So we have a number of questions from the internet that we would like to try and answer today.
One person asked, Why is the picture so blurry?
Well, that's an interesting question.
And the answer is that it's not blurry.
And the reason it's not blurry is because we've zoomed in so much, that we're at the
very limit of the resolving power of the telescope when we show that image.
In fact, that's the sharpest image that's ever been made by any technique.
But what was the biggest challenge in imaging a black hole?
Well, hey, this is a big question, because there were many big challenges in imaging
the black hole.
First, based upon the size of the black holes, and how far away they are, we knew that at
the wavelength we needed to use to image them, we would have to build a telescope that was
the size of the entire Earth.
So obviously, we couldn't build this Earth size telescope.
And so a bunch of scientists got together and figured out okay, how do we make a computational
telescope the size of the Earth?
And so this has been something that for over a decade, the collaboration has been building.
And so there's been a lot of technology that had to be developed to get over this hurdle
of how do we connect telescopes from around the world?
But then once we had collected this data, there were also a number of challenges.
How do we… one was how do we get the data, it's so much data?
And that in itself is a challenge.
And then how do we reduce it down to the get the measurements that we can use to make an
image?
And then the part that I was had a big focus on is how do we take those measurements and
make a picture?
And that in itself is also a challenge because if we had covered the globe, in telescopes,
if we had tiled the entire globe in telescopes, we would have the information we need to make
a picture.
But because we only have a small number of telescopes around, that means there's gaps
of missing information.
And so we had to come up with techniques to intelligently fill in those gaps.
And we had to do it in a way that we weren't biasing our picture, it was a big challenge
to make sure that what we were seeing in that image was real, and not just something that
we wanted to see.
So really every step of the way.
It was difficult from going to exotic places like the South Pole and gathering the data
and designing the systems that could take these data in such volumes.
And making the data robust and reliable.
All the way through to your imaging efforts.
It was I'm not sure that we can really identify which one is the most difficult.
We literally went to the ends of the earth to make the picture.
How much data is actually contained in that single image?
So that's an interesting question.
Because when we take the data at the telescopes, it's an enormous amount of data.
So much data that the disk drives on which the data are stored way several tunnels is
petabytes of data.
But the image itself, the picture that you've seen, is just 100 by 100 pixels.
It’s a tiny amount of data, what we're trying to do is distill, tease out the information
from this vast volume of data until we're left with the information that we really want,
which was a picture.
Yeah, I think one point to, to make sure we clarify is that just because you have a lot
of data doesn't mean there's a lot of information in that data, right?
So we collected petabytes of data, but it could be reduced to megabytes of measurements
that we then used to make a picture.
So although we had lots of data, we actually had a problem of not having enough information
to, on its own without the algorithms that we've developed to make that picture, and
so that's why they all it all works together.
One analogy might be like panning for gold, you may need to plan through hundreds of tons
of material to get just a little bit of gold.
Well, the raw data that we collect at the telescopes, is that tons and tons of material.
And the gold is the picture at the end.
What would it look like?
Or how would it feel like if someone crosses over the event horizon?
Well, it's not a wise thing to do.
But it actually depends, tremendous amount on how massive the black hole how big it is.
If it's a small one, somewhat paradoxically, the tidal forces as you get close to the event
horizon would be so strong, that it would get very uncomfortable very quickly, and you
would soon start to resemble toothpaste and you may or may not go over the event horizon
before that happens with a really massive black hole, like M87.
The tidal forces are very small, at the event horizon, so you would cross over the event
horizon.
And you really wouldn't feel anything, the only thing that you would notice is that your
view of the rest of the universe would start to fade away.
Is the color true to what would be observed at a fixed distance away?
Actually, no.
The color that we used is just a, we just used that color, so you can easily see what
the black hole looks like.
And actually, the wavelength that we used to see the black hole is longer than what
red wavelengths are.
So these are longer radio wavelengths.
So we actually can't see what color it would be.
It's not a visible wavelength.
And so we use the color to-- pseudo color basically-- to help show different contrasts
and different features in the image.
And also to give you the impression that it's hot, because this, this around the black hole
of hundreds of billions of degrees, it's incredibly hot.
And that's what allows it to glow brightly like that.
But really, we could have used any color.
And we played around with different colors.
And when we were deciding what color to use, we showed it in blue and purple, and in grayscale
as well.
And we thought that it was it came across best and most accurately in the orange and
red color scheme that we used.
And it seems like everybody liked it!
Hopefully!
What's next? will you be imaging the center of the Milky Way galaxy so
So there are two primary targets for the Event Horizon telescope.
One is that black hole that we showed you a picture of the black hole in the center
of the M87 galaxy 55 million light years away.
And the one is called Sagittarius A star which is at the center of our own Milky Way galaxy.
So those are the two that we think that with the resolution of an earth size telescope
that we would be able to see.
But these are actually very different black holes.
So because of their size, the M87 black hole because it is 6.5 billion solar masses, that
means that it's so big that gas is not moving around that fast.
And so over the course of a night, we can assume that the measurements that we take
are all coming from the same picture of the black hole, it's essentially you can think
of it as a static black hole within the course of the night.
However, it's a very different case for the black hole in the center of our Milky Way.
So this is a because it's a much smaller black hole.
That means that gas is zipping around it incredibly fast.
And depending on how fast the black hole is spinning, you can make a full orbiter matter
every four to 30 minutes.
And so that means that as we are watching the black hole and getting measurements over
the course of the night that we use to make these pictures, it's evolved drastically.
And so in order to make an image of our are Milky Way's black hole, we have to consider
oh, not just what image are we seeing, but what video are we seeing over the course of
a night?
So Colin were asked: Are there plans to get more detailed images of black holes?
Yes, absolutely.
And there's various ways that we can do that.
We want to get more resolution, more magnification to see more details as these black holes.
And there's two ways to do that.
One is to take the radio frequency that we're using, which is 230 gigahertz, that's 1.3
millimeter wave, and go to even higher frequencies, even shorter wavelengths.
That gives you more resolution, more sharpness.
The other way is to go to a telescope that has an extent that's even larger than the
Earth and only way to do that is supposed to go into space.
There are indeed plans to do both of these things.
And if we do both of them together, then the resolution it builds upon both of the these
mechanisms.
The more resolution we can get the better.
There's lots of very fine scale structure that is predicted to be in these black hole
images that we can't yet see.
But we're certainly going after it.
Yeah, I think one thing is, you know, this image is really just the beginning.
You know, we now we have shown that there is this extreme laboratory where we can use
this instrument to basically study to study gravity and, and black holes.
And we can go back and refine our instrument and improve it, both the instrument and the
algorithms to see more.
And I think that that's really…
Another way that we can improve the image besides just making the image sharper, we
can also make the image so that we can see fainter things on the picture.
And there's really interesting things that are expected to be happening around that black
hole that we currently can't see in the image that was just produced.
If someone is interested in pursuing research in the area… in this area, what advice would
you give to them?
Well, first, I think that we need lots of people working on this.
This project really required an international collaboration of people with different backgrounds
to come together to make this result.
So we're happy to recruit you, you know, and come to the project and work on it.
But one thing is, yeah, if you're interested in working on this, I think, follow your passion
first.
Because I think that whenever you work on things that you are curious about that you're
passionate about, you do the best work.
And so that's I think a number one.
Number two is, you know, work hard in school, study the fundamentals, math, you know, science,
you know, all these, these skills are things that you actually do use.
And I know that even classes I took in college that I thought I'd never use again, I'm using
all the time now in this project.
And so you never know when they're going to crop up.
And you know, but even so, doing research is so different than doing homework.
You know, there's a it's a different level, it's not just you don't know that there's
a correct answer all the time.
And so, you know, don't get discouraged with homework too, because creativity, along with
this knowledge is learned through school, I think is so important in order to do this
these projects and to to think about what we can do in the future.
I think so.
Continue, I think with that spark.
And be curious all the time.
Yes.
This has been great.
Thank you for all the questions, great questions, and we certainly had fun answering them.
One thing that's really stunned us is how popular this result has been how much attention
had gotten.
And we've been delighted today to be able to answer just a few of the millions of questions
that must be out there.