TEDxPerth
Natasha Hurley-Walker: How radio telescopes show us unseen galaxies
娜塔莎·赫利·沃克: 射電望遠鏡如何呈現出看不到的星系
Filmed:
Readability: 4
1,295,837 views
天文學家娜塔莎 · 赫利 · 沃克說，我們的宇宙很奇異、美妙、浩瀚。目前太空船尚無法帶你深入它，但射電望遠鏡可以。在這場迷人且有著許多影像的演說中，赫利 · 沃克告訴我們她如何用特別的技術來探索宇宙之謎，展現出人眼所看不見的光譜。
Natasha Hurley-Walker - Astronomer
Natasha Hurley-Walker uses novel radio telescopes to explore the universe at some of the longest wavelengths of light. Full bio
Natasha Hurley-Walker uses novel radio telescopes to explore the universe at some of the longest wavelengths of light. Full bio
Double-click the English transcript below to play the video.
00:13
Space, the final frontier.
0
1080
2760
太空，最後的邊境。
00:17
I first heard these words
when I was just six years old,
when I was just six years old,
1
5880
3456
我 6 歲時第一次聽到這句話，
00:21
and I was completely inspired.
2
9360
2256
並因此深受啓發。
00:23
I wanted to explore strange new worlds.
3
11640
2376
我想要去探索新奇的世界。
00:26
I wanted to seek out new life.
4
14040
1496
我要去尋找新的生命。
00:27
I wanted to see everything
that the universe had to offer.
that the universe had to offer.
5
15560
3200
我想要去見識宇宙的一切。
00:31
And those dreams, those words,
they took me on a journey,
they took me on a journey,
6
19840
3696
這些夢想和話語
讓我踏上了這個旅程，
讓我踏上了這個旅程，
00:35
a journey of discovery,
7
23560
1456
充滿發現的旅程，
00:37
through school, through university,
8
25040
2176
經過中學、經過大學，
00:39
to do a PhD and finally
to become a professional astronomer.
to become a professional astronomer.
9
27240
3440
唸博士、最後成為專業天文學家。
00:43
Now, I learned two amazing things,
10
31920
3016
我學到了兩件很棒的事，
00:46
one slightly unfortunate,
11
34960
1536
第一件稍微有點不幸，
00:48
when I was doing my PhD.
12
36520
2056
當我在唸博士時。
00:50
I learned that the reality was
13
38600
2416
我學到現實是，
00:53
I wouldn't be piloting
a starship anytime soon.
a starship anytime soon.
14
41040
3160
駕駛太空船不是近期可實現的事。
00:57
But I also learned that the universe
is strange, wonderful and vast,
is strange, wonderful and vast,
15
45440
4616
但我也學到，宇宙是
奇異、美妙、浩瀚的，
奇異、美妙、浩瀚的，
01:02
actually too vast
to be explored by spaceship.
to be explored by spaceship.
16
50080
2800
事實上，它太浩瀚了
太空船也無法探索完。
太空船也無法探索完。
01:05
And so I turned my attention
to astronomy, to using telescopes.
to astronomy, to using telescopes.
17
53720
3360
因此我把注意力轉向天文學，
轉向使用望遠鏡。
轉向使用望遠鏡。
01:09
Now, I show you before you
an image of the night sky.
an image of the night sky.
18
57840
2776
我現在呈現在你們眼前的
是夜晚天空的影像。
是夜晚天空的影像。
01:12
You might see it anywhere in the world.
19
60640
1920
你在世界任何地方都可以看到它。
01:15
And all of these stars are part
of our local galaxy, the Milky Way.
of our local galaxy, the Milky Way.
20
63040
3960
所有這些星星都是
我們這個銀河系的一部份。
我們這個銀河系的一部份。
01:19
Now, if you were to go
to a darker part of the sky,
to a darker part of the sky,
21
67560
2696
如果你到比較暗的一個地方，
01:22
a nice dark site, perhaps in the desert,
22
70280
2536
一個不錯的黑暗之地，
也許是在沙漠，
也許是在沙漠，
01:24
you might see the center
of our Milky Way galaxy
of our Milky Way galaxy
23
72840
2416
你也許能看到銀河系的中心，
01:27
spread out before you,
hundreds of billions of stars.
hundreds of billions of stars.
24
75280
2960
上千億顆星星在你面前展開。
01:30
And it's a very beautiful image.
25
78840
1576
這是個非常美的畫面。
01:32
It's colorful.
26
80440
1336
非常多彩。
01:33
And again, this is just
a local corner of our universe.
a local corner of our universe.
27
81800
3616
同樣的，這也只是
我們這個宇宙的一小角。
我們這個宇宙的一小角。
01:37
You can see there's
a sort of strange dark dust across it.
a sort of strange dark dust across it.
28
85440
3296
你可以看到有種奇怪的、類似
暗色灰塵的東西橫越它。
暗色灰塵的東西橫越它。
01:40
Now, that is local dust
29
88760
1976
這是此處的塵埃，
01:42
that's obscuring the light of the stars.
30
90760
2656
它遮蔽了星體的亮光。
01:45
But we can do a pretty good job.
31
93440
1576
但我們可以看得很清楚。
01:47
Just with our own eyes, we can explore
our little corner of the universe.
our little corner of the universe.
32
95040
3456
只要用我們的雙眼
就可探索宇宙中我們所處的小角落。
就可探索宇宙中我們所處的小角落。
01:50
It's possible to do better.
33
98520
1336
還有可能看得更清楚。
01:51
You can use wonderful telescopes
like the Hubble Space Telescope.
like the Hubble Space Telescope.
34
99880
3760
你可以使用很好的望遠鏡，
如哈伯空間望遠鏡。
如哈伯空間望遠鏡。
01:56
Now, astronomers
have put together this image.
have put together this image.
35
104200
2176
天文學家做出了這張影像。
01:58
It's called the Hubble Deep Field,
36
106400
1896
稱為「哈伯深領域」，
02:00
and they've spent hundreds of hours
observing just a tiny patch of the sky
observing just a tiny patch of the sky
37
108320
4336
他們花了幾百小時觀察
天空的小小一部分，
天空的小小一部分，
02:04
no larger than your thumbnail
held at arm's length.
held at arm's length.
38
112680
2400
比你伸直手臂時看到的
指甲蓋的大小差不多。
指甲蓋的大小差不多。
02:07
And in this image
39
115520
1256
在這張影像中，
02:08
you can see thousands of galaxies,
40
116800
1656
你可以看到數千個銀河系，
02:10
and we know that there must be
hundreds of millions, billions of galaxies
hundreds of millions, billions of galaxies
41
118480
3456
我們知道在整個宇宙中
必定有數億數兆個
必定有數億數兆個
02:13
in the entire universe,
42
121960
1376
銀河系存在，
02:15
some like our own and some very different.
43
123360
2656
有些很像我們的銀河系，
有些則非常不同。
有些則非常不同。
02:18
So you think, OK, well,
I can continue this journey.
I can continue this journey.
44
126040
2656
所以你心想，好，我可以繼續這旅程。
02:20
This is easy. I can just
use a very powerful telescope
use a very powerful telescope
45
128720
2696
這很簡單。
我只要用強大的望遠鏡對準天空，
我只要用強大的望遠鏡對準天空，
02:23
and just look at the sky, no problem.
46
131440
1800
然後只要看著天空，沒問題的。
02:25
It's actually really missing out
if we just do that.
if we just do that.
47
133960
4016
但如果我們真的這樣做，
其實會錯過很多。
其實會錯過很多。
02:30
Now, that's because
everything I've talked about so far
everything I've talked about so far
48
138000
2736
那是因為目前我所講的一切，
02:32
is just using the visible spectrum,
just the thing that your eyes can see,
just the thing that your eyes can see,
49
140760
3896
都只用到可見光譜，也就是
你眼睛可以看到的電磁波範圍，
你眼睛可以看到的電磁波範圍，
02:36
and that's a tiny slice,
50
144680
1416
那只是極小的一部分，
02:38
a tiny, tiny slice
of what the universe has to offer us.
of what the universe has to offer us.
51
146120
3360
宇宙一切中極小、極小的一部份。
02:42
Now, there's also two very important
problems with using visible light.
problems with using visible light.
52
150160
4736
使用可見光，會有兩個重要的問題。
02:46
Not only are we missing out
on all the other processes
on all the other processes
53
154920
2736
我們不只會錯過其他的景象──
02:49
that are emitting other kinds of light,
54
157680
3176
因為它們發出的是
其他種類的、不可見的光，
其他種類的、不可見的光，
02:52
but there's two issues.
55
160880
1416
還有兩個問題。
02:54
Now, the first is that dust
that I mentioned earlier.
that I mentioned earlier.
56
162320
3376
第一我之前提到的灰塵，
02:57
The dust stops the visible light
from getting to us.
from getting to us.
57
165720
2936
灰塵阻擋，讓可見光無法傳到我們這裡。
03:00
So as we look deeper
into the universe, we see less light.
into the universe, we see less light.
58
168680
4696
所以當我們看向宇宙更深處，
我們看到的光就更少。
我們看到的光就更少。
03:05
The dust stops it getting to us.
59
173400
1560
灰塵阻擋讓光無法傳到我們這裡。
03:07
But there's a really strange problem
with using visible light
with using visible light
60
175520
3416
但當我們試圖使用
可見的光來探索宇宙時，
可見的光來探索宇宙時，
03:10
in order to try and explore the universe.
61
178960
1960
會有一個非常奇特的問題。
03:13
Now take a break for a minute.
62
181640
2256
現在先休息一下。
03:15
Say you're standing on a corner,
a busy street corner.
a busy street corner.
63
183920
2680
假設你站在一個角落，繁忙的街角。
03:19
There's cars going by.
64
187080
1496
有車子經過。
03:20
An ambulance approaches.
65
188600
1400
有一輛救護車接近，
它有著高音頻的警笛聲。
03:22
It has a high-pitched siren.
66
190840
1376
03:24
(Imitates a siren passing by)
67
192240
3736
（模仿警笛經過）
03:28
The siren appeared to change in pitch
68
196000
2336
警笛朝你而來和遠離你時，
03:30
as it moved towards and away from you.
69
198360
2080
音高明顯有所不同。
03:32
The ambulance driver did not change
the siren just to mess with you.
the siren just to mess with you.
70
200960
3880
救護車司機並沒有改變警笛來玩弄你。
03:38
That was a product of your perception.
71
206040
2576
那是你的感知所造成的。
03:40
The sound waves,
as the ambulance approached,
as the ambulance approached,
72
208640
2736
當救護車接近時，聲波
03:43
were compressed,
73
211400
1216
會被壓縮，
03:44
and they changed higher in pitch.
74
212640
1936
它們的音高會變更高。
03:46
As the ambulance receded,
the sound waves were stretched,
the sound waves were stretched,
75
214600
2776
隨著救護車離開，聲波被延展，
03:49
and they sounded lower in pitch.
76
217400
2056
警笛聲的音高聽起來就比較低。
03:51
The same thing happens with light.
77
219480
2000
光也有同樣的現象，
03:54
Objects moving towards us,
78
222040
2376
當物體向我們移動，
03:56
their light waves are compressed
and they appear bluer.
and they appear bluer.
79
224440
3176
它們的光波被壓縮，因此顯得比較藍。
03:59
Objects moving away from us,
80
227640
2216
遠離我們的物體，
04:01
their light waves are stretched,
and they appear redder.
and they appear redder.
81
229880
2656
它們的光波被延展，因此顯得比較紅。
04:04
So we call these effects
blueshift and redshift.
blueshift and redshift.
82
232560
2880
我們稱這些效應為藍移和紅移。
04:08
Now, our universe is expanding,
83
236440
2936
現在，我們的宇宙正在擴張，
04:11
so everything is moving away
from everything else,
from everything else,
84
239400
4176
所以所有東西都在遠離其他東西，
04:15
and that means
everything appears to be red.
everything appears to be red.
85
243600
2680
那就意味著所有東西
看起來都是紅的。
看起來都是紅的。
04:19
And oddly enough, as you look
more deeply into the universe,
more deeply into the universe,
86
247040
3736
奇怪的是，當你看向宇宙更深處，
04:22
more distant objects
are moving away further and faster,
are moving away further and faster,
87
250800
4296
距離越遠的物體，
也在越快地遠離我們，
也在越快地遠離我們，
04:27
so they appear more red.
88
255120
1719
所以它們看起來變得更紅。
如果我回到「哈伯深領域」
04:29
So if I come back to the Hubble Deep Field
89
257560
2935
04:32
and we were to continue
to peer deeply into the universe
to peer deeply into the universe
90
260519
2697
並且我們持續窺探宇宙深處，
04:35
just using the Hubble,
91
263240
1536
僅僅只使用哈伯，
04:36
as we get to a certain distance away,
92
264800
2696
當我們到達一定距離之後，
04:39
everything becomes red,
93
267520
1600
每樣東西都變成紅色，
04:41
and that presents something of a problem.
94
269920
1976
那就呈現出了一個問題。
04:43
Eventually, we get so far away
95
271920
2056
最終，地方距離我們如此之遠，
04:46
everything is shifted into the infrared
96
274000
2976
一切都轉變成紅外線，
04:49
and we can't see anything at all.
97
277000
2000
我們就完全看不到任何東西。
04:51
So there must be a way around this.
98
279680
1696
那必須要有解決之道。
04:53
Otherwise, I'm limited in my journey.
99
281400
1816
否則，我的旅程將受到限制。
04:55
I wanted to explore the whole universe,
100
283240
1896
我想要探索整個宇宙，
04:57
not just whatever I can see,
you know, before the redshift kicks in.
you know, before the redshift kicks in.
101
285160
3920
不僅僅是肉眼可見的部份，
可現在，「紅移」造成了麻煩。
可現在，「紅移」造成了麻煩。
05:02
There is a technique.
102
290160
1256
有一種技術，
05:03
It's called radio astronomy.
103
291440
1376
叫射電天文學。
05:04
Astronomers have been
using this for decades.
using this for decades.
104
292840
2336
天文學家已使用這技術數十年了。
05:07
It's a fantastic technique.
105
295200
1296
它是種很棒的技術。
05:08
I show you the Parkes Radio Telescope,
affectionately known as "The Dish."
affectionately known as "The Dish."
106
296520
3486
我讓你們看看帕克斯射電望遠鏡
也就是所謂的「碟子」（The Dish）。
也就是所謂的「碟子」（The Dish）。
05:12
You may have seen the movie.
107
300040
1776
你可能看過《不簡單的任務
（The Dish）》這部電影。
（The Dish）》這部電影。
05:13
And radio is really brilliant.
108
301840
1576
無線電棒極了。
05:15
It allows us to peer much more deeply.
109
303440
2536
它可以讓我們能窺探得更深入。
05:18
It doesn't get stopped by dust,
110
306000
2696
它不會被灰塵阻擋，
05:20
so you can see everything in the universe,
111
308720
2256
所以你可以看到在宇宙中的任何東西，
05:23
and redshift is less of a problem
112
311000
1856
紅移問題就不算什麼了，
05:24
because we can build receivers
that receive across a large band.
that receive across a large band.
113
312880
3200
因為我們可以建造接收器
來接收很廣的波段。
來接收很廣的波段。
05:28
So what does Parkes see when we turn it
to the center of the Milky Way?
to the center of the Milky Way?
114
316600
3936
所以當我們把帕克斯轉向銀河的中央
我們會看到什麼？
我們會看到什麼？
05:32
We should see something fantastic, right?
115
320560
1960
我們應該會看到很炫的東西，對吧？
05:35
Well, we do see something interesting.
116
323160
2896
嗯，我們確實看到了有趣的東西。
05:38
All that dust has gone.
117
326080
1656
所有的灰塵都不見了。
05:39
As I mentioned, radio goes
straight through dust, so not a problem.
straight through dust, so not a problem.
118
327760
3440
如我先前提到的，無線電波可以
直接穿透灰塵，這不是個問題。
直接穿透灰塵，這不是個問題。
05:43
But the view is very different.
119
331840
1896
但看到的景象非常不同。
05:45
We can see that the center
of the Milky Way is aglow,
of the Milky Way is aglow,
120
333760
3816
我們可以看到銀河的中央在發光，
05:49
and this isn't starlight.
121
337600
1680
這不是星光。
05:51
This is a light called
synchrotron radiation,
synchrotron radiation,
122
339960
3136
這種光叫做同步加速輻射
（synchrotron radiation），
（synchrotron radiation），
05:55
and it's formed from electrons
spiraling around cosmic magnetic fields.
spiraling around cosmic magnetic fields.
123
343120
4600
它是由電子繞著宇宙磁場
螺旋轉動所形成，
螺旋轉動所形成，
06:00
So the plane is aglow with this light.
124
348280
3096
是這種光讓這個平面看來在發光。
06:03
And we can also see
strange tufts coming off of it,
strange tufts coming off of it,
125
351400
3296
我們可以看到來自它的奇特簇束，
06:06
and objects which don't appear to line up
126
354720
2496
以及一些物體，
它們顯然並不符合
它們顯然並不符合
06:09
with anything that we can see
with our own eyes.
with our own eyes.
127
357240
2320
我們肉眼所見的一切。
06:12
But it's hard to really
interpret this image,
interpret this image,
128
360520
2136
這個影像很難詮釋，
06:14
because as you can see,
it's very low resolution.
it's very low resolution.
129
362680
2776
因為如你所見，它的解析度很低。
06:17
Radio waves have a wavelength that's long,
130
365480
2176
無線電波的波長很長，
06:19
and that makes their resolution poorer.
131
367680
2296
這使得它的解析度更差。
06:22
This image is also black and white,
132
370000
2056
這個影像也是黑白的，
06:24
so we don't really know
what is the color of everything in here.
what is the color of everything in here.
133
372080
3760
所以其實我們不知道
那裡的任何東西是什麼顏色。
那裡的任何東西是什麼顏色。
06:28
Well, fast-forward to today.
134
376640
1376
快轉到現今，
06:30
We can build telescopes
135
378040
1456
我們可以建造出
06:31
which can get over these problems.
136
379520
2616
能解決這些問題的望遠鏡。
06:34
Now, I'm showing you here an image
of the Murchison Radio Observatory,
of the Murchison Radio Observatory,
137
382160
3336
現在我要給你們看的是
默奇森電波天文臺的影像，
默奇森電波天文臺的影像，
06:37
a fantastic place
to build radio telescopes.
to build radio telescopes.
138
385520
2776
那兒是設置射電望遠鏡的絕佳地點。
06:40
It's flat, it's dry,
139
388320
2296
它很平坦，很乾燥，
06:42
and most importantly, it's radio quiet:
140
390640
2976
最重要的是，沒有電波幹擾：
06:45
no mobile phones, no Wi-Fi, nothing,
141
393640
3096
沒有手機，沒有無線網路，都沒有。
06:48
just very, very radio quiet,
142
396760
2496
就是完全無電波幹擾。
06:51
so a perfect place
to build a radio telescope.
to build a radio telescope.
143
399280
2720
因此是設置電波望遠鏡的完美地點。
06:54
Now, the telescope that I've been
working on for a few years
working on for a few years
144
402880
2856
我這些年來工作中的望遠鏡
06:57
is called the Murchison Widefield Array,
145
405760
1936
叫「默奇森寬場陣列（MWA）」，
06:59
and I'm going to show you
a little time lapse of it being built.
a little time lapse of it being built.
146
407720
3016
我要給各位看一段它建造過程的縮時影片。
07:02
This is a group of undergraduate
and postgraduate students
and postgraduate students
147
410760
3256
這是一群大學和研究生，
07:06
located in Perth.
148
414040
1256
地點在伯斯。
07:07
We call them the Student Army,
149
415320
1736
我們稱他們為「學生軍隊」，
07:09
and they volunteered their time
to build a radio telescope.
to build a radio telescope.
150
417080
2816
他們是自願協助架設望遠鏡的義工。
07:11
There's no course credit for this.
151
419920
1640
做這工作是沒有學分奬勵的。
07:14
And they're putting together
these radio dipoles.
these radio dipoles.
152
422320
2896
他們在裝配無線電的偶極。
07:17
They just receive at low frequencies,
a bit like your FM radio or your TV.
a bit like your FM radio or your TV.
153
425240
4960
它們可以收到很低的頻率，
有點像是FM廣播或電視。
有點像是FM廣播或電視。
07:23
And here we are deploying them
across the desert.
across the desert.
154
431000
3096
我們將它們佈署到沙漠中。
07:26
The final telescope
covers 10 square kilometers
covers 10 square kilometers
155
434120
2416
最終望遠鏡含蓋了10平方公里。
07:28
of the Western Australian desert.
156
436560
2136
位在西澳洲的沙漠上。
07:30
And the interesting thing is,
there's no moving parts.
there's no moving parts.
157
438720
2976
有趣的是，沒有可活動的部件。
07:33
We just deploy these little antennas
158
441720
2256
我們只是佈署了這些小天線，
07:36
essentially on chicken mesh.
159
444000
1856
基本上是放在六角形網格上。
07:37
It's fairly cheap.
160
445880
1416
價格非常便宜。
07:39
Cables take the signals
161
447320
1976
從天線取得的信號
07:41
from the antennas
162
449320
2056
透過覽線
07:43
and bring them
to central processing units.
to central processing units.
163
451400
2536
被送到中央處理單位。
07:45
And it's the size of this telescope,
164
453960
1776
是因為這望遠鏡的大小，
07:47
the fact that we've built it
over the entire desert
over the entire desert
165
455760
2656
大到我們得在整個沙漠上建造它，
07:50
that gives us a better
resolution than Parkes.
resolution than Parkes.
166
458440
2800
因而才有比帕克斯更好的解析度。
07:53
Now, eventually all those cables
bring them to a unit
bring them to a unit
167
461880
3536
最後，所有這些覽線
把數據傳送給一個處理單位，
把數據傳送給一個處理單位，
07:57
which sends it off
to a supercomputer here in Perth,
to a supercomputer here in Perth,
168
465440
3536
處理單位又將資訊
傳到位在伯斯的超級電腦，
傳到位在伯斯的超級電腦，
08:01
and that's where I come in.
169
469000
1286
這就是我發揮功能的地方了。
08:03
(Sighs)
170
471320
1216
（嘆氣）
08:04
Radio data.
171
472560
1216
無線電波資料。
08:05
I have spent the last five years
172
473800
1816
我花了過去五年
08:07
working with very difficult,
very interesting data
very interesting data
173
475640
2856
處理非常困難但非常有趣的資料，
08:10
that no one had really looked at before.
174
478520
1976
都是過去沒人看過的。
08:12
I've spent a long time calibrating it,
175
480520
2136
我花了好多時間校調它，
08:14
running millions of CPU hours
on supercomputers
on supercomputers
176
482680
3896
花了數百萬中央處理器小時
來用超級電腦做運算，
來用超級電腦做運算，
08:18
and really trying to understand that data.
177
486600
2200
並真正嘗試去瞭解資料。
08:21
And with this telescope,
178
489360
1936
有了這個望遠鏡，
08:23
with this data,
179
491320
1256
有了這些資料，
08:24
we've performed a survey
of the entire southern sky,
of the entire southern sky,
180
492600
3936
我們針對整個南方天空進行了一項調查，
08:28
the GaLactic and Extragalactic
All-sky MWA Survey,
All-sky MWA Survey,
181
496560
5096
稱為「銀河系及銀銀河外星系的
全天空的 MWA 調查」。
全天空的 MWA 調查」。
08:33
or GLEAM, as I call it.
182
501680
1880
我簡稱它叫 GLEAM 。
08:36
And I'm very excited.
183
504440
1456
我非常興奮。
08:37
This survey is just about to be published,
but it hasn't been shown yet,
but it hasn't been shown yet,
184
505920
3381
這調查即將要發表，
但目前尚未公開過，
但目前尚未公開過，
08:41
so you are literally the first people
185
509325
1931
所以你們就是最早
08:43
to see this southern survey
of the entire sky.
of the entire sky.
186
511280
2800
看到這南方天空調查的人。
08:46
So I'm delighted to share with you
some images from this survey.
some images from this survey.
187
514799
3321
我很高興能在此與你們分享
這次調查中的一些影像。
這次調查中的一些影像。
08:50
Now, imagine you went to the Murchison,
188
518880
1895
現在，想像一下你去默奇森，
08:52
you camped out underneath the stars
189
520799
2096
你在星空下野營，
08:54
and you looked towards the south.
190
522919
1617
你向南方看去，
08:56
You saw the south's celestial pole,
191
524560
1667
看到了南天極，
08:58
the galaxy rising.
192
526251
1205
銀河系在上升。
08:59
If I fade in the radio light,
193
527480
2616
如果我逐漸加強無線電的光，
09:02
this is what we observe with our survey.
194
530120
2656
我們的調查中所看到的
畫面就是這樣的。
畫面就是這樣的。
09:04
You can see that the galactic plane
is no longer dark with dust.
is no longer dark with dust.
195
532800
3056
你可以看到
銀河平面不再因為灰塵而那麼暗了。
銀河平面不再因為灰塵而那麼暗了。
09:07
It's alight with synchrotron radiation,
196
535880
2416
同步加速輻射讓它亮起來，
09:10
and thousands of dots are in the sky.
197
538320
2496
天上有著數以千計的點。
09:12
Our large Magellanic Cloud,
our nearest galactic neighbor,
our nearest galactic neighbor,
198
540840
3296
我們的大麥哲倫雲，
也就是我們最近的銀河鄰居，
也就是我們最近的銀河鄰居，
09:16
is orange instead
of its more familiar blue-white.
of its more familiar blue-white.
199
544160
3216
它是橘色的，
而非我們比較熟悉的藍白色。
而非我們比較熟悉的藍白色。
09:19
So there's a lot going on in this.
Let's take a closer look.
Let's take a closer look.
200
547400
3376
所以這裡有很多學問，
我們再近一點看。
我們再近一點看。
09:22
If we look back
towards the galactic center,
towards the galactic center,
201
550800
2416
如果我們回頭看銀河中心，
09:25
where we originally saw the Parkes image
that I showed you earlier,
that I showed you earlier,
202
553240
3216
我先前給大家看的帕克斯影像，
09:28
low resolution, black and white,
203
556480
2376
是低解析度且黑白的，
09:30
and we fade to the GLEAM view,
204
558880
2080
我們漸漸轉換到 GLEAM 的畫面，
09:34
you can see the resolution
has gone up by a factor of a hundred.
has gone up by a factor of a hundred.
205
562200
3856
可以看到解析度提升百倍。
09:38
We now have a color view of the sky,
206
566080
2856
我們現在能看到彩色的天空了，
09:40
a technicolor view.
207
568960
1336
特藝彩色的天空。
09:42
Now, it's not a false color view.
208
570320
2976
畫面上的這些顏色並不是假的。
09:45
These are real radio colors.
209
573320
2400
它們是真實的無線電波顏色。
09:48
What I've done is I've colored
the lowest frequencies red
the lowest frequencies red
210
576600
2816
我做的是將最低頻率設定為紅色，
09:51
and the highest frequencies blue,
211
579440
1616
最高頻率設定為藍色，
09:53
and the middle ones green.
212
581080
1576
中間頻率則是綠色。
09:54
And that gives us this rainbow view.
213
582680
2216
就產生了這個彩虹色影像。
09:56
And this isn't just false color.
214
584920
2256
這不只是假的顏色。
09:59
The colors in this image
tell us about the physical processes
tell us about the physical processes
215
587200
2936
畫面中的顏色能告訴我們在宇宙中
10:02
going on in the universe.
216
590160
1240
所發生的物理過程。
10:03
So for instance, if you look
along the plane of the galaxy,
along the plane of the galaxy,
217
591974
2762
比如，如果你延著銀河系的平面看去，
10:06
it's alight with synchrotron,
218
594760
1456
它因為同步加速輻射而亮著，
10:08
which is mostly reddish orange,
219
596240
2376
大部份是橘紅色，
10:10
but if we look very closely,
we see little blue dots.
we see little blue dots.
220
598640
3120
但如果我們非常近看，
可以看到些小藍點。
可以看到些小藍點。
10:14
Now, if we zoom in,
221
602320
1576
如果我們把影像放大，
10:15
these blue dots are ionized plasma
222
603920
2536
這些藍點是電離的等離子體，
10:18
around very bright stars,
223
606480
1640
圍繞在非常亮的星體旁邊，
10:20
and what happens
is that they block the red light,
is that they block the red light,
224
608680
2776
原因是因為它們阻擋了紅光，
10:23
so they appear blue.
225
611480
1640
所以會顯現藍色。
10:25
And these can tell us
about these star-forming regions
about these star-forming regions
226
613880
2936
這些資訊能讓我們瞭解
我們的銀河系中這些由星體
我們的銀河系中這些由星體
10:28
in our galaxy.
227
616840
1256
形成的區域。
10:30
And we just see them immediately.
228
618120
1616
我們能立即看到它們。
10:31
We look at the galaxy,
and the color tells us that they're there.
and the color tells us that they're there.
229
619760
3056
我們看向銀河系，
顏色就能顯示它們的所在。
顏色就能顯示它們的所在。
10:34
You can see little soap bubbles,
230
622840
1576
你們可以看見小小的肥皂泡，
10:36
little circular images
around the galactic plane,
around the galactic plane,
231
624440
3416
在銀河系平面周圍的小圓圈，
10:39
and these are supernova remnants.
232
627880
2000
它們是超新星的遺跡。
10:42
When a star explodes,
233
630600
1696
當一顆星星爆炸，
10:44
its outer shell is cast off
234
632320
2456
它的外殼會被脫去，
10:46
and it travels outward into space
gathering up material,
gathering up material,
235
634800
3296
它會向外移動進入太空
收集物質，
收集物質，
10:50
and it produces a little shell.
236
638120
1960
產生出小的殼。
10:52
It's been a long-standing
mystery to astronomers
mystery to astronomers
237
640800
3376
對天文學家而言，
超新星的遺跡在何處
超新星的遺跡在何處
10:56
where all the supernova remnants are.
238
644200
2080
一直是長久以來的謎。
10:58
We know that there must be a lot
of high-energy electrons in the plane
of high-energy electrons in the plane
239
646960
4336
我們知道在平面中一定
有許多高能量的電子，
有許多高能量的電子，
11:03
to produce the synchrotron
radiation that we see,
radiation that we see,
240
651320
2656
才能產生我們看見的
同步加速輻射。
同步加速輻射。
11:06
and we think they're produced
by supernova remnants,
by supernova remnants,
241
654000
2576
我們認為這些電子是
由超新星遺跡產生的，
由超新星遺跡產生的，
11:08
but there don't seem to be enough.
242
656600
1776
但似乎光這些遺跡
還不夠證實猜測。
還不夠證實猜測。
11:10
Fortunately, GLEAM is really, really
good at detecting supernova remnants,
good at detecting supernova remnants,
243
658400
3896
幸運的是，GLEAM非常擅長
偵測超新星遺跡，
偵測超新星遺跡，
11:14
so we're hoping to have
a new paper out on that soon.
a new paper out on that soon.
244
662320
2480
所以我們希望很快能
發表這方面的論文。
發表這方面的論文。
11:17
Now, that's fine.
245
665800
1256
好了，
11:19
We've explored our little local universe,
246
667080
2336
我們已經探索了我們所處的小宇宙，
11:21
but I wanted to go deeper,
I wanted to go further.
I wanted to go further.
247
669440
2376
但我還想要更深入，更進一步，
11:23
I wanted to go beyond the Milky Way.
248
671840
2080
我想要超越到銀河之外。
11:26
Well, as it happens, we can see a very
interesting object in the top right,
interesting object in the top right,
249
674520
3776
這麼做時，在右上角可以
看到一個很有趣的物體，
看到一個很有趣的物體，
11:30
and this is a local radio galaxy,
250
678320
2216
這是一個本地的射電星系
11:32
Centaurus A.
251
680560
1240
半人馬星座A。
11:34
If we zoom in on this,
252
682240
1256
如果我們把它放大，
11:35
we can see that there are
two huge plumes going out into space.
two huge plumes going out into space.
253
683520
3400
可看到有兩大塊羽狀物
向外進入太空。
向外進入太空。
11:39
And if you look right in the center
between those two plumes,
between those two plumes,
254
687600
2896
往兩塊羽狀物的中心看，
11:42
you'll see a galaxy just like our own.
255
690520
2376
你會看到一個星系
就像我們的銀河系一樣。
就像我們的銀河系一樣。
11:44
It's a spiral. It has a dust lane.
256
692920
2456
它是螺旋形的，有一道灰塵帶。
11:47
It's a normal galaxy.
257
695400
1616
是個正常的星系。
11:49
But these jets
are only visible in the radio.
are only visible in the radio.
258
697040
3616
但只能透過無線電波
才能看得到這些噴流。
才能看得到這些噴流。
11:52
If we looked in the visible,
we wouldn't even know they were there,
we wouldn't even know they were there,
259
700680
3176
如果只看肉眼可見的部份，
就完全不會知道它們存在，
就完全不會知道它們存在，
11:55
and they're thousands of times larger
than the host galaxy.
than the host galaxy.
260
703880
3040
它們比宿主星系還要大數千倍。
11:59
What's going on?
What's producing these jets?
What's producing these jets?
261
707480
2400
怎麼回事？這些噴流是如何形成的？
12:03
At the center of every galaxy
that we know about
that we know about
262
711160
3536
在我們所知的每個星系的中心
12:06
is a supermassive black hole.
263
714720
2256
都有個超大質量的黑洞。
12:09
Now, black holes are invisible.
That's why they're called that.
That's why they're called that.
264
717000
3416
黑洞是看不見的，
所以才叫黑洞。
所以才叫黑洞。
12:12
All you can see is the deflection
of the light around them,
of the light around them,
265
720440
3016
只能看見它們周圍的光線偏折，
12:15
and occasionally, when a star
or a cloud of gas comes into their orbit,
or a cloud of gas comes into their orbit,
266
723480
4296
偶爾，當星體或氣體雲進入它們的軌道，
12:19
it is ripped apart by tidal forces,
267
727800
2736
會被引潮力給撕碎，
12:22
forming what we call an accretion disk.
268
730560
2480
形成我們所謂的吸積盤。
12:25
The accretion disk
glows brightly in the x-rays,
glows brightly in the x-rays,
269
733640
3216
用X光來看，吸積盤非常亮，
12:28
and huge magnetic fields
can launch the material into space
can launch the material into space
270
736880
4416
強大的磁場能以近光速的速度
12:33
at nearly the speed of light.
271
741320
1720
將物質射入太空中。
12:35
So these jets are visible in the radio
272
743520
3160
所以從無線電波上可看到這些噴流，
12:39
and this is what we pick up in our survey.
273
747240
2160
這是我們的調查中發現的。
12:42
Well, very well, so we've seen
one radio galaxy. That's nice.
one radio galaxy. That's nice.
274
750040
4016
好，我們看過了一個
射電星系，很好。
射電星系，很好。
12:46
But if you just look
at the top of that image,
at the top of that image,
275
754080
2176
但如果你看一下影像的上方，
12:48
you'll see another radio galaxy.
276
756280
1736
會看到另一個射電星系。
12:50
It's a little bit smaller,
and that's just because it's further away.
and that's just because it's further away.
277
758040
3240
它稍微小了一點，
那只是因為它比較遠。
那只是因為它比較遠。
12:53
OK. Two radio galaxies.
278
761800
2656
好，有兩個射電星系。
12:56
We can see this. This is fine.
279
764480
1576
我們能看見這些，沒問題。
12:58
Well, what about all the other dots?
280
766080
1736
那所有其他的光點又是什麼？
12:59
Presumably those are just stars.
281
767840
1560
假設它們都只是星體。
13:01
They're not.
282
769880
1216
但它們不是。
13:03
They're all radio galaxies.
283
771120
1600
它們都是射電星系。
13:05
Every single one of the dots in this image
284
773320
2896
這張影像上的每一個點都是
13:08
is a distant galaxy,
285
776240
1736
一個遙遠的星系，
13:10
millions to billions of light-years away
286
778000
2856
離我們有數百萬甚至數十億光年之遙
13:12
with a supermassive
black hole at its center
black hole at its center
287
780880
2616
中心有個超大質量的黑洞，
13:15
pushing material into space
at nearly the speed of light.
at nearly the speed of light.
288
783520
3576
將物質以近光速的速度推入太空中。
13:19
It is mind-blowing.
289
787120
1760
這太震撼了。
13:21
And this survey is even larger
than what I've shown here.
than what I've shown here.
290
789680
3736
這項調查比我們在這裡
所呈現的部份還要大。
所呈現的部份還要大。
13:25
If we zoom out to
the full extent of the survey,
the full extent of the survey,
291
793440
2536
如果我們縮小影像來看整個調查，
13:28
you can see I found 300,000
of these radio galaxies.
of these radio galaxies.
292
796000
4096
可以看到，我找到了300,000個
像這樣的射電星系。
像這樣的射電星系。
13:32
So it's truly an epic journey.
293
800120
2896
這真是段壯觀的旅程。
13:35
We've discovered all of these galaxies
294
803040
2656
我們發現了所有這些星系，
13:37
right back to the very first
supermassive black holes.
supermassive black holes.
295
805720
3560
追溯到最早先的超大質量黑洞。
13:41
I'm very proud of this,
and it will be published next week.
and it will be published next week.
296
809960
2780
我對此感到非常驕傲，
這項調查下週就會發佈。
這項調查下週就會發佈。
13:45
Now, that's not all.
297
813280
2816
但還不只如此。
13:48
I've explored the furthest reaches
of the galaxy with this survey,
of the galaxy with this survey,
298
816120
4336
這項調查中，我已經探索了
所能觸及的最遠的星系，
所能觸及的最遠的星系，
13:52
but there's something
even more in this image.
even more in this image.
299
820480
2960
但在這影像中呈現的還不只如此。
13:56
Now, I'll take you right back
to the dawn of time.
to the dawn of time.
300
824320
3296
讓我帶大家回到宇宙初開之時。
13:59
When the universe formed,
it was a big bang,
it was a big bang,
301
827640
3656
當宇宙形成時，是一場大爆炸，
14:03
which left the universe
as a sea of hydrogen,
as a sea of hydrogen,
302
831320
4056
讓宇宙變成了氫元素的海洋，
14:07
neutral hydrogen.
303
835400
1496
中性氫。
14:08
And when the very first stars
and galaxies switched on,
and galaxies switched on,
304
836920
2776
當最早的星體及星系出現，
14:11
they ionized that hydrogen.
305
839720
2096
它們將氫給離子化了。
14:13
So the universe went
from neutral to ionized.
from neutral to ionized.
306
841840
3440
所以宇宙從中性的變成離子化的。
14:18
That imprinted a signal all around us.
307
846160
3176
這在我們周圍留下了信號。
14:21
Everywhere, it pervades us,
308
849360
1736
無所不在，它滲透了我們，
14:23
like the Force.
309
851120
1416
就像原力一樣。
14:24
Now, because that happened so long ago,
310
852560
3720
因為這發生在非常古早之前，
14:29
the signal was redshifted,
311
857000
1800
這個信號發生了紅移，
14:31
so now that signal
is at very low frequencies.
is at very low frequencies.
312
859560
3296
現在這個信號的頻率非常非常低。
14:34
It's at the same frequency as my survey,
313
862880
2456
和我的調查中的頻率一樣，
14:37
but it's so faint.
314
865360
1376
但它太微弱。
14:38
It's a billionth the size
of any of the objects in my survey.
of any of the objects in my survey.
315
866760
3880
和我的調查中的任何物體相比
它只有十億分之一。
它只有十億分之一。
14:43
So our telescope may not be quite
sensitive enough to pick up this signal.
sensitive enough to pick up this signal.
316
871320
4896
所以我們的望遠鏡敏感度
不足以接收到這個信號。
不足以接收到這個信號。
14:48
However, there's a new radio telescope.
317
876240
2496
然而，有一個新的電波望遠鏡。
14:50
So I can't have a starship,
318
878760
1656
所以，我無法擁有一艘太空船，
14:52
but I can hopefully have
319
880440
1256
但我有希望能擁有
14:53
one of the biggest
radio telescopes in the world.
radio telescopes in the world.
320
881720
2856
世界上最大的射電望遠鏡之一。
14:56
We're building the Square Kilometre Array,
a new radio telescope,
a new radio telescope,
321
884600
3616
我們正在建造一個新的望遠鏡
叫「平方公里陣列」，
叫「平方公里陣列」，
15:00
and it's going to be a thousand
times bigger than the MWA,
times bigger than the MWA,
322
888240
2736
它將會比默奇森寬場陣列
還要大上一千倍，
還要大上一千倍，
15:03
a thousand times more sensitive,
and have an even better resolution.
and have an even better resolution.
323
891000
3216
敏感度高上一千倍，
解析度也更高。
解析度也更高。
15:06
So we should find
tens of millions of galaxies.
tens of millions of galaxies.
324
894240
2216
我們應該可以發現上千萬個銀河系。
15:08
And perhaps, deep in that signal,
325
896480
2336
也許，在那信號中，
15:10
I will get to look upon the very first
stars and galaxies switching on,
stars and galaxies switching on,
326
898840
4176
我可以找到最初的星體和星系。
15:15
the beginning of time itself.
327
903040
2360
找到時間的起源。
15:17
Thank you.
328
905920
1216
謝謝大家。
15:19
(Applause)
329
907160
2760
（鼓掌）
ABOUT THE SPEAKER
Natasha Hurley-Walker - AstronomerNatasha Hurley-Walker uses novel radio telescopes to explore the universe at some of the longest wavelengths of light.
Why you should listen
Dr. Natasha Hurley-Walker recently completed an astronomical survey of the entire southern sky, revealing the radio glow of our own Milky Way galaxy as well as hundreds of thousands of distant galaxies: the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. Unlike previous work, GLEAM is the first "radio color" survey, observed across such a wide range of frequencies that the unique spectrum of every object can be used to understand its underlying physics.
An Early-Career Research Fellow based at the Curtin University node of the International Centre for Radio Astronomy Research, in Perth, Western Australia, Hurley-Walker is part of the international Murchison Widefield Array (MWA) collaboration, spanning thirteen institutes across six countries. At her fingertips are tens of petabytes of data collected by the MWA since 2013, which she processes using powerful supercomputers at the nearby Pawsey Centre. Hurley-Walker earned a PhD in Radio Astronomy at the University of Cambridge by commissioning and using a new radio telescope to perform its first science observations. The experience directly transferred to the MWA, which she also helped to commission.
The MWA is a precursor to the Square Kilometer Array (SKA), what will be the largest radio telescope in the world, set to come online in the 2020s. By developing software and techniques to deal with data from the MWA, creating pathfinding maps of the sky and training a new generation of astronomers in cutting-edge techniques, Hurley-Walker is working to lay the scientific groundwork for the commissioning of the SKA. In 2016 Hurley-Walker was awarded an Australian SKA Fellowship in order to visit the SKA headquarters and transfer lessons from her commissioning experiences as well as develop her survey into a useful calibration model for the SKA.
Hurley-Walker is passionate about scientific outreach and keynoted talks in 2013 and 2017 at Astrofest, Australia's largest public astronomy festival. So that anyone in the world can see the sky with the same radio eyes as her, she created the GLEAMoscope , an interactive online viewer that shows the universe at radio wavelengths compared to other frequencies, including the more familiar "optical" spectrum. It being the 21st century, there's also an app: check out GLEAM on the Google Play store. In 2017 Natasha won the "Best Timelapse" category in the Astofest astrophotography competition with her colleague John Goldsmith for their creation of a composite video showing both the optical and radio sky. For more detail on Hurley-Walker's work, check out her article on TheConversation.
Working with cutting-edge data is tough, but sometimes hides serendipitous gems which Hurley-Walker has unearthed, like the faintest dying radio galaxy ever discovered, whistling plasma ducts in the Earth's ionosphere and some of the youngest and weirdest radio galaxies ever found. View a complete list of Hurley-Walker's publications.
Natasha Hurley-Walker | Speaker | TED.com