TEDGlobal 2009
Garik Israelian: How spectroscopy could reveal alien life
Garik Israelian:星星裡面是什麼？
Filmed:
Readability: 4.5
659,672 views
Garik Isralian是個光譜學家，專門利用星星釋放出來的光譜來研究星星成分和他的行為。這是個少見但可行的專業，或許會引領我們找到另一個適合生活的行星。
Garik Israelian - Astrophysicist
Garik Israelian's stargazing on the Canary Islands has led to high-profile discoveries about space's big disasters -- including the first evidence that supernova explosions make black holes. Full bio
Garik Israelian's stargazing on the Canary Islands has led to high-profile discoveries about space's big disasters -- including the first evidence that supernova explosions make black holes. Full bio
Double-click the English transcript below to play the video.
00:18
I have a very difficult task.
0
0
3000
我有一個困難的任務。
00:21
I'm a spectroscopist.
1
3000
3000
我是個光譜學家。
00:24
I have to talk about astronomy without showing you
2
6000
2000
我要講天文學可是我不要給你們看
00:26
any single image of nebulae or galaxies, etc.
3
8000
4000
任何一張有星雲或銀河的圖片
00:30
because my job is spectroscopy.
4
12000
2000
因為我的工作是光譜學
00:32
I never deal with images.
5
14000
3000
我從來不看實際圖像。
00:35
But I'll try to convince you
6
17000
2000
可是我要試著說服你們
00:37
that spectroscopy is actually something which can
7
19000
2000
光譜學圖片是真的能夠
00:39
change this world.
8
21000
3000
改變世界的。
00:42
Spectroscopy can probably answer the question,
9
24000
3000
光譜學或許可以回答下面這樣的問題：
00:45
"Is there anybody out there?"
10
27000
2000
「真的有外星人嗎?」
00:47
Are we alone? SETI.
11
29000
2000
是只有我們嗎?SETI(尋找外太空星球智慧生命計畫)
00:49
It's not very fun to do spectroscopy.
12
31000
3000
做光譜學不是很有趣。
00:52
One of my colleagues in Bulgaria,
13
34000
2000
我一個在保加利亞的同事
00:54
Nevena Markova, spent about 20 years
14
36000
2000
Naviana Markova花了大約二十年的時間
00:56
studying these profiles.
15
38000
3000
研究這些資料。
00:59
And she published 42 articles
16
41000
2000
她發表了42篇文章
01:01
just dedicated to the subject.
17
43000
2000
就只討論這個主題。
01:03
Can you imagine? Day and night, thinking,
18
45000
2000
你可以想像嗎？二十年來日以繼夜地思考、
01:05
observing, the same star for 20 years
19
47000
3000
觀察同樣的星星，
01:08
is incredible.
20
50000
2000
太不可思議了。
01:10
But we are crazy. We do these things.
21
52000
2000
可是我們是瘋狂的。我們做這樣的事情。
01:12
(Laughter)
22
54000
2000
(笑聲)
01:14
And I'm not that far.
23
56000
2000
我還沒那麼瘋狂。
01:16
I spent about eight months working on these profiles.
24
58000
3000
我花了八個月研究這些資料。
01:19
Because I've noticed
25
61000
2000
因為我發現
01:21
a very small symmetry
26
63000
2000
一個很小的對稱性
01:23
in the profile of one of the planet host stars.
27
65000
2000
在主恆星的資料裡。
01:25
And I thought, well maybe there is Lithium-6 in this star,
28
67000
4000
然後我想，或許這個星星含有鋰6(Lithium-6)，
01:29
which is an indication that this star
29
71000
2000
這暗示著這個星星
01:31
has swallowed a planet.
30
73000
2000
可能曾經吞噬過另一個星球。
01:33
Because apparently you can't have this fragile isotope
31
75000
3000
因為顯然的像鋰6(Lithium-6)這樣不穩定的同位素
01:36
of Lithium-6 in the atmospheres of sun-like stars.
32
78000
4000
不可能存在於恆星的環境中。
01:40
But you have it in planets and asteroids.
33
82000
3000
但是在星球和小行星中都含有這個東西。
01:43
So if you engulf planet or large number of asteroids,
34
85000
6000
所以如果吞噬了行星和很多個小行星，
01:49
you will have this Lithium-6 isotope
35
91000
3000
那麼就會有鋰6(Lithium-6)這個同位素
01:52
in the spectrum of the star.
36
94000
2000
在行星的光譜中。
01:54
So I invested more than eight months
37
96000
4000
所以我花了超過八個月的時間
01:58
just studying the profile of this star.
38
100000
2000
就是來研究這個星星資料中的鋰線。
02:00
And actually it's amazing,
39
102000
2000
而且事實上是非常驚人的，
02:02
because I got phone calls from many reporters asking,
40
104000
2000
因為我接到很多記者的電話問我
02:04
"Have you actually seen the planet going into a star?"
41
106000
3000
「你真的有看到一個行星進入一個星星嗎？」
02:07
Because they thought that if you are having a telescope,
42
109000
4000
因為他們以為可以有一個望遠鏡
02:11
you are an astronomer so what you are doing
43
113000
2000
你是天文學家而你做的事情
02:13
is actually looking in a telescope.
44
115000
2000
就是透過望遠鏡看。
02:15
And you might have seen the planet going into a star.
45
117000
4000
然後你有可能有看到一個行星進入一個星星。
02:19
And I was saying, "No, excuse me.
46
121000
2000
然後我會說：「不，對不起。
02:21
What I see is this one."
47
123000
2000
我看到的是這個。」
02:23
(Laughter)
48
125000
1000
(笑聲)
02:24
It's just incredible. Because nobody understood really.
49
126000
3000
這是很不可思議的。因為沒有人真正了解。
02:27
I bet that there were very few people
50
129000
2000
我賭只有非常少數的人
02:29
who really understood what I'm talking about.
51
131000
3000
真正知道我在講什麼。
02:32
Because this is the indication that the planet went into the star.
52
134000
4000
因為這正是代表著一個行星進入一個星星。
02:36
It's amazing.
53
138000
3000
這是驚人的。
02:39
The power of spectroscopy
54
141000
2000
光譜學的能耐
02:41
was actually realized
55
143000
2000
事實上是在1973年
02:43
by Pink Floyd already in 1973.
56
145000
4000
被Pink Floyd發現的。
02:47
(Laughter)
57
149000
1000
(笑聲)
02:48
Because they actually said that
58
150000
3000
因為他們真的曾經說過
02:51
you can get any color you like
59
153000
2000
你可以在光譜中得到
02:53
in a spectrum.
60
155000
2000
任何你想要的顏色。
02:55
And all you need is time and money
61
157000
2000
你需要的只是時間和金錢
02:57
to make your spectrograph.
62
159000
2000
來製作你的光譜。
02:59
This is the number one high resolution,
63
161000
3000
這是個這個星球上解析度最高、
03:02
most precise spectrograph on this planet, called HARPS,
64
164000
3000
最精準的光譜儀器，叫做HARPS，
03:05
which is actually used to detect
65
167000
2000
是用來偵測
03:07
extrasolar planets and sound waves
66
169000
2000
外太陽系行星和星星大氣層中
03:09
in the atmospheres of stars.
67
171000
2000
的聲波。
03:11
How we get spectra?
68
173000
3000
我們怎麼得到光譜呢？
03:14
I'm sure most of you know from school physics
69
176000
3000
我想你們從學校教得物理得知
03:17
that it's basically splitting a white light
70
179000
4000
事實上是把白光
03:21
into colors.
71
183000
2000
分成其他顏色。
03:23
And if you have a liquid hot mass,
72
185000
3000
而且如果你有液態熱體，
03:26
it will produce something which we call a continuous spectrum.
73
188000
4000
他會產生連續光譜。
03:30
A hot gas is producing emission lines only,
74
192000
3000
熱氣只釋放出線條，
03:33
no continuum.
75
195000
2000
不會連續。
03:35
And if you place a cool gas in front of a
76
197000
4000
如果你把冷氣團放在
03:39
hot source,
77
201000
2000
熱源前面，
03:41
you will see certain patterns
78
203000
2000
你會看到特定的圖樣，
03:43
which we call absorption lines.
79
205000
2000
我們稱為吸收光譜。
03:45
Which is used actually to identify chemical elements
80
207000
3000
這就是我們鑑定冷質中
03:48
in a cool matter,
81
210000
2000
化學組成的方法，
03:50
which is absorbing exactly at those frequencies.
82
212000
3000
就是吸收一樣的頻率。
03:53
Now, what we can do with the spectra?
83
215000
3000
現在，光譜能做什麼呢？
03:56
We can actually study line-of-sight velocities
84
218000
3000
我們可以研究天體的
03:59
of cosmic objects.
85
221000
2000
視相速度。
04:01
And we can also study chemical composition
86
223000
3000
我們也可以研究星星、星系、星雲
04:04
and physical parameters of stars,
87
226000
2000
的化學組成
04:06
galaxies, nebulae.
88
228000
2000
及物理參數。
04:08
A star is the most simple object.
89
230000
2000
星星是做簡單的物體。
04:10
In the core, we have thermonuclear reactions going on,
90
232000
4000
在中心有一個熱核能反應
04:14
creating chemical elements.
91
236000
2000
製造化學元素。
04:16
And we have a cool atmosphere.
92
238000
2000
而我們有一個涼的大氣層。
04:18
It's cool for me.
93
240000
2000
這對我來說是涼的。
04:20
Cool in my terms is three or four or five thousand degrees.
94
242000
4000
涼在我的定義中是三或四或五千度。
04:24
My colleagues in infra-red astronomy
95
246000
2000
我的同事研究紅外線天文學
04:26
call minus 200 Kelvin is cool for them.
96
248000
5000
他說對他們來說負兩百凱爾文是涼。
04:31
But you know, everything is relative.
97
253000
2000
但是你們知道，所有事情都是相對的。
04:33
So for me 5,000 degrees is pretty cool.
98
255000
3000
對我來說，五千度是蠻涼的。
04:36
(Laughter)
99
258000
1000
(笑聲)
04:37
This is the spectrum of the Sun --
100
259000
3000
這是太陽的光譜。
04:40
24,000 spectral lines,
101
262000
3000
兩萬四千條光譜線
04:43
and about 15 percent of these lines is not yet identified.
102
265000
4000
而且大約百分之十五的線還沒被鑑定出來。
04:47
It is amazing. So we are in the 21st century,
103
269000
3000
這是很驚人的。我們在二十一世紀，
04:50
and we still cannot properly understand
104
272000
2000
但我們仍然沒有辦法正確了解
04:52
the spectrum of the sun.
105
274000
2000
太陽的光譜。
04:54
Sometimes we have to deal with
106
276000
2000
有時候我們必須從
04:56
just one tiny, weak spectral line
107
278000
3000
一條又小又微弱的光譜線中
04:59
to measure the composition of that chemical element in the atmosphere.
108
281000
4000
找出氣層中的化學成分組成。
05:03
For instance, you see the spectral line of the gold
109
285000
3000
譬如說你看到金的光譜線
05:06
is the only spectral line in the spectrum of the Sun.
110
288000
3000
是太陽光譜裡面唯一的一條線。
05:09
And we use this weak feature
111
291000
2000
我們就用這個微薄的特色
05:11
to measure the composition
112
293000
2000
來測量太陽大氣層中
05:13
of gold in the atmosphere of the Sun.
113
295000
3000
金的含量。
05:16
And now this is a work in progress.
114
298000
3000
現在這是個正在進行的研究。
05:19
We have been dealing with a similarly very weak feature,
115
301000
4000
我們在研究鋨的時候
05:23
which belongs to osmium.
116
305000
2000
也同樣面對類似的微弱信號。
05:25
It's a heavy element produced in thermonuclear
117
307000
4000
鋨是一個重金屬元素
05:29
explosions of supernovae.
118
311000
2000
在超級新星的熱合爆炸中產生。
05:31
It's the only place where you can produce, actually, osmium.
119
313000
3000
事實上這是唯一可以產生鋨的狀況。
05:34
Just comparing the composition of osmium
120
316000
4000
單單只是比較其中一個主行星
05:38
in one of the planet host stars,
121
320000
2000
的鋨成分，
05:40
we want to understand why there is so much
122
322000
2000
我們想要了解為什麼
05:42
of this element.
123
324000
2000
有這麼多這種元素。
05:44
Perhaps we even think that maybe
124
326000
3000
或許我們更會想
05:47
supernova explosions trigger formations of planets and stars.
125
329000
4000
或許超級新星的爆炸會導致行星及星星的誕生。
05:51
It can be an indication.
126
333000
3000
這有可能是個暗示。
05:54
The other day, my colleague from Berkeley,
127
336000
2000
那天我在柏克萊的同事
05:56
Gibor Basri, emailed me
128
338000
2000
Gibor Basri用電郵傳了
05:58
a very interesting spectrum,
129
340000
2000
一張非常有趣的光譜圖給我，
06:00
asking me, "Can you have a look at this?"
130
342000
2000
問我：「你可以看看這個嗎？」
06:02
And I couldn't sleep, next two weeks,
131
344000
4000
然後我接下來兩個禮拜都沒有睡覺，
06:06
when I saw the huge amount of oxygen
132
348000
3000
當我看到有大量的氧氣
06:09
and other elements in the spectrum of the stars.
133
351000
2000
和其他元素出現在星星的光譜中，
06:11
I knew that there is nothing like that observed in the galaxy.
134
353000
4000
我知道沒有其他星系跟這個一樣。
06:15
It was incredible. The only conclusion we could make from this
135
357000
4000
這是非常驚人的。我們唯一可以從中得到的
06:19
is clear evidence that there was a supernova explosion
136
361000
3000
確切結論是這代表著在這個系統中曾經有個
06:22
in this system, which polluted the atmosphere
137
364000
3000
超級新星爆炸，且汙染了這個星星的
06:25
of this star.
138
367000
2000
大氣層。
06:27
And later a black hole was formed
139
369000
2000
然後在這二原體系下
06:29
in a binary system,
140
371000
2000
一個黑洞產生了，
06:31
which is still there with a mass of about
141
373000
2000
它現在還在那裡且集中了
06:33
five solar masses.
142
375000
2000
五個太陽的質量。
06:35
This was considered as first evidence that actually black holes
143
377000
3000
這被認為是第一個證明黑洞是從
06:38
come from supernovae explosions.
144
380000
4000
超級新星爆炸來的的證據。
06:42
My colleagues, comparing composition of chemical elements
145
384000
2000
我的同事在比較不同星系的
06:44
in different galactic stars,
146
386000
2000
化學成分組成，
06:46
actually discovered alien stars in our galaxy.
147
388000
4000
他發現我們星系有外來星星。
06:50
It's amazing that you can go so far
148
392000
3000
能夠只從星星的化學成分資料
06:53
simply studying the chemical composition of stars.
149
395000
4000
得到這麼多訊息是很驚人的。
06:57
They actually said that one of the stars you see in the spectra
150
399000
3000
他們還說其中一顆在光譜上看到的星星事實上是
07:00
is an alien. It comes from a different galaxy.
151
402000
3000
外來星。它是從其他星系來的。
07:03
There is interaction of galaxies. We know this.
152
405000
3000
星系之間是有相互作用的。我們知道這個。
07:06
And sometimes they just capture stars.
153
408000
5000
有時候他們捕捉星星。
07:11
You've heard about solar flares.
154
413000
3000
你們有聽過太陽耀斑。
07:14
We were very surprised to discover
155
416000
2000
我們很驚訝地發現
07:16
a super flare,
156
418000
2000
一個太陽耀斑，
07:18
a flare which is thousands of millions of times
157
420000
4000
一個比我們現在看到的太陽威力大
07:22
more powerful than those we see in the Sun.
158
424000
2000
幾十億倍的耀斑。
07:24
In one of the binary stars in our galaxy
159
426000
3000
在我們星系中的一個雙星系
07:27
called FH Leo,
160
429000
2000
叫做FH Leo，
07:29
we discovered the super flare.
161
431000
2000
我們發現了這個超級耀斑。
07:31
And later we went to study the spectral stars
162
433000
4000
後來我們去研究光譜線
07:35
to see is there anything strange with these objects.
163
437000
2000
來看看有沒有其他奇怪的事情。
07:37
And we found that everything is normal.
164
439000
3000
我們發現所有事情都是正常的。
07:40
These stars are normal like the Sun. Age, everything was normal.
165
442000
3000
這些星星就跟太陽一樣正常。年紀什麼都是正常的。
07:43
So this is a mystery.
166
445000
2000
所以是個謎。
07:45
It's one of the mysteries we still have, super flares.
167
447000
3000
超級耀斑是到現在仍然存在的謎。
07:48
And there are six or seven similar cases
168
450000
3000
而且在文獻上大約有
07:51
reported in the literature.
169
453000
2000
六到七個類似的例子。
07:53
Now to go ahead with this,
170
455000
2000
現在我們繼續往下走，
07:55
we really need to understand chemical evolution of the universe.
171
457000
4000
我們很需要了解這個宇宙的化學演化。
07:59
It's very complicated. I don't really want you to
172
461000
2000
這很複雜。我沒有很希望你們
08:01
try to understand what is here.
173
463000
4000
試圖去了解。
08:05
(Laughter)
174
467000
1000
(笑聲)
08:06
But it's to show you how complicated is the whole story
175
468000
3000
可是現在是要給你們看整個化學元素的產生
08:09
of the production of chemical elements.
176
471000
2000
有多們複雜。
08:11
You have two channels --
177
473000
2000
你有兩個管道：
08:13
the massive stars and low-mass stars --
178
475000
2000
一個高質量星星和一個低質量星星
08:15
producing and recycling matter and chemical elements in the universe.
179
477000
3000
正在產生和回收宇宙間的質體和化學元素。
08:18
And doing this for 14 billion years,
180
480000
3000
一百四十億年來一直這麼做，
08:21
we end up with this picture,
181
483000
2000
我們就有了這張圖片。
08:23
which is a very important graph,
182
485000
2000
這是張非常重要的圖表，
08:25
showing relative abundances of chemical elements
183
487000
3000
顯示了恆星及星際介質中
08:28
in sun-like stars
184
490000
2000
各種化學成分的
08:30
and in the interstellar medium.
185
492000
3000
相對含量。
08:33
So which means that it's really impossible
186
495000
2000
也就是說是不可能找到
08:35
to find an object where you find about 10 times more sulfur than silicon,
187
497000
5000
一個物體其硫含量是矽含量的十倍，
08:40
five times more calcium than oxygen. It's just impossible.
188
502000
4000
或是鈣含量比氧含量多五倍。就是不可能。
08:44
And if you find one, I will say that
189
506000
2000
而且如果你真的找到這樣的物體我會說
08:46
this is something related to SETI,
190
508000
3000
這一定跟SETI(尋找外太空智慧)有關。
08:49
because naturally you can't do it.
191
511000
4000
因為自然界中是不可能的。
08:53
Doppler Effect is something very important
192
515000
2000
都普勒效應是基礎物理學中
08:55
from fundamental physics.
193
517000
2000
非常重要的。
08:57
And this is related to the change of the frequency
194
519000
2000
而且這個跟移動源頭的
08:59
of a moving source.
195
521000
2000
頻率有關。
09:01
The Doppler Effect is used to discover extrasolar planets.
196
523000
5000
都普勒效應是用來發現太陽系外的行星。
09:06
The precision which we need
197
528000
2000
要找到一個
09:08
to discover a Jupiter-like planet
198
530000
2000
像木星的行星，
09:10
around a sun-like star
199
532000
2000
我們需要的精準度
09:12
is something like 28.4 meters per second.
200
534000
4000
是大約每秒28.4公尺。
09:16
And we need nine centimeters per second
201
538000
2000
要發現一個像地球的行星，
09:18
to detect an Earth-like planet.
202
540000
3000
我們需要每秒九公分。
09:21
This can be done with the future spectrographs.
203
543000
3000
這個在未來的光譜研究上可以做到。
09:24
I, myself, I'm actually involved in the team
204
546000
4000
我，我自己有餐與一個團隊，
09:28
which is developing a CODEX,
205
550000
2000
在研發一種規則，
09:30
high resolution, future generation spectrograph
206
552000
2000
高解析度，新一代的的光譜法
09:32
for the 42 meter E-ELT telescope.
207
554000
4000
可以用在42米E-ELT望遠鏡上。
09:36
And this is going to be an instrument
208
558000
3000
這會是一個未來可以探測
09:39
to detect Earth-like planets
209
561000
2000
在似太陽星星附近
09:41
around sun-like stars.
210
563000
2000
像地球這樣的行星。
09:43
It is an amazing tool called astroseismology
211
565000
3000
這是個驚人的工具叫做星震學。
09:46
where we can detect sound waves
212
568000
3000
我們可以用來探測星星大氣層中
09:49
in the atmospheres of stars.
213
571000
2000
的聲波。
09:51
This is the sound of an Alpha Cen.
214
573000
3000
這是半人馬座阿爾法星的聲音。
09:54
We can detect sound waves
215
576000
2000
我們可以探測到
09:56
in the atmospheres of sun-like stars.
216
578000
2000
恆星大氣層中的聲波。
09:58
Those waves have frequencies
217
580000
3000
這些波有頻率，
10:01
in infrasound domain, the sound actually nobody knows, domain.
218
583000
4000
在亞聲區塊，就是沒有人知道是什麼聲音的區塊。
10:05
Coming back to the most important question,
219
587000
2000
回到最重要的問題：
10:07
"Is there anybody out there?"
220
589000
2000
「外面到底有沒有人？」
10:09
This is closely related
221
591000
2000
這跟行星的地質構造及
10:11
to tectonic and volcanic activity of planets.
222
593000
4000
火山活動是非常有關係的。
10:15
Connection between life
223
597000
2000
生命跟放射性原子核
10:17
and radioactive nuclei
224
599000
2000
中間的關係
10:19
is straightforward.
225
601000
2000
是很直接的。
10:21
No life without tectonic activity,
226
603000
3000
沒有地質構造的改變
10:24
without volcanic activity.
227
606000
2000
或是沒有火山活動就沒有生命。
10:26
And we know very well that geothermal energy
228
608000
2000
我們知道地熱
10:28
is mostly produced by decay of uranium, thorium, and potassium.
229
610000
5000
大部分來自鈾、釷和鉀的衰變。
10:33
How to measure, if we have planets
230
615000
4000
怎麼測量？如果我們有一個行星，
10:37
where the amount of those elements is small,
231
619000
4000
這些元素的含量非常少，
10:41
so those planets are tectonically dead,
232
623000
3000
就是說沒有地質構造的改變，
10:44
there cannot be life.
233
626000
2000
那麼不可能有生命。
10:46
If there is too much uranium or potassium or thorium,
234
628000
3000
如果有太多鈾或鉀或釷，
10:49
probably, again, there would be no life.
235
631000
3000
那麼，或許，也不會有生命。
10:52
Because can you imagine everything boiling?
236
634000
2000
因為你可以想像所有東西都在沸騰嗎？
10:54
It's too much energy on a planet.
237
636000
2000
那對一個行星來說是太多能量的。
10:56
Now, we have been measuring abundance
238
638000
2000
現在我們正在測量
10:58
of thorium in one of the stars with extrasolar planets.
239
640000
4000
一個外星系行星的釷含量。
11:02
It's exactly the same game. A very tiny feature.
240
644000
4000
這是完全一樣的。一個很小的特徵。
11:06
We are actually trying to measure this profile
241
648000
2000
我們真的在試圖測量這個資料
11:08
and to detect thorium.
242
650000
2000
去探測釷。
11:10
It's very tough. It's very tough.
243
652000
2000
這很困難。這很困難。
11:12
And you have to, first you have to convince yourself.
244
654000
2000
而且你必須先說服你自己。
11:14
Then you have to convince your colleagues.
245
656000
2000
然後必須說服你的同事們。
11:16
And then you have to convince the whole world
246
658000
3000
然後你必須說服全世界
11:19
that you have actually detected something like this
247
661000
3000
你真的有在百秒差距外
11:22
in the atmosphere of an extrasolar planet
248
664000
2000
一個外星系主行星的大氣層中
11:24
host star somewhere in 100 parsec away from here.
249
666000
3000
探測到這樣的東西。
11:27
It's really difficult.
250
669000
2000
這非常艱難。
11:29
But if you want to know about a life on extrasolar planets,
251
671000
5000
但是如果你想要知道外太陽系行星上的生命，
11:34
you have to do this job.
252
676000
2000
你就必須做這種工作。
11:36
Because you have to know how much of radioactive element you have
253
678000
3000
因為你需要知道在這些系統中
11:39
in those systems.
254
681000
2000
有多少放射性物質。
11:41
The one way to discover about aliens
255
683000
3000
一個可以發現外星人的方法，
11:44
is to tune your radio telescope and listen to the signals.
256
686000
4000
是調整收音機望遠鏡且傾聽信號。
11:48
If you receive something interesting,
257
690000
3000
如果你收到有趣的東西，
11:51
well that's what SETI does actually,
258
693000
2000
事實上SETI就是這麼做，
11:53
what SETI has been doing for many years.
259
695000
3000
SETI已經好幾年都在這麼做了。
11:56
I think the most promising way
260
698000
2000
我認為最有希望的方法
11:58
is to go for biomarkers.
261
700000
3000
是找生物印記。
12:01
You can see the spectrum of the Earth, this Earthshine spectrum,
262
703000
3000
你可以看到地球的光譜，這個地球反照光譜，
12:04
and that is a very clear signal.
263
706000
3000
有非常清楚的信號。
12:07
The slope which is coming, which we call a Red Edge,
264
709000
3000
這個傾斜的地方我們稱之為紅邊(Red Edge)，
12:10
is a detection of vegetated area.
265
712000
4000
是代表著植被區。
12:14
It's amazing that we can detect vegetation
266
716000
4000
我們可以從光譜針測到植被
12:18
from a spectrum.
267
720000
2000
是非常驚人的。
12:20
Now imagine doing this test
268
722000
2000
現在想像對其他行星
12:22
for other planets.
269
724000
3000
做這樣的測試。
12:25
Now very recently, very recently,
270
727000
3000
現在很近期，非常近期，
12:28
I'm talking about last six, seven, eight months,
271
730000
3000
我是在講說大約這六、七、八個月，
12:31
water, methane, carbon dioxide
272
733000
4000
水、甲烷、二氧化碳
12:35
have been detected in the spectrum
273
737000
2000
在一個外星系行星的光譜上
12:37
of a planet outside the solar system.
274
739000
3000
被偵測到了。
12:40
It's amazing. So this is the power of spectroscopy.
275
742000
4000
這很驚人。這就是光譜學的厲害。
12:44
You can actually go and detect
276
746000
3000
你可以真的去偵測
12:47
and study a chemical composition of planets
277
749000
3000
和研究一個離太陽系很遠很遠的行星
12:50
far, far, far from solar system.
278
752000
3000
的化學組成。
12:53
We have to detect oxygen or ozone
279
755000
3000
我們必須偵測到氧氣或是臭氧
12:56
to make sure that we have all necessary conditions
280
758000
3000
才能確定我們有生命存在
12:59
to have life.
281
761000
4000
必須的條件。
13:03
Cosmic miracles are something
282
765000
2000
宇宙奇蹟是一些
13:05
which can be related to SETI.
283
767000
2000
跟SETI有關的現象。
13:07
Now imagine an object, amazing object,
284
769000
2000
現在想像一個物體，一個驚奇的物體，
13:09
or something which we cannot explain
285
771000
2000
或是一個我們無法解釋的東西
13:11
when we just stand up and say,
286
773000
2000
我們只能站起來然後說：
13:13
"Look, we give up. Physics doesn't work."
287
775000
2000
「好吧！我們放棄，物理不適用。」
13:15
So it's something which you can always refer to SETI and say,
288
777000
3000
所以這是你們可以永遠歸因於SETI然後說：
13:18
"Well, somebody must be doing this, somehow."
289
780000
5000
「嗯，總有人用某種方法在做這個。」
13:23
And with the known physics etc,
290
785000
2000
以現知的物理，
13:25
it's something actually which has been pointed out
291
787000
2000
這事實上是個已經被Frank Drake
13:27
by Frank Drake,
292
789000
2000
在好幾年前
13:29
many years ago, and Shklovsky.
293
791000
2000
指出的事情。
13:31
If you see, in the spectrum of a planet host star,
294
793000
3000
如果你看到一個主行星的光譜，
13:34
if you see strange chemical elements,
295
796000
4000
如果你看到奇怪的化學元素，
13:38
it can be a signal from a civilization
296
800000
3000
這有可能是文明的信號。
13:41
which is there and they want to signal about it.
297
803000
3000
文明存在而且他們想要示意。
13:44
They want to actually signal their presence
298
806000
4000
他們想要示意他們的存在，
13:48
through these spectral lines,
299
810000
2000
利用光譜線，
13:50
in the spectrum of a star, in different ways.
300
812000
3000
用不同的方式表現在星星的光譜中。
13:53
There can be different ways doing this.
301
815000
2000
有不同種方式可以達成這個目的。
13:55
One is, for instance, technetium
302
817000
2000
其中一個方式是用鎝元素，
13:57
is a radioactive element
303
819000
2000
一個大約42萬年才會衰退的
13:59
with a decay time of 4.2 million years.
304
821000
3000
放射性元素。
14:02
If you suddenly observe technetium
305
824000
3000
如果你突然在一個類太陽星星
14:05
in a sun-like star,
306
827000
2000
的大氣層中
14:07
you can be sure that somebody has put this
307
829000
2000
發現鎝元素，你可以確定
14:09
element in the atmosphere,
308
831000
2000
有人把他放在那的，
14:11
because in a natural way it is impossible to do this.
309
833000
4000
因為自然界中不可能發生。
14:15
Now we are reviewing the spectra of about
310
837000
3000
現在我們正在研究
14:18
300 stars with extrasolar planets.
311
840000
3000
大約300個外星系行星的光譜。
14:21
And we are doing this job since 2000
312
843000
4000
我們從2000年開始這麼做，
14:25
and it's a very heavy project.
313
847000
3000
這是個很龐大的計劃。
14:28
We have been working very hard.
314
850000
2000
我們很認真地做，
14:30
And we have some interesting cases,
315
852000
4000
而且我們也有些非常有趣的例子，
14:34
candidates, so on, things which we can't really explain.
316
856000
4000
一些我們無法解釋的例子。
14:38
And I hope in the near future
317
860000
3000
我希望在不遠的將來
14:41
we can confirm this.
318
863000
2000
我們可以確認這個。
14:43
So the main question: "Are we alone?"
319
865000
2000
所以主要的問題是：「我們是孤獨的嗎？」
14:45
I think it will not come from UFOs.
320
867000
3000
我覺得不會從UFO中得到答案。
14:48
It will not come from radio signals.
321
870000
4000
我覺得不會從收音訊號中得到答案。
14:52
I think it will come from a spectrum like this.
322
874000
4000
我覺得會從這類的光譜中得到答案。
14:56
It is the spectrum of a planet like Earth,
323
878000
5000
這是個類地行星的光譜
15:01
showing a presence of nitrogen dioxide,
324
883000
3000
顯示著氮氧化物，
15:04
as a clear signal of life,
325
886000
3000
明確代表生命存在，
15:07
and oxygen and ozone.
326
889000
2000
和氧和臭氧。
15:09
If, one day, and I think it will be
327
891000
2000
如果哪一天，而且我覺得
15:11
within 15 years from now, or 20 years.
328
893000
3000
大約再十五年或二十年
15:14
If we discover a spectrum like this
329
896000
3000
我們發現一個像這樣的光譜，
15:17
we can be sure that there is life on that planet.
330
899000
2000
那麼我們可以確定那顆行星上有生命。
15:19
In about five years we will discover
331
901000
3000
大約再五年我們會發現
15:22
planets like Earth, around sun-like stars,
332
904000
3000
其他類地行星在類太陽恆星附近，
15:25
the same distance as the Earth from the Sun.
333
907000
3000
距離大約與地球和太陽間距相似。
15:28
It will take about five years.
334
910000
2000
這大概需要五年。
15:30
And then we will need another 10, 15 years
335
912000
2000
然後我們需要十、十五年
15:32
with space projects
336
914000
2000
利用太空計劃
15:34
to get the spectra of Earth-like planets like the one I showed you.
337
916000
3000
來取得像我剛剛給你們看的類地行星的光譜。
15:37
And if we see the nitrogen dioxide
338
919000
2000
然後如果我們看到氮氧化物
15:39
and oxygen,
339
921000
2000
或氧，
15:41
I think we have the perfect E.T.
340
923000
2000
我想我們就有E.T.(外星人)了。
15:43
Thank you very much.
341
925000
2000
非常謝謝你們。
15:45
(Applause)
342
927000
4000
(掌聲)
ABOUT THE SPEAKER
Garik Israelian - AstrophysicistGarik Israelian's stargazing on the Canary Islands has led to high-profile discoveries about space's big disasters -- including the first evidence that supernova explosions make black holes.
Why you should listen
Garik Israelian studies the spectral signatures of stars and other bodies as an astrophysicist at the Gran Telescopio Canarias, home of the world's largest optical-infrared telescope mirror, part of the Institute of Astrophysics on the Canary Islands. He has published more than 150 articles on topics such as extra-solar planets and black hole binary systems, and his observational work -- poring over the spectral data that points to the composition of distant stars -- has led to the discovery of a lithium signature that suggests Sun-sized stars gobble up their planets.
In 1999, Israelian led a collaboration that found the first observational evidence that supernova explosions are responsible for the formation of black holes. He's on the verge of announcing more big news. (And he is one of the astronomers whom Brian May, the guitarist of Queen, credits with persuading him to finish his PhD after 30 years as a rock star.)
Garik Israelian | Speaker | TED.com