What the discovery of gravitatio
00:13
1.3 billion years ago, in a distant,distant galaxy, two black holes locked into a spiral, falling inexorably towards each other and collided, converting three Suns' worth of stuff into pure energy in a tenth of a second. For that brief moment in time, the glow was brighter than all the stars in all the galaxies in all of the known Universe.It was a very big bang.
1. spiral /ˈspaɪrəl/ n
a shape or design, consisting of a continuous curved line that winds around a central point, with each curve further away from the centre2.inexorably /ɪnˈeksərəbli/ ad
in a way that cannot be stopped or changed（想到The Big Band Theory~)
00:51
But they didn't release their energy in light. I mean, you know, they're black holes. All that energy was pumped into the fabric of space and time itself, making the Universe explode in gravitational waves.
3. the fabric of space and time
fabric /æ/ n
1>material made by weaving wool, cotton, silk, etc., used for making clothes, curtains, etc. and for covering furniture
2>the fabric (of something) (formal) the basic structure of a society, an organization, etc. that enables it to function successfully
eg:a trend which threatens the very fabric of society
01:06
Let me give you a sense of the time scale at work here. 1.3 billion years ago, Earth had just managed to evolve multicellular life. Since then, Earth has made and evolved corals, fish,plants, dinosaurs, people and even -- God save us -- the Internet. And about 25 years ago, a particularly audacious set of people -- Rai Weiss at MIT, KipThorne and Ronald Drever at Caltech -- decided that it would be really neat to build a giant laser detector with which to search for the gravitational waves from things like colliding black holes.
4. multicellular /ˌmʌltiˈseljələ(r)/ a （cellular）
5.audacious /ɔːˈdeɪʃəs/ a willing to take risks or to do something that shocks people
eg:an audacious decision
01:47
Now, most people thought they were nuts.But enough people realized that they were brilliant nuts that the US National Science Foundation decided to fund their crazy idea. So after decades of development, construction and imagination and a breath taking amount of hardwork, they built their detector, called LIGO: The Laser Interferometer Gravitational-Wave Observatory.
6. interferometer /ˌɪntəfɪəˈrɒmɪtə/ n 干涉仪
02:17
For the last several years, LIGO's been undergoing a huge expansion in its accuracy, a tremendous improvement in its detection ability. It's now called Advanced LIGO as a result.
02:28
In early September of 2015, LIGO turned on for a final test run while they sorted out a few lingering details. And on September 14 of 2015, just days after the detector had gone live, the gravitational waves from those colliding black holes passed through the Earth. And they passed through you and me. And they passed through the detector.
7. turn on
1>to attack somebody suddenly and unexpectedly
eg:The dogs suddenly turned on each other.
2> depend on
eg:Much turns on the outcome of the current peace talks.
3> have sth as its main topic
eg:The discussion turned on the need to raise standards.
02:59
(Audio) Scott Hughes: There's two momentsin my life more emotionally intense than that. One is the birth of my daughter.The other is when I had to say goodbye to my father when he was terminally ill.You know, it was the payoff of my career, basically. Everything I'd beenworking on -- it's no longer science fiction! (Laughs)
03:22
Allan Adams: So that's my very good friend and collaborator, Scott Hughes, a theoretical physicist at MIT, who has been studying gravitational waves from black holes and the signals that they could impart on observatories like LIGO, for the past 23 years.
03:37
So let me take a moment to tell you what I mean by a gravitational wave. A gravitational wave is a ripple in the shape of space and time. As the wave passes by, it stretches space and everything in it in one direction, and compresses it in the other. This has led to countless instructors of general relativity doing a really silly dance to demonstrate in their classes on general relativity. "It stretches and expands, itstretches and expands."
04:08
So the trouble with gravitational waves is that they're very weak; they're preposterously weak. For example, the waves that hit us on September 14 -- and yes, every single one of you stretched and compressed under the action of that wave -- when the waves hit, they stretched the average person by one part in 10 to the 21. That's a decimal place, 20 zeroes, and a one. That's why everyone thought the LIGO people were nuts. Even with a laser detector five kilometers long -- and that's already crazy -- they would have to measure the length of those detectors to less than one thousandth of the radius of the nucleus of an atom. And that's preposterous.
8. preposterous /prɪˈpɒstərəs/ a
completely unreasonable, especially in a way that shocks or annoys you
eg: These claims are absolutely preposterous!9. decimal /ˈdesɪml/ a based on or counted in tens or tenths （十进制）
10. radius /ˈreɪdiəs/ n a straight line between the centre of a circle and any point on its outer edge; the length of this line半径
11. nucleus /ˈnjuːkliəs/ n (physics) the part of an atom that contains most of its mass and that carries a positive electric charge 原子，细胞核
proton /ˈprəʊtɒn/ 质子
neutron /ˈnjuːtrɒn/ 中子
04:57
So towards the end of his classic text on gravity, LIGO co-founder Kip Thorne described the hunt for gravitational waves as follows: He said, "The technical difficulties to be surmounted in constructing such detectors are enormous. But physicists are ingenious, and with the support of a broad lay public, all obstacles will surely be overcome." Thorne published that in 1973, 42 years before he succeeded.
12. surmount /səˈmaʊnt/ v to deal successfully with a difficulty
eg:There are several obstacles to be surmounted.13. ingenious /ɪnˈdʒiːniəs/ a (of an object, a plan, an idea, etc.) very suitable for a particular purpose and resulting from clever new ideas 精巧/新颖的
eg:an ingenious device/invention/experiment
ingenious ways of saving energy14. lay public （下图解释三）
05:35
Now, coming back to LIGO, Scott likes to say that LIGO acts like an ear more than it does like an eye. I want to explain what that means. Visible light has a wavelength, a size, that's much smaller than the things around you, the features on people's faces, the size of your cell phone. And that's really useful, because it lets you make an image or a map of the things around you, by looking at the light coming from different spots in the scene about you.
此段和下段，解释光波与声波的不同，为了引出引力波
06:02
Sound is different. Audible sound has a wavelength that can be up to 50 feet long. And that makes it really difficult-- in fact, in practical purposes, impossible -- to make an image of something you really care about. Your child's face. Instead, we use sound to listen for features like pitch and tone and rhythm and volume to infer a story behind the sounds. That's Alice talking. That's Bob interrupting. Silly Bob.
15. pitch /pɪtʃ/ 音高
1> n area of ground specially prepared and marked for playing a sports game
2>how high or low a sound is, especially a musical note
3> [U] the degree or strength of a feeling or activity; the highest point of something
eg: Speculation has reached such a pitch that a decision will have to be made immediately.16. tone /təʊn/ 音质/音色
1>the quality of somebody’s voice, especially expressing a particular emotion
2> [singular] the general character and attitude of something such as a piece of writing, or the atmosphere of an event
eg: She set the tone for the meeting with a firm statement of company policy.17. rhythm /ˈrɪðəm/ 节奏/韵律
a strong regular repeated pattern of sounds or movements
eg: Lack of sleep can upset your daily rhythm.18. volume /ˈvɒljuːm/ the amount of something 音量/响度
19. infer /ɪnˈfɜː(r)/ v
to reach an opinion or decide that something is true on the 1> basis of information that is available
eg: It is reasonable to infer that the government knew about these deals.
2> to suggest indirectly that something is true
eg:Are you inferring (that) I’m not capable of doing the job?
06:34
So, the same is true of gravitational waves. We can't use them to make simple images of things out in the Universe.But by listening to changes in the amplitude and frequency of those waves, we can hear the story that those waves are telling. And at least for LIGO, the frequencies that it can hear are in the audio band. So if we convert the wave patterns into pressure waves and air, into sound, we can literally hear the Universe speaking to us. For example, listening to gravity, just in this way,can tell us a lot about the collision of two black holes, something my colleague Scott has spent an awful lot of time thinking about.
20. amplitude /ˈæmplɪtjuːd/ n
the greatest distance that a wave, especially a sound or radio wave, vibrates (= moves up and down) 振幅
07:18
(Audio) SH: If the two black holes are non-spinning, you get a very simple chirp: whoop! If the two bodies are spinning very rapidly, I have that same chirp, but with a modulation on top of it, so it kind of goes: whir, whir, whir! It's sort of the vocabulary of spin imprinted on this wave form.
21. chirp /tʃɜːp/ n
a short high sound made by small birds and some insects
eg: the chirp of birds/crickets22. modulation /ˌmɑːdʒəˈleɪʃn/ n 调频/变调/
1> the act of changing the quality of your voice in order to create a particular effect by making it louder, softer, lower, etc.
eg: Her vocal modulation was most impressive.
2> (music) a change from one musical key (= set of notes) to another
eg: the harmony and modulations of JS Bach
3> (specialist) the act of changing the rate at which a sound wave or radio signal vibrates (= the frequency) so that it is clearer
eg: Radio transmission employs deliberate modulation of a complex audio signal.
4> (specialist) the act of influencing something by changing or controlling it
eg: This effect indicates long-lasting modulation of neural activity.
（3和4都有种，好像知道，也好像不知道在讲什么，的感觉 ==）23. whir /wɜː(r)/ v
to make a continuous, low sound like the parts of a machine moving
eg: Three large fans whirred overhead in the afternoon heat. // The clock began to whir before striking the hour.24. imprint
1> to have a great effect on something so that it cannot be forgotten, changed, etc.eg: imprint A in/on B The terrible scenes were indelibly imprinted on his mind.
imprint B with A His work is imprinted with his own personal style.
2> to print or press a mark or design onto a surface
eg: imprint A in/on B Their footprints were imprinted in the snow.
imprint B with A clothes imprinted with the logos of sports teams*indelible /ɪnˈdɛləbl/ a
impossible to forget or remove
eg: The experience made an indelible impression on me.
07:35
AA: So on September 14, 2015, a date that's definitely going to live in my memory, LIGO heard this:
07:44
[Whirring sound]
07:47
So if you know how to listen, that is the sound of --
07:52
(Audio) SH: ... two black holes, each of about 30 solar masses, that were whirling around at a rate comparable to what goes on in your blender.
25. mass / mæs/ n
1> a large amount of a substance that does not have a definite shape or form
eg： The hill appeared as a black mass in the distance.
a mass of something = masses of sth
a mass of snow and rocks falling down the mountain ； The sky was full of dark masses of clouds.
2> the masses [plural] the ordinary people in society who are not leaders or who are considered to be not very well educated
eg: the image of America with arms open wide to the world's huddled masses
3> (specialist) the quantity of material that something contains
eg: calculating the mass of a planet*huddle /ˈhʌdl/ v
1> [Vi] huddle (up/together) (+ adv./prep.) (of people or animals) to gather closely together, usually because of cold or fear
eg: People huddled up close to each other.*befuddle /bɪˈfʌdl/ v confuse
befuddled a =confused* 生活大爆炸联想：(E05E18)
Howard: And at some opint during the night, an armadillo crawled in and spooned me.
1> armadillo /ˌɑːməˈdɪləʊ/ an American animal with a hard shell made of pieces of bone
犰狳（读音：qiú yú），又称“铠鼠”。犰狳是生活在中美和南美热带森林、草原、半荒漠及温暖的平地和森林的一种濒危物种。 犰狳区别于其他动物的最明显特征是它的一副鳞状铠甲。就是因为这副甲胄，它被西班牙征服者冠以“披甲猪”之称。
2> spoon /spuːn/ v lie together
(of two people) to lie with their bodies against each other, facing the same direction; to lie against someone with your body facing in the same direction as theirs:
eg: "I saw them spooning on the beach," she added, rather wistfully.
*wistful sad and thinking about something that is impossible or in the past:
08:00
AA: It's worth pausing here to think about what that means. Two black holes, the densest thing in the Universe, one with a mass of 29 Suns and one with a mass of 36 Suns, whirling around each other 100 times per second before they collide. Just imagine the power of that. It's fantastic. And we know it because we heard it.
26. dense
1> difficult to see through (thick)
eg: fog/smoke/fumes/crowd/forest/population
2> stupid
eg: There are some really dense people in our class.
3> (specialist) heavy in relation to its size
eg: All that is left of the star is a small, dense core.
Less dense substances move upwards to form a crust.27. whirl /wɜːl/ v
1> to move, or make somebody/something move, around quickly in a circle or in a particular direction
eg: They ducked to avoid the whirling blades of the helicopter.
2> [Vi] if your mind, thoughts, etc. whirl, you feel confused and excited and cannot think clearly("23" whir /wɜː(r)/ to make a continuous, low sound like the parts of a machine moving eg: Three large fans whirred overhead in the afternoon heat. )
*density /ˈdensəti/ n
(physics) how thick a solid, liquid or gas is, measured by its mass per unit of volume* crust /krʌst/ n
a hard layer or surface, especially above or around something soft or liquid*duck v
to move your head or body downwards to avoid being hit or seen
duck (down) (behind/under something)
eg: We ducked down behind the wall so they wouldn't see us.
08:24
That's the lasting importance of LIGO. It's an entirely new way to observe the Universe that we've never had before. It's a way that lets us hear the Universe and hear the invisible.
08:40
And there's a lot out there that we can't see -- in practice or even in principle. So supernova, for example: I would love to know why very massive stars explode in supernovae. They're very useful; we've learned a lot about the Universe from them. The problem is, all the interesting physics happens in the core, and the core is hidden behind thousands of kilometers of iron and carbon and silicon. We'll never see through it, it's opaque to light. Gravitational waves go through iron as if it were glass -- totally transparent. The Big Bang: I would love to be able to explore the first few moments of the Universe, but we'll never see them, because the Big Bang itself is obscured by its own afterglow. With gravitational waves, we should be able to see all the way back to the beginning. Perhaps most importantly, I'm positive that there are things out there that we've never seen that we may never be able to see and that we haven't even imagined -- things that we'll only discover by listening.
28. supernova /ˈsuːpənəʊvə/ n 超新星
a star that has exploded, strongly increasing its brightness for a few months
nova /ˈnəʊ.və/ 新星(短期内突然变得很亮);
a type of star that shines much more brightly for a few months as a result of a nuclear explosion29
1> opaque: preventing light from travelling through, and therefore not transparent
sys: impentrable; oppo:transparent/translucent
/trænˈsluː.sənt/ almost transparent
2> thick
3> dense30. obcure /əbˈskjʊə(r)/
1> not well known / unknown
2> difficult to understand
09:44
And in fact, even in that very first event,LIGO found things that we didn't expect. Here's my colleague and one of the key members of the LIGO collaboration, Matt Evans, my colleague at MIT, addressing exactly that:
09:57
(Audio) Matt Evans: The kinds of stars which produce the black holes that we observed here are the dinosaurs of the Universe. They're these massive things that are old, from prehistoric times,and the black holes are kind of like the dinosaur bones with which we do this archeology. So it lets us really get a whole nother angle on what's out therein the Universe and how the stars came to be, and in the end, of course, how we came to be out of this whole mess.
31. archeology /ˌɑːkiˈɒlədʒi/ or archaeology
the study of cultures of the past, and of periods of history by examining the parts of buildings and objects found in the ground32. nother /ˈnʌðə(r)/ aanother
eg: nother thing just occurred to me.
10:23
AA: Our challenge now is to be as audacious as possible. Thanks to LIGO, we know how to build exquisite detectors that can listen to the Universe, to the rustle and the chirp of the cosmos. Our job is to dream up and build new observatories -- a whole new generation of observatories -- on the ground, in space. I mean, what could be more glorious than listening to the Big Bang itself? Our job now is to dream big. Dream withus.
33. rustle /ˈrʌsl/ v
if something dry and light rustles or you rustle it, it makes a sound like paper, leaves, etc. moving or rubbing together
eg: the sound of the trees rustling in the breeze/ Her silk dress rustled as she moved.* "见21"chirp /tʃɜːp/ n a short high sound made by small birds and some insects eg: the chirp of birds/crickets
34. exquisite /ɪkˈskwɪzɪt/ or /ˈekskwɪzɪt/
1> extremely beautiful or carefully made
2> (formal) (of a feeling) strongly felt =acute
eg: ~ pain/pleasure
3> (formal) very sensitive
eg: The room was decorated in exquisite taste.
10:53
Thank you.
