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  • When we look up we see moons, planets, asteroids, pulsars, star clusters, nebulae, stars as

  • big as whole solar systems, and millions of galaxies -- you know what we don't see?

  • Black holes.

  • Because no one has ever seen a black hole.

  • Black holes are deep, dark, swirling sinkholes of collapsed matter.

  • That gravitational whirlwind that consumes everything and crushes it.

  • That place where not even light can escape...

  • Except...THIS isn't a black hole.

  • This is an artist's idea of what a black hole might look like, or more precisely, the

  • light around it - called the Event Horizon.

  • Think about t.v. shows and movies like stargate SG-1, Lost In Space, Star Trek..The Black

  • Hole, and most famously Interstellar.

  • They all have images of black holes, but no one has ever actually photographed one.

  • So, how close are we to taking a picture of a black hole?

  • Taking a picture of a black hole is expensive, difficult, and takes a lot of smart people's

  • time.

  • You've probably never even thought about what a black hole looks like, because you

  • thoughtthis is what a black hole looks like!”

  • But it's not.

  • So, why are scientists so desperate to see one?

  • Why does it matter?

  • First.

  • Science.

  • Second.

  • Black holes are incredible, and right now, artists and filmmakers build conceptions based

  • on what scientists tell them is important, but we don't know if these are right...

  • these pictures are based on math...not in reality.

  • We've known about Black holes since the early days of Einstein's theories, but until

  • we actually see one, there's a part of us that doesn't want to believe that they're

  • real.

  • This actually all started with that famous equation: E = mc2.

  • But math can only get us so far...I mean, we knew Pluto was out there since the early

  • 1900's, and our best guesses told us it was a boring icy ball.

  • Until we flew by it in 2016, and actually saw it.

  • Imagine how we'll feel when we see a black hole with our jelly-filled light buckets.

  • And this is what scientists are going to use to snap a photo of a black hole.

  • The event horizon telescope.

  • It's not just one telescope, it's a network of many all over the planet.

  • This effectively creates a single telescope as big as the Earth.

  • The bigger the telescope, the more detail they can see, and the further away.

  • Which we definitely need to take the image of a something like this black hole...Meet

  • Sagittarius-A Star.

  • Sag A-Star is at the center of our galaxy.

  • It's thousands of light-years away.

  • There's a second object that we're also very interested in and that is the black hole in

  • the center of the galaxy, M87, also known as Virgo A...

  • M87 is an elliptical galaxy that's located about 17 megaparsecs away, so about 15 million

  • light-years away.

  • That'd be like trying to photograph an orange on the surface of the moon from the earth

  • or trying to pick out individual molecules in a piece of paper in front of you.

  • And they do this with a whole array of radio telescopes spread around the world... not

  • the kind you look through.

  • They use radio wavelengths instead of visible wavelengths...

  • It's a process called interferometry.

  • Interferometry is a general technique to take the signals from two separate receiving systems,

  • in this case telescopes and interfering the signals with each other.

  • The word interferometry is the combination of interfere -- and meter or to measure.

  • They're measuring a pattern of interference of the radio waves entering the telescope.

  • By analyzing the interference pattern, the data from the telescopes can be merged together,

  • and images can be filtered from all the noise.

  • These astronomers are using Very Long Baseline Interferometry (VBLI), meaning the radio telescopes

  • are far apart but are working together, .Which brings us to April of 2017, when these astronomers

  • pointed their telescopic array at the black holes in Sagittarius-A Star and in M8716 for

  • 5 nights.

  • So, doesn't that mean we took the picture?

  • no.

  • We didn't.

  • We took the data.We're now starting to process the data into a picture.

  • Part of the difficulty of reconstructing an image is that we don't have all the data

  • that we need.

  • The cosmic signals that we are interested are very weak.

  • most of what we are recording is from the receiver and is noise the data that we interested

  • in is roughly 1 millionth of all that data.

  • It is definitely a lot of astronomy and it is a lot of computer science as well... so

  • We're talking about hundred of terabytes of data per station.

  • add it all together and it's Petabytes.

  • A petabyte of data is 1,000 Terabytes.

  • That's a lot.

  • That's 3,900 of the largest iphones.

  • It's so much that they can't even upload it.

  • It's physical.

  • On hard drives.

  • All that data has to be shipped to processing centers from telescopes around the world --including

  • at the South Pole, which has extreme weather... so, the scientists have to wait months to

  • even receive that data.

  • There are two sites working on the data.

  • The Max Planck Institute for Radio Astronomy in Bonn, Germany and here at the MIT's Haystack

  • Observatory outside Boston.

  • Once the data is all in one place, the scientists have to correlate it.

  • It's like watching a 3D movie but where each eye is seeing something different.

  • The scientists need to match them up with timing that's more precise than atomic clocks

  • on the GPS satellites.

  • One of the possibilities is that this year's data won't be sufficient to provide a good

  • image, but with the addition of next year, we will.

  • Again, again we won't know until we actually are at that point in the analysis.

  • With any luck, we'll see the first image of a black hole in 2018.

  • If we can gather enough data, correlate it, and analyze it to find the image of something

  • thousands or millions of light years away.

  • If.

  • Then what will we see?

  • The accretion flow will probably look more or less like a crescent.

  • That's because we're not viewing the accretion flow face-on.

  • We're not quite viewing it edge-on but closer to edge-on.

  • So, We really don't know what we will see, was einstein correct? we won't know until

  • we see the image.

  • If we produce a really nice picture, people will say, "Wow, so that's what a black hole

  • looks like.

  • That's cool."

  • So we are pretty close to seeing our first photographs of a black hole.

  • If not in 2018, then maybe 2019.

  • What do you think Astronomers will learn?

  • What Will it look like?

  • Do you think it's gonna be different than what we thought?

  • Let us know

  • and thanks for watching Seeker.

When we look up we see moons, planets, asteroids, pulsars, star clusters, nebulae, stars as

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ブラックホールの撮影にどれだけ近いのか? (How Close Are We to Photographing a Black Hole?)

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    fang に公開 2021 年 01 月 14 日
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