Placeholder Image

字幕表 動画を再生する

  • When I was a kid, I was afraid of the dark.

  • The darkness is where the monsters are.

  • And I had this little night light outside of my bedroom

  • so that it would never get too dark.

  • But over time, my fear of the dark turned to curiosity.

  • What is out there in the "dark-dark?"

  • And it turns out

  • that trying to understand the darkness is something that's fascinated humans

  • for thousands of years, maybe forever.

  • And we know this

  • because we find their ancient relics of their attempts to map the sky.

  • This tusk is over 30,000 years old.

  • Some people think that it's a carving of Orion

  • or maybe a calendar.

  • We don't know.

  • The Fuxi star map is over 6,000 years old,

  • and it's from a neolithic tomb in ancient China.

  • And that little pile of clamshells

  • underneath the dead guy's foot in the middle --

  • that's supposed to be the Big Dipper.

  • Maybe.

  • The Nebra disk is uncontroversial.

  • You don't have to be an astronomer to know that you're looking at the Moon phases

  • or the Sun in eclipse.

  • And that little group of seven stars, that's the Pleiades, the Seven Sisters.

  • But in any case, the point is clear:

  • astronomers have been mapping the sky for a long time.

  • Why?

  • It's our calling card as a species in the galaxy

  • to figure things out.

  • We know our planet,

  • we cure our diseases,

  • we cook our food,

  • we leave our planet.

  • But it's not easy.

  • Understanding the universe is battle.

  • It is unrelenting, it is time-varying,

  • and it is one we are all in together.

  • It is a battle in the darkness against the darkness.

  • Which is why Orion has weapons.

  • In any case, if you're going to engage in this battle,

  • you need to know the battlefield.

  • So at its core,

  • mapping the sky involves three essential elements.

  • You've got objects that are giving off light,

  • you've got telescopes that are collecting that light,

  • and you've got instruments

  • that are helping you understand what that light is.

  • Many of you have mapped the Moon phases over time

  • with your eyes, your eyes being your more basic telescope.

  • And you've understood what that means with your brains,

  • your brains being one of your more basic instruments.

  • Now, if you and a buddy get together,

  • you would spend over 30 years,

  • you would map 1,000 stars extremely precisely.

  • You would move the front line to the battle.

  • And that's what Tycho Brahe and his buddy, or his assistant, really,

  • Johannes Kepler did back in the 1600s.

  • And they moved the line,

  • figured out how planets worked,

  • how they moved around the Sun.

  • But it wasn't until about 100 years ago

  • that we realized

  • it's a big universe.

  • It seems like the universe is just infinite, which it is,

  • but the observable universe is finite.

  • Which means we can win the battle.

  • But if you're going to map the universe,

  • you're not going to do it with one or two of your besties.

  • Mapping the universe takes an army,

  • an army of curious, creative, craftspeople

  • who, working together, can accomplish the extraordinary.

  • I lead this army of creatives,

  • in the fifth generation of the Sloan Digital Sky Survey, SDSS.

  • And this is how astronomers have managed to shepherd individual curiosity

  • through its industrial age,

  • preserving the individual ability to make discoveries

  • but putting into place mega machinery to truly advance the frontier.

  • In SDSS, we divide the sky into three mappers:

  • one for the stars, one for the black holes

  • and one for the galaxies.

  • My survey has two hemispheres,

  • five telescopes, or 11, depending on how you count,

  • 10 spectrographs

  • and millions of objects.

  • It's a monster.

  • So let's go through the mappers.

  • The Milky Way galaxy has 250 billion plus or minus a few hundred billion stars.

  • That is not a number that you hold in your head.

  • That is a number that doesn't make practical sense

  • to pretty much anybody.

  • You never get 250 billion jelly beans in your hand. You know?

  • We're nowhere near mapping all of those stars yet.

  • So we have to choose the most interesting ones.

  • In SDSS-V, we're mapping six million stars

  • where we think we can measure their age.

  • Because if you can measure the age of a star,

  • that's like having six million clocks spread all throughout the Milky Way.

  • And with that information,

  • we can unravel the history and fossil record of our galaxy

  • and learn how it formed.

  • I'm just going to cut right to the chase here.

  • Black holes are among the most perplexing objects in the universe.

  • Why?

  • Because they are literally just math incarnate, in a physical form,

  • that we barely understand.

  • It's like the number zero being animated and walking around the corridors here.

  • That would be super weird.

  • These are weirder.

  • And it's not just like a basketball

  • that you smoosh down into a little point and it's super dense and that's weird.

  • No, smooshed basketballs have a surface.

  • These things don't have surfaces, and we know that now.

  • Because we've seen it.

  • Or the lack of it.

  • What's really interesting about black holes

  • is that we can learn a lot about them by studying the material

  • just as it passes through that point of no information return.

  • Because at that point,

  • it's emitting lots of X-rays and optical and UV and radio waves.

  • We can actually learn how these objects grow.

  • And in SDSS, we're looking at over half a million supermassive black holes,

  • to try to understand how they formed.

  • Like I said,

  • we live in the Milky Way, you guys are all familiar with that.

  • The Milky Way is a completely average galaxy.

  • Nothing funny going on.

  • But it's ours, which is great.

  • We think that the Milky Way, and all the Milky Ways,

  • have this really disturbing past

  • of literally blowing themselves apart.

  • It's like every average guy you know

  • has a history as a punk rock teenager.

  • That's very bizarre.

  • Stars are blowing up in these systems,

  • black holes are growing at their centers

  • and emitting a tremendous amount of energy.

  • How does that happen, how does this transformation happen?

  • And at SDSS, we're going to the bellies of the beast

  • and zooming way in,

  • to look at these processes where they are occurring

  • in order to understand how Sid Vicious grows up into Ward Cleaver.

  • My arsenal.

  • These are my two big telescopes.

  • The Apache Point Observatory hosts the Sloan telescope in New Mexico,

  • and the Las Campanas Observatory in Chile

  • hosts the two-and-a-half-meter telescope, the du Pont.

  • Two and a half meters is the size of our mirror,

  • which was huge for Tycho and Kepler.

  • But it's actually not so big today.

  • There are way bigger telescopes out there.

  • But in SDSS we use new instruments on these old telescopes

  • to make them interesting.

  • We capture light from all of those objects into our aperture,

  • and that light is then focused at the focal plane,

  • where our instruments sit and process that light.

  • What's new in SDSS-V

  • is that we're making the focal plane entirely robotic.

  • That's right: robots.

  • (Laughter)

  • So I'm going to show them to you,

  • but they're fierce and terrifying,

  • and I want you all to just take a breath.

  • (Exhales) Trigger warning.

  • And with no apologies to all the Blade Runners among you,

  • here they are.

  • (Laughter)

  • I have 1,000 of these,

  • 500 in the focal plane of each telescope in each hemisphere.

  • And this is how they move on the sky.

  • So these are our objects and a star field,

  • so you've got stars, galaxies, black holes.

  • And our robots move to those objects as we pass over them

  • in order to capture the light

  • from those stars and galaxies and black holes, and yes,

  • it is weird to capture black hole light,

  • but we've already gone over that black holes are weird.

  • One more thing.

  • Stars are exploding all the time,

  • like this one did back in 1987 in our cosmic backyard.

  • Black holes are growing all the time.

  • There is a new sky every night.

  • Which means we can't just map the sky one time.

  • We have to map the sky multiple times.

  • So in SDSS-V, we're going back to each part of the sky multiple times

  • in order to see how these objects change over time.

  • Because those changes in time encode the physics,

  • and they encode how these objects are growing and changing.

  • Mow the sky.

  • OK, let me just recap.

  • Global survey, two hemispheres,

  • five telescopes, 10 spectrographs, millions of objects, mow the sky,

  • creative army, robots, yeah.

  • So you're thinking, "Wow.

  • She must have this industrial machine going,

  • no room for the individual, curious, lone wolf genius," right?

  • And you'd be 100 percent wrong.

  • Meet Hanny's Voorwerp.

  • Hanny van Arkel was a Dutch schoolteacher

  • who was analyzing the public versions of the SDSS data,

  • when she found this incredibly rare type of object,

  • which is now a subject of major study.

  • She was able to do this

  • because SDSS, since its beginning and by mandate from the Sloan Foundation,

  • has made its data both publicly available

  • and usable to a broad range of audiences.

  • She's a citizen -- yeah, clap for that.

  • Clap for that.

  • (Applause)

  • Hanny is a citizen scientist,

  • or as I like to call them,

  • "citizen warriors."

  • And she shows that you don't have to be a fancy astrophysicist to participate.

  • You just have to be curious.

  • A few years ago,

  • my four-year-old asked, "Can moons have moons?"

  • And I set about to answer this question

  • because even though many four-year-olds over all of time

  • have probably asked this question,

  • many experts, including myself, didn't know the answer.

  • These are the moons in our solar system that can host hypothetical submoons.

  • And that just goes to show you that there are so many basic questions

  • left to be understood.

  • And this brings me to the most important point about SDSS.

  • Because, yeah, the stars, the galaxies, the black holes, the robots --

  • that's all super cool.

  • But the coolest thing of all

  • is that eensy-weensy creatures on a rubble pile

  • around a totally average star in a totally average galaxy

  • can win the battle to understand their world.

  • Every dot in this video is a galaxy.

  • Every dot.

  • (Cheers) (Applause)

  • I'm showing here the number of galaxies

  • that astronomers have mapped in large surveys since about 1980.

  • You can see SDSS kick in around Y2K.

  • If we stay on this line,

  • we will map every large galaxy in the observable universe by 2060.

  • Think about that.

  • Think about it: we've gone from arranging clamshells

  • to general relativity to SDSS in a few thousand years --

  • and if we hang on 40 more,

  • we can map all the galaxies.

  • But we have to stay on the line.

  • Will that be our choice?

  • There are dark forces in this world

  • that will rob our entire species of our right to understand our universe.

  • Don't be afraid of the dark.

  • Fight back.

  • Join us.

  • Thank you.

  • (Applause)

When I was a kid, I was afraid of the dark.

字幕と単語

B1 中級

【TED】The most detailed map of galaxies, black holes and stars ever made | Juna Kollmeier

  • 61 1
    林宜悉   に公開 2019 年 07 月 10 日
動画の中の単語