Space, the final frontier.
宇宙,无穷无尽
I first heard these words when I was just six years old, and I was completely inspired. I wanted to explore strange new worlds. I wanted to seek out new life. I wanted to see everything that the universe had to offer. And those dreams, those words, they took me on a journey, a journey of discovery, through school, through university, to do a PhD and finally to become a professional astronomer. Now, I learned two amazing things, one slightly unfortunate, when I was doing my PhD. I learned that the reality was I wouldn't be piloting a starship anytime soon. But I also learned that the universe is strange, wonderful and vast, actually too vast to be explored by spaceship. And so I turned my attention to astronomy, to using telescopes.
我六岁的时候就听到了这样的话 这激励了我 我想探索新奇的世界 新的生命 我想了解宇宙中的每一件事物 带着这些梦想,这些信念 我就踏上了追梦旅程 一个读书 上大学,读博士 最后成为一个专业的天文学家的旅程 目前为止,我了解了两件有趣的事情 第一件有点令我小伤心 当我读博士的时候 我才知道,实际上 我以后根本不能驾驶宇宙飞船 但是我同时也了解到宇宙是 奇妙、壮观、广阔的 实际上宇宙太大,大到用宇宙飞船 根本不可能探索得完 所以我把注意力转移到了天文学 用望远镜来探索宇宙
Now, I show you before you an image of the night sky. You might see it anywhere in the world. And all of these stars are part of our local galaxy, the Milky Way. Now, if you were to go to a darker part of the sky, a nice dark site, perhaps in the desert, you might see the center of our Milky Way galaxy spread out before you, hundreds of billions of stars. And it's a very beautiful image. It's colorful. And again, this is just a local corner of our universe. You can see there's a sort of strange dark dust across it. Now, that is local dust that's obscuring the light of the stars. But we can do a pretty good job. Just with our own eyes, we can explore our little corner of the universe. It's possible to do better. You can use wonderful telescopes like the Hubble Space Telescope. Now, astronomers have put together this image. It's called the Hubble Deep Field, and they've spent hundreds of hours observing just a tiny patch of the sky no larger than your thumbnail held at arm's length. And in this image you can see thousands of galaxies, and we know that there must be hundreds of millions, billions of galaxies in the entire universe, some like our own and some very different. So you think, OK, well, I can continue this journey. This is easy. I can just use a very powerful telescope and just look at the sky, no problem. It's actually really missing out if we just do that. Now, that's because everything I've talked about so far is just using the visible spectrum, just the thing that your eyes can see, and that's a tiny slice, a tiny, tiny slice of what the universe has to offer us. Now, there's also two very important problems with using visible light. Not only are we missing out on all the other processes that are emitting other kinds of light, but there's two issues.
在你们展开想象之前 我先给大家展示一下星空吧 在世界的任何地方 都能看到这样的景象 这些星体是我们星系的一部分,银河系 现在如果你看一看夜空中黑暗的部分 选一个好地方观察,沙漠就行 你也许会看到银河的中心 上千亿的星体在你面前散布着 景象极其壮观 五彩斑斓 当然,这只是我们宇宙的 一个局部的中心 许多奇怪的黑色尘埃分散其中 这些是局部尘埃 他们阻挡了其他星体发出来的光线 但是我们做的还不错 仅仅用肉眼,我们就能 探索宇宙的一个小角落 所以我们有进步的余地 你可以用神奇的哈勃空间望远镜 (来探索宇宙) 现在天文学家已经把 收集到的景象放在一起 叫做哈勃深空视场 他们花数百个小时观察这一小块天空 相当于比你整条胳膊上的一小块 指甲还小的地方 在这个景象中 你可以看到上千个星系 我们知道在整个宇宙中一定还存在 上亿的星系 一些星系跟我们的星系相似 另一些和我们的完全不同 所以你就想着,没问题啊 我可以继续研究 很简单,我只要有一个 足够牛的望远镜就行 然后再拿它看看天空,没问题的 实际上,如果我们真的这么做的话 就什么都探索不到了 因为我们到目前为止所说的一切 仅仅是用可见光看到的, 你们的眼睛就可以看到, 这只是宇宙中 很小的一部分,非常非常小 而且现在就可见光来说,我们也有两个 非常重要的问题需要解决 现在不仅不能研究那些 发出其他不可见光的东西 (在可见光范围内) 我们也有两个问题
Now, the first is that dust that I mentioned earlier. The dust stops the visible light from getting to us. So as we look deeper into the universe, we see less light. The dust stops it getting to us. But there's a really strange problem with using visible light in order to try and explore the universe.
第一个是我之前提到的尘埃 这些尘埃阻挡了可见光 我们看不到后边的东西 所以我们进一步探索宇宙的话 光线就比之前更少 尘埃阻挡了光线 在研究宇宙的过程中,我们在如何应用 可见光方面也有问题
Now take a break for a minute. Say you're standing on a corner, a busy street corner. There's cars going by. An ambulance approaches. It has a high-pitched siren.
我们先不说这个 假设你现在站在 喧闹大街的角落,很热闹 大街上的车川流不息 这时候一辆救护车正驶来 警报器发出尖锐的声音
(Imitates a siren passing by)
(模仿警报声呼啸而过)
The siren appeared to change in pitch as it moved towards and away from you. The ambulance driver did not change the siren just to mess with you. That was a product of your perception. The sound waves, as the ambulance approached, were compressed, and they changed higher in pitch. As the ambulance receded, the sound waves were stretched, and they sounded lower in pitch. The same thing happens with light. Objects moving towards us, their light waves are compressed and they appear bluer. Objects moving away from us, their light waves are stretched, and they appear redder. So we call these effects blueshift and redshift.
在警报器靠近你之后 又远离你的过程中 它的声调似乎在改变 救护车司机不是为了 引起你的注意而改变声调的 而是你自身的感觉造成的 随着救护车的靠近 波长变短 所以声调变高 之后救护车远离我们,波长变长 所以听起来声调比较低 光线同样是如此 当物体靠近我们的时候 光波波长变得短,它们看起来更蓝 当物体远离我们的时候 波长变长,它们看起来更红 我们称此为光波的蓝移效应和红移效应
Now, our universe is expanding, so everything is moving away from everything else, and that means everything appears to be red. And oddly enough, as you look more deeply into the universe, more distant objects are moving away further and faster, so they appear more red. So if I come back to the Hubble Deep Field and we were to continue to peer deeply into the universe just using the Hubble, as we get to a certain distance away, everything becomes red, and that presents something of a problem. Eventually, we get so far away everything is shifted into the infrared and we can't see anything at all.
我们的宇宙在不断扩张 所以事物之间在彼此远离 这就意味着,在我们看来,所有的事物 都在向红移的方向发展 有趣的是,你越向宇宙深处看 远处的物体移动的就越快越远 他们看起来就越红 所以我们回到哈勃深空视场 通过哈勃望远镜 看向宇宙深处 我们看得越远 事物在我们的视线中就越红 这就出现问题了 实际上在更远处 所有的东西都转换成了红外线 我们根本什么都看不看到
So there must be a way around this. Otherwise, I'm limited in my journey. I wanted to explore the whole universe, not just whatever I can see, you know, before the redshift kicks in. There is a technique. It's called radio astronomy. Astronomers have been using this for decades. It's a fantastic technique. I show you the Parkes Radio Telescope, affectionately known as "The Dish." You may have seen the movie. And radio is really brilliant. It allows us to peer much more deeply. It doesn't get stopped by dust, so you can see everything in the universe, and redshift is less of a problem because we can build receivers that receive across a large band.
所以这个问题必须要解决 否则我就被困住了 在红移效应困扰我之前 我想探索的是全宇宙 并不只是我用肉眼看到的 我们有一项技术 叫做射电天文学 天文学家已经应用了十几年 这是个非常有趣的技术 这个是帕克斯射电望远镜 我们亲切的叫它“盘子” 你们也许看过这个电影 无线电简直棒极了 它让我们进一步探索宇宙 我们不用被那些尘埃遮挡视线了 所以你可以看到宇宙中的任何事物 红移效应的问题也不那么棘手了 因为我们有接收器 能够接受穿过岩石的射线
So what does Parkes see when we turn it to the center of the Milky Way? We should see something fantastic, right? Well, we do see something interesting. All that dust has gone. As I mentioned, radio goes straight through dust, so not a problem. But the view is very different. We can see that the center of the Milky Way is aglow, and this isn't starlight. This is a light called synchrotron radiation, and it's formed from electrons spiraling around cosmic magnetic fields. So the plane is aglow with this light. And we can also see strange tufts coming off of it, and objects which don't appear to line up with anything that we can see with our own eyes. But it's hard to really interpret this image, because as you can see, it's very low resolution. Radio waves have a wavelength that's long, and that makes their resolution poorer. This image is also black and white, so we don't really know what is the color of everything in here.
所以我们用帕克斯 看向宇宙中心的时候 能看到一些有趣的东西对吧 我们的确看到了一些有趣的东西 那些尘埃看不到了 就像我之前说的, 无线电穿过了尘埃,所以问题解决了 但是景象却变得不一样了 我们能看到银河的中心在闪烁 这些并不是星光 这种光叫做同步加速器辐射 来自宇宙磁场周围旋转的电子 所以这一平面里的光线就会闪烁 我们也能够看到奇怪的成团的东西 以及在我们肉眼看起来 分散、没有序列的东西 我很难分析这个图像 因为很明显,它的分辨率非常低 射电具有很长的波长 使其分辨率更低 而且这个图像还是黑白的 所以我们不知道那些景象 到底是什么颜色的
Well, fast-forward to today. We can build telescopes which can get over these problems. Now, I'm showing you here an image of the Murchison Radio Observatory, a fantastic place to build radio telescopes. It's flat, it's dry, and most importantly, it's radio quiet: no mobile phones, no Wi-Fi, nothing, just very, very radio quiet, so a perfect place to build a radio telescope. Now, the telescope that I've been working on for a few years is called the Murchison Widefield Array, and I'm going to show you a little time lapse of it being built. This is a group of undergraduate and postgraduate students located in Perth. We call them the Student Army, and they volunteered their time to build a radio telescope. There's no course credit for this. And they're putting together these radio dipoles. They just receive at low frequencies, a bit like your FM radio or your TV. And here we are deploying them across the desert. The final telescope covers 10 square kilometers of the Western Australian desert. And the interesting thing is, there's no moving parts. We just deploy these little antennas essentially on chicken mesh. It's fairly cheap. Cables take the signals from the antennas and bring them to central processing units. And it's the size of this telescope, the fact that we've built it over the entire desert that gives us a better resolution than Parkes.
快进到当下, 我们建造的望远镜 能克服这些问题了 这是来默奇森射电天文观测台的照片 这是一个建造射电望远镜的好地方 很平坦,很干燥 最重要的是,不受其他无线电的干扰 没有移动电话,没有无线网,什么都没有 十分十分清净 作为搭建射电望远镜的地方堪称完美 现在这个我已经使用好几年的望远镜 叫做默奇森广角阵列 这是它一点点建造的过程 这是一群在珀斯的大学本科生和 研究生 我们叫他们学生军 他们牺牲自己的时间来 建造这个射电望远镜 没有课程学分 这些学生把偶极子组装起来 它们能像调频收音机或者 电视一样接收低频信号 我们把它们建在了沙漠里 最后一部分占澳大利亚西部沙漠的 10平方公里 有趣的是,它们不能移动 我们把这些小天线 放在在六角形的网上 成本相当的低 天线上的电缆 接收信号 然后把信号传递给中央处理器 这样的望远镜遍布整个沙漠 它的占地面积使它在 处理问题能力的方面 比帕克斯的望远镜更好
Now, eventually all those cables bring them to a unit which sends it off to a supercomputer here in Perth, and that's where I come in.
所有的电缆最后汇成一股 把信息传递到珀斯的 一个超级计算机上 那就是我要工作的部分
(Sighs)
(叹气)
Radio data. I have spent the last five years working with very difficult, very interesting data that no one had really looked at before. I've spent a long time calibrating it, running millions of CPU hours on supercomputers and really trying to understand that data. And with this telescope, with this data, we've performed a survey of the entire southern sky, the GaLactic and Extragalactic All-sky MWA Survey, or GLEAM, as I call it. And I'm very excited. This survey is just about to be published, but it hasn't been shown yet, so you are literally the first people to see this southern survey of the entire sky. So I'm delighted to share with you some images from this survey.
研究无线电数据 过去五年的时间 我一直在研究这些困难却有趣 之前没有人了解过的数据 我在这个超级计算机上花了 数以百万计的CPU时数校对 并试图弄清楚这些数据 通过这套望远镜 这些数据 我们对整个南半球的 星空做了一番仔细观察 银河系及超银河系默奇森 广角阵列全天候研究 或者简称GLEAM 我非常兴奋 这个研究结果快要公之于世了 但是目前还没有 所以你们还算是第一批了解这些 关于南半球星空研究的人 我也很高兴分享给你们 研究中的部分图像
Now, imagine you went to the Murchison, you camped out underneath the stars and you looked towards the south. You saw the south's celestial pole, the galaxy rising. If I fade in the radio light, this is what we observe with our survey. You can see that the galactic plane is no longer dark with dust. It's alight with synchrotron radiation, and thousands of dots are in the sky. Our large Magellanic Cloud, our nearest galactic neighbor, is orange instead of its more familiar blue-white.
现在,请想象一下你们就在默奇森 在满天星斗下露营 你抬头仰望南部星空 看到了南极 看到银河在上升 如果我让射电光弱一点 就会看到我们研究中所观察到的景象 你会看到银河不再黑乎乎的充满尘埃 它被星空中数以千计的点点 和同步加速器辐射点亮 广袤的,靠近我们星系的麦哲伦云 其实是橘色的,而不是接近蓝白色的
So there's a lot going on in this. Let's take a closer look. If we look back towards the galactic center, where we originally saw the Parkes image that I showed you earlier, low resolution, black and white, and we fade to the GLEAM view, you can see the resolution has gone up by a factor of a hundred. We now have a color view of the sky, a technicolor view. Now, it's not a false color view. These are real radio colors. What I've done is I've colored the lowest frequencies red and the highest frequencies blue, and the middle ones green. And that gives us this rainbow view. And this isn't just false color. The colors in this image tell us about the physical processes going on in the universe. So for instance, if you look along the plane of the galaxy, it's alight with synchrotron, which is mostly reddish orange, but if we look very closely, we see little blue dots. Now, if we zoom in, these blue dots are ionized plasma around very bright stars, and what happens is that they block the red light, so they appear blue. And these can tell us about these star-forming regions in our galaxy. And we just see them immediately. We look at the galaxy, and the color tells us that they're there.
这里面有很多的东西值得研究 让我们放大看一下 如果我们想想看我刚刚给你们展示的 帕克森拍摄的银河中心的景象 低分辨率,黑白色的 然后再看GLEAM的图像 你们会发现这个分辨率提升了一百倍 我们看到的是充满色彩的星空 五彩斑斓 这些颜色并不是有偏差的颜色 他们是真正的无线电波发射出来的颜色 我们已经实现把低频率的显示成红色 把高频率的显示成蓝色 中间频率偏绿色 这就给我们呈现了五颜六色的景象 这些也不仅仅是伪色 这个图片里的颜色是在显示 宇宙中事物的物理过程 举个例子,如果你看向银河的一个平面 同步加速器使它变亮 呈现出带鲜红的橙色画面 但是我们仔细再看一下 我们会看到蓝色的点 现在,我们再放大 这些蓝色的点实际上就是离子化等离子体 它们在明亮的星体周围 并且挡住了红色光线 所以它们看起来是蓝色的 我们通过这些可以知道在我们银河中 形成星体的地方 并且一下子就能看出来 因为当我们望向宇宙 颜色就会告诉我们它们在那儿
You can see little soap bubbles, little circular images around the galactic plane, and these are supernova remnants. When a star explodes, its outer shell is cast off and it travels outward into space gathering up material, and it produces a little shell. It's been a long-standing mystery to astronomers where all the supernova remnants are. We know that there must be a lot of high-energy electrons in the plane to produce the synchrotron radiation that we see, and we think they're produced by supernova remnants, but there don't seem to be enough. Fortunately, GLEAM is really, really good at detecting supernova remnants, so we're hoping to have a new paper out on that soon.
你们还能在这一银河平面中看到 小的,肥皂泡一样的圆形图像 这些是超新星残余物 当一个星体爆炸的时候 它的外表壳就会被炸开 然后这颗星体会飘忽在宇宙中 聚合其他的物质 由此形成新的小的保护壳 对天文学家来讲 那些超新星残余物的去向 一直是一个神秘的过程 我们都知道在宇宙空间中 一定有许多高能电子 它们产生我们所看见的 同步加速器辐射 我们认为它们是由超新星残余物产生的 但是它们看起来好像还不是很多 幸运的是,GLEAM能够非常非常准确的 探测到超新星残余物 所以我们有望于 这一方面研究成果的产生
Now, that's fine. We've explored our little local universe, but I wanted to go deeper, I wanted to go further. I wanted to go beyond the Milky Way. Well, as it happens, we can see a very interesting object in the top right, and this is a local radio galaxy, Centaurus A. If we zoom in on this, we can see that there are two huge plumes going out into space. And if you look right in the center between those two plumes, you'll see a galaxy just like our own. It's a spiral. It has a dust lane. It's a normal galaxy. But these jets are only visible in the radio. If we looked in the visible, we wouldn't even know they were there, and they're thousands of times larger than the host galaxy.
好,我们再继续说 我们已经探索了我们的局部宇宙 但是我想更进一步的探索,深入研究 我想探索银河以外的宇宙 现在在图片的右上方我们能够看到 一个很有意思的东西 这是局部电波星系 半人马座A 如果我们放大来看 我们能够看到两片巨大的羽毛一样的东西 然后你们再看两片羽毛的中间 你会看到和一个我们银河很像的星系 它是螺旋状的,有一条尘埃带 就是一个普通的星系 但是这些星点只能在无线电中才能看到 如果我们用肉眼看的话 根本不知道它们在那里 他们比主星系还要大上千倍
What's going on? What's producing these jets? At the center of every galaxy that we know about is a supermassive black hole. Now, black holes are invisible. That's why they're called that. All you can see is the deflection of the light around them, and occasionally, when a star or a cloud of gas comes into their orbit, it is ripped apart by tidal forces, forming what we call an accretion disk. The accretion disk glows brightly in the x-rays, and huge magnetic fields can launch the material into space at nearly the speed of light. So these jets are visible in the radio and this is what we pick up in our survey.
那么发生了什么 这些星点是从哪里来的呢 我们都知道每个星系中心 都有一个超级大的黑洞 黑洞是不可见的 这就是为什么叫做黑洞 你们能看见的只有 它们周围改变轨迹的光线 当一颗星体或者一团星云进入其轨道 就会被潮汐力分裂 形成我们所说的吸积盘 吸积盘在X光下很明亮 并且巨大的磁场可以让物质 以光速进入宇宙空间 所以这些星点对无线电可见 这就是我们的研究成果
Well, very well, so we've seen one radio galaxy. That's nice. But if you just look at the top of that image, you'll see another radio galaxy. It's a little bit smaller, and that's just because it's further away. OK. Two radio galaxies. We can see this. This is fine. Well, what about all the other dots? Presumably those are just stars. They're not. They're all radio galaxies. Every single one of the dots in this image is a distant galaxy, millions to billions of light-years away with a supermassive black hole at its center pushing material into space at nearly the speed of light. It is mind-blowing. And this survey is even larger than what I've shown here. If we zoom out to the full extent of the survey, you can see I found 300,000 of these radio galaxies. So it's truly an epic journey. We've discovered all of these galaxies right back to the very first supermassive black holes. I'm very proud of this, and it will be published next week.
所以我们现在看到的是 一个电波星系,很不错 但是我们再看最上方 也有一个电波星系 这个就小一点了,因为离我们较远 好了,两个星系了 我们能够看到这样,很不错了 那么剩下那些点怎么办呢 你们可能会觉得那些就是星体 但你们错了 那些都是电波星系 每一个在这上面成点状的 都是一个遥远的星系 离我们数十亿光年远 这些星系的中心也是把物质以光速 甩进宇宙空间的黑洞 很令人兴奋 我展示的只是研究成果的冰山一角 如果我把整个研究成果都展示出来 你会看到30万个这样的无线电星系 的确是个费劲的活儿 我们对所有这些星系的 研究都追溯到了最早的超质量黑洞 我很为之自豪 下周研究成果就会公开
Now, that's not all. I've explored the furthest reaches of the galaxy with this survey, but there's something even more in this image. Now, I'll take you right back to the dawn of time. When the universe formed, it was a big bang, which left the universe as a sea of hydrogen, neutral hydrogen. And when the very first stars and galaxies switched on, they ionized that hydrogen. So the universe went from neutral to ionized. That imprinted a signal all around us. Everywhere, it pervades us, like the Force. Now, because that happened so long ago, the signal was redshifted, so now that signal is at very low frequencies. It's at the same frequency as my survey, but it's so faint. It's a billionth the size of any of the objects in my survey. So our telescope may not be quite sensitive enough to pick up this signal. However, there's a new radio telescope. So I can't have a starship, but I can hopefully have one of the biggest radio telescopes in the world. We're building the Square Kilometre Array, a new radio telescope, and it's going to be a thousand times bigger than the MWA, a thousand times more sensitive, and have an even better resolution. So we should find tens of millions of galaxies. And perhaps, deep in that signal, I will get to look upon the very first stars and galaxies switching on, the beginning of time itself.
这还不是全部 我已经探究了迄今为止宇宙的最深处 但在这幅图像之外还有很多信息 现在我们回顾一下时间伊始 宇宙形成之时经历了大爆炸 留下一片氢的汪洋 中性氢 当第一个星系形成的时候 它们把氢气电离了 所以宇宙从中性不带电 变成了电离的了 我们周围就产生了电信号 无形中像力一样渗透到了 我们周围 因为这是很长很长以前发生的事情了 现在那些信号已经红移了 所以是低频的 和我研究的是一样的频率 但是这频率太微弱了 是我们研究的物体频率的十亿分之一 所以我们的望远镜并不能很灵敏的 探索到这些信号 然而,又有了新的射电望远镜 所以虽然我不能乘坐宇宙飞船 但是我很高兴拥有 世界上最大的射电望远镜 我们正在建平方公里阵列射电望远镜 一个新的射电望远镜 比默契森广角阵列还大上千倍 灵敏上千倍,效果也更好 所以我们会发现数千万的星系 或许,再深入研究那些信号 我们会发现宇宙中形成的 第一颗星体和星系 以及时间诞生的那一刻
Thank you.
谢谢
(Applause)
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