaxies are held together
73
265000
3000
04:52
by the gravitational pull of so-called dark matter:
74
268000
3000
04:55
particles in huge swarms, far smaller even than atomic nuclei.
75
271000
5000
05:01
But we'd like to know the synthesis symbolized at the very top.
76
277000
6000
05:07
The micro-world of the quantum is understood.
77
283000
3000
05:10
On the right hand side, gravity holds sway. Einstein explained that.
78
286000
4000
05:15
But the unfinished business for 21st-century science
79
291000
3000
05:18
is to link together cosmos and micro-world
80
294000
2000
05:20
with a unified theory -- symbolized, as it were, gastronomically
81
296000
4000
05:24
at the top of that picture. (Laughter)
82
300000
2000
05:26
And until we have that synthesis,
83
302000
2000
05:28
we won't be able to understand the very beginning of our universe
84
304000
3000
05:31
because when our universe was itself the size of an atom,
85
307000
3000
05:34
quantum effects could shake everything.
86
310000
2000
05:37
And so we need a theory that unifies the very large and the very small,
87
313000
4000
05:41
which we don't yet have.
88
317000
2000
05:44
One idea, incidentally --
89
320000
2000
05:46
and I had this hazard sign to say I'm going to speculate from now on --
90
322000
4000
05:51
is that our Big Bang was not the only one.
91
327000
2000
05:53
One idea is that our three-dimensional universe
92
329000
4000
05:57
may be embedded in a high-dimensional space,
93
333000
2000
05:59
just as you can imagine on these sheets of paper.
94
335000
3000
06:02
You can imagine ants on one of them
95
338000
2000
06:04
thinking it's a two-dimensional universe,
96
340000
2000
06:06
not being aware of another population of ants on the other.
97
342000
2000
06:08
So there could be another universe just a millimeter away from ours,
98
344000
4000
06:12
but we're not aware of it because that millimeter
99
348000
3000
06:15
is measured in some fourth spatial dimension,
100
351000
2000
06:17
and we're imprisoned in our three.
101
353000
2000
06:19
And so we believe that there may be a lot more to physical reality
102
355000
5000
06:24
than what we've normally called our universe --
103
360000
2000
06:26
the aftermath of our Big Bang. And here's another picture.
104
362000
3000
06:29
Bottom right depicts our universe,
105
365000
2000
06:31
which on the horizon is not beyond that,
106
367000
2000
06:33
but even that is just one bubble, as it were, in some vaster reality.
107
369000
5000
06:38
Many people suspect that just as we've gone from believing
108
374000
3000
06:41
in one solar system to zillions of solar systems,
109
377000
4000
06:45
one galaxy to many galaxies,
110
381000
2000
06:47
we have to go to many Big Bangs from one Big Bang,
111
383000
4000
06:51
perhaps these many Big Bangs displaying
112
387000
2000
06:53
an immense variety of properties.
113
389000
2000
06:55
Well, let's go back to this picture.
114
391000
2000
06:57
There's one challenge symbolized at the top,
115
393000
2000
07:00
but there's another challenge to science symbolized at the bottom.
116
396000
4000
07:04
You want to not only synthesize the very large and the very small,
117
400000
3000
07:07
but we want to understand the very complex.
118
403000
2000
07:10
And the most complex things are ourselves,
119
406000
2000
07:12
midway between atoms and stars.
120
408000
2000
07:14
We depend on stars to make the atoms we're made of.
121
410000
2000
07:16
We depend on chemistry to determine our complex structure.
122
412000
5000
07:22
We clearly have to be large, compared to atoms,
123
418000
2000
07:25
to have layer upon layer of complex structure.
124
421000
2000
07:27
We clearly have to be small, compared to stars and planets --
125
423000
3000
07:30
otherwise we'd be crushed by gravity. And in fact, we are midway.
126
426000
4000
07:34
It would take as many human bodies to make up the sun
127
430000
2000
07:36
as there are atoms in each of us.
128
432000
2000
07:38
The geometric mean of the mass of a proton
129
434000
2000
07:40
and the mass of the sun is 50 kilograms,
130
436000
3000
07:43
within a factor of two of the mass of each person here.
131
439000
3000
07:46
Well, most of you anyway.
132
442000
1000
07:47
The science of complexity is probably the greatest challenge of all,
133
443000
5000
07:52
greater than that of the very small on the left
134
448000
2000
07:54
and the very large on the right.
135
450000
2000
07:57
And it's this science,
136
453000
2000
07:59
which is not only enlightening our understanding of the biological world,
137
455000
4000
08:03
but also transforming our world faster than ever.
138
459000
3000
08:07
And more than that, it's engendering new kinds of change.
139
463000
3000
08:11
And I now move on to the second part of my talk,
140
467000
4000
08:16
and the book "Our Final Century" was mentioned.
141
472000
4000
08:20
If I was not a self-effacing Brit, I would mention the book myself,
142
476000
4000
08:24
and I would add that it's available in paperback.
143
480000
3000
08:27
(Laughter)
144
483000
2000
08:30
And in America it was called "Our Final Hour"
145
486000
3000
08:33
because Americans like instant gratification.
146
489000
2000
08:35
(Laughter)
147
491000
2000
08:37
But my theme is that in this century,
148
493000
3000
08:40
not only has science changed the world faster than ever,
149
496000
3000
08:43
but in new and different ways.
150
499000
2000
08:46
Targeted drugs, genetic modification, artificial intelligence,
151
502000
4000
08:50
perhaps even implants into our brains,
152
506000
2000
08:52
may change human beings themselves. And human beings,
153
508000
3000
08:55
their physique and character, has not changed for thousands of years.
154
511000
4000
08:59
It may change this century.
155
515000
2000
09:01
It's new in our history.
156
517000
2000
09:03
And the human impact on the global environment -- greenhouse warming,
157
519000
3000
09:06
mass extinctions and so forth -- is unprecedented, too.
158
522000
3000
09:10
And so, this makes this coming century a challenge.
159
526000
3000
09:15
Bio- and cybertechnologies are environmentally benign
160
531000
3000
09:18
in that they offer marvelous prospects,
161
534000
2000
09:20
while, nonetheless, reducing pressure on energy and resources.
162
536000
3000
09:24
But they will have a dark side.
163
540000
2000
09:27
In our interconnected world, novel technology could empower
164
543000
4000
09:31
just one fanatic,
165
547000
2000
09:33
or some weirdo with a mindset of those who now design computer viruses,
166
549000
4000
09:37
to trigger some kind on disaster.
167
553000
2000
09:39
Indeed, catastrophe could arise simply from technical misadventure --
168
555000
4000
09:43
error rather than terror.
169
559000
2000
09:45
And even a tiny probability of catastrophe is unacceptable
170
561000
5000
09:50
when the downside could be of global consequence.
171
566000
3000
09:55
In fact, some years ago, Bill Joy wrote an article
172
571000
4000
09:59
expressing tremendous concern about robots taking us over, etc.
173
575000
4000
10:03
I don't go along with all that,
174
579000
1000
10:04
but it's interesting that he had a simple solution.
175
580000
2000
10:06
It was what he called "fine-grained relinquishment."
176
582000
3000
10:09
He wanted to give up the dangerous kind of science
177
585000
3000
10:12
and keep the good bits. Now, that's absurdly naive for two reasons.
178
588000
4000
10:16
First, any scientific discovery has benign consequences
179
592000
4000
10:20
as well as dangerous ones.
180
596000
2000
10:22
And also, when a scientist makes a discovery,
181
598000
3000
10:25
he or she normally has no clue what the applications are going to be.
182
601000
4000
10:29
And so what this means is that we have to accept the risks
183
605000
5000
10:34
if we are going to enjoy the benefits of science.
184
610000
4000
10:38
We have to accept that there will be hazards.
185
614000
2000
10:41
And I think we have to go back to what happened in the post-War era,
186
617000
6000
10:47
post-World War II, when the nuclear scientists
187
623000
3000
10:50
who'd been involved in making the atomic bomb,
188
626000
2000
10:52
in many cases were concerned that they should do all they could
189
628000
4000
10:56
to alert the world to the dangers.
190
632000
2000
10:58
And they were inspired not by the young Einstein,
191
634000
4000
11:02
who did the great work in relativity, but by the old Einstein,
192
638000
5000
11:07
the icon of poster and t-shirt,
193
643000
3000
11:10
who failed in his scientific efforts to unify the physical laws.
194
646000
4000
11:14
He was premature. But he was a moral compass --
195
650000
3000
11:17
an inspiration to scientists who were concerned with arms control.
196
653000
5000
11:22
And perhaps the greatest living person
197
658000
2000
11:24
is someone I'm privileged to know, Joe Rothblatt.
198
660000
3000
11:27
Equally untidy office there, as you can see.
199
663000
3000
11:30
He's 96 years old, and he founded the Pugwash movement.
200
666000
4000
11:34
He persuaded Einstein, as his last act,
201
670000
2000
11:36
to sign the famous memorandum of Bertrand Russell.
202
672000
3000
11:39
And he sets an example of the concerned scientist.
203
675000
4000
11:44
And I think to harness science optimally,
204
680000
3000
11:47
to choose which doors to open and which to leave closed,
205
683000
3000
11:50
we need latter-day counterparts of people like Joseph Rothblatt.
206
686000
5000
11:55
We need not just campaigning physicists,
207
691000
2000
11:57
but we need biologists, computer experts
208
693000
2000
11:59
and environmentalists as well.
209
695000
2000
12:02
And I think academics and independent entrepreneurs
210
698000
3000
12:05
have a special obligation because they have more freedom
211
701000
2000
12:07
than those in government service,
212
703000
2000
12:09
or company employees subject to commercial pressure.
213
705000
3000
12:12
I wrote my book, "Our Final Century," as a scientist,
214
708000
5000
12:17
just a general scientist. But there's one respect, I think,
215
713000
3000
12:20
in which being a cosmologist offered a special perspective,
216
716000
4000
12:24
and that's that it offers an awareness of the immense future.
217
720000
4000
12:28
The stupendous time spans of the evolutionary past
218
724000
3000
12:31
are now part of common culture --
219
727000
3000
12:34
outside the American Bible Belt, anyway --
220
730000
3000
12:37
(Laughter)
221
733000
1000
12:38
but most people, even those who are familiar with evolution,
222
734000
4000
12:42
aren't mindful that even more time lies ahead.
223
738000
3000
12:46
The sun has been shining for four and a half billion years,
224
742000
3000
12:49
but it'll be another six billion years before its fuel runs out.
225
745000
4000
12:53
On that schematic picture, a sort of time-lapse picture, we're halfway.
226
749000
5000
12:59
And it'll be another six billion before that happens,
227
755000
5000
13:04
and any remaining life on Earth is vaporized.
228
760000
4000
13:09
There's an unthinking tendency to imagine that humans will be there,
229
765000
3000
13:12
experiencing the sun's demise,
230
768000
2000
13:14
but any life and intelligence that exists then
231
770000
3000
13:17
will be as different from us as we are from bacteria.
232
773000
4000
13:21
The unfolding of intelligence and complexity
233
777000
2000
13:23
still has immensely far to go, here on Earth and probably far beyond.
234
779000
5000
13:29
So we are still at the beginning of the emergence of complexity
235
785000
3000
13:32
in our Earth and beyond.
236
788000
2000
13:35
If you represent the Earth's lifetime by a single year,
237
791000
4000
13:39
say from January when it was made to December,
238
795000
3000
13:42
the 21st-century would be a quarter of a second in June --
239
798000
5000
13:48
a tiny fraction of the year.
240
804000
2000
13:51
But even in this concertinaed cosmic perspective,
241
807000
4000
13:55
our century is very, very special,
242
811000
2000
13:58
the first when humans can change themselves and their home planet.
243
814000
4000
14:03
As I should have shown this earlier,
244
819000
3000
14:06
it will not be humans who witness the end point of the sun;
245
822000
3000
14:09
it will be creatures as different from us as we are from bacteria.
246
825000
3000
14:14
When Einstein died in 1955,
247
830000
3000
14:17
one striking tribute to his global status was this cartoon
248
833000
3000
14:20
by Herblock in the Washington Post.
249
836000
2000
14:22
The plaque reads, "Albert Einstein lived here."
250
838000
3000
14:26
And I'd like to end with a vignette, as it were, inspired by this image.
251
842000
4000
14:30
We've been familiar for 40 years with this image:
252
846000
6000
14:36
the fragile beauty of land, ocean and clouds,
253
852000
3000
14:39
contrasted with the sterile moonscape
254
855000
2000
14:41
on which the astronauts left their footprints.
255
857000
3000
14:45
But let's suppose some aliens had been watching our pale blue dot
256
861000
4000
14:49
in the cosmos from afar, not just for 40 years,
257
865000
4000
14:53
but for the entire 4.5 billion-year history of our Earth.
258
869000
4000
14:58
What would they have seen?
259
874000
2000
15:00
Over nearly all that immense time,
260
876000
2000
15:02
Earth's appearance would have changed very gradually.
261
878000
3000
15:05
The only abrupt worldwide change
262
881000
2000
15:07
would have been major asteroid impacts or volcanic super-eruptions.
263
883000
6000
15:13
Apart from those brief traumas, nothing happens suddenly.
264
889000
4000
15:17
The continental landmasses drifted around.
265
893000
3000
15:20
Ice cover waxed and waned.
266
896000
2000
15:22
Successions of new species emerged, evolved and became extinct.
267
898000
3000
15:26
But in just a tiny sliver of the Earth's history,
268
902000
4000
15:30
the last one-millionth part, a few thousand years,
269
906000
3000
15:34
the patterns of vegetation altered much faster than before.
270
910000
3000
15:37
This signaled the start of agriculture.
271
913000
3000
15:40
Change has accelerated as human populations rose.
272
916000
4000
15:44
Then other things happened even more abruptly.
273
920000
2000
15:46
Within just 50 years --
274
922000
2000
15:48
that's one hundredth of one millionth of the Earth's age --
275
924000
4000
15:52
the amount of carbon dioxide in the atmosphere started to rise,
276
928000
4000
15:56
and ominously fast.
277
932000
2000
15:58
The planet became an intense emitter of radio waves --
278
934000
2000
16:00
the total output from all TV and cell phones
279
936000
4000
16:04
and radar transmissions. And something else happened.
280
940000
3000
16:07
Metallic objects -- albeit very small ones, a few tons at most --
281
943000
5000
16:12
escaped into orbit around the Earth.
282
948000
3000
16:15
Some journeyed to the moons and planets.
283
951000
2000
16:17
A race of advanced extraterrestrials
284
953000
2000
16:19
watching our solar system from afar
285
955000
3000
16:22
could confidently predict Earth's final doom in another six billion years.
286
958000
5000
16:27
But could they have predicted this unprecedented spike
287
963000
4000
16:31
less than halfway through the Earth's life?
288
967000
3000
16:34
These human-induced alterations
289
970000
2000
16:36
occupying overall less than a millionth of the elapsed lifetime
290
972000
4000
16:40
and seemingly occurring with runaway speed?
291
976000
3000
16:43
If they continued their vigil,
292
979000
2000
16:45
what might these hypothetical aliens witness
293
981000
2000
16:47
in the next hundred years?
294
983000
2000
16:50
Will some spasm foreclose Earth's future?
295
986000
3000
16:53
Or will the biosphere stabilize?
296
989000
2000
16:56
Or will some of the metallic objects launched from the Earth
297
992000
3000
16:59
spawn new oases, a post-human life elsewhere?
298
995000
4000
17:03
The science done by the young Einstein will continue
299
999000
3000
17:06
as long as our civilization, but for civilization to survive,
300
1002000
5000
17:11
we'll need the wisdom of the old Einstein --
301
1007000
2000
17:13
humane, global and farseeing.
302
1009000
2000
17:15
And whatever happens in this uniquely crucial century
303
1011000
5000
17:20
will resonate into the remote future and perhaps far beyond the Earth,
304
1016000
6000
17:26
far beyond the Earth as depicted here.
305
1022000
2000
17:28
Thank you very much.
306
1024000
2000
17:30
(Applause)
307
1026000
3000
ABOUT THE SPEAKER
Martin Rees - AstrophysicistLord Martin Rees, one of the world's most eminent astronomers, is an emeritus professor of cosmology and astrophysics at the University of Cambridge and the UK's Astronomer Royal. He is one of our key thinkers on the future of humanity in the cosmos.
Why you should listen
Lord Martin Rees has issued a clarion call for humanity. His 2004 book, ominously titled Our Final Hour, catalogues the threats facing the human race in a 21st century dominated by unprecedented and accelerating scientific change. He calls on scientists and nonscientists alike to take steps that will ensure our survival as a species.
One of the world's leading astronomers, Rees is an emeritus professor of cosmology and astrophysics at Cambridge, and UK Astronomer Royal. Author of more than 500 research papers on cosmological topics ranging from black holes to quantum physics to the Big Bang, Rees has received countless awards for his scientific contributions. But equally significant has been his devotion to explaining the complexities of science for a general audience, in books like Before the Beginning and Our Cosmic Habitat.
Martin Rees | Speaker | TED.com