(bright music) - Hi, everyone, and welcome to "Conversations at the Perimeter." I'm Lauren Hayward here with Colin Hunter. - Hello. - Today we're excited to share with you our discussion with Dustin Lang. Dustin is a computational scientist here at Perimeter Institute who specializes in astrophysical data sets, which means he works on software solutions that help researchers study some of the biggest open questions in our universe.
- And my mind really reeled when Dustin described the enormous quantities of data involved in these projects that he and his colleagues are working on. It's literally astronomical amounts of data that he and his colleagues have to sift through looking for these faint signatures of phenomena that are incredibly far away. - And they're far away both in space and in time.
Dustin tells us about his work with an international project called DESI, which is building maps of the universe to look back over its history and gain insight into dark energy. And he explains the Canadian CHIME Project as well, which is searching for mysterious fast radio bursts from deep in the cosmos. - Dustin tells us too about his work in both optical astronomy and radio astronomy, which are more different than I had realized.
He also tells us about the important roles played by chicken wire and a metaphorical sad trombone. Whomp-whomp. It's a really fascinating chat. So let's step inside the Perimeter with Dustin Lang. Dustin, thank you for being here at "Conversations at the Perimeter." - Oh, my pleasure. - We've been looking forward to talking to you for a number of reasons.
There's much that we want to explore with you, including a number of acronyms of projects that you're working on that have to do with deep space and distant explosions and everything else. But before we get to that, you're a computer, No- - Computational scientist. - Computational scientist.
So first I wanna get into what that means, but I want to do so by saying that a couple years ago I interviewed you for a story and you joke that when the job posting for a computational scientist came online at Perimeter Institute, that your friends basically said "This job was written for you Dustin, you have to get this job," because it blended big data analysis and astrophysics. So can you tell us what do you do as a computational scientist? - Sure. So I have a kind of unusual job here.
I'm half in the IT department helping other researchers make use of computing and half a researcher myself. So I work on astronomical surveys, surveys that go out and measure big chunks of sky, often without preconceived notions of what we're going to find in order to kind of make new discoveries. - And when you talk about big chunks of sky, like how big are we talking here?
- In the one project we are looking at basically all of the sky we can see from the Northern hemisphere except for the parts that are filled with the Milky Way galaxy. We care about things that are beyond the Milky Way for this particular project so the Milky Way gets in the way. There are too many stars in our own galaxy to see the stuff behind it. - We're getting in our own way, in our own galaxy? - Pretty much.
And then you can't see the southern part of the sky because there's too much dirt in the way. (Colin laughs) - So you're looking basically everywhere you can look. - Pretty much. - And why is a computational scientist essential to doing this work? - So my degree was in computer science.
I kind of picked up physics on the job (both laugh) and a lot of physicists are in the opposite position where they know the physics and they're suddenly faced with ever-growing data sets and there's just a real challenge to process some of them. So having people with expertise in both is kinda key to making some of the advancements that we want to do in this kinda to push the next generation of understanding of the universe.
- Would you say that astronomy and cosmology is an area in particular where researchers with expertise in how to do these computations is really necessary? - Lots of areas of physics are pushing computational boundaries. I know that our data rates, for example, aren't anywhere near what you would encounter at CERN, at the Large Hadron Collider, but we're probably in the ballpark.
I know that we use a Department Of Energy supercomputer for one of my jobs and my group uses basically the second or third largest user of the whole center, which has like 1,000s of users. So we're kind of up there I guess in terms of data rates. - Is there so much data because the universe is so enormous and you're looking at so much of it? - Pretty much.
- Like when we see images from telescopes, we see billions of stars and billions of galaxies, is essentially all of that stuff out there in the universe is data that needs to be crunched? - Yep. Exactly. Basically the sky is big at the scales that you can see from the ground and that kind of sets the basic scale of the problem. So with the largest camera we have right now, it still takes 1,000s of images to cover the entire sky.
And we want not just one image but multiple images to understand not only what's going on at any instant, but trying to understand some of the changes with time. - So some of the work that you've done has been with DESI. That's one of the acronyms that we'll be bringing up today. I like that one 'cause it's a nice name but it stands for more than just a nice name. Can you tell us what DESI is and what it's for? - Sure, so DESI stands for the Dark Energy Spectroscopic Instrument.
So this is an instrument, it's a device that is sitting at the top of a telescope in Arizona. Instruments on these telescopes can be either cameras or spectrographs for the most part. Cameras, most people are pretty familiar with. Spectrographs are a little bit different. This one is called a multi-object spectrograph. So basically we can observe many galaxies at once and break their light into spectra or rainbows and take precise measurements of like the brightness at each point in the rainbow.
So the innovation with DESI is that it can take many more at once than previous generations of instruments. It can observe 5,000 stars or galaxies every exposure. It's really cool. - That's like- - Part of the- - One camera taking, well sorry, it's not a camera, it's a spectograph. But one instrument taking 5,000 observations all at the same time. - Yeah, that's right. So this is the real innovation of this instrument.
So to give you a kind of a context, the previous generation could take 1,000 at once. That was the Sloan Digital Sky Survey. And that project is also cool. But basically in these projects you have to choose ahead of time which objects you're going to observe because how they work is you stick a fiber optic cable and point it directly at each object that you wanna observe. The light comes from your galaxy down the fiber optic cable to a spectrograph that actually splits it into the rainbow.
So then the challenge is, you know, how do you point 1,000 little fiber optics at once and- - How do you point one at once let alone 1,000 or 5,000? - Well so, and the other challenge is you have to like, the fibers are like this kind of the size of a human hair and you have to point them to finer than that precision. - At galaxies that are- - Yeah, exactly. - Billions of gajillions of miles- - And your telescope weighs many tons. So the thing like it's really, the engineering is really amazing.
- How do you do it? It's not a person with tweezers, right? (both laugh) - Right, well... - Or is it? - In the Sloan Digital Sky Survey, what they did was they chose which galaxies they want to observe ahead of time. They compute where they'll appear on the sky. Oh, you have to choose a set of nights that you're going to observe it on and a time within that night.
And given that, you can predict where they're going to be, they take an aluminum plate, drill little precision holes in the plate, 1,000 holes for 1,000 galaxies. Ship those plates to the mountain and then a crew of people, by hand, plug in fiber optic cables into each of those holes. - Wow. That's not how I imagine this would happen. - Yeah, exactly, it doesn't sound very high tech. - Right.
- So during the night they would go out and plug one of these plates into the telescope and that plate steers the light. You know, the fibers are in just the right place to steer the light down those fibers to be collected in the spectrographs and make those measurements of 1,000 galaxies at once. Let me say just for a second, 'cause I was talking about the hand-plugged fibers in SDSS.
When DESI was being designed or proposed, one of the challenges was scaling up from 1,000 to 5,000, doing that by hand just started to get like to be infeasible. So the way that DESI instrument operates is really cool. It uses these little robots, so 5,000 of them and each of them has two little motors that allow it to rotate the fiber to any place within its little region. So it's sort of like your shoulder and elbow joints.
One of the motors moves the shoulder or like rotates the shoulder in a circle and the other can rotate the elbow in a circle. So between that, they can position the fiber anywhere within their reach and then they're placed close enough together that they can just reach their, or like they have a little bit of overlap with their neighbor.
So no matter where a star or galaxy lands on the focal plane of the instrument, at least one of them can reach it with its fiber and it holds out its fiber and the light pours down and goes into our spectrographs. So another innovation of DESI was that in the previous generation, the spectrographs were bolted to the side of the telescope and they flopped around during the night and were subject to the surrounding temperature.
So for DESI, what we do instead is the spectrographs are put in a nice climate-controlled cleanroom, but then we have to get the light from the top of the telescope down through the telescope. It has moving parts of course. So there's a 50 meter run of fiber, 5,000 fibers that goes down to this cleanroom. So 500 fibers each plug into these spectrographs, there's 10 of them.
And the fibers come in in a big stack, like they're lined up in a big stack and then their light shines onto a prism, basically, that splits their light into a rainbow. And then that rainbow lands on like a sensor, a CCD sensor, like a camera basically. So what you see in the images are 500 like rows of rainbows. But of course they're not, these sensors themselves are monochrome, like they only, they're just measured black and white.
So you see kind of a brighter or fainter line, 500 of those spaced together across the chip. So brighter spots are places in the spectrum that are brighter. So during the afternoon we use these calibration sources. So like you know, you can shine light of a known wavelength and measure where it appears in the images. So you can say, oh that little bump is red 540 nanometers and this little bump is some other wavelength.
The thing that's kind of amazing looking at the raw data though, is that all of them look the same basically. And that's because the sky is pretty bright, (chuckles) even the night sky at the darkest times is actually the thing that we detect most strongly in the images. So it's only by subtracting out the contribution of the sky that we get to see the stars and galaxies in kind. It's not an easy way to live.
(both laugh) - And once all that information is collected from those 1,000 or 5,000 points, does it then go to you to figure out, or you and your team, to then do all of the computational work to understand it? - Yeah, other people on my teams. (chuckles) My work on DESI comes earlier actually. I've been involved in, remember I said you have to choose ahead of time which things you want to observe, which we do from images. So first you go out and take an image of the sky.
in our case in like three different filters or three colors, and you measure all the stars and galaxies and measure their brightnesses and colors and choose some set of them that are interesting for follow up. We get to choose about 1% of them. So when we started DESI, there was no imaging survey that existed that was deep enough to make those measurements, right.
We wanted to measure things that were faint enough that they just didn't appear in the existing generation of imaging surveys so we had to go out and do those imaging surveys. So that's the part that I was kind of most mostly involved with. - And I'm hoping you can tell us a little bit more about this idea you referred to as splitting up the electromagnetic spectrum.
So the electromagnetic spectrum is quite wide and only a small portion of it is visible and then you also do some splitting up within that visible piece. Can you just tell us a little bit more about that and how different telescopes focus on different parts of the spectrum?
- Sure. I call myself mostly an optical astronomer, which means I work in more or less the visible part of the spectrum, which then also now bleeds into the infrared a little bit because you can use the same technologies to do that, to observe light that we can't quite observe. So different telescopes tend to be optimized for observing different parts of the spectrum. Partly from the ground, only parts of the spectrum actually make it through our atmosphere.
If you go very much bluer than we can see with our eyes, that atmosphere just blocks everything. Just the air absorbs all of that light. As you go toward the infrared, water is actually one of the annoyances. So water vapor in the atmosphere also emits at those same frequencies, so... - You don't often hear water called an annoyance. It's also essential for life on planet. - Some people enjoy it. Yeah. (all laughing) - It has its pros and cons. - Right. As long as it would just-
- Stay outta the way. - Stay outta the upper atmosphere or just the couple of cubic kilometers around our telescopes, that would be great. And then if you go further into the infrared, that is just heat and then it's really hard to observe something faint in the sky when like your telescope and your mirrors are all glowing, which is basically what happens in the infrared.
And then so there's a big chunk of the infrared that we can't reach, which is why people launch things into space to observe in that frequency range. So JWST for example, and a telescope I really love, the Wide-Field Infrared Survey Explorer, WISE, also a NASA mission, and they go to space because basically you can't observe or it's very, very difficult to observe that from the ground.
My advisor did a bunch of infrared observing as part of his PhD and spent many, many nights on some of the biggest telescopes in the world in order to make these measurements, despite the fact that your telescope is glowing at those frequencies. And he said the Spitzer Space Telescope, one of the first infrared missions, totally made obsolete all of his observations within its first second of observation. (laughs) - Wow. - Like it's really good to observe when the sky is dark, basically.
It's not easy, basically, observing during the daytime. I mean basically, the atmosphere sets what we can do from the ground and sets what we can do with telescopes. And then there's another atmospheric window, we call it in the radio. So I think we'll come back to that later. - Mm-hmm, DESI is called the Dark Energy Spectroscopic Instrument. You've told us a bit about the spectroscopic part. What is the dark energy aspect of this experiment? - (laughs) Dark energy. - (laughs) Big subject?
- Pretty big subject, yep. Dark energy is one of the real mysteries in astrophysics these days, or cosmology. To explain that, go right back to the beginning, to the Big Bang. Around 100 years ago, the observation was made by Hubble that if you look at galaxies, you can measure whether they're moving towards us or away from us. And Hubble observed that all the galaxies are moving away from us. And not only that, the ones that are further away are moving away faster.
So that tells you basically that the universe is expanding, which then kind of leads you to the idea that, oh, in the past it must have been smaller. What's the end point of that? Is all of the universe being in a very small place and they're being kind of a big bang that makes it expand out from there. So if you just imagine there's a big bang, everything starts expanding away from everything else and then gravity is trying to pull it back together.
You might think there're kind of three possibilities there. So one would be like the Big Bang gives it a kick, it expands and then gravity starts pulling it back together. And then gravity is strong enough to pull everything back together and everything collapses again and there's a big crunch. Option two is there's a big bang, gravity is trying to pull everything back together and it's just not quite strong enough to pull everything back together.
But everything kind of stops or slowly drifts down to zero speed. - So it's expanding but it's slowing down. - Yeah. - Until it reaches an equilibrium and stays there? - Maybe, it's pretty hard to hit a perfect balance like that. So then the third option is the big bang kick is big enough that gravity can't pull it back together. It tries, but as you get further apart, gravity gets weaker.
So then it's sort of, you hit a constant drift rate where everything's drifting further apart at a constant speed, basically. The mystery of dark energy, which was discovered in the '90s is that there's a different thing going on. Not only the drifting apart at a constant speed, it's drifting apart and there's an acceleration that's pushing it faster than that. It's like not only was there the big bang, there's something else that's continuing to give it a kick.
So there's something that we don't know what it is and things that we don't know what they are in astronomy, we call them dark. So we've got dark matter, we've got dark energy, we dunno what they are. And it's just making the size of the universe accelerate, like grow larger and speed up right in its growth. And it's a basically a mystery of what it is.
When Einstein first wrote down the equations for general relativity that there is a term in those equations that Einstein put in to keep the universe stable, to keep the universe from collapsing again 'cause Einstein wanted the universe to be able to be stable. And then with Hubble's findings, Einstein called that his greatest blunder.
But then it turns out that that same factor, that same constant in the equations, if you make it negative, it gives you dark energy, it explains dark energy or like at least appears in the equations. That doesn't really help us to understand what it physically is. Is it something that we can ever interact with in any kind of real way or is it just like a fact of the way space and the universe works?
There are lots of ideas about what dark energy is or how it could work and with DESI we're basically just trying to go out and make the measurements and those measurements will help to disentangle or to tell the difference between different models of what dark energy might be. So the goal of DESI is to measure the size of the universe at different times in the past.
So basically we're trying to chart that growth of the size of the universe over time and different models of what dark energy will predict, different shapes of that curve of how fast the universe grows over time. So by just going out and making the measurement, we should be able to kind of tell the difference between different models of dark energy and help to rule out some possible explanations.
- When you mention over time, you don't mean you do an observation one week and then the next week and the next week, you mean over like cosmic time, right? You're essentially looking back at where galaxies were billions of years ago versus where they were, I dunno, another amount of billion years ago. Is that generally fair? - Yeah, that's exactly right. - And how can you tell how fast they're moving?
Or if you know were they at one point and another point, then you know the speed of acceleration? - So like you said, on human time-scales, basically the extra-galactic universe is static. We can see the stars moving, they don't move very much. But with precision instruments you can tell that they're moving. But the galaxies more or less are stationary on the skies to the precisions that we can measure. Distances in cosmology are really complicated.
(both laugh) It's hard to just talk about the distances between things when the whole fabric that they're sitting on is growing. So distances in cosmology are complicated. So the two things we can really measure are angles on the sky and redshifts. So redshifts, lots of people have heard explained before, but basically the light from the galaxy, if you break it into a rainbow has a certain signature. And what we observe is not that signature as we'd expect to see it, but that signature shifted.
It's sort of like the Doppler effect when you know, when you hear the train goes from moving towards you, from moving away from you, the whistle shifts from higher to lower. So if you're talking about light, lower is redder toward the red. So what we observe is all the galaxies signatures are shifted toward the red by different amounts. So they're redshifted by different amounts. And that observation from Hubble was that galaxies that are more distant are more shifted to the red.
So that's one thing we can actually measure, redshifts, and that's what DESI's real thing is. The other is angles on the sky. Another thing that DESI is very good at doing, because we have to know where the galaxies are to actually observe them. So the thing that lets us tie those two things together and measure the scale of the universe over time is this nice little feature that the universe gave us.
A little bit after the Big Bang the universe was this, we kinda call it a hot soup I guess, of plasma and photons. Basically, everything's so hot that there aren't atoms. There's basically just a big roil of plasma and light and it's all exchanging energy and it wasn't uniformly spread. There were kind of denser and less dense spots. And that soup kind of allows things like sound waves to propagate. So if you have like a dense spot, you get a ring that comes out from it.
And then there's a magical point 380,000 years after the Big Bang where the universe has grown and cooled enough that plasma can cool down and you can form atoms. It's not a soup anymore. The photons kind of get liberated and are allowed to escape. But those rings of over densities are frozen-in at that point. - They're sort of imprinted for good? - That's right. They're imprinted for good. We can see them by observing the light from that time.
That light is now really redshifted into the microwave and we can see it in all directions. And it's called the cosmic microwave background. It's currently three degrees above absolute zero. So it's at three Calvin.
- It's chilly. - Yep. (laughs) And it looks like it's three degrees in all directions, but if you make very, very precise measurements, you see that there are little variations above and below that three degrees, 1 part in 10,000 where you can just see the places that were brighter and colder, more dense and less dense at that time. And the parts that were more dense, remember our good old friend gravity, pulls all of that matter together to form stars and galaxies.
So that little ring that was frozen-in at that point has stuck around. So what we get to observe is that if you look at a single galaxy, galaxies aren't spread uniformly on the sky, they cluster. Around a galaxy, you're likely to find other galaxies nearby and then they sort of drop off in density around the galaxy. But then at the radius of that ring, there's a little bump where you're a little bit more likely to find another galaxy. It's about 1% more likely.
It's a little bit of a subtle signal. The universe is very kind to give us anything but it's- - You may not wanna place money on it being there all the time 1% off. - Well by building DESI, we've placed a lot of money on on it being there. But the beautiful thing about it is that that scale was frozen-in, there's kind of nothing you can do to it to change what that scale is. So it just basically gets stretched along with the fabric of the universe or the fabric of spacetime.
So what we can do, finally, with DESI is measure the angular scale of that feature at different redshifts. - Right. - Whew. (Colin laughs) Remember when I said distances in cosmology are complicated? - Yes. Yeah. - It's a long way to go from- - It's not how we think of, you know, driving distances. This is, it's a very different sense of distance. - Or just taking out a ruler or something.
- (laughs) Well, so this is called a standard ruler because it's a thing that we think we know the physical size of and then we measure what angular scale on the sky it fills at different times. If you think about this in your everyday life, you take a ruler and you serve it at arms length, it fills a certain angle, right? If you move it twice as far away, it fills half the angle and so on.
So the weird thing about cosmology is that that doesn't hold because the universe was growing while all of this was going on. That angular diameter distance, it's called, it's one of many different kinds of distances in astronomy, angular diameter distance, gets smaller as things get further away, but then it turns over and actually gets bigger again. Things that are very distant are actually bigger in the sky.
You know, with DESI we get to kind of chart out this angular size of a ruler of a known size. - And have you personally been one of the people who pokes tiny holes in aluminum and feeds fiber optic cables through them? Have you been there on the site doing this kind of work? - So it's embarrassing. I'm like an expert on some of these telescopes that I've never been to and the Sloan telescope is one of them. I've still not managed to get to that site.
So in these projects, they're large projects, they have 100s of people involved, usually, dozens of institutions. So we do complicated time tracking to keep track of like who has actually contributed and I'm a, what am I? I'm an architect in the SDSS project but I still haven't managed to go to the telescope. It looks nice. (Colin laughs) I have seen the machine shop in the University of Washington where they drill the holes but that's not quite as glamorous.
- You were telling us before that a lot of your work was in this pre-analysis stage to decide where the instrument should be pointed. What are you doing now that that pre-analysis, I guess, is finished? - It's funny being involved in these projects from the early part because our work was mostly done by the time the instrument was on the mountain mounted on the telescope, taking observations.
Because we're trying to measure these really subtle signals where there's like a 1% more galaxies at a certain radius than you'd expect. It's pretty important to understand not only the ones you observe but the ones you don't observe. So we go to a lot of effort to track all of the effects, all of the statistical effects that can cause us to not observe a galaxy or observe more galaxies on a certain part of sky than uniform.
For that reason, to make the bookkeeping easier, basically, these projects usually freeze the sample like we choose the set of galaxies we want to observe at the start of the project and then hold that fixed. Like just proceed with that plan for the next five years in the case of DESI. Our work had to be done before the main survey started. So one of the things I'm doing is figuring out what we should do with DESI next.
It was funded for a five-year mission or five-year survey, but at the end of that time it's still gonna be the, or at least one of the best instruments in the world for this work. So we're currently kind of trying to devise some plans of what to do with it next, which is kind of a combination of an interesting science case and a feasible set of galaxies to observe. And part of that might involve going out and doing more imaging.
- Are you confident that the mystery of dark energy can be solved or maybe will be solved through some of these efforts and the ones that will follow? - That is a fascinating question. - I know it requires some optimism and you don't have all the information but there's a lot of progress being made it seems. - Yeah, it's one of the big mysteries in cosmology so we're putting in a fair bit of effort toward it.
The thing that is a challenge is that all of the current observations point to it, are consistent with it being kind of the simplest explanation, which is kind of that cosmological constant that Einstein's equations allow. So everything so far is consistent with kind of the most boring explanation, which is still like mind boggling and really difficult to understand or like to have a a real like intuitive sense for.
We don't really have an explanation for it, it's just kind of like, it's just a fact of how space behaves. That there's this weird fluid kind of thing that pushes space apart (laughs) and when you push space apart you make more space and then there's more of that stuff in it that's pushing it apart more. It's pretty noodle-bending. - Yeah. I was gonna say.
(both laugh) Yeah, I saw it described sort of like: if you had a balloon, just a normal party balloon and you squeezed it, the analog would be the balloon would just keep collapsing even after, it wouldn't resume it's original shape. But in this case, no matter what you do to the universe, it seems to be accelerating and getting bigger. - Yeah, I guess with DESI it's possible for us to make this next generation of measurements of like how big the universe is over time.
So for some of us that is good enough the fact that it's there and we can do it. And those measurements then kind of push theorists toward coming up with different explanations or refining their explanations. A lot of cosmology ends up being this kind of back and forth between theory and observation and computation and simulation. So basically this is just our next step on the observational side is to make the measurements and see what the theorists can do with it.
- And you mentioned observational astronomy being more of your bread and butter than radio astronomy, but you're also involved in radio astronomy. And until you told us this couple days ago when we were chatting, I never really made the distinction in my head that there's two different, or at least two different, could you tell us sort of the difference and then maybe tell us how you work in radio astronomy as well?
- Yeah, it's funny, astronomy is not that big of a scientific field, but we're still split into these silos and part of it is just basically technologies. The trick with observational astronomy is focusing and capturing the light and the tools you need to do that depend on the kind of light you're trying to gather. So for optical astronomy, the wavelengths are really short. So if you wanna make a mirror that focuses that light, it has to be ground really precisely.
It takes years to make an astronomical mirror. And when new projects get funded, that's often the first thing they do is book a spot in the mirror lab to get their mirror built and polished because that will take as long as the rest of the project put together. - 'Cause even if there's a tiny little defect in the mirror it could ruin everything right? - As long as the whole thing is basically the right shape, you can get away with small parts of it being imperfect.
But if the whole thing is the wrong shape, then you're just in a world of hurt. So when Hubble was originally launched, it had this issue and that just means that you want all of the light that comes from a distant point to bounce off your mirror and hit the sensor at the same place. And if your mirror's the wrong shape, that doesn't happen.
If your mirror is too rough, then that also doesn't happen because the wave's hitting different parts of the mirror instead of adding together, interfere with each other and subtract. So in optical astronomy the mirrors have to be just beautiful. In radio astronomy, the wavelengths are really long. So in CHIME, this experiment that I'm involved with, the radio waves are like 40 centimeters long.
So if you wanna make something that looks like smooth to a radio wave that's 40 centimeters long, it doesn't have to be very smooth. You know, it has to be like within millimeters kind of smooth. So radio telescopes, the mirrors or reflectors tend to be really cheap compared to everything else. In CHIME they're made outta a kinda metal mesh. But then the challenge is collecting that light and processing it. So radio astronomy's often kinda thought of as chicken wire and supercomputers.
- I love it. - I do too. - So I love how you say that radio astronomy is basically chicken wire and supercomputers. What really is the role of the chicken wire? - The chicken wire is the mirror or the equivalent of the mirror. I'm kind of by training an optical astronomer so it's really bizarre to be working in radio astronomy where the light acts so differently than what we're used to.
But as far as a radio wave is concerned, a parabolic-shaped mesh of wire looks like a mirror and it can focus it so it bounces right off the chicken wire. And if your chicken wire's shaped in just the right way, it can focus it onto a place like onto, in the case of CHIME, onto the antennas. So the half-pipe shape is a parabola, so it focuses all of the light coming from one point on the sky to a point onto the antenna. - You mentioned CHIME, we should explain a little bit.
It's not like any telescope I've seen before and when I first saw it, I don't know if I would've guessed telescope, I might have guessed skateboard park. So can you tell us what CHIME is and why it's like the it is? - Yeah, CHIME is wonderful. CHIME is the Canadian Hydrogen Intensity Mapping Experiment. You can see why you just use the acronym? And it's a radio telescope at the Dominion Radio Astrophysical Observatory near Penticton, British Columbia. So it's a really unusual telescope design.
It doesn't focus light in two dimensions, it only focuses light in one dimension. So it's made out of these parabola-shaped, like half-pipe-shaped tubes. So it focuses light in the direction across the tube but not the direction along the tube.
So if you have light coming from a distant galaxy, say, it hits the reflector and it's focused onto a line along the middle of that half-pipe and then CHIME has a bunch of antennas along that line that gather all the light and then it goes into our handy supercomputer. - Behind the chicken wire? (both laugh) - That's a- - That's a different part? - That's a different challenge, so... - Yeah, we'll get to that.
- Yep. And so the cool thing about that is that you can focus in that other dimension after the fact in the supercomputer. So if you think about a star that's to the north of the telescope, it will hit the northern part of the half-pipe sooner than the southern part and all those waves will bounce up to the antennas along that line.
In the supercomputer, then take the northernmost telescope, sorry, northernmost antenna and then take that value, the antenna just to the south of it, and delay it a little bit and add them together and take the one just to the south of that and delay it a little bit more. You can add together the waves that hit the telescope at different times and that basically like acts as though you tilted the telescope by that amount so that they would hit at the same time.
- 'Cause the telescope itself, it doesn't have moving parts. - Yeah, the telescope is huge. It's 20 meters wide. And sorry, each half-pipe is 20 meters wide. There are four of them and it's 100 meters long and it's heavy and huge. Yeah, so it has no moving parts. We can't steer it in any direction. It basically just sees a strip of the sky and then the Earth conveniently rotates. So we get to see basically half of the sky or two-thirds of the sky every day. - That's handy.
Nice of the Earth to do that for you. - It's pretty kind. - Yeah. - But the cool thing then is that you know, we can by more or less delaying the signal from the different antennas and adding them together, it acts like a telescope is pointed in a certain direction but then if you just delay it by a different amount, you can point it in another direction. - And this is all done by software? - Yeah, that's right.
It's all done in software and you can do it all at this, you can point it in all of those directions at the same time. And then with the four half-pipes you can combine those in different ways and point it in-software in the other, in the east-west direction as well. - And this is not dark energy search, this is a different or is it related? - It is related.
So the CHIME telescope was built for doing this thing called hydrogen intensity mapping, the HIM part of CHIME, And the idea there is that as you go further away or farther back in cosmic time or to higher redshift, it gets harder and harder to observe galaxies 'cause they're just faint.
So doing this trick that we do in DESI of trying to measure galaxies and then measure the slightly more likely to observe one at that magical distance away, that trick just gets really hard 'cause the galaxies are faint. And the thing that's kind of frustrating about it is that you're gonna measure a bunch of them, but you know that they cluster and like you have to measure a whole bunch of them to kind of map out this cosmic web.
So the idea with hydrogen intensity mapping is let's not measure individual galaxies, let's just measure all of the hydrogen collectively. And that hydrogen is around all the galaxies and along the cosmic web and filaments and everything so that to understand the growth of the universe over time. So CHIME was built to do that experiment and they're trying to map range of redshifts that slightly overlap DESI, but go further than we can really go with galaxies.
So it's looking back closer toward the Big Bang with this totally different technique of mapping hydrogen which emits in the radio and then gets stretched out. So I'm not actually involved in that side of it, the cosmology side, the hydrogen intensity mapping side. And this is another kind of cool thing about radio telescopes. While CHIME was being kind of proposed and built and designed, people realized that it would also be really well-suited to uncovering another astrophysical mystery.
The mystery of fast radio bursts. So fast radio bursts were first discovered in 2007. (both laugh) - That's recent, that's not that long ago in- - Yep, exactly. And they were discovered in archival observations or rather the first one was discovered in archival observations and what fast radio bursts are or what we observe are these really brief, they're like a millisecond long, burst of radio light. That's the (laughs) quick, they're fast, they're in the radio, they're bursts.
- Oh, it's a good name for them. Yeah. - Yep, and in the time between the first one discovered in 2007 and when CHIME was being constructed, a few more had been discovered. So they were getting to be not a one-off event but something that kinda existed in the universe that we could possibly go out and try to measure a bunch of.
So the fact that CHIME can see a huge chunk of the sky at once and observes the whole sky once a day thanks to the Earth rotating makes it a really good instrument for searching over the whole sky for something that you don't know where it's gonna come from. So funding was secured to build an addition to the CHIME's telescope, which was just a fast radio burst search part of CHIME. So it's called CHIME/FRB. So remember how I said in software you can focus the telescope at different directions.
Basically we ask that supercomputer to do some different computations and send the data to the CHIME/FRB system, which is itself another little supercomputer that does this real-time search for fast radio bursts. So all over the sky. - When you say a real-time search all over the sky, is this where the big data comes in? Lots and lots of data? - Yeah, that's right.
So the CHIME correlator, that's the, well one of the supercomputers involved in this whole thing, focuses the light in 1,000 spots in the sky for us and breaks it into 16,000 frequency channels. So you know when you're tuning the radio and you can choose different FM stations, we have 16,000 stations to choose from. Some of them are just full of people's cell phone LTE traffic. (both laugh) Thankfully we can just ignore those ones. Everyone has a radio station they don't like, right?
- Yeah. Just tune them out. - Yep. Just skip those ones. - But how many of them are taken up by the cell phone? - More and more. - It's a noisy world with all the communication? - It is a noisy world. Yeah, that's right. We lose 10 or 20%. It's pretty bad. - But it's kind of a consistent range? - For the most part. The 4G LTE bands are just lost to us entirely. (chuckles) And then there's some other ones that come on and off periodically that we have to filter out.
So anyway, the correlator sends us 1,000 places on the sky, 16,000 channels, and the brightness in each channel one time per millisecond. - Okay. - So that's 1,000 times 1,000 times 16,000 per second. And that is basically just too fast for us. It's too much data for us to write to disc. So those signals get sent to this set of 128 computers that are searching through the data in real-time looking for the signature of a fast radio burst.
So I said that they're a burst, but they're a burst at their origin but then they have to travel through a bunch of space to get to us and space isn't quite empty. So when those radio waves interact with electrons, what happens is the high frequencies arrive first and the lower frequencies arrive later. It's called dispersion. So what we observe is that there's kind of a sweep down from high frequency to low frequency that can be tens of seconds long or like a minute long.
So this real-time search has to store like a minute of data and look for kind of all the possible different sweeps down depending on how many electrons were between us and the source that determines the shape of that sweep. So it's searching for all these different sweeps corresponding to kind of different distances of the fast radio burst being away from us for these 1,000 places on the sky simultaneously.
And then basically, if we find something that looks interesting we write down just the data around that place on the sky and that little chunk of time for later analysis. - So in those cases you'll save everything that's coming in, but most of the time you'll just get rid of most of the data? - Yeah, that's right.
So we'll save everything that comes to the CHIME fast radio burst side that's been reduced a lot already from the raw data rate collected by the first supercomputer in the chain for things that are really bright. We'll also ask that one, it also saves a little chunk of past data and we can ask it to also save a little chunk of data around the sweep. That one collects 800 gigabytes of data per second. So we only ask it for a 10th of a second around where the sweep was.
- Wow. Sorry, how much per how little time? I'm trying to wrap my head around this. Like in the sense of data, the way we understand it, this is enormous right? - Yeah that's right. 800 gigabytes a second. So if you go out and buy the biggest hard drive you can, these days, say 12 terabytes, that fills up in like 15 seconds. - And this is the data to CHIME or just CHIME/FRB. - That's the data to CHIME. Yeah.
So that's reading all of the voltages from all of the antennas along the half-pipe of CHIME that then can get added together in different ways to point the telescope in different directions on the sky. - You told us the other day when we were chatting that just the sheer volume of data is equivalent to, or it's a portion of the entire data exchange on our cell phone networks in North America. - So yeah, I looked it up.
It's a moving target but if you look at the international data transfers on the internet, inside the CHIME supercomputer, it's doing 1% of that. So 1% of the world internet traffic is being exchanged within that CHIME correlator to do those additions of like the pointing the telescope at different points on the sky. - And it's doing that over and over again. - Just continuously. - It's amazing. - Whoa. - Yeah, during the day radio telescopes don't care.
We can see the sun but it's not the brightest thing in the sky. Rain is a little bit of a downer. - And you mentioned airplanes are a bit of a pain as well. - Airplanes are terrible. It's not so much the signals that the airplanes themselves are emitting as far as the radio waves are concerned, they're a mirror in the sky so we can like see over the horizon down to the noisy cities and cell phones and other things around. The CHIME telescope's not that far from the Kelowna Airport.
So we see many, many airplanes and have to filter them out. - The Milky Way's in our way, waters in our way. All these things we take for granted. - Noisy world out there. Yeah. - And where do you actually process this data? - So for CHIME it's almost all on-site just because the data rates are too big to move anything off, it would be way too much traffic to try to compute, like to move it somewhere else and compute there. So all the computing is done on-site basically.
- When you say on-site, my first thought maybe would be this huge bank of computers in a sophisticated room with monitors, but there's steel shipping containers on site, right? - Yep. Steel shipping containers. Good old 40' shipping cans or sea cans are kind of the building of choice to stick these things in. They're cheap enough to get and robust. So yeah, one of the challenges is that a big computer cluster is itself really noisy in the radio.
It emits a lot of, it just makes a lot of electrical noise. So inside of the steel shipping container we also have to build like a shielded room that the computers can go in so that they don't make a bunch of noise that we then hear with the telescope. - So there's natural challenges and challenge that we create ourselves with our technology that we have to get around. - Yeah, that's right.
And the kind of fun thing is that because the radio waves are pretty long, if you drill a small hole in the shipping container, the radio waves can't get through it. So the shipping containers have all of these, you know, basically small holes where all of the cables and power and cooling and everything come into the shipping container and into the supercomputers inside.
- I'm wondering if you can also speak maybe a little bit more broadly to a challenge that you might face when collecting all of this data in an experiment and then having to figure out how to store it. And maybe we can play the question from Dominica. - My name is Dominica, I'm a student at the Yachay Tech University and the PSI Start Program. I was wondering if, is it a fundamental issue, the fact that computations depend on the discrete whereas the physical laws depend on the continuum?
- Yeah, that's a deep question. The physical world is continuous as far as we observe. Quantum theorists might argue about that, but at our scales it's continuous. But we have to do all this. Our current computing is all discrete. So in CHIME the antennas are really measuring this continuous signal. But those come through cables into the first supercomputer in CHIME and basically the first thing we do is turn them into digital signals.
So there's a resolution problem there basically where you have to choose how many bits to use to represent it. So if you look at your computer display, you know, it sort of looks like it can make all of the colors that you can observe, right? But modern computer displays use eight bits for each of red, green, and blue. So they can make 256 different levels of red, green, and blue. And that's enough that we kind of can't distinguish between them.
So as far as like, you know, we can observe with our eyes or our brains that's fine enough that a discrete set of levels looks continuous to us. And it's kind of, it's a little bit similar in the radio. It turns out that partly because while the world is so noisy and in radio you have to add together a lot of individual samples before you actually measure something significant, it turns out that it's okay to do that discretization or conversion from analog to digital.
In CHIME actually they only use four bits. So there's only 16 levels of the signal and that's still enough to kinda recover the continuous phenomena that are observed. - CHIME has been extremely successful in this FRB mission. The fast radio bursts, they're a relatively new phenomenon and then there was only a few detected. And then with chicken wire and supercomputers and ingenuity, CHIME ramped up the game so to speak.
Can you tell us, you know, what it's discovered and what we're learning about fast radio bursts? - Sure, so when CHIME came online, there were about 50 fast radio bursts known and intriguingly one of them was seen to repeat. So there's not only just one boom, but then the same one was emitting multiple bursts, which really threw the theorists for a loop because some of their explanations required the thing to be destroyed to make a burst of energy.
The challenge is that fast radio bursts, we've now discovered that they're far away, which means that they're intrinsically really bright. So it's hard for theorists to come up with ways of kind of generating that much radio energy. And if you don't get to destroy the thing in the process then that puts even more limits on what you can contrive, what can think of ways of explaining what they can possibly be.
Right, so when CHIME came online, about 50 were known and the fun thing is there was a catalog of known fast radio bursts and there was also a catalog of theories of what they could be like, possible explanations of what could produce a fast radio burst. And there were more theories than there were fast radio bursts.
(both laughing) And then CHIME, in the first two months while we were still kind of putting the thing together, the chicken wire was in place, but the supercomputers were still being built, discovered 13 new ones and one new repeating one. And then after the first year of observations, our first catalog paper has 492 sources, including 18 repeaters. So basically just blew the lid off the fast radio burst game.
But I think a lot of the current feelings are that the repeaters and the one-off bursts are different populations. Now the theorists can still destroy the regular fast radio bursts, but then they still have to explain where the repeating ones come from through some other mechanism. - You've mentioned a term that I just love in our previous chat, sad trombone. That actually has a meaning in this research. What is a sad trombone in the CHIME effort?
- (laughs) This was one of those, like when the term was coin, you knew it would stick. So the repeating fast radio bursts tend to have this structure. They're not just a single burst, they kind of have a burst and then maybe a few milliseconds later a repeat at a lower frequency and then it'll often in three like, so they'll sort of have a initial burst lower and lower. So it's like whomp-whomp-whomp. - Sad trombone. - Sad trombone. - But it's only these repeating FRBs that do this?
- One of the things that the CHIME data really contributed to this is kind of understanding the diversity of the fast radio bursts. Like some of the non-repeating ones cover the whole band. Like we see them being bright all across the frequencies that we measure. Some of them are just bright in the top, some of them are just bright in the bottom, some in the middle even.
Some are really brief and some are scattered, which you get through kind of traversing different kinds of material between us and the source.
Part of the beauty of doing this large-scale search, observing 1,000 places on the sky all the time and observing the northern half of the sky every day, is that we get to build up statistics about what they are and collect it in a kind of uniform way so that it's much easier to try to understand what the real population is before whatever affects cause you to observe some more, like the unable to observe some or others. So it looks like many of the repeaters have the sad trombone.
So now sometimes if we see a new burst in CHIME and it has the sad trombone structure, we'll say, "Oh maybe that one's gonna come back again." - Is there a prevailing theory or theories about what these things actually, what's causing these distant bursts? Or do you need to do your cataloging and tracking them first to even come up with an explanation of what they could be? - One thing is just that they're fast, right?
So they're a millisecond long, so it's really hard to generate something a millisecond long from some astrophysical thing that's bigger than a light millisecond in size, just 'cause you know, you have to emit it all at the same time from all over the source. So you know, you can't really generate something that's that short from something that's like the size of the sun 'cause it just won't all arrive at the same time so it won't be a millisecond-long burst.
So that pushes you toward things that are small and one of the like families of things that could be are neutron stars. So if you start with a star that's, I forget the numbers exactly, 8 to 20ish times heavier than the sun. It goes through its life burning hydrogen and then burning some other things toward the end of its desperate life trying to stay a star and eventually runs outta fuel and collapses to a neutron star.
And neutron star material is really bizarre 'cause you take all of like, say something most of the size, like bigger than the mass of the sun and squeeze it down to 10 kilometers in size. There aren't atoms anymore. Everything's been squeezed so far together that it's just like a big ball of neutrons. So it's really bizarre. One teaspoon of neutron star material weighs billions of tons. Like it's just mind boggling. - Right, it really does make the mind reel.
- Like it's a number that you just can't really like comprehend. So they're pretty weird. (laughs) But the other interesting things are that, like when this process happens, if the star was spinning initially, it keeps spinning, but now instead of you know, a very stately slow rotation of something the size of a sun, if you can picture a figure skater spinning and then pulling in their arms and spinning faster and faster and faster, imagine that just continuing on to go.
Instead of spinning, you know, once a week or once a day or something, some of the neutron stars that are observed will spin like 1,000 times a second or more. So they're the like incredibly heavy things that can be spinning really fast. And similarly their magnetic fields, they often keep, So then you have something with a magnetic field that's spinning really fast. If you're a theorist, that's good ingredients to make something that can emit radio waves.
So these pulsars are known, like neutron stars that are observed to emit periodic pulses of radio waves. They were first discovered in 1967 by Jocelyn Bell Burnell who is amazing. Some of the theories for what fast radio bursts could be are kind of exotic types of neutron stars of some kind. The problem is that the fast radio bursts are like millions of times brighter than neutron stars that we know in the Milky Way.
And you can't just make them bigger because if you make them too big they collapse to black holes. So you can't just make a bigger neutron star. There has to be kind of something else going on. We got another kind of clue or a hint maybe in 2021. There was a fast radio burst from a neutron star in our own galaxy, a special kind called a magnetar. So it has kind of neutron stars with really extreme magnetic fields.
And CHIME observed that, like we caught that one, we saw it go streaming by and we said, "Ooh, that's interesting." And it kind of has an energy that's in between. So it's a few 100 times brighter, I think, than usual pulsars. So it's kind of filling in a bit of that factor of a million you need to get to fast radio bursts. So maybe they're an extreme, kind of this extreme kind of magnetar.
So there're kind of hints and clues, but it's still a pretty big mystery and we keep kind of finding odd things. Another thing discovered last year, or the year before, by a graduate student in the CHIME group was that one of the repeaters not only repeats but it repeats on a clock. She found that if she took all of the pulses, she was looking at all when we had observed the fast radio bursts and she said it looks like it's repeating every 16 days.
So she took the signal and like folded it and found that all of the bursts come within a five-day period around that 16 days. So it's like, you know, on for five days and then off for 11 days, on for five days off for 11. And most of them appear within like a one-day window around the peak. So it's like mostly on and on day one and then it's kind of on a little bit for the next four days and then off for 11 days. So that adds another element to the mystery.
And we don't know if all of the repeaters do this, but maybe some of them we haven't, maybe they have different periods and we haven't observed most of them for long enough to be able to notice that. So then that maybe makes you think that maybe there's like a neutron star and something else in a binary, like orbiting each other.
And then when you have that, you can get it so that the neutron star is spinning and it's sort of like a lighthouse or like a top that's wobbling and when you're looking straight down on the top you can see a burst from it. So maybe that's what's doing it and that, you know, wobbles once every 16 days and it's when it's pointed like more at us that we see the bursts. So now you know, you make the picture more and more complicated.
Like it has to be a really extreme magnetar in a binary with something else that's giving it this wobble. - The mystery remains. - Yep. The mysteries remain. - Well that's the exciting part. There's lots for you to do. (chuckles) - It's really, it's the first time I've been involved in a project like this that's kind of broken open a new part of observing space and is really just like finding all kinds of cool things there. So it's been really fast-paced and really fun.
And part of the way Canadian projects work, there are a lot of graduate students involved. So a lot of the people making these discoveries are, you know, people who are working on their PhDs or master's degrees, you know, they're just at the forefront of this field. So it's really exciting, it's really neat to see all the things they're discovering. - On the topic of being at the forefront.
You have told us also that lots of the work here relies on being at the forefront of computational technology and we had a question sent in on the topic of GPUs. This was sent in from Craig in the IT and AV department here at Perimeter. - Hi Dustin. I heard it mentioned here recently at Perimeter, this specific piece of hardware known as an Einstein equation code GPU, which is the graphics processor from a video card, reprogrammed to run the Einstein equation code for simulations.
I wonder if you could explain in a little more detail what an Einstein equation code GPU is, how one is programmed to run the Einstein equation code and how successful it has actually been in simulations. - I'm gonna first talk a little bit about CHIME, I guess. I said that, you know, it's chicken wire and supercomputers, multiple supercomputers in this case. So in CHIME the first supercomputer it comes into are these custom-built computer boards that use FPGAs, field-programmable gate arrays.
And they're these kind of really low-level, it's sort of like a computer chip where you get to choose where the wires go. So they're really difficult to program but really fast at what they do. Program them once and they do a single task very fast. The task that first computer has to do is simple enough that this is achievable and then it sends all the data to the second supercomputer, the CHIME correlator that has to do more complicated tasks.
You can't do that in these really difficult-to-program FPGAs, but it turns out that you can use these GPUs, graphics processing units, to do the computations. And GPUs are harder to program than garden-variety CPUs but they're way more flexible than like FPGAs. So the CHIME correlator has to use these GPUs basically to get the amount of computation out that that it has to do. And it uses 1,024 what were at the time, very cutting-edge GPUs.
I love the whole thing, I love all of the technology involved in it. They're water-cooled and the water kind of comes in and goes over each GPU in turn and we have sensors on them and you can kind of see the water heating up as it goes through each GPU and cools it.
But yeah, basically these GPUs, although they were originally built for doing graphics for video games, if you think about it, graphics for video games, a lot of the tasks are like running something that's going to produce, a color say, for each pixel on your screen. And you know, if you have a screen that's like 2000 by 2000 pixels, I'm making that number up, then you have 4 million computations to do but you're doing kind of the same thing for each one, right?
So GPUs are kind of specialized for doing relatively simple tasks but in massively parallel. And that just turns out to be a really good match to some of the tasks that we have to do. 'Cause in radio, you know, for the radio astronomy computations, it's the same task done a lot of times in parallel. So say 1,000 places on the sky or 16,000 frequencies, that computation is the same for each one.
So it's basically, you know, kind of a fairly simple process that you just have to repeat a bunch of times. So that really works well for GPUs. So GPUs are really widely used for, also now, a bunch of machine learning or AI applications because a lot of those problems can also be phrased as doing a fairly simple operation, a lot of times in parallel.
They're kind of just a way of accessing a lot of computing power at the expense that you they're harder to program so you have to put more effort into describing the problem you want to solve and especially how to solve it in massive parallel. So this Einstein equations, this was actually work done by people including my boss and office mate, Erik Schnetter at Perimeter, they work on computer programs that solve the Einstein's general relativity equations.
So you might have heard it said that in general relativity matter tells space how to bend and space tells matter how to move. So you know, when there's mass it changes the shape of space and then mass moves along straight lines in bendy space. So if you're a mathematician, that sounds like differential equations. It's, you know, there's sort of two things and they're affecting each other. Those are equations that you can solve.
You know, if you put a bunch of mass down, you can compute how this space will be bent and then you can compute how the mass will move around in that bendy space. And you only need this when you're dealing with really extreme kinds of situations. So black holes often come up, neutron stars probably, but in order to understand situations like that, basically you can either try to understand really simple situations with math on a blackboard or you can do computer simulations of them.
And those computer simulations involve doing a lot of the same computation in parallel so they lend themselves to GPUs. Erik's group have made implementations of solving the Einstein equations on GPUs. That's the sense in which there's a, you know, a graphics card that can solve the Einstein equations. - Right, yeah. That's fascinating. I knew that that question was coming up.
I was looking forward to your answer 'cause that's an area that I know very little about and now I know something as opposed to nothing, thanks to you. We have two more questions from students. Let's hear. - Hi Dustin. I'm Summer from Waterloo. If you could travel anywhere in the universe to see something with your own eyes, what would it be? - Oh goodness. I don't think I'd wanna put my own eyes close enough to a fast radio burst to see it.
- Let's say you're safe, you're in a safe space vehicle somehow. - Okay good with enough shielding, (laughs) I would love to see a fast radio burst. 'Cause what on earth are they? You know, like I said, you have to, the theorists really are working hard to contrive scenarios that can make a fast radio burst. So there's gonna be all sorts of wild stuff going on around something that can make a fast radio burst is my guess or my hope at least.
Black holes of course, or like the accretion disc and like the, you know, we don't see bendy space in our everyday lives. So there was a recent news article of looking at light behind a black hole and it's bent all the way around or sometimes bends around and makes multiple laps before it gets out and sees you. So like we don't really experience the fact that space is bendy so it would be pretty cool to see bendy space around a black hole.
- I agree. (laughs) And we have a second question that may follow from the first. - Hi Dustin, I'm Justina from Waterloo. I was wondering, what's the most fascinating thing to you about the universe? - Wow that's going right to the core of it. (all laughing) One of the really bizarre things is that the universe seems to be like kind of comprehensible with math.
It's kind of bizarre that you can, in cosmology you can write down like, you know, a set of equations with like five or six parameters that kind of explain at the large scales, like how the universe grows over time. Like that to me is just bizarre.
The weirdest thing is that it seems to be like comprehensible or like within the realm of possibility that we could understand things about the universe with like basically math and that we can like understand things about the universe by writing computer code and that somehow people will pay me to do this for a job.
Like it's... (laughs) - Yeah, I suppose you would be, that job posting that your friends joked to you, you had to go for it, Perimeter wouldn't have existed had the universe not been somewhat comprehensible and that there would be mysteries for you to dive into. - Yeah, well some people say that like, we are like the universe's way of understanding itself. - Mm-hmm.
You mentioned that one of the downsides of your job is you don't always get to go to the telescopes that are doing the work and you haven't been to CHIME even though it's really close to where you grew up, right? - Yeah, it's just one mountain range away from where I grew up in Christina Lake, British Columbia. - It's a long way, it's over the mountain. So yeah, you're from British Columbia originally and you still haven't made it to the telescope that's one mountain range across the way.
- I know, I still have, my mom is quite upset. (laughs) My work somehow hasn't contrived to manage to make me go out there. We have staff members on-site and team members on-site. So the goal is for the whole system to be remotely operable. From time to time we have to get somebody to go and unplug something by hand or turn it off.
But for most of it, it's all set up for remote observation partly because whenever people are on-site they just, they tend to, not the staff, the staff are very good, but whenever we have visitors, contractors, whatever, they never turn their cell phones off. - And that interferes with- - That's the loudest thing in the sky. It's louder than anything in the sky. So the fewer people on the site the better, actually for the most part.
During the building of CHIME there was a huge amount of physical effort put in as far as as like pulling cables, 'cause you know, there's 2000 cables that come from the half-pipes into the first supercomputer and then hundreds of fiber optic lines that come from that one to the next computer and so on. So there was a huge amount of effort, but I thankfully came on the project a little bit after that. It was all in place. It is still a huge treat to go to the telescopes.
I spent a lot of time at the DESI site and at its twin telescope in Chile and it's just beautiful up there. It's a real treat too to have the privilege to observe from those places. - Well, you'll have to get to CHIME and then visit your mother or vice versa. Your enthusiasm for this stuff, especially the real mysterious stuff is just infectious and you know, I've learned so much and my mind is reeling at some of the data and the sizes and the scale.
So thank you so much for sharing with us today. - Thank you. It was my pleasure. (bright music) - Thanks so much for listening. Perimeter Institute is a not-for-profit charitable organization that shares cutting-edge ideas with the world thanks to the ongoing support of the governments of Ontario and Canada, and also thanks to donors like you. Thank you for being part of the equation.