TEDxBoulder
Dave Brain: What a planet needs to sustain life
戴夫·布莱恩: 行星维持生命的要素
Filmed:
Readability: 4.1
1,867,290 views
“金星太热，火星太冷，地球刚刚好”，行星科学家戴夫·布莱恩说。但为什么？在这个关于行星的幽默的演讲中，布莱恩解释了一个有生命行星背后的有趣科学，以及为什么人类可以在正确的时间、正确的地点，出现在有生命星球的时间线上。
Dave Brain - Planetary scientist
Dave Brain studies the plasma environments and atmospheres of unmagnetized planets. Full bio
Dave Brain studies the plasma environments and atmospheres of unmagnetized planets. Full bio
Double-click the English transcript below to play the video.
00:12
I'm really glad to be here.
0
943
1421
我很高兴能在这里。
00:15
I'm glad you're here,
1
3015
1688
很高兴你们也在这里，
00:16
because that would be a little weird.
2
4727
1833
因为这会有点奇怪。
00:19
I'm glad we're all here.
3
7460
2105
我很高兴我们都在这里。
00:22
And by "here," I don't mean here.
4
10303
2853
我说的"这里"，并不是指这里，
00:26
Or here.
5
14831
1150
或者这里，
00:28
But here.
6
16728
1152
而是这里。
00:29
I mean Earth.
7
17904
1150
我指的是地球。
00:31
And by "we," I don't mean
those of us in this auditorium,
those of us in this auditorium,
8
19627
3943
我说的"我们"并不是指
我们坐在会场里的人，
我们坐在会场里的人，
00:35
but life,
9
23594
1470
而是生命，
00:37
all life on Earth --
10
25088
1449
地球上所有的生命。
00:38
(Laughter)
11
26561
5382
（笑声）
00:44
from complex to single-celled,
12
32280
1991
从复杂的生命到单细胞的生命，
00:46
from mold to mushrooms
13
34295
2324
从霉菌到蘑菇，
00:48
to flying bears.
14
36643
1378
到会飞的熊。
00:50
(Laughter)
15
38045
1366
（笑声）
00:53
The interesting thing is,
16
41736
1509
有趣的是，
00:55
Earth is the only place
we know of that has life --
we know of that has life --
17
43269
3031
地球是我们已知的
唯一有生命的地方，
唯一有生命的地方，
00:58
8.7 million species.
18
46324
1877
870万种生物。
01:00
We've looked other places,
19
48660
1254
我们曾经在其他星球寻找生命，
01:01
maybe not as hard
as we should or we could,
as we should or we could,
20
49938
2097
或许没有尽全力，
01:04
but we've looked and haven't found any;
21
52059
1927
但我们确实没有发现过。
01:06
Earth is the only place
we know of with life.
we know of with life.
22
54010
2276
地球是我们已知的
唯一有生命的地方，
唯一有生命的地方，
01:09
Is Earth special?
23
57318
1274
地球很特别吗？
01:11
This is a question I've wanted
to know the answer to
to know the answer to
24
59591
2454
从我小时候起，
我就一直想要知道这个问题的答案，
01:14
since I was a small child,
25
62069
1254
01:15
and I suspect 80 percent
of this auditorium
of this auditorium
26
63347
2032
我觉得这个会场里80%的人
01:17
has thought the same thing
and also wanted to know the answer.
and also wanted to know the answer.
27
65403
3008
都曾经思考过同样的问题，
并且想要知道答案。
并且想要知道答案。
01:20
To understand whether
there are any planets --
there are any planets --
28
68879
2167
为了知道是否有其他星球
01:23
out there in our solar system or beyond --
29
71070
2278
—在我们太阳系中或是之外的—
01:25
that can support life,
30
73372
1458
能够支持生命的存在，
01:26
the first step is to understand
what life here requires.
what life here requires.
31
74854
3197
第一步就是要理解生命需要什么。
01:30
It turns out, of all of those
8.7 million species,
8.7 million species,
32
78575
3563
事实表明，
虽然地球上有着870万种生命，
虽然地球上有着870万种生命，
01:34
life only needs three things.
33
82162
2198
但生命的存在只需要三样东西。
01:37
On one side, all life
on Earth needs energy.
on Earth needs energy.
34
85032
2852
首先，所有地球上的生命都需要能量。
01:39
Complex life like us derives
our energy from the sun,
our energy from the sun,
35
87908
3485
复杂的生命，例如我们，
从太阳那里获得能量。
从太阳那里获得能量。
01:43
but life deep underground
can get its energy
can get its energy
36
91417
2101
但是在地底的生命则
通过其他方式，
通过其他方式，
01:45
from things like chemical reactions.
37
93542
1722
比如化学反应，来获得能量。
01:47
There are a number
of different energy sources
of different energy sources
38
95288
2151
在所有的星球上，
都有很多能够获得能量的方式。
01:49
available on all planets.
39
97463
1243
01:51
On the other side,
40
99400
1156
另一方面，
01:52
all life needs food or nourishment.
41
100580
2705
所有的生命都需要食物和营养。
01:55
And this seems like a tall order,
especially if you want a succulent tomato.
especially if you want a succulent tomato.
42
103741
4474
这看起来很难满足，尤其是
如果你想吃一个多汁的番茄。
如果你想吃一个多汁的番茄。
02:00
(Laughter)
43
108239
1716
（笑声）
02:01
However, all life on Earth
derives its nourishment
derives its nourishment
44
109979
3066
但是，地球生命所需的全部营养
02:05
from only six chemical elements,
45
113069
2030
都只基于六种化学元素，
02:07
and these elements can be found
on any planetary body
on any planetary body
46
115123
3004
这些元素在太阳系中
所有的星体上都可以找到。
02:10
in our solar system.
47
118151
1336
02:12
So that leaves the thing
in the middle as the tall pole,
in the middle as the tall pole,
48
120537
3227
中间那幅图中的东西
反而是最难得到的。
02:15
the thing that's hardest to achieve.
49
123788
1954
02:17
Not moose, but water.
50
125766
1892
不是那只鹿，而是水。
02:19
(Laughter)
51
127682
2781
（笑声）
02:23
Although moose would be pretty cool.
52
131285
1794
虽然那只鹿也很酷。
02:25
(Laughter)
53
133103
1158
（笑声）
02:26
And not frozen water, and not water
in a gaseous state, but liquid water.
in a gaseous state, but liquid water.
54
134285
5535
并且不是固态，也不是气态的水，
而是液态的水。
而是液态的水。
02:32
This is what life needs
to survive, all life.
to survive, all life.
55
140748
2453
水是所有生命的前提。
02:35
And many solar system bodies
don't have liquid water,
don't have liquid water,
56
143680
3336
很多太阳系的天体上没有液态水，
02:39
and so we don't look there.
57
147040
1636
所以就可以排除了。
02:40
Other solar system bodies
might have abundant liquid water,
might have abundant liquid water,
58
148700
2993
其他的太阳系天体可能有充足的液态水，
02:43
even more than Earth,
59
151717
1335
甚至比地球上还多，
02:45
but it's trapped beneath an icy shell,
60
153076
2450
但是那些水被阻隔在冰盖下面，
02:47
and so it's hard to access,
it's hard to get to,
it's hard to get to,
61
155550
2261
因此很难得到并加以利用。
02:49
it's hard to even find out
if there's any life there.
if there's any life there.
62
157835
2719
即使那里有生命，我们也很难找到。
02:53
So that leaves a few bodies
that we should think about.
that we should think about.
63
161475
2995
所以只需要考虑
剩下的很少几个星球。
剩下的很少几个星球。
02:56
So let's make the problem
simpler for ourselves.
simpler for ourselves.
64
164494
2429
让我们进一步简化，
02:58
Let's think only about liquid water
on the surface of a planet.
on the surface of a planet.
65
166947
3341
先只考虑星球表面上
存在液态水的问题。
存在液态水的问题。
03:02
There are only three bodies
to think about in our solar system,
to think about in our solar system,
66
170312
2956
在太阳系中，只有三个星球的表面
03:05
with regard to liquid water
on the surface of a planet,
on the surface of a planet,
67
173292
2582
可能存在液态水，
03:07
and in order of distance from the sun,
it's: Venus, Earth and Mars.
it's: Venus, Earth and Mars.
68
175898
4826
按照距离太阳的远近，
他们是：金星、地球、火星。
他们是：金星、地球、火星。
03:13
You want to have an atmosphere
for water to be liquid.
for water to be liquid.
69
181265
3372
你需要一个让水保持液态的大气层，
03:16
You have to be very careful
with that atmosphere.
with that atmosphere.
70
184661
2378
需要非常小心这个大气层，
03:19
You can't have too much atmosphere,
too thick or too warm an atmosphere,
too thick or too warm an atmosphere,
71
187063
3412
不能太多，不能太厚，不能太热，
03:22
because then you end up
too hot like Venus,
too hot like Venus,
72
190499
2905
因为如果太热，像金星一样，
03:25
and you can't have liquid water.
73
193428
1737
就无法保持液态水。
03:27
But if you have too little atmosphere
and it's too thin and too cold,
and it's too thin and too cold,
74
195189
3953
但如果大气太少，太薄或太冷，
03:31
you end up like Mars, too cold.
75
199166
2024
结果就像火星，太冷。
03:33
So Venus is too hot, Mars is too cold,
76
201865
2475
所以金星太热，火星太冷，
03:36
and Earth is just right.
77
204364
1164
地球刚刚好。
03:37
You can look at these images behind me
and you can see automatically
and you can see automatically
78
205552
3475
从我身后的图片，你很容易看出
03:41
where life can survive
in our solar system.
in our solar system.
79
209051
2597
哪个星球能让生命存活。
03:44
It's a Goldilocks-type problem,
80
212296
1600
这是个“金发姑娘问题”，
03:45
and it's so simple
that a child could understand it.
that a child could understand it.
81
213920
2490
即使是小孩子也会明白。
03:49
However,
82
217452
1180
但是，
03:51
I'd like to remind you of two things
83
219450
2928
我想提醒你们，
金发姑娘的故事中，
有两件我们不太在意的事，
有两件我们不太在意的事，
03:54
from the Goldilocks story
that we may not think about so often
that we may not think about so often
84
222402
2954
03:57
but that I think are really relevant here.
85
225380
2096
在这里却非常关键。
04:00
Number one:
86
228056
1150
第一：
04:02
if Mama Bear's bowl is too cold
87
230311
2792
如果金发姑娘走进房间的时候，
熊妈妈的碗太凉，
04:05
when Goldilocks walks into the room,
88
233833
2008
04:08
does that mean it's always been too cold?
89
236642
2143
是否意味着碗会一直很凉呢？
04:11
Or could it have been just right
at some other time?
at some other time?
90
239825
3268
会不会某一个时间，
它的温度会变得刚刚好呢？
它的温度会变得刚刚好呢？
04:15
When Goldilocks walks into the room
determines the answer
determines the answer
91
243650
3681
金发姑娘走进房间的时间，
决定了我们能获得什么样的答案。
04:19
that we get in the story.
92
247355
1332
04:21
And the same is true with planets.
93
249114
1730
对于行星是同样的道理，
04:22
They're not static things. They change.
94
250868
2026
他们不是一成不变的，他们在改变，
04:24
They vary. They evolve.
95
252918
1742
在变化，在发展。
04:26
And atmospheres do the same.
96
254684
2043
大气层也是一样。
04:28
So let me give you an example.
97
256751
1702
我举个例子，
04:30
Here's one of my favorite
pictures of Mars.
pictures of Mars.
98
258477
2002
这是我最喜欢的一张火星的照片，
04:32
It's not the highest resolution image,
it's not the sexiest image,
it's not the sexiest image,
99
260503
3131
它的分辨率不算最高，
也不算最漂亮，
也不算最漂亮，
04:35
it's not the most recent image,
100
263658
1503
也不是最近的照片，
04:37
but it's an image that shows riverbeds
cut into the surface of the planet;
cut into the surface of the planet;
101
265185
3494
但它展示了火星表面的河床。
04:41
riverbeds carved by flowing, liquid water;
102
269320
2584
这些河床是由流动的液态水，
04:45
riverbeds that take hundreds or thousands
or tens of thousands of years to form.
or tens of thousands of years to form.
103
273515
4886
经过成千上万年的侵蚀所形成。
04:50
This can't happen on Mars today.
104
278425
1618
但如今火星上不会再形成河床了，
04:52
The atmosphere of Mars today
is too thin and too cold
is too thin and too cold
105
280067
2481
现在火星的大气层太薄太冷，
04:54
for water to be stable as a liquid.
106
282572
2141
液态水已经无法稳定存在。
04:56
This one image tells you
that the atmosphere of Mars changed,
that the atmosphere of Mars changed,
107
284737
4348
这张图显示了火星大气的变化，
05:01
and it changed in big ways.
108
289109
2032
并且是巨大的变化。
05:03
And it changed from a state
that we would define as habitable,
that we would define as habitable,
109
291714
4809
它从一个我们认为
可居住的状态变化而来，
可居住的状态变化而来，
05:08
because the three requirements
for life were present long ago.
for life were present long ago.
110
296547
3590
因为它很久以前呈现出了
那三个生命存活的要素。
那三个生命存活的要素。
05:13
Where did that atmosphere go
111
301049
2068
那个可以维持液态水的
大气层哪去了？
大气层哪去了？
05:15
that allowed water
to be liquid at the surface?
to be liquid at the surface?
112
303141
2820
一种观点是大气逃逸到了太空，
05:17
Well, one idea is it escaped
away to space.
away to space.
113
305985
3347
05:21
Atmospheric particles
got enough energy to break free
got enough energy to break free
114
309356
2667
大气粒子获得了脱离星球重力的能量，
05:24
from the gravity of the planet,
115
312047
1653
逃逸到太空，再也无法回来。
05:25
escaping away to space, never to return.
116
313724
2689
05:28
And this happens with all bodies
with atmospheres.
with atmospheres.
117
316437
2688
在所有存在大气层的天体上都会发生。
05:31
Comets have tails
118
319149
1172
彗星的尾巴，
05:32
that are incredibly visible reminders
of atmospheric escape.
of atmospheric escape.
119
320345
3257
就是大气逃逸的一种直观表现。
05:35
But Venus also has an atmosphere
that escapes with time,
that escapes with time,
120
323626
3409
但金星同样有正在逃逸的大气层，
05:39
and Mars and Earth as well.
121
327059
1660
火星和地球也一样，
05:40
It's just a matter of degree
and a matter of scale.
and a matter of scale.
122
328743
2968
只是逃逸的程度和规模的问题。
05:44
So we'd like to figure out
how much escaped over time
how much escaped over time
123
332092
2676
我们希望计算出逃逸的速度，
05:46
so we can explain this transition.
124
334792
2116
以解释这种变迁。
05:48
How do atmospheres
get their energy for escape?
get their energy for escape?
125
336932
2611
大气如何获得逃逸的能量？
05:51
How do particles get
enough energy to escape?
enough energy to escape?
126
339567
2131
粒子是怎么获得足够能量的？
05:53
There are two ways, if we're going
to reduce things a little bit.
to reduce things a little bit.
127
341722
3185
简而言之有两种方式，
05:56
Number one, sunlight.
128
344931
1151
第一，太阳光。
05:58
Light emitted from the sun can be absorbed
by atmospheric particles
by atmospheric particles
129
346106
3412
太阳发出的光可以被大气粒子吸收
06:01
and warm the particles.
130
349542
1714
并被加温。
06:03
Yes, I'm dancing, but they --
131
351280
2108
是的，我在跳舞，但它们…
06:05
(Laughter)
132
353412
1471
（笑声）
06:07
Oh my God, not even at my wedding.
133
355693
1912
天哪，我结婚那天都没跳过舞。
06:09
(Laughter)
134
357629
1492
（笑声）
06:11
They get enough energy
to escape and break free
to escape and break free
135
359145
3003
通过加温，它们获得了冲破星球重力
06:14
from the gravity of the planet
just by warming.
just by warming.
136
362172
2500
以逃逸的足够能量。
06:16
A second way they can get energy
is from the solar wind.
is from the solar wind.
137
364696
3162
它们可以获得能量的第二种方式是，
太阳风。
太阳风。
06:19
These are particles, mass, material,
spit out from the surface of the sun,
spit out from the surface of the sun,
138
367882
5026
太阳表面会发射出例子、质量、材料，
06:24
and they go screaming
through the solar system
through the solar system
139
372932
2404
它们以400千米每秒的速度
06:27
at 400 kilometers per second,
140
375360
1785
在太阳系中冲撞，
06:29
sometimes faster during solar storms,
141
377169
2594
有太阳风暴时会更快。
06:31
and they go hurtling
through interplanetary space
through interplanetary space
142
379787
2722
它们在星际空间中，
06:34
towards planets and their atmospheres,
143
382533
2446
朝着行星和大气层飞奔，
06:37
and they may provide energy
144
385003
1625
它们也会为大气粒子
的逃逸提供能量。
的逃逸提供能量。
06:38
for atmospheric particles
to escape as well.
to escape as well.
145
386652
2128
06:41
This is something that I'm interested in,
146
389182
1969
我对这个很感兴趣，
06:43
because it relates to habitability.
147
391175
1713
因为这会和可居住相关。
06:45
I mentioned that there were two things
about the Goldilocks story
about the Goldilocks story
148
393378
3132
我刚才提到金发姑娘故事中
06:48
that I wanted to bring to your attention
and remind you about,
and remind you about,
149
396534
2984
有两个我们需要关注的问题，
06:51
and the second one
is a little bit more subtle.
is a little bit more subtle.
150
399542
2239
第二个问题会更微妙。
06:53
If Papa Bear's bowl is too hot,
151
401805
2788
如果熊爸爸的碗太烫，
06:58
and Mama Bear's bowl is too cold,
152
406180
3234
而熊妈妈的碗太凉，
07:03
shouldn't Baby Bear's bowl be even colder
153
411057
3111
如果按这个规律，
熊宝宝的碗不是应该更凉吗？
07:07
if we're following the trend?
154
415081
1796
07:10
This thing that you've accepted
your entire life,
your entire life,
155
418195
2312
这件你一直没怀疑的事，
07:12
when you think about it a little bit more,
may not be so simple.
may not be so simple.
156
420531
3070
如果仔细一想，可能没那么简单。
07:16
And of course, distance of a planet
from the sun determines its temperature.
from the sun determines its temperature.
157
424513
4028
当然，
大气温度取决于行星和太阳的距离，
大气温度取决于行星和太阳的距离，
07:20
This has to play into habitability.
158
428565
2266
这也决定了可居住性。
07:22
But maybe there are other things
we should be thinking about.
we should be thinking about.
159
430855
2930
但可能有其他我们需要考虑的事，
07:25
Maybe it's the bowls themselves
160
433809
1616
可能碗本身，
07:27
that are also helping to determine
the outcome in the story,
the outcome in the story,
161
435449
3056
也可以决定故事的结局，
07:30
what is just right.
162
438529
1300
这恰恰是事实。
07:32
I could talk to you about a lot
of different characteristics
of different characteristics
163
440765
2865
我讲一个不太一样的特性，
07:35
of these three planets
164
443654
1151
它可以影响这三个行星的可居住性，
07:36
that may influence habitability,
165
444829
1569
07:38
but for selfish reasons related
to my own research
to my own research
166
446422
2594
但由于我的一点私心，
因为这是我自己的研究，
因为这是我自己的研究，
07:41
and the fact that I'm standing up here
holding the clicker and you're not --
holding the clicker and you're not --
167
449040
3588
并且遥控器在我这儿
而不在你们手里，
而不在你们手里，
07:44
(Laughter)
168
452652
1006
（笑声）
07:45
I would like to talk
for just a minute or two
for just a minute or two
169
453682
2109
我想花一两分钟
07:47
about magnetic fields.
170
455815
1297
聊一下磁场。
07:49
Earth has one; Venus and Mars do not.
171
457715
2532
地球有磁场，而金星和火星没有。
07:52
Magnetic fields are generated
in the deep interior of a planet
in the deep interior of a planet
172
460825
3123
磁场是从星球的内部产生，
07:55
by electrically conducting
churning fluid material
churning fluid material
173
463972
3717
由电荷驱动旋转的流体，
07:59
that creates this big old magnetic field
that surrounds Earth.
that surrounds Earth.
174
467713
2905
形成了地球周围的
巨大而古老的磁场。
巨大而古老的磁场。
08:02
If you have a compass,
you know which way north is.
you know which way north is.
175
470642
2396
你用指南针可以分辨出哪里是北，
08:05
Venus and Mars don't have that.
176
473062
1494
但金星和火星没有磁场，
08:06
If you have a compass on Venus and Mars,
177
474580
1914
如果你在金星和火星上用指南针，
08:08
congratulations, you're lost.
178
476518
1396
恭喜，你迷路了。
08:09
(Laughter)
179
477938
1903
（笑声）
08:11
Does this influence habitability?
180
479865
2040
这会影响可居住性吗？
08:15
Well, how might it?
181
483175
1302
会怎么影响？
08:17
Many scientists think
that a magnetic field of a planet
that a magnetic field of a planet
182
485024
2604
有些科学家认为
行星的磁场为大气层提供保护，
行星的磁场为大气层提供保护，
08:19
serves as a shield for the atmosphere,
183
487652
2395
08:22
deflecting solar wind particles
around the planet
around the planet
184
490071
3355
通过力场效应影响带电粒子，
08:25
in a bit of a force field-type effect
185
493450
1815
08:27
having to do with electric charge
of those particles.
of those particles.
186
495289
2700
从而改变太阳风粒子的方向。
08:30
I like to think of it instead
as a salad bar sneeze guard for planets.
as a salad bar sneeze guard for planets.
187
498362
3627
我倒喜欢把它比喻成
食品柜台的防喷嚏罩。
食品柜台的防喷嚏罩。
08:34
(Laughter)
188
502013
2279
（笑声）
08:36
And yes, my colleagues
who watch this later will realize
who watch this later will realize
189
504962
3381
是的，我的同事看到这个后，
08:40
this is the first time in the history
of our community
of our community
190
508367
2544
会发现这是我们圈里有史以来
08:42
that the solar wind has been
equated with mucus.
equated with mucus.
191
510935
2279
第一次把太阳风等同成喷嚏口水。
08:45
(Laughter)
192
513238
1650
（笑声）
08:48
OK, so the effect, then, is that Earth
may have been protected
may have been protected
193
516978
3475
因此，地球可能因为存在磁场，
08:52
for billions of years,
194
520477
1169
而被保护了数十亿年，
08:53
because we've had a magnetic field.
195
521670
1850
08:55
Atmosphere hasn't been able to escape.
196
523544
2179
使得大气层无法逃逸。
08:57
Mars, on the other hand,
has been unprotected
has been unprotected
197
525747
2107
然而火星没有受到这样的保护，
08:59
because of its lack of magnetic field,
198
527878
1842
因为没有磁场，
09:01
and over billions of years,
199
529744
1952
经历了数十亿年，
09:03
maybe enough atmosphere
has been stripped away
has been stripped away
200
531720
2180
足够的大气层逃逸出去
09:05
to account for a transition
from a habitable planet
from a habitable planet
201
533924
2593
使得它变成了不可居住的星球，
09:08
to the planet that we see today.
202
536541
1666
就是今天我们看到的样子。
09:11
Other scientists think
that magnetic fields
that magnetic fields
203
539059
2989
其他科学家认为磁场
09:14
may act more like the sails on a ship,
204
542072
2163
更像是船上的帆，
09:16
enabling the planet to interact
with more energy from the solar wind
with more energy from the solar wind
205
544958
5037
让行星可以通过太阳风
获得更多能量，
获得更多能量，
09:22
than the planet would have been able
to interact with by itself.
to interact with by itself.
206
550019
3272
比星球自己产生的更多。
09:25
The sails may gather energy
from the solar wind.
from the solar wind.
207
553315
2491
船帆可能从太阳风中收集能量。
09:27
The magnetic field may gather
energy from the solar wind
energy from the solar wind
208
555830
2666
但磁场从太阳风中吸收能量，
09:30
that allows even more
atmospheric escape to happen.
atmospheric escape to happen.
209
558520
3244
会让更多的大气逃逸。
09:33
It's an idea that has to be tested,
210
561788
2254
这个想法还有待验证，
09:36
but the effect and how it works
211
564066
1885
但它的影响和原理也是显而易见的。
09:37
seems apparent.
212
565975
1151
09:39
That's because we know
213
567150
1151
因为我们知道，
09:40
energy from the solar wind
is being deposited into our atmosphere
is being deposited into our atmosphere
214
568325
3075
太阳风中的能量会被存储到
地球的大气中。
地球的大气中。
09:43
here on Earth.
215
571424
1151
09:44
That energy is conducted
along magnetic field lines
along magnetic field lines
216
572599
2405
这些能量随着磁场被导入两极，
09:47
down into the polar regions,
217
575028
1348
09:48
resulting in incredibly beautiful aurora.
218
576400
2136
形成绚丽无比的极光。
09:50
If you've ever experienced them,
it's magnificent.
it's magnificent.
219
578560
2656
如果你体验过，那真是非常壮丽。
09:53
We know the energy is getting in.
220
581240
2006
我们知道能量正在源源不断的进入，
09:55
We're trying to measure
how many particles are getting out
how many particles are getting out
221
583270
3033
我们也试着测量有多少粒子跑出去，
09:58
and if the magnetic field
is influencing this in any way.
is influencing this in any way.
222
586327
3038
以及磁场是不是在影响这个过程。
10:02
So I've posed a problem for you here,
223
590722
2380
所以我刚刚抛给各位一个问题，
10:05
but I don't have a solution yet.
224
593126
1546
但我还没有答案，
10:06
We don't have a solution.
225
594696
1276
我们没有答案，
10:08
But we're working on it.
How are we working on it?
How are we working on it?
226
596702
2357
但我们正在努力。
我们怎么做的呢？
我们怎么做的呢？
10:11
Well, we've sent spacecraft
to all three planets.
to all three planets.
227
599083
2298
我们往三颗行星都发射了航天器。
10:13
Some of them are orbiting now,
228
601405
1476
有些已经在轨运行了，
10:14
including the MAVEN spacecraft
which is currently orbiting Mars,
which is currently orbiting Mars,
229
602905
3072
包括正围绕火星运行的
MAVEN 航天器，
MAVEN 航天器，
10:18
which I'm involved with
and which is led here,
and which is led here,
230
606001
3532
这个项目由这里的
科罗拉多大学主导，
科罗拉多大学主导，
10:21
out of the University of Colorado.
231
609557
1809
我也参与了这个项目。
10:23
It's designed to measure
atmospheric escape.
atmospheric escape.
232
611390
2282
它被设计用来观测大气逃逸，
10:26
We have similar measurements
from Venus and Earth.
from Venus and Earth.
233
614022
2474
在金星和地球，
我们也有类似的测量项目。
我们也有类似的测量项目。
10:28
Once we have all our measurements,
234
616953
1665
一旦我们完成测量，
10:30
we can combine all these together,
and we can understand
and we can understand
235
618642
2875
综合分析这些数据，我们就可以了解
10:33
how all three planets interact
with their space environment,
with their space environment,
236
621541
3417
这三颗行星是如何与他们的太空环境
以及自身周围的环境相互作用。
10:36
with the surroundings.
237
624982
1162
10:38
And we can decide whether magnetic fields
are important for habitability
are important for habitability
238
626168
3522
我们也可以清楚，
磁场对可居住性是否关键。
磁场对可居住性是否关键。
10:41
or not.
239
629714
1158
10:42
Once we have that answer,
why should you care?
why should you care?
240
630896
2265
一旦我们有了答案，
你们为什么会在意？
你们为什么会在意？
10:45
I mean, I care deeply ...
241
633185
1300
我是说，我很在意…
10:48
And financially as well, but deeply.
242
636128
2006
财务上很在意，但也确实很在意…
10:50
(Laughter)
243
638158
1842
（笑声）
10:52
First of all, an answer to this question
244
640763
1918
首先，这个问题的答案
10:54
will teach us more
about these three planets,
about these three planets,
245
642705
2103
会告诉我们更多关于
这三颗行星的事情，
这三颗行星的事情，
10:56
Venus, Earth and Mars,
246
644832
1160
金星、地球、火星，
10:58
not only about how they interact
with their environment today,
with their environment today,
247
646016
2911
不只是它们今天如何与
周边环境互相作用，
周边环境互相作用，
11:00
but how they were billions of years ago,
248
648951
1927
更多是几十亿年前的情形，
11:02
whether they were habitable
long ago or not.
long ago or not.
249
650902
2062
很久以前它们是否是可居住的。
11:04
It will teach us about atmospheres
250
652988
1644
它会告诉更多关于围绕着我们、
11:06
that surround us and that are close.
251
654656
1995
与我们息息相关的大气层的事情。
11:09
But moreover, what we learn
from these planets
from these planets
252
657127
2184
此外，从这些行星身上学到的经验，
11:11
can be applied to atmospheres everywhere,
253
659335
2021
可以用在其他任何星球的大气层。
11:14
including planets that we're now
observing around other stars.
observing around other stars.
254
662485
2913
包括我们正在观测的
其他恒星系的行星，
其他恒星系的行星，
11:17
For example, the Kepler spacecraft,
255
665422
1755
比如，建造并管理于博尔德的
开普勒望远镜，
开普勒望远镜，
11:19
which is built and controlled
here in Boulder,
here in Boulder,
256
667201
3208
11:22
has been observing
a postage stamp-sized region of the sky
a postage stamp-sized region of the sky
257
670433
3285
近几年一直在观测
一块邮票大小的天空区域，
11:25
for a couple years now,
258
673742
1247
11:27
and it's found thousands of planets --
259
675013
2228
它已经发现了几千颗行星，
11:29
in one postage stamp-sized
region of the sky
region of the sky
260
677265
2913
仅仅在一块邮票大小的天空，
11:32
that we don't think is any different
from any other part of the sky.
from any other part of the sky.
261
680202
4089
和别的区域并没有什么不同。
11:36
We've gone, in 20 years,
262
684815
1810
在这20年里，
11:38
from knowing of zero planets
outside of our solar system,
outside of our solar system,
263
686649
4037
我们从对太阳系外的行星一无所知，
11:42
to now having so many,
264
690710
1753
到目前我们知道这么多，
11:44
that we don't know
which ones to investigate first.
which ones to investigate first.
265
692487
3139
以至于我们不知道该从哪一个下手。
11:49
Any lever will help.
266
697269
1460
每一条线索都很重要。
11:52
In fact, based on observations
that Kepler's taken
that Kepler's taken
267
700539
3584
事实上，从开普勒的观测
11:56
and other similar observations,
268
704147
2129
以及其他类似的观测中，
11:58
we now believe that,
269
706300
1169
我们目前相信，
11:59
of the 200 billion stars
in the Milky Way galaxy alone,
in the Milky Way galaxy alone,
270
707493
4699
仅在银河系的2000亿颗恒星中，
12:04
on average, every star
has at least one planet.
has at least one planet.
271
712786
4604
通常每颗恒星都至少有一颗行星。
12:10
In addition to that,
272
718819
1503
除此之外，
12:12
estimates suggest there are somewhere
between 40 billion and 100 billion
between 40 billion and 100 billion
273
720346
5701
这些行星中，
据估算有400亿至1000亿颗
据估算有400亿至1000亿颗
12:18
of those planets
that we would define as habitable
that we would define as habitable
274
726071
3332
可以被定义为可居住的，
12:23
in just our galaxy.
275
731139
1412
这仅仅是在我们的银河系。
12:26
We have the observations of those planets,
276
734590
2037
我们在观察这些行星，
12:28
but we just don't know
which ones are habitable yet.
which ones are habitable yet.
277
736651
2484
但我们还不知道哪些是适合居住的。
12:31
It's a little bit like
being trapped on a red spot --
being trapped on a red spot --
278
739159
3606
就像被困在这个红点上一样，
12:34
(Laughter)
279
742789
1171
（笑声）
12:35
on a stage
280
743984
1232
在台上，
12:38
and knowing that there are
other worlds out there
other worlds out there
281
746178
3562
并且知道这外面有其他的世界，
12:43
and desperately wanting to know
more about them,
more about them,
282
751042
2776
拼命想要了解它们，
12:47
wanting to interrogate them and find out
if maybe just one or two of them
if maybe just one or two of them
283
755174
3934
想调查并找到是否有那么一两个
12:51
are a little bit like you.
284
759132
1610
和你有点像。
12:54
You can't do that.
You can't go there, not yet.
You can't go there, not yet.
285
762244
2559
但你做不到，
你还无法到达那里。
你还无法到达那里。
12:56
And so you have to use the tools
that you've developed around you
that you've developed around you
286
764827
3993
所以你只能用你身边的工具，
13:00
for Venus, Earth and Mars,
287
768844
1295
金星，地球，火星，
13:02
and you have to apply them
to these other situations,
to these other situations,
288
770163
2813
用他们来推演其他的情况，
13:05
and hope that you're making
reasonable inferences from the data,
reasonable inferences from the data,
289
773000
4696
并祈祷你正在做有意义的尝试，
13:09
and that you're going to be able
to determine the best candidates
to determine the best candidates
290
777720
3118
你将可以做出最佳的判断，
13:12
for habitable planets,
and those that are not.
and those that are not.
291
780862
2399
关于哪些星球可居住，哪些不可以。
13:16
In the end, and for now, at least,
292
784139
2715
最终，至少是目前，
13:18
this is our red spot, right here.
293
786878
2787
这是我们的红点，就在这里。
13:22
This is the only planet
that we know of that's habitable,
that we know of that's habitable,
294
790376
3336
这是我们唯一知道的宜居的星球，
13:25
although very soon we may
come to know of more.
come to know of more.
295
793736
3191
虽然可能很快就会发现还有其他的。
13:28
But for now, this is
the only habitable planet,
the only habitable planet,
296
796951
2736
但目前，这是唯一宜居的星球，
13:31
and this is our red spot.
297
799711
1302
这是我们的红点。
13:33
I'm really glad we're here.
298
801976
1420
我很高兴我们在这里。
13:36
Thanks.
299
804507
1175
谢谢。
13:37
(Applause)
300
805706
3231
（掌声）
ABOUT THE SPEAKER
Dave Brain - Planetary scientistDave Brain studies the plasma environments and atmospheres of unmagnetized planets.
Why you should listen
Dave Brain is an Assistant Professor of Astrophysics and Planetary Science at the University of Colorado at Boulder. He's interested in the evolution of the atmospheres of planets such as Mars, Venus and Earth, and in particular how planets lose (and gain) atmosphere over time. He uses spacecraft data and computer models to help figure out how light and particles from our sun strip away atmospheric particles, possibly changing them from habitable worlds.
More profile about the speakerDave Brain | Speaker | TED.com