TEDxBoulder
Dave Brain: What a planet needs to sustain life
Dave Brain: 行星維持生命嘅條件
Filmed:
Readability: 4.1
1,867,290 views
行星科學家 Dave Brain 話「金星太熱，火星太冷，地球啱啱好」。但係點解？Dave Brain 喺呢場開心幽默嘅演講，講解咗行星維持生命所需要嘅幾項有趣科學條件，同埋點解人類喺地球上生活只係因為天時同埋地利。
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.
我好高興可以喺度
00:12
I'm really glad to be here.
0
943
1421
00:15
I'm glad you're here,
1
3015
1688
我都好高興你哋可以喺度
00:16
because that would be a little weird.
2
4727
1833
因爲冇你哋嘅話，會些少奇怪
我好高興我哋都喺度
00:19
I'm glad we're all here.
3
7460
2105
我講嘅「呢度」 唔係指 TED 呢度
00:22
And by "here," I don't mean here.
4
10303
2853
或者呢度
00:26
Or here.
5
14831
1150
00:28
But here.
6
16728
1152
係呢度
我指嘅係地球
00:29
I mean Earth.
7
17904
1150
00:31
And by "we," I don't mean
those of us in this auditorium,
those of us in this auditorium,
8
19627
3943
而我所講嘅「我哋」唔係指
呢度演講廳嘅咁多位
呢度演講廳嘅咁多位
而係生命
00:35
but life,
9
23594
1470
00:37
all life on Earth --
10
25088
1449
地球上所有嘅生命
（笑聲）
00:38
(Laughter)
11
26561
5382
由複雜細胞到單細胞
00:44
from complex to single-celled,
12
32280
1991
00:46
from mold to mushrooms
13
34295
2324
由黴菌到蘑菇
到飛天熊都係
00:48
to flying bears.
14
36643
1378
00:50
(Laughter)
15
38045
1366
（笑聲）
00:53
The interesting thing is,
16
41736
1509
有趣嘅係
00:55
Earth is the only place
we know of that has life --
we know of that has life --
17
43269
3031
地球係我哋知道唯一有生命嘅地方
00:58
8.7 million species.
18
46324
1877
八百七十萬種生物
我哋人類其實有睇過其他地方
01:00
We've looked other places,
19
48660
1254
01:01
maybe not as hard
as we should or we could,
as we should or we could,
20
49938
2097
不過可能冇畀心機搵喇
但係我哋搵咗之後都冇發現有生物
01:04
but we've looked and haven't found any;
21
52059
1927
01:06
Earth is the only place
we know of with life.
we know of with life.
22
54010
2276
地球係我哋知道唯一有生命嘅地方
01:09
Is Earth special?
23
57318
1274
地球特殊嗎？
01:11
This is a question I've wanted
to know the answer to
to know the answer to
24
59591
2454
呢個問題由我細時就已經想知
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
而我估呢座禮堂八成嘅人
都諗過同樣嘅事
都諗過同樣嘅事
01:17
has thought the same thing
and also wanted to know the answer.
and also wanted to know the answer.
27
65403
3008
亦都想知道答案
01:20
To understand whether
there are any planets --
there are any planets --
28
68879
2167
要知道有冇其他行星
01:23
out there in our solar system or beyond --
29
71070
2278
喺我哋太陽系或者其他地方
能夠支持生命
能夠支持生命
01:25
that can support life,
30
73372
1458
01:26
the first step is to understand
what life here requires.
what life here requires.
31
74854
3197
第一步需要了解地球嘅生命需要啲乜
01:30
It turns out, of all of those
8.7 million species,
8.7 million species,
32
78575
3563
事實證明，喺呢八百七十萬個物種之中
01:34
life only needs three things.
33
82162
2198
生命只需要三件事
01:37
On one side, all life
on Earth needs energy.
on Earth needs energy.
34
85032
2852
三張相嘅一邊
地球上所有生命都需要能量
地球上所有生命都需要能量
01:39
Complex life like us derives
our energy from the sun,
our energy from the sun,
35
87908
3485
好似我哋咁嘅複合生物體
需要從太陽取得能量
需要從太陽取得能量
01:43
but life deep underground
can get its energy
can get its energy
36
91417
2101
但係地下深處嘅生物
可以由化學反應取得能量
可以由化學反應取得能量
01:45
from things like chemical reactions.
37
93542
1722
01:47
There are a number
of different energy sources
of different energy sources
38
95288
2151
能量嘅來源喺每個星球都有好多種
01:49
available on all planets.
39
97463
1243
01:51
On the other side,
40
99400
1156
相片另一邊
01:52
all life needs food or nourishment.
41
100580
2705
所有生命都需要食物或者營養
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
咁聽起嚟係過分要求
尤其當你想要一隻多汁嘅番茄時
02:00
(Laughter)
43
108239
1716
（笑聲）
但係地球上所有嘅生命
只需由六種化學元素取得營養
只需由六種化學元素取得營養
02:01
However, all life on Earth
derives its nourishment
derives its nourishment
44
109979
3066
02:05
from only six chemical elements,
45
113069
2030
02:07
and these elements can be found
on any planetary body
on any planetary body
46
115123
3004
呢啲元素都可以喺我哋嘅太陽系
任何一個行星上面發現
任何一個行星上面發現
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
所以剩低中間嘅嘢最難達到
02:15
the thing that's hardest to achieve.
49
123788
1954
02:17
Not moose, but water.
50
125766
1892
唔係麋鹿，係水
（笑聲）
02:19
(Laughter)
51
127682
2781
02:23
Although moose would be pretty cool.
52
131285
1794
雖然如果係麋鹿都幾型
02:25
(Laughter)
53
133103
1158
（笑聲）
唔係冰結嘅水，亦唔係氣態嘅水
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
而係液態水
水係所有生命生存都需要嘅嘢
02:32
This is what life needs
to survive, all life.
to survive, all life.
55
140748
2453
太陽系好多星球都冇液態水
02:35
And many solar system bodies
don't have liquid water,
don't have liquid water,
56
143680
3336
所以我哋唔去呢啲星球度搵
02:39
and so we don't look there.
57
147040
1636
02:40
Other solar system bodies
might have abundant liquid water,
might have abundant liquid water,
58
148700
2993
但有啲太陽系嘅星球可能有大量液態水
02:43
even more than Earth,
59
151717
1335
甚至多過地球
02:45
but it's trapped beneath an icy shell,
60
153076
2450
但啲水都係困喺冰層底下
02:47
and so it's hard to access,
it's hard to get to,
it's hard to get to,
61
155550
2261
所以好難接近，好難用到
02:49
it's hard to even find out
if there's any life there.
if there's any life there.
62
157835
2719
亦都令到我哋好難探測
冰層下面有冇生命
冰層下面有冇生命
咁只剩低幾個星球值得考慮
02:53
So that leaves a few bodies
that we should think about.
that we should think about.
63
161475
2995
所以等我哋簡化一下問題
02:56
So let's make the problem
simpler for ourselves.
simpler for ourselves.
64
164494
2429
02:58
Let's think only about liquid water
on the surface of a planet.
on the surface of a planet.
65
166947
3341
我哋只要諗喺星球表面搵到液態水就好
03:02
There are only three bodies
to think about in our solar system,
to think about in our solar system,
66
170312
2956
咁我哋嘅太陽系裡邊
只有三個星球可以諗
只有三個星球可以諗
03:05
with regard to liquid water
on the surface of a planet,
on the surface of a planet,
67
173292
2582
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
按太陽嘅距離依次序為：
金星、地球、火星
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
因為你想大氣層畀到水係液體狀態
03:16
You have to be very careful
with that atmosphere.
with that atmosphere.
70
184661
2378
所以要對大氣層非常講究
大氣層唔可以太厚或者太暖
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
因為咁樣嘅話會好似金星一樣咁熱
03:22
because then you end up
too hot like Venus,
too hot like Venus,
72
190499
2905
03:25
and you can't have liquid water.
73
193428
1737
而且冇可能有液態水
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
但係如果你嘅大氣層太薄太凍
結果就會好似火星一樣咁凍
03:31
you end up like Mars, too cold.
75
199166
2024
所以金星太熱，火星太凍
03:33
So Venus is too hot, Mars is too cold,
76
201865
2475
地球就啱啱好
03:36
and Earth is just right.
77
204364
1164
03:37
You can look at these images behind me
and you can see automatically
and you can see automatically
78
205552
3475
睇下我後邊嘅相，你自然會睇到
03:41
where life can survive
in our solar system.
in our solar system.
79
209051
2597
我哋嘅太陽系邊度可以有生命
呢個係「金髮女孩
與三隻熊故事」嘅問題
與三隻熊故事」嘅問題
03:44
It's a Goldilocks-type problem,
80
212296
1600
03:45
and it's so simple
that a child could understand it.
that a child could understand it.
81
213920
2490
簡單到兒童都可以理解
03:49
However,
82
217452
1180
不過，我想提醒各位兩件事
03:51
I'd like to remind you of two things
83
219450
2928
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
喺金髮女孩與三隻熊個故事裡面
03:57
but that I think are really relevant here.
85
225380
2096
我哋經常忽略、但我認為非常切題嘅事
04:00
Number one:
86
228056
1150
第一
04:02
if Mama Bear's bowl is too cold
87
230311
2792
當金髮女孩行入屋時
如果熊媽媽碗粥太凍
04:05
when Goldilocks walks into the room,
88
233833
2008
咁碗粥係咪一路都係凍嘅呢？
04:08
does that mean it's always been too cold?
89
236642
2143
04:11
Or could it have been just right
at some other time?
at some other time?
90
239825
3268
定係喺之前係暖嘅呢？
金髮女孩行入屋時就一口咬定咗個答案
04:15
When Goldilocks walks into the room
determines the answer
determines the answer
91
243650
3681
04:19
that we get in the story.
92
247355
1332
04:21
And the same is true with planets.
93
249114
1730
行星都一樣
行星唔係靜態嘅嘢，佢哋一直改變緊
04:22
They're not static things. They change.
94
250868
2026
04:24
They vary. They evolve.
95
252918
1742
佢哋會變化、會演化
04:26
And atmospheres do the same.
96
254684
2043
大氣層都一樣
我舉一個例子
04:28
So let me give you an example.
97
256751
1702
呢個係我最鍾意嘅火星圖片
04:30
Here's one of my favorite
pictures of Mars.
pictures of Mars.
98
258477
2002
佢唔係最高解析度，亦唔係最靚
04:32
It's not the highest resolution image,
it's not the sexiest image,
it's not the sexiest image,
99
260503
3131
都唔係最新嘅相
04:35
it's not the most recent image,
100
263658
1503
但係佢顯示行星表面嘅河床
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
液態水流動而形成嘅河床
04:41
riverbeds carved by flowing, liquid water;
102
269320
2584
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
河床要上百上千甚至上萬年先能形成
依家嘅火星冇可能發生呢件事
04:50
This can't happen on Mars today.
104
278425
1618
04:52
The atmosphere of Mars today
is too thin and too cold
is too thin and too cold
105
280067
2481
依家嘅火星大氣層太薄太冷
導致水唔可以維持液態
04:54
for water to be stable as a liquid.
106
282572
2141
呢張相話我哋知火星嘅大氣層改變咗
04:56
This one image tells you
that the atmosphere of Mars changed,
that the atmosphere of Mars changed,
107
284737
4348
05:01
and it changed in big ways.
108
289109
2032
而且改變好大
05:03
And it changed from a state
that we would define as habitable,
that we would define as habitable,
109
291714
4809
佢由可居住嘅狀態變成依家咁
以前之所以可居住係因為
生命三大要素曾經喺嗰度出現過
生命三大要素曾經喺嗰度出現過
05:08
because the three requirements
for life were present long ago.
for life were present long ago.
110
296547
3590
以前大氣層可以令地表維持液態水
05:13
Where did that atmosphere go
111
301049
2068
05:15
that allowed water
to be liquid at the surface?
to be liquid at the surface?
112
303141
2820
但依家火星嘅大氣層去咗邊度？
05:17
Well, one idea is it escaped
away to space.
away to space.
113
305985
3347
一種理論係佢逃逸去到太空
05:21
Atmospheric particles
got enough energy to break free
got enough energy to break free
114
309356
2667
話大氣粒子有足夠嘅能量
走出行星嘅引力
走出行星嘅引力
05:24
from the gravity of the planet,
115
312047
1653
05:25
escaping away to space, never to return.
116
313724
2689
散逸到太空，一去不返
05:28
And this happens with all bodies
with atmospheres.
with atmospheres.
117
316437
2688
呢種現象喺有大氣層嘅星球上面
都會發生
都會發生
05:31
Comets have tails
118
319149
1172
彗星嘅尾就係大氣逃逸嘅最佳例子
05:32
that are incredibly visible reminders
of atmospheric escape.
of atmospheric escape.
119
320345
3257
05:35
But Venus also has an atmosphere
that escapes with time,
that escapes with time,
120
323626
3409
但係金星嘅大氣都會隨著時間逃逸
火星與地球都會
05:39
and Mars and Earth as well.
121
327059
1660
05:40
It's just a matter of degree
and a matter of scale.
and a matter of scale.
122
328743
2968
只不過係程度同規模嘅問題
所以我哋要搵出逃逸嘅速率
先能夠解釋大氣層消失嘅現象
先能夠解釋大氣層消失嘅現象
05:44
So we'd like to figure out
how much escaped over time
how much escaped over time
123
332092
2676
05:46
so we can explain this transition.
124
334792
2116
05:48
How do atmospheres
get their energy for escape?
get their energy for escape?
125
336932
2611
大氣點得到逃逸所需嘅能量？
05:51
How do particles get
enough energy to escape?
enough energy to escape?
126
339567
2131
粒子點得到足以逃逸嘅能量？
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
如果我哋簡單嚟睇，有兩種方法
第一，陽光
05:56
Number one, sunlight.
128
344931
1151
大氣粒子吸收太陽發出嘅光
05:58
Light emitted from the sun can be absorbed
by atmospheric particles
by atmospheric particles
129
346106
3412
06:01
and warm the particles.
130
349542
1714
令到粒子增溫
06:03
Yes, I'm dancing, but they --
131
351280
2108
係，我跳緊舞，不過粒子佢哋…
06:05
(Laughter)
132
353412
1471
（笑聲）
該煨，我喺自己嘅婚禮都冇跳過…
06:07
Oh my God, not even at my wedding.
133
355693
1912
06:09
(Laughter)
134
357629
1492
（笑聲）
佢哋增溫就已經得到足夠嘅能量
去逃離引力
去逃離引力
06:11
They get enough energy
to escape and break free
to escape and break free
135
359145
3003
06:14
from the gravity of the planet
just by warming.
just by warming.
136
362172
2500
06:16
A second way they can get energy
is from the solar wind.
is from the solar wind.
137
364696
3162
第二種方法係靠太陽風
由太陽表面噴出嘅粒子、物質
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
06:24
and they go screaming
through the solar system
through the solar system
139
372932
2404
會喺太陽系裡邊
以每秒 400 公里嘅速度呼嘯而過
以每秒 400 公里嘅速度呼嘯而過
06:27
at 400 kilometers per second,
140
375360
1785
06:29
sometimes faster during solar storms,
141
377169
2594
太陽風暴嚟嗰陣有時仲會快啲添
06:31
and they go hurtling
through interplanetary space
through interplanetary space
142
379787
2722
佢哋穿梭行星之間
向著行星同行星嘅大氣飛去
向著行星同行星嘅大氣飛去
06:34
towards planets and their atmospheres,
143
382533
2446
06:37
and they may provide energy
144
385003
1625
佢哋可能畀到大氣粒子能量去逃逸
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
呢個就係我覺得有興趣嘅嘢
因為呢個同適居性有關
06:43
because it relates to habitability.
147
391175
1713
06:45
I mentioned that there were two things
about the Goldilocks story
about the Goldilocks story
148
393378
3132
我講過金髮女孩嘅故事
有兩樣嘢你哋要留意一下
有兩樣嘢你哋要留意一下
06:48
that I wanted to bring to your attention
and remind you about,
and remind you about,
149
396534
2984
而第二件事更加微妙︰
06:51
and the second one
is a little bit more subtle.
is a little bit more subtle.
150
399542
2239
如果熊爸爸碗粥太熱
06:53
If Papa Bear's bowl is too hot,
151
401805
2788
而熊媽媽碗粥太凍
06:58
and Mama Bear's bowl is too cold,
152
406180
3234
07:03
shouldn't Baby Bear's bowl be even colder
153
411057
3111
咁熊寶寶碗粥咪應該更加凍？
如果我哋跟著個趨勢諗
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
呢件你成世人都以為嘅事
如果仔細諗下，可能冇咁簡單
如果仔細諗下，可能冇咁簡單
07:12
when you think about it a little bit more,
may not be so simple.
may not be so simple.
156
420531
3070
當然，行星溫度取決於佢同太陽嘅距離
07:16
And of course, distance of a planet
from the sun determines its temperature.
from the sun determines its temperature.
157
424513
4028
07:20
This has to play into habitability.
158
428565
2266
就同適居性有關
但係我哋可能需要考慮其他事情
07:22
But maybe there are other things
we should be thinking about.
we should be thinking about.
159
430855
2930
可能碗本身都會決定個故事嘅結局︰
07:25
Maybe it's the bowls themselves
160
433809
1616
07:27
that are also helping to determine
the outcome in the story,
the outcome in the story,
161
435449
3056
07:30
what is just right.
162
438529
1300
亦即係乜為之啱啱好
我可以同大家講好多
關於呢三個行星唔同嘅特性
關於呢三個行星唔同嘅特性
07:32
I could talk to you about a lot
of different characteristics
of different characteristics
163
440765
2865
07:35
of these three planets
164
443654
1151
07:36
that may influence habitability,
165
444829
1569
點樣影響適居性
07:38
but for selfish reasons related
to my own research
to my own research
166
446422
2594
但係因為我研究嘅關係
同埋因為我係講者
同埋因為我係講者
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
（笑聲）
07:44
(Laughter)
168
452652
1006
07:45
I would like to talk
for just a minute or two
for just a minute or two
169
453682
2109
所以我想花一兩分鐘同你哋講下磁場
07:47
about magnetic fields.
170
455815
1297
07:49
Earth has one; Venus and Mars do not.
171
457715
2532
地球有磁場；金星同火星就冇
地球內部深處有一啲電導液體物質
07:52
Magnetic fields are generated
in the deep interior of a planet
in the deep interior of a planet
172
460825
3123
07:55
by electrically conducting
churning fluid material
churning fluid material
173
463972
3717
呢啲電導液體物質流動嗰陣
會形成地球嘅磁場
會形成地球嘅磁場
07:59
that creates this big old magnetic field
that surrounds Earth.
that surrounds Earth.
174
467713
2905
如果你有指南針，你就會知道邊邊係北
08:02
If you have a compass,
you know which way north is.
you know which way north is.
175
470642
2396
但金星同火星都冇磁場
08:05
Venus and Mars don't have that.
176
473062
1494
08:06
If you have a compass on Venus and Mars,
177
474580
1914
如果你喺金星同火星上面用指南針
恭喜！你盪失路
08:08
congratulations, you're lost.
178
476518
1396
08:09
(Laughter)
179
477938
1903
（笑聲）
磁場會影響適居性嗎？
08:11
Does this influence habitability?
180
479865
2040
08:15
Well, how might it?
181
483175
1302
會點影響？
08:17
Many scientists think
that a magnetic field of a planet
that a magnetic field of a planet
182
485024
2604
好多科學家認為行星嘅磁場
就好似大氣層嘅防護罩
就好似大氣層嘅防護罩
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
令行星四周嘅太陽粒子改變方向
屬於力場效應嘅一種
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
亦都同粒子嘅電荷有關
我鐘意將佢比喻為
麫包鋪廚窗揭得開嘅玻璃蓋
麫包鋪廚窗揭得開嘅玻璃蓋
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
08:34
(Laughter)
188
502013
2279
（笑聲）
08:36
And yes, my colleagues
who watch this later will realize
who watch this later will realize
189
504962
3381
係嘅，之後睇呢段片嘅同事會發覺
08:40
this is the first time in the history
of our community
of our community
190
508367
2544
呢個係我哋第一次
將太陽風等同為口水唾沫
將太陽風等同為口水唾沫
08:42
that the solar wind has been
equated with mucus.
equated with mucus.
191
510935
2279
08:45
(Laughter)
192
513238
1650
（笑聲）
08:48
OK, so the effect, then, is that Earth
may have been protected
may have been protected
193
516978
3475
好，所以地球之所以
幾十億年嚟都受到保護
幾十億年嚟都受到保護
08:52
for billions of years,
194
520477
1169
08:53
because we've had a magnetic field.
195
521670
1850
全因我哋有磁場
以至大氣冇辦法逃脫
08:55
Atmosphere hasn't been able to escape.
196
523544
2179
另一方面因為火星冇磁場
08:57
Mars, on the other hand,
has been unprotected
has been unprotected
197
525747
2107
08:59
because of its lack of magnetic field,
198
527878
1842
火星嘅大氣冇保護
09:01
and over billions of years,
199
529744
1952
以致可能幾十億年嚟火星失去嘅大氣
09:03
maybe enough atmosphere
has been stripped away
has been stripped away
200
531720
2180
足以令到呢個原本可以居住嘅行星
09:05
to account for a transition
from a habitable planet
from a habitable planet
201
533924
2593
09:08
to the planet that we see today.
202
536541
1666
變成今日我哋睇到嘅樣
其他科學家認為磁場可能更似船嘅帆
09:11
Other scientists think
that magnetic fields
that magnetic fields
203
539059
2989
09:14
may act more like the sails on a ship,
204
542072
2163
09:16
enabling the planet to interact
with more energy from the solar wind
with more energy from the solar wind
205
544958
5037
令行星可以同太陽風交換更多嘅能量
09:22
than the planet would have been able
to interact with by itself.
to interact with by itself.
206
550019
3272
09:25
The sails may gather energy
from the solar wind.
from the solar wind.
207
553315
2491
磁場可以收集太陽風嘅能量
畀更加多嘅大氣脫逃到
畀更加多嘅大氣脫逃到
09:27
The magnetic field may gather
energy from the solar wind
energy from the solar wind
208
555830
2666
09:30
that allows even more
atmospheric escape to happen.
atmospheric escape to happen.
209
558520
3244
09:33
It's an idea that has to be tested,
210
561788
2254
呢個理論仲需要去證實
09:36
but the effect and how it works
211
564066
1885
但係佢嘅效應同運作方式睇起來好明顯
09:37
seems apparent.
212
565975
1151
09:39
That's because we know
213
567150
1151
咁係因為我哋知道
09:40
energy from the solar wind
is being deposited into our atmosphere
is being deposited into our atmosphere
214
568325
3075
太陽風嘅能量已經注入緊
我哋地球嘅大氣層度
我哋地球嘅大氣層度
09:43
here on Earth.
215
571424
1151
嗰股能量順著磁力線傳導
09:44
That energy is conducted
along magnetic field lines
along magnetic field lines
216
572599
2405
向下導入兩極
09:47
down into the polar regions,
217
575028
1348
09:48
resulting in incredibly beautiful aurora.
218
576400
2136
化成無比璀璨嘅極光
09:50
If you've ever experienced them,
it's magnificent.
it's magnificent.
219
578560
2656
如果你有睇過極光，你就知佢有幾壯麗
09:53
We know the energy is getting in.
220
581240
2006
我哋知道能量入緊嚟
09:55
We're trying to measure
how many particles are getting out
how many particles are getting out
221
583270
3033
我哋想計下有幾多粒子逃逸
同埋睇下磁場係咪真係有影響
09:58
and if the magnetic field
is influencing this in any way.
is influencing this in any way.
222
586327
3038
我有一個問題畀大家
10:02
So I've posed a problem for you here,
223
590722
2380
但係我未有答案，我們冇答案
10:05
but I don't have a solution yet.
224
593126
1546
10:06
We don't have a solution.
225
594696
1276
但係我哋努力緊。我哋係點努力呢？
10:08
But we're working on it.
How are we working on it?
How are we working on it?
226
596702
2357
我哋送咗太空船去呢三個行星度
10:11
Well, we've sent spacecraft
to all three planets.
to all three planets.
227
599083
2298
10:13
Some of them are orbiting now,
228
601405
1476
有啲圍繞緊行星
10:14
including the MAVEN spacecraft
which is currently orbiting Mars,
which is currently orbiting Mars,
229
602905
3072
包括 MAVEN 太空船
目前喺火星嘅軌道上面
目前喺火星嘅軌道上面
10:18
which I'm involved with
and which is led here,
and which is led here,
230
606001
3532
呢項計劃我都有參與
而且係由呢度嘅科羅拉多大學帶領
10:21
out of the University of Colorado.
231
609557
1809
個計劃為咗測量大氣逃脫
10:23
It's designed to measure
atmospheric escape.
atmospheric escape.
232
611390
2282
我哋喺金星同地球都有類似嘅量度
10:26
We have similar measurements
from Venus and Earth.
from Venus and Earth.
233
614022
2474
當我哋集齊所有嘅量度數據
10:28
Once we have all our measurements,
234
616953
1665
10:30
we can combine all these together,
and we can understand
and we can understand
235
618642
2875
我哋就可以將佢哋併埋一齊
就可以了解呢三個行星
點樣同周圍嘅太空環境互動
點樣同周圍嘅太空環境互動
10:33
how all three planets interact
with their space environment,
with their space environment,
236
621541
3417
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
我哋就可以決定磁場係咪對適居性重要
10:41
or not.
239
629714
1158
就算我哋有咗答案
但係點解你哋要咁在乎？
但係點解你哋要咁在乎？
10:42
Once we have that answer,
why should you care?
why should you care?
240
630896
2265
10:45
I mean, I care deeply ...
241
633185
1300
我意思係，我好在乎
10:48
And financially as well, but deeply.
242
636128
2006
我亦都在乎研究經費
10:50
(Laughter)
243
638158
1842
（笑聲）
10:52
First of all, an answer to this question
244
640763
1918
首先，呢個問題嘅答案
會教我哋更多關於
金星、地球以及火星嘅事
金星、地球以及火星嘅事
10:54
will teach us more
about these three planets,
about these three planets,
245
642705
2103
10:56
Venus, Earth and Mars,
246
644832
1160
唔單止包括佢哋點樣同現今嘅環境互動
10:58
not only about how they interact
with their environment today,
with their environment today,
247
646016
2911
仲包括佢哋幾十億以前嘅狀態
11:00
but how they were billions of years ago,
248
648951
1927
同埋佢哋好耐以前係咪適合居住
11:02
whether they were habitable
long ago or not.
long ago or not.
249
650902
2062
11:04
It will teach us about atmospheres
250
652988
1644
答案會揭示大氣層嘅嘢
11:06
that surround us and that are close.
251
654656
1995
11:09
But moreover, what we learn
from these planets
from these planets
252
657127
2184
另外，我哋從呢幾個行星嘅
大氣層學到嘅知識
大氣層學到嘅知識
11:11
can be applied to atmospheres everywhere,
253
659335
2021
可以應用喺其他星球嘅大氣層度
包括我哋觀察緊嘅
幾個環繞著其他恆星嘅行星
幾個環繞著其他恆星嘅行星
11:14
including planets that we're now
observing around other stars.
observing around other stars.
254
662485
2913
舉個例子，喺波德呢度
建造同埋控制嘅哈勃太空望遠鏡
建造同埋控制嘅哈勃太空望遠鏡
11:17
For example, the Kepler spacecraft,
255
665422
1755
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
已經好幾年觀察緊
一塊郵票咁大嘅天空範圍
一塊郵票咁大嘅天空範圍
11:25
for a couple years now,
258
673742
1247
11:27
and it's found thousands of planets --
259
675013
2228
佢目前已經喺郵票咁大嘅天空裏面
發現咗幾千個行星
發現咗幾千個行星
11:29
in one postage stamp-sized
region of the sky
region of the sky
260
677265
2913
而我哋唔覺呢塊天空
同其他天空有咩唔同
同其他天空有咩唔同
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
11:36
We've gone, in 20 years,
262
684815
1810
廿年裏邊
我哋由一個太陽系以外嘅
行星都唔認識
行星都唔認識
11:38
from knowing of zero planets
outside of our solar system,
outside of our solar system,
263
686649
4037
到依家知道有咁多行星
11:42
to now having so many,
264
690710
1753
11:44
that we don't know
which ones to investigate first.
which ones to investigate first.
265
692487
3139
我哋都唔知應該由邊度開始探索
11:49
Any lever will help.
266
697269
1460
任何幫手都歡迎
11:52
In fact, based on observations
that Kepler's taken
that Kepler's taken
267
700539
3584
其實，跟據哈勃太空望遠鏡得到嘅觀察
11:56
and other similar observations,
268
704147
2129
加上其他類似嘅觀測，我哋宜家相信
11:58
we now believe that,
269
706300
1169
剩係我哋銀河系二千億個星裡邊
11:59
of the 200 billion stars
in the Milky Way galaxy alone,
in the Milky Way galaxy alone,
270
707493
4699
平均每個恆星至少有一個行星
12:04
on average, every star
has at least one planet.
has at least one planet.
271
712786
4604
12:10
In addition to that,
272
718819
1503
除此之外，單單喺我哋嘅銀河
12:12
estimates suggest there are somewhere
between 40 billion and 100 billion
between 40 billion and 100 billion
273
720346
5701
我哋估計有大概四百億
到一千億個行星係適居嘅
到一千億個行星係適居嘅
12:18
of those planets
that we would define as habitable
that we would define as habitable
274
726071
3332
12:23
in just our galaxy.
275
731139
1412
12:26
We have the observations of those planets,
276
734590
2037
我哋得到呢啲行星嘅觀測資料
但係我哋仲未知邊一個係適合居住嘅
12:28
but we just don't know
which ones are habitable yet.
which ones are habitable yet.
277
736651
2484
有點似被困喺台上嘅呢塊紅地氈一樣
12:31
It's a little bit like
being trapped on a red spot --
being trapped on a red spot --
278
739159
3606
（笑聲）
12:34
(Laughter)
279
742789
1171
12:35
on a stage
280
743984
1232
12:38
and knowing that there are
other worlds out there
other worlds out there
281
746178
3562
但係你又知道仲有其他世界存在
12:43
and desperately wanting to know
more about them,
more about them,
282
751042
2776
你又極想了解佢哋
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
你又想調查睇下有冇一兩個星球
好似自己嘅星球
好似自己嘅星球
12:51
are a little bit like you.
284
759132
1610
12:54
You can't do that.
You can't go there, not yet.
You can't go there, not yet.
285
762244
2559
但係你就係做唔到，你去唔到
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
所以你要用上
為到金星、地球同火星開發嘅工具
為到金星、地球同火星開發嘅工具
13:00
for Venus, Earth and Mars,
287
768844
1295
13:02
and you have to apply them
to these other situations,
to these other situations,
288
770163
2813
你要將工具用喺其他情況度
並確保能夠從數據裏面作出合理嘅推斷
13:05
and hope that you're making
reasonable inferences from the data,
reasonable inferences from the data,
289
773000
4696
從而揀出最有可能適居嘅行星
13:09
and that you're going to be able
to determine the best candidates
to determine the best candidates
290
777720
3118
同埋搵出最冇可能適居嘅行星
13:12
for habitable planets,
and those that are not.
and those that are not.
291
780862
2399
最終，同埋至少目前
13:16
In the end, and for now, at least,
292
784139
2715
呢個就係我哋嘅紅地氈，就喺呢度
13:18
this is our red spot, right here.
293
786878
2787
呢個係目前我哋所知唯一適居嘅行星
13:22
This is the only planet
that we know of that's habitable,
that we know of that's habitable,
294
790376
3336
雖然好快我哋可能會發現仲有其他嘅
13:25
although very soon we may
come to know of more.
come to know of more.
295
793736
3191
但係目前，呢個係唯一適居嘅行星
13:28
But for now, this is
the only habitable planet,
the only habitable planet,
296
796951
2736
呢個就係我哋嘅紅地氈
13:31
and this is our red spot.
297
799711
1302
我真係好高興我哋都喺度
13:33
I'm really glad we're here.
298
801976
1420
多謝
13:36
Thanks.
299
804507
1175
（掌聲）
13:37
(Applause)
300
805706
3231
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