What is…Dark Matter? with Mark Richardson and Renée Hložek


Why are we talking about dark matter at an art museum? What even IS dark matter (spoiler: scientists still aren’t totally sure)? Mark Richardson and Renée Hložek present a dark matter 101, discuss creativity in scientific research and how this links to the exhibition “Drift: Art and Dark Matter.”

Speaker Biographies
Mark Richardson is the Education and Outreach Officer at the Arthur B. McDonald Canadian Astroparticle Physics Research Institute. Richardson was born and raised in Halifax, Nova Scotia, where he fell in love with the night skies. After completing a Bachelor of Science in Astrophysics at Saint Mary’s University, he escaped the winter weather and did a PhD in Astrophysics at Arizona State University. Richardson studies how galaxies form and change over time in an effort to understand our own place in the cosmos. He has since held research positions at Oxford University and the American Museum of Natural History in New York and joined Queen’s University and the McDonald Institute in 2018.

Renée Hložek is Assistant Professor at the Dunlap Institute of Astronomy and Astrophysics and the Department of Astronomy and Astrophysics at University of Toronto. She uses data from telescopes around the world to understand how the universe started, what it is made of, and how it changes with time. She was born in Pretoria, South Africa where she completed her undergraduate degree. She completed her DPhil at Oxford University in 2011 as a South African Rhodes Scholar. After four years as the Lyman Spitzer Fellow at Princeton University, she moved to Toronto in 2016. She has collaborated with artist Pamela Neil and Anishinabek innovator Melanie Goodchild on an oral performance piece our manifest galaxy about space exploration and colonization and artist Caecilia Tripp on Interstellar Sleep at the Sharjah Biennial’ and Going Space and Other Worlding at the AGYU, Toronto Biennale. She was recently named a 2019 CIFAR Azrieli Global Scholar, a 2020 Sloan Fellow and is a TED Senior Fellow.

Image: Josèfa Ntjam, “Organic Nebula,” 2019, carpet, photomontage. Collection of the artistWhy are we talking about dark matter at an art museum? What even IS dark matter (spoiler: scientists still aren’t totally sure)? Mark Richardson and Renée Hložek present a dark matter 101, discuss creativity in scientific research and how this links to the exhibition “Drift: Art and Dark Matter.” …


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What is the Universe
What is the Universe

What is the Universe


What is Dark Matter
What is Dark Matter

What is Dark Matter


How to detect Dark Matter
How to detect Dark Matter

How to detect Dark Matter


Snow Lab
Snow Lab

Snow Lab


Dark Matter Detection
Dark Matter Detection

Dark Matter Detection


What If
What If

What If


Fibonacci Sequence
Fibonacci Sequence

Fibonacci Sequence


Autogenerated Transcript from YouTube (if available)

Use CTRL+F to find key words if it is a longer transcript​.



thanks for joining us this afternoon everyone my name is charlotte gagne and i’m the program assistant at agnes etherington art center


i’d like to begin by acknowledging that queen’s university and agnes etherington arts center are situated on traditional anishinaabe and


haudenosaunee territory this is also where i’m joining you from today so to acknowledge this territory


is to recognize its longer history one predating the establishment of the earliest european colonies


it’s also to acknowledge this territory’s significance for indigenous peoples who lived and continued to live


upon it people whose practices and spiritualities were tied to land and continued to develop


in relationship to the territory and its other inhabitants today the kingston indigenous community


continues to reflect the area’s anishinaabeg and haudenosaunee routes and is also a significant metis community and there are first peoples


from other nations across turtle island present here today um as i share this i’m thinking about


how i can move from saying to acting and i know that i have a lot to learn and unlearn


i move to think about my own positionality and the privileges that have led me to being able to live here and work and what


reconciliation looks like for me as a settler i also welcome you to spend some time


researching and reflecting on the land that you’re coming from and to consider how you can contribute to the work of decolonizing your


institutions your communities and your minds uh and it’s lovely to see everyone


sharing the comments i can see lots of people from kingston joining us from ottawa someone from texas


so without further ado we’d like to welcome you to the first iteration of our new series what is uh the impetus for this series is to


take big topics relating to current agnes exhibitions in this case drift uh and discuss them in a casual


and accessible way so discuss these concepts uh so today renee and mark will be discussing


dark matter and how and how it connects it eventually to drift art and dark matter the current exhibition


so renee flores is the assistant professor at the dunlap institute of astronomy and astrophysics


astrophysics and the department of astronomy and astrophysics at university toronto


she uses data from telescopes around the world to understand how the universe started what it’s made


of and how it changes with time she was born in pretoria south africa where she


completed her undergraduate degree she completed her d fill at oxford in 2011


as a south african rhodes scholar after four years as the lyman spitzer


fellow at princeton university she moved to toronto in 2016. she’s collaborated with artists pamela


neal and anishnabek innovator melanie goodchild on an oral performance piece our manifest galaxy about space


exploration and colonization and the artist cecilia tripp on the interstellar sleep


at the sharjah uh biennale and going space and other worlding at agyu toronto being alley


she was recently named a 2019 c-i-f-a-r uh as really global scholar a 2020


sloane fellow and she is a ted senior fellow


our other speaker mark richardson is the education and outreach officer at the arthur b mcdonald canadian


astroparticle physics research institute and an adjunct professor at queen’s university


mark was born and raised in halifax nova scotia where he fell in love with the night skies after completing a bachelor of science


in astrophysics at st mary’s university he escaped the winter weather and did a phd in astrophysics at arizona state


university mark studies had galaxies form and change over time in an effort to understand how our own


place in an effort to stand understand our own place in the cosmos he has since held research positions at


oxford university and the american museum of natural history in new york and he joined


queen’s university and mcdonald institute in 2018. so welcome to renee and mark i’m really


excited to uh watch your presentation learn a bit more about um


astrophysics uh cosmology and dark matter so i’d like to hand it over to you now and welcome you


thank you so much charlotte it’s really great to be here um i’m super excited for everyone to um


engage with the agnes um drift and dark matter exhibit and i know we’re going to talk about that a little bit at the end


um but uh in order to get us excited about what dark matter is we need to


sort of set the stage for this cosmic mystery this cosmic conundrum


that i am lucky enough to get to try and answer and address um in my job um so let’s get started


um i um it’s yeah absolutely so let’s take it

What is the Universe


away this is actually me in cartoon form giving you a super brief introduction into what we’re going


to be talking about today


[Music] looking up at the night sky we are amazed by how it seems to go on forever


but what will the sky look like billions of years from now a particular type of scientist called a cosmologist spends her time


thinking about that very question the end of the universe is intimately linked to what the universe contains


over 100 years ago einstein developed the theory of general relativity formed of equations that help us


understand the relationship between what a universe is made of and its shape it turns out that the


universe could be curved like a ball or sphere we call this positively curved or closed or it could be shaped like a saddle we


call this negatively curved or open or it could be flat and that shape determines how the


universe will live and die we now know that the universe is very close to flat however


the components of the universe can still affect its eventual fate we can predict how the universe will


change with time if we measure the amounts or energy densities of the various components in


the universe today so what is the universe made of so this contains all the things


sorry thank you so much so the rest of the video please um look it up and take a take a look at it


but the key question that um we address as cosmologists and astrophysicists


is understanding what the universe is made of and this is really connected to


everything else it seems like uh we would just be done because there’s a lot of stuff in the universe and we can measure it


but it’s not only important to understand what the universe is made of because we care about the universe in


general but it actually sets um how the sky behaves and how galaxies cluster and form


and as a corollary you can actually look at observations of the night sky and


things um clustering galaxies moving in the sky and you can kind of back out what the


universe is made of and that’s a lot of what i do as an astrophysicist is i do that sort of reverse i look at


the sky and i say can i understand how what the universe contains based on what i


see and if we go to the next slide i’ll illustrate this in a really simple example so later


tonight if you have a glass of wine and maybe you have some candles because it feels good like spring is coming i want you to hold


up the bottom of the glass over the candle flame and what you’ll notice is as you get closer


to being completely in front of the candle flame with the lens and completely face on


and you’ll go from sort of stretchy uh wibbly bits and to a full circle


and that we can understand just in terms of optics the glass is acting like a lens and it is


distorting the path of the light of the candle um as on the way to your eyes on the way


to your eyes and so the stuff of the lens distorts the light now that’s the kind of thing that we


would teach children in high school which is fantastic but what is so incredible to me is that


the same physical principle works in space and so we actually can look at a picture


of galaxy clusters this is the galaxy the abell cluster 2218 and we see the same thing so what are we


looking at here what you’ll notice is that in the foreground there are these big clusters of galaxies


these big fuzzy blobs all together that makes a galaxy cluster these are massive elliptical galaxies


and there’s a lot of stuff in that galaxy cluster the sort of stretched out


bits that you see are background galaxies which is sort of like the analog of the candle flame and the light of


those galaxies has been stretched out by all the mass in this galaxy cluster


in exactly the same way that that um glass is is moving the candle uh the light from the candle


and so we can do this we can say well if we measure the distortion of the light can we learn something about the mass


that’s doing the distortion and can we learn something about that lens and we do just that


what we find is that there is too much distortion relative to the galaxies


that we can actually see with our eyes and so we make these measurements to try and figure out


um what the universe is made of and if we actually just add up all the things we can see


so neutrinos and stars and gas and planets all the things that we can


see we actually only make up a fraction of the total stuff in the universe we know from


observations of the galaxy cluster i just showed you that that a lot of the universe has to


be dark in fact we think that about a quarter of the total stuff in the universe


is made of dark matter and it’s dark matter is a bit of a misnomer we should really say


matter that we can’t uh see because it’s not like actually black it’s just that it isn’t interacting with light


and we’re going to get into that in a lot more detail there’s also a lot of dark energy which isn’t the topic of our


talk today but it’s also super super interesting and something i work on


so if we go to the next slide why uh how can we live in a universe where

What is Dark Matter


we don’t understand the majority of the stuff in the universe we know that it is there because we see


observations of the night sky and observation and i mentioned one galaxy cluster but i should say we have multiple different


examples of um observations that suggest that dark matter is there


so most of the universe is dark and it but what do i actually mean by dark


because uh as i said it seems like i’m saying you know blackness in the sky and it’s really important to be quite


clear scientifically what me what we mean by dark okay so we uh know that in general if you


you can either give off light so this is a movie of the sun it’s actually an hour long if you want


to go and look it up on youtube we’re only going to show you just a few seconds of this


but every second in this video is a day and so you’ll see how the sun is being


super active and we think the sun is a reasonably typical star there’s nothing special


about it thanks mark but you see the sun is giving off light now you can either give off light like


the sun or you can reflect light this is a lovely um artistic photo that i found of a


building reflecting light and so the only reason that you know i’m here today is because the light in this room is bouncing off


my skin and that means you can see me so my body the material in my body is interacting


with light um i also am making my own light if you looked in infrared goggles you would actually see that i’m glowing


maybe a little bit more now because i’m nervous giving a talk but i give off my own light so you and i we give off light and we reflect light


and that’s how you know we’re here dark matter doesn’t do in either of those things efficiently


and so when we say it’s dark we mean that it doesn’t reflect light and it doesn’t make its own light


and so that makes it really really difficult to find um and that’s partly why it’s so


exciting uh next slide okay


how what observations can we look at i showed you the abel cluster from before


and there are many other observations um and what i’m going to show you now is what we do we measure um we take


observations of the sky but we measure them in different frequencies of light and the frequencies of light give you


different um insights into the physics that’s happening so if we look at an optical galaxy this is something called the


bullet cluster you’ll see why it’s called the bullet cluster in a second but if i take an observation from the


hubble space from a ground-based optical telescope it’s interesting there lots of stars and galaxies but there’s nothing


particularly special about it you just see clusters of galaxies if i then move to looking at it instead


in um a different wavelength so i think the next one we have actually is uh um gas observations oh


the next one is dark matter okay so thanks thanks moxie i’ll stick on the gas so if i look at it in x-ray gas if i


take x-ray um observations then i’m actually sensitive to what the electrons are doing in this cluster we know that there


are lots of electrons in a gas and they’re very hot and what you can actually see


is that it looks like one of these galaxy clusters has kind of moved through the other one you actually


see the kind of shock that you would imagine from a bullet so as mark is pointing out now


very kindly with his mouse the one galaxy really looks like the gas has moved through the other galaxy


and there’s a shock but if we use weak lensing observations like the candle example i talked about earlier


we can look at the gam the galaxy cluster in weak landing and we can see where the mass actually is


and the dark matter it hasn’t really moved at all it’s almost as if those two galaxies just passed through each other


without any shock waves without any interactions and that’s what we mean by dark matter not interacting it can


pass through um it’s you know two pieces of dark matter can pass through um it themselves without having strong


interactions and that makes it really difficult but very exciting so when we’re trying to understand the full picture of this


cluster we actually really need to look at it in optical x-ray and make measurements


of where we think the dark matter is based on um the observations that that we see so it’s incredibly exciting


to be able to make measurements and to look and think about you know what the universe is made of because


it gives us this pie chart this cosmic energy budget but what i haven’t actually done is told


you anything about what dark matter is and mark is going to take us in another journey where we actually think


well how could we actually figure out what it is yeah thanks renee so i’ll actually start


with this picture so this is giving us information about kind of what it does right it’s clearly it has gravity and


it’s it’s showing its effect but it doesn’t kind of reveal itself i kind of think


about um maybe like you go out in the woods when we used to have snow it’s all gone


now at least here um and maybe you see footprints so you know there’s something there leaving its its impact but you don’t


know whether it’s an elephant or maybe a fox um and so you know it’s given us these


hints these clues that it exists there’s this dark matter there’s this stuff that has gravity it’s having this


gravitational effect like everything else but it’s not like something that we’ve ever studied in a lab it’s not something


we can do cool experiments with and confirm its nature and so all we have right now are just


really cool ideas and so what are some of those ideas i’m gonna start with um probably the favorite at the


mcdonald institute and that is dark matter could it just be like everything else after all


and what do i mean when i say everything else well i mean you me um the planets that renee spoke


about the lego castles that you or maybe your kids but i certainly encourage adults to keep playing with


lego um and the stars around us maybe it’s needed the same kind of stuff as those


and of course when you think about lego castles you know that they’re made out of these smaller pieces of lego and you


can’t break them up any smaller you can certainly step on them and hurt your foot but actually you know you can take maybe


a saw to them or scissors and cut them up even smaller and you get down to the smallest bits of the universe the particles that make up


everything you and me and the lego particles and the sun and what’s really neat is if you do this


to everything we know of in the universe you end up getting down to about 17 different types of particles that we


we know exist and we study them in labs and we can explore um these different uh particles


and um so there’s 17 of them and they actually all fit onto this nice chart of what is the standard model of


elementary particles and in fact you and me and everything that we meet on


every part of our day is actually just made of these three here two quarks and the electron that make up


all the electronics that we use and so uh those make up the vast majority of what we do


uh see and study unless you have really really energetic labs you can study some of these other


other 14 particles okay so if we know everything that we study in


labs that we can tangibly kind of see and experiment with is one of these 17 particles


a really cool idea is that dark matter something like these it just interacts very rarely very


weakly and so we call it a weakly interacting massive particle


that’s that’s one of these leading theories that it is sometimes known as a wimp um and uh and if that’s the case


then um that could be quite exciting because everything else is a particle as well so all we know of


is a particle these 17 particles they fit onto this pie chart i’ve thrown out the dark energy from


renee’s uh pie chart and we’re just focusing on the stuff that’s matter and so there’s kind of 25 versus


five five percent of everything in the universe like get rid of dark uh energy i’m left with matter is about


85 of this dark matter and then the 15 of the stuff that you and i see the


computer that we’re looking through today the desk in front of me and so of course the question that we’re trying to ask is what is dark matter


because what i’m saying with this idea of weakly interacting mass of particle is maybe itself is a particle and if it is and


something we can study in a lab then we can find where it belongs on this table and it becomes just like


everything else it just seems to be very difficult to find and that would kind of unite


this idea of dark matter and regular matter being the same kind of stuff just one is a bit more elusive like the


camouflaged rabbit in winter but if it’s a particle how could we detect it um

How to detect Dark Matter


this is a great theory it everything else we know of in the universe is a particle that we get to interact


with so it makes sense that maybe dark matter is this particle as well we want to confirm that theory we want


to do cool science find it in a lab um or maybe somewhere else in the universe and be able to study it


so how do you go about studying a particle and particularly dark matter as a particle there’s about three different


ways you can go about doing this and we call them affectionately the make it break it or shake it approaches


and so the first of these is to make it and maybe you’re familiar with cern this really energetic


um particle accelerator in europe it actually crosses the france and switzerland borders and in it


we have these abilities to accelerate particles extremely quickly and have them smash into each other and


you can kind of imagine this if you didn’t know anything about quantum mechanics it kind of makes sense if you have maybe two pocket watches you


accelerate really really quickly and smash them together they break apart and that’s how you find all the little pieces


that make up those watches quantum mechanics is even weirder you can smash particles together and when they break


apart they make other stuff that wasn’t even there to begin with and one of those things that you can make in this kind of collision is


dark matter and so there’s a lot of researchers are trying to do just this that at


places like cern they accelerate these particles together and when they smash they make all these other kind of particles and actually


these kind of interactions that helped us reveal those other 14 particles on that table


ones that are difficult to form they’re rare but we have found them and so the idea is maybe with getting


more energy we’re able to make dark matter of course it’s difficult in this situation because dark matter interacts


rarely if it’s a particle and so you won’t actually detect it in here what you do is you detect it’s


missing you’re putting in very specific amounts of energy and mass when it maybe it makes dark matter that


leaves the system and so when you kind of account for the energy and mass at the end what do you see you see that that amount


of energy or mass that’s in the dark matter has left the system you don’t measure it and so that’s what these experiments are


looking for is you know how much you put in if what you get out is lower then you know something


got away without being detected this is a very difficult experiment to run and so


before we could ever be certain we found that you’d have to do lots of confirmation across different types of experiments


and uh lots of really cool work is moving on that so that’s one of the three ways we could


try to detect the particle the make it approach the next one is


break it and this is where the universe does the job for us and so we go back to these really cool


astronomical um objects these huge structures like the uh the bullet cluster that rene


highlighted and here we see that from all these weak lensing measurements


that we can determine where dark matter is located in these pictures and something you don’t really see with


your naked eye with how how sensitive you are to the color blue but there’s actually more of this dark


matter at the center of this blue halo than at the outer outskirts so the center of these


clusters particularly ones that aren’t running into other clusters it is found from these kind of


observations that dark matter seems to kind of be a bit clumpy and really really clumpy at the center of these clusters


and so universe the the universe through its like use of gravity seems to be kind of doing the job for us


and making kind of a cosmic accelerator at the center of these clusters where dark matter is dense and it


actually is probably moving pretty fast and so that could be an interesting place where dark matter could actually


hit itself and when this happens it will actually maybe convert into stuff that we are used to seeing things


like light or other really energetic particles of course there’s lots of um so there


are actual observations of um of this kind of excess light coming from the center of galaxies and


it’s a big question is is this a sign of dark matter is it a sign of just really massive supermassive


black holes at the center that are creating this energy is it star formation


and to answer those questions we have to go to these cool simulations or we put in everything that we think we understand


about the laws of physics and they are able to fortunately take the millions of years that we would have


to wait as astronomers to see these galaxies interact with each other and recreate them in the computer over maybe


a month and or or the big ones like this one i think took about a year or so


and when you do these simulations you’re recreating these environments and we can now do comparisons and say like is


could dark matter be uh able to explain what we see and this is kind of this idea of


confirming these these these this data these experiments by recreating what we think we understand


about the systems and so these simulations are very very effective for basically saying if dark matter behaves in this way if it


is this kind of weakly interacting massive particle then it should be seen using x-rays or


whatnot and we’re able to confirm that between observations and these theories


and so this is the idea of breaking it it’s very hard uh uh process to do to try to detect these


because there’s so much kind of messy physics involved at the center of these objects but a lot of really cool uh scientists


are working on just that now the last way that you can try to detect these particles is the shake it


and i’m all about the dances so um i i will always like to shake it to the particles


and so one of the ways we do this is you build a detector and you wait for dark matter to basically hit your


detector and shake your detector and so this is a detector that we have at the mcdonald institute


called a cloud chamber and it’s specifically designed to measure some particles unfortunately


not dark matter and you can see it in action here you should be able to see a collection of different particles this is a muon


coming in which is the heavier cousin of the electron you see these little


tracks those are uh the electron particles the beta particles and then there was a particle that you just saw there called an alpha


particle so this and and all of these particles um are coming from maybe radioactive gas


in the air some of them are coming from energetic particles from outer space hitting the earth’s atmosphere


and you can see it’s extremely busy we can make it even busier if i put in some more radioactive gas


into the cloud chamber and you can see these alpha particles are going crazy you get a lot of them


and so it’s with this kind of technology where particles are kind of shaking your detector that you can study the nature of those


particles but this is happening very often this isn’t sped up in any way you’re seeing


this live and dark matter as we’ve seen seems to interact very rarely we’ve never detected it before


so if we want to detect that we need to we need to um be a little bit more sensitive and so


what i’m kind of picturing here is we need to build some other kind of detector not a cloud chamber that’s going to be very sensitive um


to maybe this special type of particle and so what you can imagine is we have the idea the theory that dark matter


sits on this collection of other 17 particles maybe we can build a special


detector not a cloud table but i’m using a picture of a cloud chamber and wait for that particle to come along


and shake our detector and so that’s what’s happening at a place called snow lab


and so if you remember the cloud chamber it was going on and on always seeing


these particles and that’s because they’re coming in from outer space and so this is an animation they made by zach kenney the


communications office of the mcdonald institute showing you where some of those particles are coming from but fortunately if you go deep


underground you start having so much earth above you that it prevents many of those particles from hitting your detector and the only ones that are


likely to get through are the ones that interact very rarely like perhaps a dark matter particle that could interact with your


detector and so the next part of our journey today about the effort of what dark matter is and confirming that and trying


to detect it is to go to snow lab so this is the cleanest deepest lab in the world it’s in an active mine

Snow Lab


in sudbury to go there you have to get on and uh


hopefully you can still hear me it looks like i can’t mute it


maybe i’ll pause it then because i know that that can sometimes cut off your ability to hear me


so you go two kilometers underground and then you still have to walk almost two more kilometers through the mine to get


to this facility where they are building all well this is this is what snow lab looks like it’s a


bit you can hear me with that well then i’ll let it play so i’m not waiting forever and so when you get to sno lab it is a


facility with lots of different rooms it kind of looks like a strip mall with all these different types of experiments


that i want to talk to you about um and i want to show you what that experience is like to go in a


snow lab because it’s really kind of like going to another world you get your uh all dressed up similar to


going with uh the miners and you have to go underground with the miners and walk through that facility to get to the


space i think i’ll just let this play [Music]


and i’ll stop there so it’s a really really cool facility where and i say it’s the cleanest deepest lab


in the room it’s in the world it’s a little bit like going into an operating room after you’ve walked two kilometers


through a mine getting covered in mine dust and everything you have to shower when you get there


um it’s a really cool facility and when you’re there that’s where you’re in a really cool


position to try to look for dark matter but you’re probably wondering dark


matter detection it’s really about finding something when you don’t quite know what you’re looking for and so maybe what you saw here

Dark Matter Detection


if you looked closely is these are a lot of names of different types of experiments i just want to give you a


taste of some of them that are happening at snow lab to to appreciate that again again we don’t quite know what


dark matter is there’s a whole bunch of ideas of maybe it has this mass or maybe it has these characteristics and each one of those


things will change how it’s going to be detected by a detector and so there’s detectors like


pico which is actually the world’s best at finding dark matter if it has a particular particle characteristic called


spin and so you can see this being built here so this is the chamber for the detector it actually


still even though you’re deep underground in a clean lab they still put it in a giant water tank and fill that with water just to give


you that much more shielding from all the stuff you don’t care about which is everything that we already have studied


on earth and in this uh in this detector you make liquids so hot it


wants to be uh gas but it’s so pure that it will not change and boil


on its own but if dark matter comes in and hits something in that detector it puts that


enough energy in to trigger it to start boiling and so inside this detector is a sequence of


cameras and microphones to capture that moment and be able to determine is it really


dark matter or is it something else that we’re not trying to study and this actually has some of the best


constraints for what dark matter at least isn’t at this point likewise there’s


another experiment news g this is a world leader of finding dark matter if it’s a little bit lighter


than most of these weakly interacting massive particles theories say it should be and it was


recently installed at snow lab just started in december there’s a cool video that’s on their website of them doing


this install and it’s a completely different way of doing this kind of detection


um just to kind of really showcase that like these different particle detectors the different dark matter detectors really can be built in


different ways that make themselves sensitive to different types of particles and so again this is if dark matter is


particularly lighter and the last one is what was at the tail end of that video that i showed which is the deep experiment this actually is


quite sensitive over a range of possible masses and here there’s liquid argon inside and


these are actually all a collection of very sensitive almost like cameras that are sensitive to any light that is generated which would be


generated if dark matter comes into this detector and interacts with some of that argon


and so these are very very different types of detectors that i’m showing you and the reason i want to say that is


like all of them kind of look for this idea of looking for that shake it so when dark matter comes in it shakes


the detectors in slightly different ways and we haven’t found anything yet but we’ve done a fantastic technology


development demonstrating that these technologies do work and that we understand them and they’re kind of the precursor to


bigger and better versions of these experiments and along the way all of these detectors


have other implications for us and society um some of these detectors can improve our medical procedures that we


use for detecting cancer others have uh really cool implications for industry and maybe speeding up how


our cameras work or our other communication channels do too and so you know in trying to solve these


big problems and trying to build a detector for something that we really don’t entirely understand


um we end up kind of making really cool progress in other ways all of this depends on the idea that


dark matter is a weakly interacting massive particle but what if dark matter isn’t described by that what else could


dark matter be and for this i want to punt it back to renee to pick up this part of the story

What If


yeah i hope thanks mark i hope you all at least started to get a taste of the


kind of continuous creativity that we need to have as scientists because


this is really really hard so we’ve seen ways to detect weakly interact interacting massive


particles or wimps for short but what if dark matter isn’t like that at all


so as a observer of the universe what we know


as mark said earlier we know the properties so we see those footprints but we need to guess what the animal is


and we know it doesn’t interact with light dark matter and it doesn’t interact it does interact gravitationally because we


can see these observations one suggestion is uh that there are


massive compact halo objects which is a bit of a mouthful the acronym is macho and it was sort of


come came up with so that it could be worms versus macho but the question is what if there are


small objects that don’t give off enough light for us to see so what if there are tons more planets


in the universe they don’t give off a lot of light if they’re very very small and so maybe we couldn’t see them what


if there was small black holes what if there are neutron stars unfortunately if you actually do the


calculation given how much matter we do see and we know something about the early universe


and how particles were created in that early universe you would need so many more planets and


neutron stars and black holes to make the um observations that we see


that it’s not really a good fit so at the moment we’re searching for wimps and haven’t found any


strong evidence yet and we don’t think it could be tons of planets that we forgot to count


and so what else could it be well what if there are primordial black holes so


these black holes could have been formed really really early on in the universe and they would again be very small if


they were big black holes we could find them because big black holes would typically be in a galaxy and there’d be lots of


interaction but what if there were these tiny orphan black holes everywhere that we couldn’t see


from the early universe uh some people come up with ways to generate these primordial black holes but again it’s


pretty hard to do so um to get the right volume and density of of objects that we need


okay so that’s tricky um what if it’s an uh not at the same kind of


particle that mark was talking about earlier in terms of the worms but what if it is a scalar field now a


scalar field the term scalar field sounds very scary because it’s not a particle that we


think of but actually all of us know scalar fields and i love to use this analogy


because it kind of demystifies um some physics so you may have heard about the higgs field and that’s


a little bit of what mark was introducing earlier but we actually know of scalar fields if we think of the distribution of


temperature as a function of position on earth which we all care about a lot especially going into summer


so the word scalar just means that you can tell everything with one number in this case


it’s the temperature there’s no direction you just have the temperature and the field part is that it’s distributed in space all over the earth


now in cosmology and physics we can take that idea of a scalar field but make it cosmological so instead of


being temperature and we have a different property that we put into a field and so one of the


things that i study is the axion it’s a really cool name but the axion is an ultra light scalar


field so we think that the axion is it’s it’s a proposed particle it’s one more idea


in our search for what dark matter could be but the axion has to be a scalar field and


we need it to be ultra light what do i mean by ultra light well astronomers sometimes change


the units of measurement because we don’t like a lot of decimal points so instead of measuring things in kilograms when we go to very small


things in the universe we actually start measuring them in electron volts so if you hear someone say a certain


electron volt it’s just a unit of mass in this case or unit of mass energy and so one electron volt is roughly uh


10 to the minus 36 kilograms so a fraction of a fraction of a fraction super super small fraction of a kilogram


uh to put that in perspective a proton weighs almost a billion uh electron volts so


it’s very heavy in electron volts units the axioms that i study they have to be


10 to the minus 22 electron volts so they are minuscule super super tiny they have


very little mass but on the largest scales in the cosmos these


axions can change the way galaxies cluster they can change the way that lensing


occurs um as we we looked earlier and they are actually


for some masses they seem to be indistinguishable from dark matter which means they could be a dark matter


candidate and they have all the same properties that we know we need in the cosmos to explain


this kind of dark matter but we haven’t detected an axion we’ve just said an axion could do the job of what we


need dark matter to do and that’s the fundamental difference in the in the sort of shake it analogy


mark and the folks who are building the detectors actually are building a thing where they’re expecting a result from a


particle in cosmology i’m more looking up at how i can describe the universe


and make sense of it with new ideas uh maybe you don’t like dark matter


particles maybe you don’t like the axion so what else what could be going on well there are some people that


don’t like any of this idea of dark matter they say we don’t need a new thing in the universe why can’t we just explain


everything with what we know already but in order to do that you have to say well what if the


laws of physics themselves are a little bit weird like we don’t fully understand them in particular um


we when we’re describing how galaxies move or the relationship between light and


mass in a galaxy we’re often using relatively simple um physical


uh laws and some of them are you know newtonian they come from newton and just describing the way mass uh


reacts and uh and moves um and there are some theorists that say well what if that modif what if newtonian dynamics or the motion


of things described by newton’s laws what if we need a different description and so there is a theory called


modified newtonian dynamics or mond which says basically we missed we incorrectly did


the calculation that that links the lights the light of stars and galaxies into the mass and if we fix


that up we can make galaxies rotate correctly we can make that lensing work and that’s fine however um as you add


more and more observations theories like modified newtonian dynamics don’t really work


and in fact there are some super exciting observations that come from canadian scientists so


um what in particular we are finding galaxies that appear to have


almost no optical light so almost no light but they’re very massive so they’re


entirely dark matter dominated or we’re finding galaxies where it looks like the relationship between


the um the light that we see and the mass effect or the gravitational effect seems


to match perfectly so we’re finding galaxies that have almost no dark matter in them and that have a lot


and these are detected by my colleague bob abraham at university of toronto and some folks in in the us


they built this telescope called dragonfly and i love the idea of dragonfly because basically they realized instead


of building a huge telescope which is very expensive they would take modern technology so these are um


very like telephoto lenses the kind of lenses that you use for sport photography and they put them all together um with


with really good filters on them so so that they can measure different wavelengths of light and so they operate


the small telescope together they’re obviously extending the telescope and they want to add more but they’re sort of doing the reverse


instead of generating new technology in the labs they’re using existing technology to do science and what they’re finding is that


there are lots of teeny fuzzy galaxies that seem to either have a lot of dark matter or no dark matter and so we’re


getting more observations that allow us to understand it’s not as simple as just


a couple of objects are lensing light in and incorrectly and so as we think about these


observations and think about the theories we have to sort of expand our creativity um and so i like to say that sciences is


a very creative profession but it’s creative in a particular way so in order for me as i’m coming up with


a new theory or trying to make some observations work i have to ask myself you know what


properties must my model have to explain the data um how does it change say the


distribution of matter so how what are the the observations that i could think of doing


how will it change galaxies clumping on the sky how will it change the early universe what signal would i expect from a


collider experiment like mark is talking about from a detector experiment if i come up with a new theory for dark


matter and i apply the make it break it shake it tests what am i going to see and then also


what predictions new predictions can i make instead of just explaining the observations that we


see i require my model to tell me something new because what i really want to do is be able to build a new experiment


that can maybe rule out my model or tell me i’m wrong or figure something out um and so this creativity where it’s


always iterative it’s coming up with an idea and then kind of thinking about why it could be wrong or thinking about a new test design is part


of the scientific journey that we have to go on all the time and it can be super exciting and


and also kind of exhausting because you have to continue to be creative so if we go to the next slide


the key piece is matching our generative creativity coming up with new models with an


observational sanity check on on the models and their validity and


this process is something that i i really love to do so an example is the image that you have here is a map


made from a telescope that measures light that comes from just after the big bang the cosmic microwave background


radiation and we put a telescope in space about a decade ago that just measured


the temperature of this light as a function of position on the sky so what are there are there big um cold


spots or big hot spots and you can see there’s a little distribution on the sky and we can go from a


two-dimensional representation which is like a map or a picture and we can also look at a


one-dimensional representation or a graph and so in this graph all we’re saying is


as a function of the size of the blob which is shown on the x-axis the angular scale or blob size


how many fluctuations how many um positive or or hot hot spots are there


relative to the average or cold spots and we see this very characteristic um distribution now one of the reasons


why i put this graph in i realized it’s a saturday afternoon no one wants to look at graphs but i want to illustrate a very specific


point so the red data points or observations that we made in fact the map that i just showed you


we turned that into this one dimensional representation it’s the same data just squashed into 1d


but the green curve is a theoretical prediction that we have for our model including dark matter so we don’t know


what dark matter is but if we include the properties of dark matter that we observe the model fits the data


incredibly so we’re in this very constrained space where we are being creative but we don’t have


a lot of wiggle room because the observations in the sky really have to be met and we have really really


pristine data so when people talk about a dark matter theory i don’t want you to take away that we don’t know what we don’t


necessarily done what we’re doing we’re throwing anything against the wall we are coming up with new ideas but they always have to be constrained by data


and it’s a really fun way to be doing uh science and it really encourages us to be


continually being creative and so i’m gonna hand over to mark uh for the for the rest of the talk


talking a little bit more about this creativity thanks renee and i think you know


being creative i think we are all you know we all have our own ways of being creative but


the benefit of really looking for new creativity is to make sure that we value the

Fibonacci Sequence


importance of different perspectives and and recognizing maybe some of the some of the


limits of any individual’s experience and so i’m gonna the next two slides are kind of like aside stories


um to try to motivate this which then feeds into some of uh what motivated the drift


artist exhibit or artist residency that we have here at the agnes and the mcdonald institute


and so this first story i like to tell is the idea behind these sequence of numbers so i don’t


know if anybody at home recognizes these numbers uh they date back almost a thousand years they are the


fibonacci sequence and so fibonacci himself he was born in the late 1100s so it’s quite a while ago


he was a famous mathematician mathematician that helped really kind of restart


mathematics in europe in a sense of reappreciation of numbers


and he was somebody that looked at these numbers he was not the first to kind of think about this sequence but


what he recognizes they’re kind of cute kind of an interesting thing and i think lots of mathematicians love just looking


at numbers that have cool and strange properties and so this sequence of numbers is 1 1 2 3 5 and so on


and what you do is if you take any two numbers in a row they add together to give you the next one and you just repeat this process


and when you do this they actually make something called the golden ratio and i’m sure many of you are familiar with this and this is me


kind of stacking cubes of sides equal to the numbers in the fibonacci sequence


and they end up stacking in this really nice way such that each times you add another


piece of the cube to grow the size of the rectangle the rectangle is growing by about 60 percent


and actually as you get bigger and bigger this number tends exactly to something called the golden ratio


which ends up you can kind of connect these corners of this cube in such a way to make this spiral and this is known as


the golden spiral and uh it’s not thought that fibonacci


alone actually recognized this idea of the golden ratio present in his numbers he just you know


as a mathematician he was very interested in the numbers alone they have some interesting applications to solving kind of neat problems that


you wouldn’t think about but it wasn’t until maybe some artists looked at this and started to see some


of the aesthetics that they were seeing in nature and when you connect um this golden spiral


actually biologists were recognizing that for example seeds as they’re oriented in


a sunflower also seemed to exhibit this pattern of the spiral that conch shells they seem to grow


following the golden spiral ratio even leonardo da vinci recognized that the presence of the


golden ratio in the anatomy of the human body in the different proportions of our limbs and our bodies


and overall um what i’m trying to emphasize here is when you want to see like maybe solve


certain problems or when you see something of interest to really maybe understand all the different aspects of it it


really benefits to get people that are used to maybe being quite creative but in their own ways


and so whether that’s bringing biologists and artists mathematicians maybe psychologists because humans


apparently really find the golden ratio present having a lot of aesthetic beauty


so why is it like convenient maybe for humans to look um at this ratio kind of in their art


there’s lots of different ways that this sequence of numbers apparently one one two three five eight so on has cool implications


and so you know this is one just example where i’m trying to motivate why we want to have different kind of

Blackwells Vorwork


sets of eyes looking at particular problems there’s another one which actually comes out of


kind of oxford university um i’ve heard it and i know that renee is similar with it too from her time at oxford


which is the idea of henley’s vorwork which is a dutch word for object


um so it turns out there was um i think he was a postdoc at oxford somebody doing research and


the research question he wanted to answer was galaxies come in a variety of shapes and sizes and


when we do simulations we’re recreating some of these galaxies or at least we’re trying to


remember in the video i showed earlier we do simulations of galaxies that we can then use those to tell us where we


should expect dark matter depending on how it interacts depending on that break-it model


well those simulations we put in what we think are the laws of physics so they should


recreate nature and it’s totally okay when they don’t that tells us that we’re wrong and


scientists actually love being told they’re wrong um that allows them to do more work


when they’ve shown to be right it’s like okay yeah i’m right and they have to move on to something else when they’re told they’re wrong then that means they


have work to do um and so simulations if they’re trying to recreate these universes they’re


trying to recreate galaxies in the universe then they should make galaxies that look


like real galaxies and so um why am i blanking on his name renee do you


remember his name um uh at oxford who started galaxy zoo kevin schwinski thank you yeah yeah


kevin schwinski so he’s realized that i want to know how often do galaxies kind of look like


this where they have nice discs versus those those uh football shaped


uh galaxies that we saw in the clusters like able cluster that rene showed you know how often do you get one


versus the other and so in wanting to answer this problem uh kevin looked at all the pictures that


he had of galaxies and realized there were over a million of them and i think he loves looking at galaxies


but he thought this is going to take a long time and as far as the question of is this galaxy


a disc or is this galaxy more like this elliptical football really i think anybody can be kind of


told the things they need to know before they could tell me the answer to that question and so kevin


and chris linta at oxford they started citizen science project called galaxy zoo


which is getting everybody else involved in this project where people that are not astronomers


not scientists have the opportunity to look at that data and report back on whether a galaxy is a disk or a football and i


think within a week they went through the million data it was this really really cool story of just how quickly they had eyes on all


these images and one of those images was this and so in this image you can see a very


clear galaxy and then you have this weird green blob next to it and the story that i hear about this


image and that it could be not quite accurate but my understanding is astronomers did look at this image


they saw that the galaxy was there and could clearly be seen and it would be one that the public could look at and tell them


whether they think it’s a disc or not and the idea was this green blob might not even be real there might have been


something wrong with the detector or maybe it’s real and this is not of interest and so they didn’t spend a lot of time


looking at this they kind of quickly dismissed it as not particularly interesting and so it was


part of this collection of a million images but then we had these different perspectives where we now had


many people looking at this image one of which was hannie van arkel and so when handy looked at this the


nice thing about this galaxy zoo platform is there’s the ability to leave a comment basically say


this is an interesting image i think more people should look at it and hanni did just that and this started


um a whole bunch of other people looking at it and also writing their own comments and so this image was suddenly getting a lot of interest in this collection


and the the system is able to tell the astronomers the non-astronomers are really interested in this image you should look


at it some more and that made them stop and pause um and uh and bye rui


um nice to see you again uh and so stop and pause and maybe just take a


second look at this image something that they looked at very quickly before with their kind of eyes


used to looking at galaxies and very much thinking they knew the question they wanted to answer and pause and bring in another kind of


ability of creativity to this question and when they stopped and looked they found something that is mind-bogglingly


fascinating this is one of the coolest images that i know of in astronomy and what has happened


is there’s a gas cloud here or we’re pretty sure this is what happened i should say that we’re never


entirely certain and this galaxy we think about 100 to 200 000 years ago was


really really really bright a lot brighter than it is right now and emitting very energetic light


from the center at which is a supermassive black hole when this light shined some of it hit


the earth some of it hit this gas cloud and caused it to light up itself to fluoresce and


form a bunch of stars and then as those stars formed they then burst and kind of emitted their own


light but because of how this is oriented it actually took a few hundred thousand years or so


for that light to then be reprocessed and then emit from this cloud and in that time this galaxy kind of


shut off to look more like a normal galaxy so what you see here is actually the afterglow of what this galaxy was doing


several hundred thousand years ago and the moral of this story is just kind of


going back to this idea of creativity that sometimes it’s really beneficial to have a fresh pair of eyes look at things


um to really make us check all of our biases and the things that we kind of have preconceived ideas about the


particular field that we’re looking at and scientists are very aware that any


human has some bias and we make efforts to account for that to take our kind of the human bias out of the equation


but it’s never perfect and sometimes just having a fresh pair of eyes can do just that


and so with this in mind this led to something called the drift artist residency the drift art and dark matter residency

Drift Artist Residency


where scientists and administrators at the mcdonald institute along with the agnes


art exhibit our art center wanted those fresh kind of artistic eyes


to look at what is a really exciting science that’s happening here in canada at snow lab


and so what we did as a partnership is we brought in a number of artists to come in to meet


with the agnes to come to the mcdonald institute and see things like the cloud chamber and understand and learn


about dark matter and how what we think it is all these different creative ideas we have to explain what it could be


and the way that we are trying to kind of answer these big questions and those artists went down to snow lab


too and got to meet with scientists there as they were building things like the pico detector and then those


artists had the opportunity to speak with the scientists about their own their own approaches and process


as well and at the end of the day those artists created art pieces that are trying to


bring in those kind of fresh eyes to look at this science dark matter and how we try to do this kind of detection


so this is an image from of joel tom’s artwork at the exhibit i really encourage you go to the agnes now


and get to see things like this and um josefa’s work here this is this


illuminated uh liquid very similar to kind of the liquid that’s used in some particle detectors


in that it is sensitive to some energy or some particles and then re-emits light


and i did want to just maybe end with one more anecdote which is that


it’s i i think this is really motivating the idea of having the artist come in having those fresh eyes on the


science and then get to re-show this this um their interpretations of this work and what that that experience meant


to them and hopefully re-engage the public with maybe getting fresh eyes on this science


and maybe that’s also what kind of helped motivate you to tune in today but in the process artists are also


speaking to scientists about you know questions that had never been asked and one of those happened actually to me um


in one of these engagements with the artists and so last june it was pride month and we were on a call


with dr cindy lynn at snow lab and joel toms and i had a pride flag on behind me and


we were talking about not just dark matter but also the neutrino physics that happens at snow


lab and art mcdonald the mcdonald’s suit is named after him he won the nobel prize in understanding


that neutrinos change their their flavors to change their type and suddenly i just suddenly realized that


most particles that we think of in the universe if you think about that plot of 17 things most particles that we


think of are a little bit fixed they come in a certain way and they don’t change


and i think um we’re very kind of used to thinking about things that way but when joel asked me about pride it


did make me think about the idea of how our social construct of gender is something itself that has been changing


recently and now we think of things maybe as being a bit more socially constructed gender fluid


and that with that kind of hat on it totally changed how i thought it was something like neutrinos


the way that they’re able to change the way that they they interact with the universe they stop being electron neutrinos that


become muon neutrinos and so neutrinos um although they’re fixed in some ways they


really they are something that can maybe change they’re almost like a gender fluid particle and they can change their type and so


the moral of this is just that the connection that we seem to have it might be just a cute allegory


but i think it’s important to realize that sometimes how we view social norms how we assign labels or whatnot to things um


the experience periods are kind of expanding in our horizons that we have new definitions and that could


apply to things in science like looking for dark matter so humans are weird we like to label things and


associate new ideas with old ones and i think that’s what comes in when you bring in new perspectives and so with drift having these new


perspectives on dark matter and the quest to kind of search for dark matter


it’s stopping us it’s allowing us the astroparticle physicists doing this to stop and maybe make sure that you


know we’re maybe there’s other cool ideas we should be bringing into this and so that’s the end of that story and


i think at the end of all of this you know what is dark matter i hope that you do understand


that we don’t know and that’s okay this means that it’s fertile ground for new ideas


and discovery and having really cool new conversations with other people um and have conversations between us and


you tonight or today i’m used to doing these events at night um so yeah so i hope you uh hope you


understand a little bit more about what is dark matter or what dark matter could be and you have the opportunity to check


out the drift exhibit as well and i think now we have lots of time for questions and so renee and i are


really really happy to hear uh what you guys what you guys think



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