Introduction

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

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

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

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

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

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

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

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

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

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

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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

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

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

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

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

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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

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

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

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

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

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astrophysics and the department of astronomy and astrophysics at university toronto

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

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

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

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

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

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

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

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

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

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sloane fellow and she is a ted senior fellow

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

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

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

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

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

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

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

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

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

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

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

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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

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

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

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

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

What is the Universe

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

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to be talking about today

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

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

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

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

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

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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

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

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

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

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

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

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

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

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

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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

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

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

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

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

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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

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

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

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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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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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

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

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

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

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

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

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

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

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

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

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

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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

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

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

What is Dark Matter

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

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

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examples of um observations that suggest that dark matter is there

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

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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

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

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

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

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

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

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

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

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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

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

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

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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

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

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

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

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exciting uh next slide okay

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

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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

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

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

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

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

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

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

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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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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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

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

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

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

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

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

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

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

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

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

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

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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

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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

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

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

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

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

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

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

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

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

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

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

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

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weakly and so we call it a weakly interacting massive particle

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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

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

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

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

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

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

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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

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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

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

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

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

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

How to detect Dark Matter

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

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

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

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

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

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

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

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

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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

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

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

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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

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

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

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

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

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

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

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

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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

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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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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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

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

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

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

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

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

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

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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

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

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

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

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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

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

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

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

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

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

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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

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

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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

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

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

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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

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

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

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

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

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

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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

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

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

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

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

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

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

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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

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

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

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

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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

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

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

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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

30:25

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

30:31

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

30:36

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

30:42

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

30:48

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

30:53

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

30:59

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

31:04

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

31:09

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

31:16

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

31:21

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

31:26

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

31:32

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

31:38

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

31:44

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

31:50

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

31:56

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

32:03

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

32:09

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

32:16

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

32:21

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

32:28

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

32:33

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

32:39

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

32:45

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

32:51

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

32:57

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

33:02

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

33:08

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

33:15

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

33:22

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

33:27

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

33:34

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

33:41

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

What If

33:48

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

33:55

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

34:01

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

34:07

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

34:12

so as a observer of the universe what we know

34:18

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

34:23

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

34:29

can see these observations one suggestion is uh that there are

34:35

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

34:41

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

34:47

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

34:52

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

34:59

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

35:04

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

35:11

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

35:17

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

35:22

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

35:27

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

35:33

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

35:39

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

35:45

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

35:51

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

35:56

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

36:02

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

36:07

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

36:13

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

36:19

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

36:24

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

36:30

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

36:36

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

36:42

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

36:48

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

36:53

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

37:01

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

37:08

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

37:14

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

37:21

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

37:26

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

37:32

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

37:38

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

37:45

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

37:51

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

37:59

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

38:05

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

38:12

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

38:17

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

38:23

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

38:28

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

38:33

occurs um as we we looked earlier and they are actually

38:38

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

38:44

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

38:49

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

38:57

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

39:03

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

39:09

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

39:14

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

39:20

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

39:26

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

39:33

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

39:38

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

39:45

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

39:51

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

39:56

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

40:03

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

40:10

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

40:16

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

40:22

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

40:28

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

40:36

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

40:41

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

40:48

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

40:53

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

40:59

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

41:05

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

41:10

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

41:16

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

41:22

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

41:29

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

41:37

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

41:43

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

41:50

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

41:55

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

42:02

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

42:08

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

42:13

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

42:20

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

42:27

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

42:33

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

42:39

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

42:45

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

42:50

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

42:57

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

43:02

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

43:09

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

43:14

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

43:21

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

43:28

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

43:35

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

43:40

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

43:46

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

43:52

observational sanity check on on the models and their validity and

43:57

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

44:05

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

44:11

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

44:17

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

44:24

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

44:30

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

44:35

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

44:40

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

44:46

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

44:53

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

45:00

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

45:07

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

45:12

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

45:17

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

45:24

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

45:30

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

45:36

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

45:42

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

45:47

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

45:54

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

46:00

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

46:06

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

46:12

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

46:17

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

Fibonacci Sequence

46:23

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

46:29

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

46:36

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

46:42

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

46:48

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

46:55

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

47:02

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

47:09

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

47:14

mathematics in europe in a sense of reappreciation of numbers

47:19

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

47:26

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

47:32

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

47:40

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

47:48

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

47:54

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

47:59

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

48:05

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

48:11

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

48:18

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

48:24

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

48:30

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

48:36

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

48:42

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

48:47

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

48:53

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

48:59

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

49:08

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

49:14

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

49:22

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

49:29

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

49:35

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

49:40

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

49:46

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

49:51

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

49:58

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

50:07

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

50:13

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

50:19

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

50:24

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

50:29

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

50:36

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

50:42

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

50:47

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

50:53

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

50:58

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

51:03

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

51:09

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

51:14

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

51:20

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

51:26

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

51:32

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

51:37

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

51:44

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

51:50

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

51:56

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

52:02

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

52:08

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

52:14

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

52:21

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

52:28

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

52:34

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

52:39

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

52:44

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

52:51

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

52:58

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

53:04

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

53:10

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

53:16

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

53:22

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

53:28

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

53:34

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

53:40

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

53:45

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

53:51

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

53:57

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

54:03

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

54:11

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

54:17

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

54:25

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

54:31

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

54:36

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

54:43

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

54:50

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

54:55

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

55:01

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

55:06

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

55:12

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

55:18

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

55:24

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

55:29

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

55:34

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

55:40

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

55:47

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

55:53

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

56:00

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

56:06

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

56:12

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

56:19

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

56:24

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

56:30

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

56:36

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

56:42

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

56:47

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

56:54

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

57:00

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

57:06

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

57:13

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

57:18

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

57:24

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

57:30

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

57:36

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

57:43

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

57:48

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

57:54

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

58:00

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

58:07

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

58:13

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

58:19

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

58:26

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

58:33

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

58:41

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

58:47

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

58:52

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

58:57

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

59:02

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

59:09

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

59:14

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

59:20

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

59:27

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

59:33

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

59:39

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

59:44

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

59:50

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

59:56

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

1:00:03

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

1:00:08

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

1:00:15

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

1:00:20

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

1:00:26

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

1:00:34

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

1:00:39

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

1:00:44

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

1:00:51

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

1:00:58

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

1:01:04

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

1:01:10

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

1:01:18

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

1:01:23

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

1:01:30

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

1:01:44

you

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