(gentle music) - Hello, everyone, and welcome back to Conversations at the Perimeter. I'm Colin and I'm with Lauren and we are just thrilled to introduce you to our guests this time. They are Ghazal Geshnizjani and Niayesh Afshordi. They are both researchers here at Perimeter Institute. They work in astrophysics and cosmology, the Big Bang and black holes, and they also happen to be married to one another. - We talk about a little bit of everything in this episode.
Niayesh also shares with us that he's recently applied some of his knowledge and skills from astrophysical modeling to studying the spread of COVID 19. And Ghazal tells us about her recent children's book called "Bella, the Black Hole" and they also tell us a lot about their work in equity, diversity and inclusion in academia. - And what's really fun about interviewing them both at once is they just have this fantastic rapport between them.
They finish one another's sentences and start one another's sentences and just have a great sort of fun relationship with science and the family and with us, so it was so fun to hear. - It really was a lot of fun. Let's step inside the Perimeter. Ghazal and Niayesh, thank you so much for sitting down with us today.
So in preparing for the conversation today, I was looking at both of your websites and I saw that Ghazal, you describe yourself there as a cosmologist, while, Niayesh, you describe yourself on your website primarily as an astrophysicist. Are you able to tell us what each of those words mean and maybe what the difference is? - Yeah, how do you possibly get along when you have such different careers?
(all laughing) - It just reminded me like yesterday, one of our friends, our colleagues on Twitter posted, "Does your Sunday morning starts with arguing about the scattering amplitude?" And I'm like, "Only Sunday morning?" (all laughing) - Why wait till Sunday? - So I'm cosmologist, I guess traditionally cosmologist, but it's hard to say these things what each field is really because all the different disciplines have so many common interests and it's always good.
I tell my students right away, you know, don't just put yourself in one box. All the amazing things that happen in science and physics is when people try to reach over to other fields and we work with other ones and see what they're doing.
A lot of technical things, a lot of methodology and other things that come in other fields, really all of them are related to nature and nature has same way of doing things, so you learn from them what they have learned and right, so cosmology, I guess technically is universe at really, really larger scales beyond galaxies and the evolution of the universe, historically how it started like and how it began, or as far as we can go back in time to today
how it's evolving and what's gonna be its fate. Obviously the little things that we see, even as small as a planet in these scales came out of the universe so everything we do in cosmology will have implication for understanding the rest of the science in the cosmos, like how the initial conditions were set back in time which gave rise or planted the seed or everything else that grew out of it. Okay, I leave the astro to Niayesh to go. - That's the excellent question and I don't really know.
I guess it's our historical differences, but as Ghazal mentioned, cosmology is a study of universe as a whole and in including its formation and its history, but astrophysics can be that, but also can be just looking at things in more detail right now.
I would say that astrophysics has a broader purview in the sense that you could get very deep in understanding the stars or molecular clouds in our galaxy, or you could get deep in understanding the early times at the Big Bang, so I would say, I mean, being an astrophysicist is like being a generalist. My own background, when I was a teenager, I was an amateur astronomer.
When we were taught what that means, the meaning is lover, so someone who loves to do something and that's using contrast to I guess professional astronomers who do this just to make money like I am now, but the amateurs do it for the love of doing things or doing astronomy. - Did you have your own telescope as a teenager? - I did have my own telescope. So I started from there. I mean, I wanted to do astronomy, study the stars and whatever out there in the heavens just for the love of it.
The question is when you start at face, hard to stop, and if you wanna understand the stars, then you try to because you love it and if you understand galaxies and if you wanna understand the Big Bang and it's hard to stop at any point and that's where you become an astrophysicist, right, so you just, yeah, universe is your playground and you just cannot limit yourself to studying one thing so you study everything. - The universe is your playground, I like that.
That should go on your business card. - Let me see. - I notice when I look through the work that both of you do, there's a couple of recurring themes. One is black holes and the other is the Big Bang or the very, very early universe. Are they related, black holes and the Big Bang, and if so, can you tell us how? - Yeah, in a way they're very related. It has to do I guess with Einstein theory of gravity.
I sometimes when I'm writing grants proposals, I would say when Einstein wrote his own theory of gravity, he didn't think it would bring also the breakdown of the theory, and I think in a way, both Big Bang and black holes are what we call singularity points of Einstein gravity of general relativity, which is like the points that general relativity is breaking down. - By singularity, that means that this tiny point.
- Doesn't have to be tiny, but it's a regime when things are not working within the theory anymore, so I guess technically there's different mathematical ways to understanding and it's not clear cut at all because when something is breaking down, how do you describe it with your theory because it's already, like your tools are breaking, so you cannot even characterize it, but the people that do it in different ways, and one way to say this, for example, a spacetime,
this whole fabric is getting so curved up that the curvature is getting infinite and we know infinity is summary. It's not anymore mathematical-like. Or like geophysics, it's trajectories that we follow the math on, then all of a sudden they have end points and then we cannot go beyond that, so in a way so they both are the same story. One is happening in time as we go past in time in our history and the other one is in space.
In certain points in a space, we see, we predict it, but at the same time we predict that things are not working, are breaking up. - So you're using both of those types of study to figure out the places where Einstein's theory needs some improvement. - Yes, exactly. - Interesting.
- This is probably a gross oversimplification, but the way I understand it is a black hole is this mass that things sort of fall into it, attracts into a singularity, and the Big Bang seems to be a singularity that does the opposite, bursts outward. Is that a gross oversimplification of the similarities? You can say yes. - I would say no. I mean, we wrote a paper saying that. - You're saying it is true.
- Yeah, I mean, I don't know if it was worth a paper, but we actually published a paper and it wasn't Scientific America. No, I mean that. Actually, literally this is true. I mean the Big Bang is, if you just turn the clock or the time backwards, then black hole looks like a Big Bang. If you hear of a black hole that collapse of a star into point, but if you imagine you just take that movie and run it backwards, it just is something came out of, well, nothing.
There is the one cast that the Big Bang happened everywhere and black hole is in one place. There lies the up basic, had to make that work. That's I guess a billion dollar question, if you will. So to make that work and make Big Bang look the way we do see it and black holes the way we do see them to be, you have to change something because black holes in one place, Big Bang everywhere. - Can studying black holes give you insight into the Big Bang or vice versa? - Yeah, I mean, I think so, yeah.
I think there's a lot of similarity in the things that could be happening. For example, if there is a improvement of gravity or quantum gravity, learning from one could shed light on the other one as well, but they also have their own differences. I would never say it's a burst. I would say it's like Big Bang is in our back like a wall or something, we come out of it.
We don't know what's happening beyond it, but doesn't have to be like, the reason I'm bringing up, but there is sometimes this misconception of its explosion and things like that and I don't know, I feel like I don't connect to that metaphor that it's explosion necessarily. It's something that, yeah, it's kind of going in the past and all of a sudden we are cut back. We don't know what's happening beyond it. - Is Big Bang maybe unfortunate term because bang implies an explosion?
- Yeah, so I often, like when I'm teaching my students, I keep saying, "Call it a Big Bang era, at least," because we know things got hotter and hotter and hotter, but I wouldn't say there was one big explosion, at least that's my way of thinking about it. - So yeah, the question is it a point in a space or is it the point in time? This actually applies to both Big Bang and black holes. There is this misconception that the singularity or Big Bang is a point in a space.
If you're far away from it, the Big Bang happened in one point in space or, I mean, there's a singularity, the percent of the black hole, that's not true. So in fact, both of these are points in time, or as Ghazal said, is an era. So Big Bang is a point in time at which basically physics breaks as we know it. Doesn't matter where you are. If you are happening or you happen to be where Big Bang is happening, then physics breaks down, basically, 'cause it's an era or a point in time.
The same is true at the center of the black hole. It's not the point, but rather anyone who happens to wander across the event horizon of a black hole, they have one eventuality. There's an era at which they will be crushed with this singularity and that's a point in time, basically. That's an era in their future. It's like saying everybody dies. - It just happens faster if you walk into a black hole. - It depends on how big the black hole is, yes.
But yes, indeed, and yeah, this is not the point in a space. If you wander in anywhere you are in there, then it's gonna happen to you. - And what are some of the ways that you both think gravity might be modified to help improve the way we describe these things? - So the big elephant in the room, in fundamental physics and especially in this building, is the quantum gravity, right?
So we know physics has this regime that things become quantized and all of our other forces of nature can be described in quantum way and there is this other force, gravity, that we have not been able and we think it should also to merge all of this together has to be also have a quantum description.
A lot of people like, I don't know, more than half of people in this building are working on that in different approaches, so that could be one thing, I think, that eventual, but there is also this idea and it's not new, I think, it's has always been like since even Newton to Einstein and other things that there is always a regime when we describe things. You don't have to go all the way to very microscopic quantum regime to understand physics.
There may be some middle ground coming from cosmology. I feel like this method has a always worked, so maybe we don't have to, I don't have to start from completely scratch to build up everything. Maybe start from things that we know like Einstein gravity, we know works. Can we start modifying that as slightly one by one?
And maybe on the other side it's gonna be, eventually gonna reach to quantum gravity, but there's a middle way that you better understand you are still connected to GR and the things that you understand, but slightly move away from that. These approaches in cosmology are called modified gravities. And there is one that Niayesh and I, for example, have been fond of and worked on and thought of, which is the Cuscutan gravity.
We have been working on that because one thing interesting about it is that we noticed this is the minimal modification of gravity. You don't add any additional player to the game, as you say. - What would a player be?
- A player, technically we call them dynamical degrees of freedom, things that can generate additional dynamics in your field, like additional car or something that moves things around, right, and gravity by itself doesn't have, has two, actually, two, which are the gravitational waves, what people call. Other things that we have, like every other thing, like varions or electrons, things like that, you add to theories, they all have this additional degree of freedom. You add them to your theory.
These are the matter field and then there is general relativity, so usually the story is that you add the matter fields and general relativity has this own gravitational ways which really didn't play much for the, and we didn't detect them until six years ago, right. Everything else we saw was this matter force as generators. This Cuscutan is somewhere in the middle.
It's a slightly modification of general relativity and it doesn't add additional generator, but modifies it, and we assume everything else is the matter fields that we had as before. - Could you explain the name again of that?
- Cuscutan, Cuscutan is a field which modifies gravity, but as I mentioned, because it doesn't have its own dynamics or generator, I thought of something that's the same thing on Earth, or like in everyday life, and I thought of a plant, the parasite plant, which can feed off other things and even modify their behavior, but doesn't have its own root. - So it winds around another plant and takes advantage of its root system. - It's called dodder, I guess it is. - I guess dodder is one, yeah.
And then I thought of what's the technical term for it and apparently in plant biology is called- - Botany. - Botany. - That's called Cuscuta. So therefore we draw, 'cause I suggested the name Cuscutan and my collaborator accepted. - Yeah. As a metaphor of this idea that it attaches to an existing theory without requiring its own sort of roots. - Right, but it slightly modifies it in a way that might have cosmological implications, but doesn't mess up other things that we don't wanna miss.
- And Ghazal, I know you said that you and Niayesh worked on some aspects of this theory together and now you've been doing some further explorations. Can you tell us about some of the things you both explored together and maybe some of the things you've continued to work on? - It's a long and winding road.
It starts far, far, far away, in fact, Madison, Wisconsin, when Ghazal was a postdoc with the Cosmologist, Daniel Chung, and I used to visit a lot, but their story was really, what is the fastest that something can travel and not violate the laws of relativity?
And you would think that nothing can travel faster than the speed of light, but it turned out, in fact, Einstein's relativity does allow for things that, on paper have things that propagate infinitely fast and it's just very counterintuitive, so we try to make sense out of it and at the time we realize that even though Einstein relativity seems to allow for it, you cannot actually send information with it.
And basically we started exploring that and then ended up with this theory of a field, which seemed to be doing this, that on paper it seemed that it has basically waves, sound waves in it that propagate infinitely fast, but in practice, you couldn't actually send signals with it, but what could you do with it? It turns out, as Ghazal mentioned, it could modify the gravitational dynamics beyond Einstein's theory of relativity.
And what was hot back then, I guess it's still hot somewhat now, is dark energy. It was just discovered so I guess when we, they got the Nobel Prize, I think it was 2011, I don't remember exactly, yeah, but it was discovered around 2000, around the turn of the century, so we kind of were halfway between those at that point. - Could you just briefly explain dark energy and what changed when it was discovered in the 1990s?
- Absolutely, so there is this big, there's been this big puzzle in Einstein's theory of relativity, in Einstein's gravity, for over a century since this was discovered. So in fact, Einstein, when he first wrote down his equations, he added this constant called the cosmological constant and he needed them to keep the universe ecstatic because otherwise he wanted to either blow up or crash and he wanted to tame it, so he just basically added this thing as just as keep it there.
It turned out that that wasn't a very effective way of doing it and he later confessed that it was his biggest blunder to actually add that there. If he hadn't, he actually would've predicted universe cannot be a static and Hubble later discovered the universe was not static. However that the cat was out of the bag, so this cosmology constant that Einstein introduced never really disappeared, so it was always there.
People always knew about it and it took another 100 years for people to actually discover a sign of that or something like that. The problem is it's just such a big surprise because it doesn't fit anything else that it has. So there is this thing that looks like a constant.
It has energy, it has pressure, it has negative pressure, so the only thing that we know that does have negative pressure and it's a scale that is smaller that by orders of magnitude than anything else we see around us in the standard physics. So it's such a bizarre thing that we kind of physicists had the field day with it. I guess they're still having. They invented all sorts of things with all sorts of funny names to kind of model it.
Unfortunately so far, the evidence doesn't show that necessarily it's anything more than a cosmology constant, but it could be. And at that time, basically one of the possibilities we saw that, okay, so I mean, Einstein theory has been so successful, maybe it's a cosmology constant, but then what is the next simplest thing that we could come up with?
And this Cuscutan was an idea, and it's the next simplest things in a sense that you're not adding anything to Einstein's theory of gravity and every other possibilities that people have studied, you're adding additional degrees of freedom, additional kind of beasts into the theory and this one was not just the same beast, but just a slightly modified behavior. That was the beginning and we had, we kind of explored the possibility, which is still there. The dark energy could be type of Cuscutan.
We haven't confirmed or ruled it out yet. - And dark energy, correct me if I'm wrong, it's what's making the universe expand in an accelerating rate. - That's right. - Yes, exactly. Basically, cosmologists love the term dark, whatever. You put that dark in front of it. - I noticed that, regarding dark matter. - We have now dark radiation, dark sirens. - Does it essentially mean unknown, it's an unknown quantity? We don't know what to call it aside from- - Most of the time.
The dark sirens are slightly different, but most of the time. - Different times means different things, but for dark energy, it's probably as dark as it gets. It doesn't seem to be interacting with anything, we don't see it, so that's a term that, I don't know. I think Mike Turner first invented that term, but I mean, people, indeed, what was discovered with cosmic acceleration, which was very surprising.
You would think gravity is attractive, so if universe is expanding, it should be slowing down because of gravity and low and behold when they measured it, they realize it's speeding up, but it turns out they already had a model waiting like for 100 years to explain it as Einstein's. - We are not sure yet, like they're still like, we talk to a string theorist.
First, I think when the astrophysicists started noticing it, they were still in the camp that no, in the string theory, there's no such thing cosmological constant, it cannot be. Then like once they observe it and then all of a sudden they started, oh, actually we have. - 10 to the 500. - 500 of them in our theory and they're like, now what do we do? Get rid of all of them. - Cannot quite decide is zero or 10 to the 500. - Ballpark. - Yeah, so now there are a couple of camps, apparently.
Some are like, there are a lot of it and some are like, "No, we cannot have it." But what is for sure certain is that it's observed, something is there. - Yeah. Is one of the goals to try to explain it with as few new variables, as few complications as possible and then add them? - For us, it is, yeah, from our point of view. I guess our approach is sometimes called bottom up.
Their approach, starting from very fundamental theories, top down approach, so they're going working our way, it's going up. - Hoping to meet at some point some. - I wanted to ask, you've both studied the early, early universe shortly after the Big Bang, is that research related to dark energy? Can we learn anything from the origins of the universe about what it's doing now, it's expansion and acceleration?
- I think because a lot of it is really mathmat, right, at the heart of it and the mathematics that is describing the same theory, gravity, so what applies back then should be applicable today as well. Some things may be more relevant back then than they are today because energy is where universe was much hotter so than today, it's much cold, but at the same time, yeah, the rules be the same. That's why it's very easy and it happens so very often.
We learn something that can be done in early universe and then few years after we try to apply the same thing in late universe, oh, this technique worked there, like in that context can we do the same thing now in late universe and there's so many examples of that.
- I guess just to follow up on that, the most popular theory for the universe is called inflation, which in fact is like a dark energy, but at like souped up or on steroids, much higher, much higher energy, so we see it happening now, but it's proposed that something like that with much, much higher rates was happening early on. That's to one possibility that could be a similar scenario, of course, on very different scales of happening at acceleration of cosmic expansion.
But beyond that, there could be other possibility if you have like a cyclic scenario of the universe, then in fact our future is our past, so yeah, what's happening now like the cosmic acceleration could be setting up the initial conditions for the next generation of the universe. So depending on the scenario, there could be even more cross-connections between early and late universe. - Could there be future Big Bangs? - There could be, yeah, in a cyclic scenario.
I mean, Roger Penrose is a big fan of that, as our previous director, Neil Turok and Paul Steinhardt. They had their different models of cyclic universes and yeah, so that's certainly one possibility that people have studied. - And is it possible that this Cuscutan model would support some of those scenarios? - To be honest, I have not considered that, but because it has, it's kind of a like a puzzle.
I have been focusing on a particular piece of it just going from one contraction to expansion, it seems, so let me back up a little bit. So if you wanna have, right now the universe is expanding and accelerating so if I wanna go back into the beginning, what scenarios could I imagine?
One is that maybe then expansion enters contraction and then again, expand, that's one possibility, but there could be other things like expands and then out of it something bubbles out or tunnels out, and then again, so depending on this, then you have to work on a different scenario for that transition to happen.
But one thing I am working on it, maybe this, at least we can figure out how you can go from a contracting universe into expanding universe, which is not an easy task, like general relativity doesn't allow it because you violate center and energy condition, which if you do that, then the things break loose, a lot of instabilities, and here it again goes through violent behaviors, but that's where right now my focus, in fact, one of my program is.
It looks like Cuscutan can make that possible, so you could make universe go through a contraction and then we call it a bounce off into a expansion, so in that context, it could fall into a bigger picture of cyclic universe. We haven't expanded too far. We are now focused on that particular phase of bouncing, but yeah, certainly could be applicable to that bigger picture.
- Yeah and I think answer leads to maybe a bigger question that when you're trying to, I guess in the end of the day, approach quantum gravity, there's so many different ways to approach that and you're talking more about modified gravity and there's so many ways within that, so we have a really good question that was sent in by a master student, Anna Canura, here at the Perimeter Institute, so let's play that question. - How would you describe each other's approach to doing physics?
Would you say you have different styles of research? - Long pause as they consider their answers carefully. - I go first or do you wanna go? - My answer is yes. (all laughing) That's it. - We request a more elaborate answer. - Maybe I, yeah, I can. - Is that correct term cynical or someone who is like, I have this approach that I question the validity of everything. Niayesh has this approach that no, of course, that's the way it is, and I'm like, "No, sit down, let's write it."
So it's a lot of back and forth argument. Like I am like, I don't know, I always like, "No, there must be something wrong with it. Let's check this aspect, let's check that aspect." He is more optimistic and like taking a leap to next big thing and, "Yeah, universe goes from this and then cycles to that." And I'm like, "No, no, no. You know there's a lot of things can go wrong. Let's work it out." - Is that an accurate depiction? - I think that's very accurate, yes.
(all laughing) - But is it useful to have both of those perspectives when you work together on something? - I think so, yeah, like he, I'm trying to, yeah. - It sounds like two halves of sort of one brain trying to, you know, check each other. - Check and balances, I guess, something. - Yeah, I think Ghazal is very good at kind of identifying the details that are important and needs to be understood to kind of for the whole picture to make sense.
My own approach is that usually I have some very big pictures that this should work and then I say, "So you need to fill out the detail," and then either I ask someone to do it or just sit down and count as hours and yeah.
Sometimes the details will be filled out, more often than not, it doesn't, and just because the whole picture was wrong sometimes, or maybe just takes much more time, but that's, yeah, that's the approach, which I don't know, it's just worked for me, but I think it's very good that Ghazal can identify all the places that it doesn't work. - Does that apply in life outside of science too? - You can imagine. - Yeah, he is like, oh. You know, let's have kids do this. I'm like, "Wait a minute.
It doesn't work that easily. I have to do this research. You have to check that, you know." - Does this apply to the Cuscutan model? Ghazal, you're still checking a lot of different aspects of that and really looking through it. - Exactly, like I am, yeah, I am that way. Like it takes me longer to make sure I feel confident, you know, even though like I have, we have I think by now three papers out, I'm still like, "Okay, next let's do one additional step, check this thing, check that thing."
And I think to his credit, he does a lot of that too. Like if he come, he has done it, like, this is very unique because most physicists our expert in one particular field, but Niayesh does this thing that he comes up with a theory, then he checks the data and they're like, you know, goes to talk to the statistician and it's all like simulation and does these things, but.
- It does seem, Niayesh, especially going through your website, the subject areas that you're interested in, it gets to be a bit of a long list. There's all sorts of subject areas that, can you explain, is that just a, have you always been curious about all sorts of different aspects of physics? - Yeah, it's kind of this thing in your head. I guess you kind of, I start exploring different things as a kid and then at some point there's a switch there. It says, okay, "That's enough, probably.
You wanna stop somewhere." And maybe that's missing in my head that kind of keep exploring. And the thing is, I mean, the more tools you have and the more experience you have at this thing, you think you can understand more things, which doesn't work, to be honest, but yeah, somehow that hasn't sunk in. Your experience doesn't necessarily lead you to, I mean, it doesn't help with solve things better, you just, there are more and more problems that needs to be solved.
But nonetheless, I mean, when I see a puzzle, be it, I mean, what happens at the center of the black hole or the Big Bang, or it could be, I mean, dark matter halos, cosmic acceleration, or how COVID spreads across the globe, it seems that, I mean, when I look at what's happening, I can see all the similarities, like when we study dark matter and dark energy, and then we study the spread of COVID, neither of them, we actually see what's happen.
We don't see the viruses going around like one by one and we don't see the dark matter particles, but what we do see are the consequences. We see the shutdowns, we see the hospitals filling up and things like that, and we see formation of galaxies and then that's where I see the similarities and it's kind of, it's hard to ignore those. That's the problem.
I kind of lie awake at night, says, "Okay, so this is very similar to that," and I cannot just fall asleep without kind of pursuing that and that's what happens. - And are there certain models or ideas from your work in astrophysics that were particularly helpful when you were studying this COVID 19 modeling?
- So my PhD is kind of an interesting story, which as similar to the rest of my academic career had lots of different things, but one thing in particular was very similar to COVID because I was interested, my supervisor was working on cosmic molecular background, but then we also had galaxy airways out there.
With galaxies, people see them with telescopes, optical telescopes, cosmomicrowave background, you have the satellite that see microwave, so different things and for the most part, they are different things, they see different things, but then what I did was I actually looked at the correlation of the two signals and then it turns out there's a tiny fraction of these different things that are same.
So there's some is the effect of the dark energy, the cosmic expansion, some was the effect of hot gas in the microwave background. And it turns out that these are the things that you couldn't see on each of these surveys on their own easily, but if you combine them, you could actually kind of get these tiny signatures are through the combination and that's what I did for my PhD and it wasn't very much off mainstreams.
I mean, I was like one of the first people who were doing it, but now everybody does it. And if you just think about it, you can do this everywhere, right? So we see very different things for very different reasons, but if you can combine them, you can learn something very different that each of those datasets cannot teach you.
And I realized that basically that technique, which I guess the technical can for this cross-correlation that can be used kind of widely, for example, in the pandemic that you could use various measures of people's activity and spread of a disease and then through carefully designing cross-correlational studies in a space and time, which is what similar to what you do in cosmology, right? We could learn about the various properties of the disease.
For example, if people are getting vaccinated and at the same time they're having lockdowns, and at the same time some people are getting immunity from prior disease, how can these three in track with each other because they could all have similar consequences and this cross-correlation is the way to do it. In fact, that's how I did, I could separate the effect of dark energy, the effect of hot gas, and effect of radio sources but through this cross-correlational study.
So if you have a lot of data, you could do it, basically. - You mentioned in one interview that data from the COVID pandemic, there's a lot more of it and it comes a lot faster than from black holes. Was it sort of a gift of data for you that you had these huge numbers? - It's a curse. (all laughing) You would think it's a gift like for a week and then it's a curse. - Too much data? - Too much data, too much too fast, too many things happening. - I don't know, it's the other way around, right?
You're losing the data. He wasn't quite like that because you were telling me and was part of the problem, like I kept telling him, "Tell me about Waterloo, like what's the economy." And he's like, "No, we don't have data in Canada. All I can tell you is what the count is in US because the data was I've been and there." It could like cross correlate between all different counties, how many there were like, I don't know, 30, like more than, 3,000. - 3,000 counties, yeah.
- Counties where each had their own dataset you can track. - And essentially you made sort of a dashboard where you input factors say whether or- - Lockdowns. - Lockdowns. - Lockdowns, yeah. - And vaccination rates. And then it was sort of a predictive model of spread. - Yeah, that's right. - One conclusion I saw that surprised me until I heard an explanation was that the effect of weather, or at least the indirect effect of weather, hot weather and cold weather.
Could you explain what you saw there? - I mean, these are all the things that come out of data. I mean, I wish I had a better understanding of it, but it's in fact, somewhat similar to what as I was talking about that you don't necessarily understand fundamentally what's happening.
Same with quantum gravity, you don't necessarily fundamentally understand what's happening, but if you have a good enough data, you could have an effective description and what we did is we got this effective description of what's happening and basically the conclusion was that if you look at a spread of COVID across thousands of counties, across thousand about, I guess you have hundreds of days now, there are these factors that are at play and one of the significant ones are weather,
that when things get colder, where the temperatures dip below around 15 degrees Celsius, then COVID spreads faster. And then this is in addition to all the other effects. So if you include effects of mobility and vaccination and everything, I guess this is probably the least surprising one because we had seen that for other prior virus like flu. In winter, they are more severe. So there are all of these.
The thing is that there is no one factor, and this is kind of one of the problems that I kind of keep rolling my eyes whenever I see an analysis of COVID anywhere, which there are so many of them it's hard to avoid them because they just kinda say, "Look, this place, this country did this, and then they're doing well, and then this state did this or this city did this and they're doing so well. Or maybe they did this and they're doing so bad."
I looked at that and said, I mean, hundreds of thousands of data points and there is no one thing. All of these happen in concert, there are various things, and that's the way science works is that we need to, I don't really know how, but if this, if we can teach people this in any way, either the school or through outreach, that science is understanding of various things that happen at the same time in face of uncertainties. That's the way science works.
You cannot say with certainty that if you do this, this is gonna happen. That that never really happens. - Right. - And another thing I keep wondering when I look at this idea of combining these different kinds of data, as you were saying, you have a lot of data, but you're trying to combine different aspects, right? And I guess some of those aspects might have more data than others so something that maybe still could be important for modeling something maybe could be harder to collect data.
So, one in particular, when I looked at this online portal that you made is the number of people wearing face masks. I would assume this is something that's probably quite hard to measure.
- We had a way to do it, which is a number of people who were Googling face mask, which was not the best and one of the challenges, I mean, actually not the challenge, part of the scientific method is not just understand your data, but understand the errors or uncertainties, and that's not just for your data, but also for your models. We have to understand our model.
We had to understand our subject and our model, and we have to understand our data and our understanding, so those were all the challenges and these are challenges that we deal with in cosmology and we deal with in COVID so I try to kind of import those techniques in from cosmology to some extent. But yeah, the thing is you can never only focus on your model or your data. It's all, uncertainty is all aware. So uncertainty is the real boss, actually.
- Can I ask us to go a little bit back in time 'cause I'm so curious to know how and when you met. - You said you met me first, right? (Niayesh laughing) - No, I think you said, you heard me say something and then you could, you didn't have your glasses, so you couldn't see. - No, but I'm talking about before that, right? In high school. - Oh yeah, high school, that's right. No, that's true, I did, yes. - Oh, I didn't know there was a high school. - There was a high school.
- Vague, I mean vague meeting as in quotation mark. - Yes. - So apparently there was a, so there was this national competition for math and computer science and things. - In Iran? - In Iran, each province, for example, you do the first round and then you get to the second round and we both have made it to the national level. And then they took us on this one week competition trip that now from all provinces people go to do the second round so I was competing in math and computer science.
- Where was that contest? - The contest, the second round was in the city of Mashhad. So there weren't, I guess, many women who in the second round got prizes and stuff and apparently Niayesh says I remember a couple of girls went up there and got a trophy. I'm like, "Oh, that was me," so you met me. - Yeah, I didn't get anything in that prize and that competition. - So anyway. - How many students were in this competition? - The second round, I think maybe 100 in each topic.
- Probably 100, 150, I would think so. - So you both already had a strong inclination towards science and math at that point. - Math, yeah, so yeah. I had a good study group in high school, especially another friend. We really loved to do math problems. I didn't think I was good at computer science so that one, I just participated for fun. No, actually, which way it is? I think I did it the other way.
I wanted to compete in computer science, the math, I participated for fun because now I remember, so they had, the days of the test were alternating so the day we had the computer science test, the night before that, me and my friend was like, "Okay, let's sleep early, tomorrow we have to be focused." - Yeah, I don't know a lot of people who say, "Do you wanna go out and have fun by going to a computer science contest with me?" It's an interesting definition.
- I don't know, and then the math one, the math one, I would go like, "Oh, let's go do it." - Then the math one was for fun. - Yeah, honestly like so there was a, because there is a funniest story about it. So at the math one, you might have heard of Maryam Mirzakhani. So she was competing from Tehran and I was competing from this other city. I'm like, look at her. Obviously she had already won the math gold medal internationally the year before.
I'm like, "What am I doing here?" So she was doing and sitting like in the exam. I was looking at her and I was having sipping my snacks. The little I know I did very better in math. I won the silver medal. I'm like, "Oh, I should have tried a little bit harder." But anyway, yeah. - But that was just a sort of fleeting meeting. - And I guess, Ghazal, you don't remember meeting Niayesh, but Niayesh, you remember seeing.
- Yeah, I was in like in the auditorium, but somewhere down there and yeah, she was on the podium on the scene. So yeah, so that was that. I think Ghazal said you heard me. I was kicked out of the class. - Yes, so there was a modern physics course and then I didn't bring my glasses that day so I couldn't see very well the board, so I sat in the front row.
Apparently some students entered the class and we had this older professor who was very much into like etiquette of the class and pain and he got really upset, started, "What are you doing?" Like started kind of yelling at you, I think. - What were you doing wrong? - Because I was at another class. I was trying to take so many. That was like my first semester at college and I was trying. Like everything else I do, I wanted to do everything.
And there were different classes overlapping and somehow decided that maybe I could just miss the first 20 minutes of my class and yeah, but then my professor was, who we turned out to be great friends afterwards, but he kicked me out and I think I lost. - So yeah, I just heard like there was a boy there and then some of my friends said, "Oh, this is the guy who won the physics context Olympian." I'm like, "Ooh, like who is that guy?" - Who's this guy getting kicked out of the class?
- And then was it shortly after that that you actually started talking? - Then you said you came to my tutorial session. - Yeah, she had a tutorial. I remember she solved for the students, including me there that day. What is the shape of a string if you hang them from two points? Cosine hyperbolic. - And you were teaching that, Ghazal.
- Yeah, so then I was like a second year undergraduate student and the first year undergraduate approached us and say, "Would your higher year students want to do some problem-solving sessions for us?" And I said, "Sure, yeah." I volunteered to do that and I thought this is a very fun problem to solve. The math is very nice and beautiful so I was solving that on the board for them. - And you didn't kick him out of your tutorial? - No, I didn't. - No, she was a nice. - Show up on time?
- That I don't remember. - Yeah, I probably thought, "What is he doing here?" - And so this was undergrad, right? And then so what happened from there? - So then the fourth year, I think I saw him here and there. Niayesh didn't take actually many undergrad courses anymore. I think at some point after the first semester he decided to just go directly through grad courses and gave up.
And then one of our professor was planning to organize international workshop in one of the islands in Persian Gulf and so therefore in a year before that in preparation, he had started this cosmology courses and cosmology and he was learning, he was a GR person, general relativity, his specialty was general relativity, but he wanted to do the workshop on cosmology and said, "I'm learning myself." And he recruited some graduate students and maybe Niayesh as well and I think I heard about that.
So I signed up for the cosmology class. Niayesh already became the TA for me. That was not the other way around. There's another story about that, which I'm, and then meanwhile, another. - Which you're good to tell us. - Really still very upset about it, I can see that. - I think just the moral of that story is that if you are a TA you shouldn't date your students.
- So meanwhile, another professor suggested another interesting like project based for undergrads and he started the cosmology project and I think you and I. - Anyway, there were lots of different. - A lot of things, so we got to know each other and then gradually we started dating, but then meanwhile, he was my TA in this cosmology class. So the story that I'm upset about is because they give a midterm, he's proctoring the exam, I am a very like a slow writer.
I can never write in time, so right now I know like me being here, I know probably had a disability, I should have asked for extension, but anyway, the example had ended and halfway through, there's a lot of problems I haven't solve and Niayesh is like, "Okay, time's up," took my paper and went and I had another good friend, same took the course and then they, a couple of days later, they posted the marks and I was like the first mark or second mark or something
and then this friend of my teases me and says, "Haha, of course you're dating him." Got really upset and then I talked to him and I said, "Oh, did he say to that?" Because I gave him extra time. I let him take the exam home and bring it the next day. And they're like, "What are you talking about?" Anyway. - So you didn't get special treatment, somebody else did. - No, even like the first and then the other guy. I'm like, "Oh, gosh." - And yet here you are.
- Yeah, he should have been disciplined for that TA. - I should have been disciplined, yes. I was a very bad TA. (Niayesh laughing) - But I relate to you, Ghazal, 'cause for me, also writing in time was really hard and I never, I, yeah, I maybe also needed to ask about something, but I just can remember after exam season, I would carry all the stress of the exam in my hand, I think and then I would need a couple weeks after exams to recover.
My hand would just be so tense from all like from trying to write everything that was there so fast. And then so it was graduate school shortly after that? - And then they went to this workshop, cosmology workshop in Kish Island, very beautiful island. If you ever go to like Coral island, is it one of the few Coral islands in the world where like the water is so clear? Like it's all the beaches is just corals. And my supervisor was there and I guess- - Future supervisor.
- Future supervisor, PhD supervisor. Back then, like he was very willing to go to this like to Brazil, to Iran, to other places and recruit graduate students. I mean, like if he's also a good graduate student, he would support them. So we met him there, he was very impressed with me at Niayesh and we said, "Well, we haven't applied, but we know coming, going to US is extremely hard for Iranian student." He said, "Okay, you know, I'm gonna go there and you send your application.
We'll see how things go." And we didn't really have much hope because not many Iranians would make it to US. And it's a are very hard even to this day, like it's a hard decision. If you go there, you're trapped for few years, you won't see your families and a lot of other complications. But anyway, he went there and then we both applied and we got admissions. In the middle, had to do a lot of things. We had to go to a third country to do GRS exams.
We had to apply for visas couple of times, got rejected, then go to another country, apply again. So after a lot of hurdles, we finally got the visa and admission. - And then we got married.
- And then we said, okay, yeah, we were, yeah, we were dating and everything for a couple of years then but then we said, "Okay, we are not gonna see our parents probably for a long time and if we are planning to get married, let's do it and celebrate it with them before moving," which I think was a good thing. Like everybody celebrated and then we moved to US. - And then we disappear. - Okay, got married, bye. - Now you're married, you're both at Perimeter Institute and you have kids.
I wanted to bring up your kids partly because of the book that you wrote. Can you tell us a bit about the book and why you wrote it? - My son was, I mean, as it is probably with a lot of children, like they get really upset, obsessed about something like one day it's the, what is it, the Sphinx in Egypt. - Sounds like something they got from their father, maybe.
- Yeah, maybe, like then for a couple of months we are just looking and reading about Sphinx and Egypt and our whole future is planned to move to Egypt to live next to the pyramids. And then there is the like human body again, like, you know, there's a phase of that and there was a phase of the black holes, like he was obsessed, like what is it? And then I'm like, okay. - Did he know about them because of what you do for a living or did he see something?
- No, I think overall space is one of those things that children, maybe it's the impact of the media and outside world, or maybe it's like kids are maybe- - He must have seen it somewhere. - But it's not from you two are arguing over singularities? - No, if anything, we probably have the reverse. - We try to keep them protected from hostile events. - Yesterday our younger son was watching something about the space on YouTube and Niayesh was like, "I don't wanna listen.
There's so many mistakes in that video." - And how old was your son when he started getting interested in black holes? - So he was almost four. - Wow. - So at that point I'm like, okay, obviously it's too soon to teach him any science, but still there's like a, I maybe I can do a small, very short story to not scientific, to include not scientifically wrong things in it, but at the same time, be just a story, you know, just like keep his mind entertained, read it to him.
- Well it's great too 'cause you have this guide for parents or teachers as well that goes a little bit deeper so you can give the book to the four-year-old and then the parents can learn a little bit more.
- I think so, I think it all, like I learn a lot because of my children in other topics that are not my specialty when they become interested in something and then he brings up the book and then I get curious, okay, what is the actual thing that is happening is you're learning about this country or geography or this plant or something else.
So I feel like it's very good bonding experiments and educational experience for parents and child if they read together things so that's why I included the guide, so if you're reading about it, they also learn a little bit about the science behind it. - For the people with, who are watching, could you show us, it's called "Bella, the Black Hole." - Yes, "Bella, the Black Hole." - Would you mind reading us a little bit? - Okay, sure.
- I wanna say it's also beautifully illustrated and I believe it's illustrated by a relative, is that right? - Yes, Niayesh's cousin, Nasim Abaeian in Toronto. I like her work. - She's an illustrator. - And it does have a little bit of a Middle Eastern teaming to it, like I feel like. - Yeah, it does. Like you said, it's scientifically accurate, but it's obviously not scientifically detailed, so that's a challenge to write for a child, to comprehend without getting the essential truth wrong.
- Yeah and I'm hoping like even as they get older, they look back at it and like, "Oh, what did she mean by that? Maybe I have to go read a little bit more about this." "My name is Bella. I am a very shiny and hot star. Do you know another star? Yes, our sun is a star too. I'm younger, but much bigger than the sun. Gravity wants to squeeze me." - I like that that's just one page in itself. Like what a beautiful condensation of an idea, wants to squeeze me.
- It's not easy to condense these content things into one phrase like that. - We all had to meet the actual motions that we had to squeeze the child at that point. - Oh, is this a participatory book? - Yes. I remember that's how it went, but it's been a while. - "But the pressure from hot gas pushes me back. At last I get tired and gravity wins." - I think you should maybe not finish it. - Leave the rest of it. (all laughing) - The origin story. - A cliffhanger. - Yeah, cliffhanger.
- So I'm not gonna of spoiled the end of it, but I guess from the name there's a black hole appearing. - Somewhere, yeah. - And what was your son's reaction to this book? - I think he really loves like those action motion, like the pushing and gravity and like and then. - There's spaghetti in there. - Spaghetti. - Actually, can you explain the spaghetti reference 'cause it does actually, spaghetti has a scientific sort of black hole meaning.
- Right, so spaghettification, that's the term, I guess, that as we get pulled into a big black hole, stellar black holes, right? Is that the. - Well, any, depends on how close you get. - Yeah and then people have this idea that they would just let go inside nicely, but that's not how it's gonna happen, unfortunately. They're gonna, does this interstella have the, they don't they go, that movie. - The movie.
They have a very big back hole, so this- - Okay, so that's when they just went in, like thinking there they went in without anything happening to them. - I don't think they got spaghettified. - No, they didn't, right, but in this one she gets pulled and get the title, you start to get stretched and stretched and then become like a spaghetti, so there is not really much of you that's gonna make it inside.
- It's nice that you could write about something that is kind of, that idea is kind of scary, but in the book, Bella is this lovable character who's explaining her life cycle. - And then you can see inside the mom or parents' mind that what they're struggling at that point, like between the different foods, like, you know, eat the broccoli, but no spaghetti.
(all laughing) - And Niayesh, I know you also have a book that you're working on and I know we're not gonna give away too many details, but do you wanna say, is there anything you wanna say about that? - Yeah, it's gonna be a slightly more elaborate version, but yeah, but more focused on the Big Bang and various ideas and characters that are involved. - Just to be clear, not a kid's book, right? This is a popular. - Yeah, I think kids' parents could read it.
Yeah, so this is going to be a popular audience. I hope teenagers could enjoy it, but we'll see. I don't actually know how much of it I can give away. I feel like I can hardly control myself, but it's gonna come out hopefully within a year or so and it's more about the Big Bang and various people and characters involved. - Another cliffhanger. - Another cliffhanger, yes. - First we have to finish reading "Bella, the Black Hole." - Yes. - That's a prerequisite, I guess.
- Exactly, start with that, and then we gonna build up our way to the bigger, the other one. - Well, another thing I really wanna make sure we ask you both about is that you're both quite involved in outreach and versed in writing books and in other forms as well and you're also both advocates for equity, diversity and inclusion, EDI, within academia. For example, Ghazal, I know you're involved with the Supernova Foundation and a few other initiatives.
Can you maybe tell us a little bit about some of these initiatives you're involved in? - EDI is quite close to my heart because I mean the journeys I've gone through to make it to today, still being able to do research has been, as I mentioned, alluded to, it hasn't been easy. - You mentioned you were the one of two women on stage in your high school contest.
- So there is a pre-immigrant phase, which I had to deal with certain things being a woman and being in science and being in math, it had its own hardship. Then being a Middle Eastern from a certain country in North America, we had to deal with another set of problems and then having a two-body problem, which is often a lot of women physicists have to deal with. I think a good proportion of them have two-body problems. - Can you tell us what that phrase means for people who might not know?
- Oh yes. So for some reason, female physicists also, their partners are also academics and therefore finding two academic jobs in the same location is quite hard, so we refer to this as a two-body problem where one body finding a second job or having two in the same institution or at the same city is quite hard. - I mean, finding even one is hard, so finding two is less possible.
- Exactly, and we have been through so many things over the years, like I had to, even pregnant with this guy, this little kind of older one, the closest job I could find here was in Buffalo. So pregnant, I had to travel back and forth to work, crossover, come back and like. - Was it like five days before he was born that we crossed the border? - Yes, also crossed. I'm glad I didn't know this, but things could get complicated if he didn't come right on time.
Because I was like, "Oh, it's no big deal. If I'm having a delivery, I'm just gonna go to the hospital." But like apparently not, no. That could be risky driving alone and going. But anyway, and I mean, again, not adding two-body problem, having families in academia, all of this have a lot of challenges so marginalized community have that on top of everything else as well so what can we do to help out?
I mean, I feel like I might not be able to move mountains, but even if I can help one person, that's my goal. I have done something, right? The little things we can do and one thing that we notice, a lot of places, a lot of challenges are easier to tackle if you have a network, if you have a friend who is there with you and can hold your hands.
And especially if they're a little bit ahead in your road and can tell you like, you know, "I faced the same thing, don't doubt yourself, you might be able to do that or there's a strategy. Like why don't you talk to another person or put you in contact with someone else?" So this Supernova Foundation came out of this idea.
The original story was that another friend in Ames, the director of cosmology group there, used to organize undergrad workshops in Moreshas, so we went for one of those, similar to what my supervisor did for us, I guess.
After a couple of years, I think we went there in 2013 and 2015 or '14, he contacted me and a few of other women who had participated and said, "What I'm noticing in this small scale community is that the students that come to our workshop, we have seen some of the men go to graduate school, but none of the women, is there anything we can do?" So seven of us, three from the people we met in a workshop, Michelle Lochner and Valeria Paterness. Michelle is in South Africa. Valeria is- - Katerina.
- Katerina is now based in Paris, France. So we volunteered to start something. I came back to my friends at Perimeter. - Nasipia Swaney. - Nasipia Swaney, Chiamata Otaley, and Sarah Chanderra. I recruited them and Renna Logic who is now professor in Toronto. Seven of us started with eight mentors. We said, "Just do whatever we can do." Like every couple of months, let's talk to this women, how they're holding up and it was not easy.
We didn't have the experience of doing this kind of work before, but at least one of those women made it to graduate school and followed up and then on to pursue her area or dreams in physics.
And then we thought about, okay, if there's only seven of us, what if there were more of us and we could have other women who can help and out of this came this a story of Supernova Foundation with no financial support, with no administration support, no nothing, just women physicists volunteering their time and good heart decided to help other women, undergraduate women in physics who are in other places who need someone else like a mentor.
Michelle put a lot of time and work into the, a little bit of like website development on that side of it. Mom D. Knight became our program administrator for free. And now I think we have around 300 mentees, 100 mentors. We have a long waiting list because unfortunately we cannot accommodate anybody.
If you will go to our website, it shows the globe and they have like anywhere from Brazil, Argentina to India and other Africa, other places, women who taking part and what we learned through this process, first of all, I learned a lot. This was a learning curve for me like how to be a good mentor. What are your role as a mentor? You are not supervisor, you are not a counselor. What things can you do to help?
But also we realize we are helping each other too, like just connecting marginalized people to each other, having a network for them to talk to each other, not to feel helpless or alone and isolated, that by itself is a big step. A lot of times it's like maybe a senior physicist asking another senior physicist, "What did you do when you had this thing?" Like, if you are in part of this collaboration and things like, it's come up, how do you handle that?
And so far working, we are growing quite fast. So we don't know, we are planning to maybe restructure it to make it more sustainable to accommodate the growth, but let's see how it goes. - And so the mentees are mostly around graduate level? - No, they're mostly undergraduate, but sometimes master students.
So now we are thinking of restructuring it, maybe we can do, so when we started, we would even have PhD students mentor undergraduate students, but now we are thinking, because as we learn, like sometimes a younger postdoc needs a mentor from the faculty or a graduate student who learned from a postdoc so we might do a little bit of restructuring, but the original plan was graduate student and higher mentoring undergraduate. And we started having even taking master's students.
I have had master students mentees just recently, like one of my mentees, have to brag about it. She's interviewing like top schools in the world, has like admissions, like, oh my God. - That's great, sounds like the kind of thing that would've been helpful if it had been around when you were their age.
- I think so, I mean, I know so many people and broke my heart along the way that we lost, right, because I make this analogy other places too, I'm saying this is like a, for marginalized people climbing the academic ladder is like a ladder which is constantly shaking so you keep losing people along the way and I've seen it, like I've seen it in my lifetime, like so far in my career how many we have lost along the way. - And it's hard because this is such a big problem.
I think so many people don't know where to start and I just love what you said a little while back that you can start with something that maybe seems small at the time. Now this has grown into something that's not at all small, but you started with something small that you thought would be helpful and that can take you into something that can really make a big difference later on. - Yeah and I feel like it fills into like, again, my personality, like we discussed this. Niayesh is big picture.
I'm gonna change and come around like, let's just focus. Let's see what I can do here and see how it goes. - It takes both types. - Yeah, exactly, both are very important. - Nice of you to say. - Niayesh, do you have like big picture ideas or? - Actually, I mean, Ghazal is the expert. Actually I have a feeling, I mean, she's, maybe we have a little bit of a role also because I Ghazal is, she's also, am I saying you're the president of the women in math in Waterloo. - Chair of the women.
- The chair of the women in math, so she has kind of the Supernova Foundation, I think it's a great, it's such a big project now, even though it started small and also all this stuff she's doing it, the women in math in Waterloo, at the University of Waterloo. I'm still at the level of helping one person at the time so I haven't really have as big of an ambition, but I try to do my best in this regard.
- Well, we have one more question that was sent in by another student, so maybe we can play that one. - I'm Matt Duchen, a PT student at Perimeter. What do you think each other's most interesting and exciting contributions have been? - We've talked about- - For the listener, they looked at each other and didn't answer this. - Well, I'm laughing because I sometimes do these interviews, postdoc interviews, and this is what I ask. - Really? - Now I'm on the hot seat.
(all laughing) - Now, but you're supposed to say that about me, right? - I think that's the question, yeah. - You brag about his contributions and vice versa. - Or bad. Doesn't have to be brag, it's okay. - Yeah, I think that cross-correlation, that was a, I think that Niayesh was a pioneer in this era.
Now it's, I mean, not that I'm saying not gonna be as big, but I'm saying that one is now tested and grown and it was a big contribution to the field, how we can extract some actual physics and separate these things out of such tiny signals in different parts of data or completely different datasets, I guess. - And I don't even think we asked you about that, Niayesh, about these black hole echoes. Do you wanna tell us a little bit about that? - It's entirely not your fault.
I do so many different things. Like each of them is like a black hole. I actually did work on actual black holes as well. So the story of echos, which I think Ghazal was alleging to, as maybe not the most exciting thing I do, but you see, maybe time will tell. So this is started with seeing LIGO gravitational waves around five or six years ago, which they won the Nobel prize for.
But in fact, it's amazing thing because it opened this door for us for looking deep into places where gravity is very, very strong, basically as strong as it gets, these back holes that we knew about them before. Like for example, from Event Horizon Telescope picture, you knew there is some place where gravity is as strong, but it was very hard to get very deep because basically just light stops at some point.
And gravitational waves actually can get deeper because gravitational waves are actually weakly interacting with matter, so they can probe very, very deeply into places where we know gravity should break these singularities we were talking about. Now, whether they will actually get there is a matter of debate since LIGO discovery gravitational waves, I've thought about this problem a lot and we've written papers on this with my students in the past five years or so.
I think it's kind of inevitable that if quantum mechanics is somewhere united with gravity, at some point, then black holes cannot be these bottomless pits that basically general relativity tells us. General relativity tells us that, I mean, black holes are, don't have any end. Basically things fall in and keep going in and in and in and never really, nobody from outside will never hear you hitting the bottom of a black hole. According to Einstein, that's a one-way street.
But if you believe in quantum mechanics, it cannot be, there should be a finite demand of a space there, so eventually, you gotta hit the bottom and you're gonna hear back and those are the echoes that we've kind of been exploring for a while. I think it's an opportune time 'cause the first time you can actually hear back holes, but also hear them so deeply basically, just when they're forming and basically you can see basically down into the very bottom of them.
We think echos is a possible signature of what could be sitting at the bottom of the back hole and a very opportunistic time to basically looking for this. I mean there is no guarantee, but I think that's what I'm most excited about.
Also Ghazal has had a lot of interesting and influential works, but I mean, she talked about some of them, for example, how Cuscutan could help us balance the universe, the contracting universe could become expanding, but probably the most important, exciting thing is that she showed, I mean the very early universe, at least one of the three tenants of, I mean physics as we know it should break down, it's either that you need to have negative pressure, that inflationary phase like we do now,
but if you don't do that, you either get propagation faster than the speed of light or you need some quantum gravity effect basically. So she actually proved the theorem to that effect, so it's a technical work, but it's a solid technical work in the spirit of the kind of thing that she does, that they're all, she crosses all the Ts and dots all the Is so that there's no doubt left. That's what's happening.
If you think you know, there are three possibilities, thanks to Ghazal we know in the early universe and everything else people have thought about falls under those three. - I guess, to explain that empirically, we noticed it, that people are coming with these scenarios, but I noticed that they either fall into one of these three and again, okay, why is that? There should be a reason for that, that people are coming up only with these three different possibilities.
- So she proved the theorem that these are the only three possibilities. - That's why it is happening. - Seems like both of these contributions you're mentioning really speak to each of your strengths and your unique approaches to research. It's neat to hear. - Thank you so much for joining us. It's just been- - Thank you, thank you for inviting us. We enjoyed the conversation. - It's a lot of fun, thank you very much for having us. (gentle music) - Thanks so much for listening.
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