Laurence Perreault Levasseur

Congrats Dave! Thanks everyone, it's been an amazing experience!

Favourite Thing: To get really confused about something, and have to think really hard to understand what’s going on. The best feeling is that moment when I finally get it, and everything makes perfect sense.



de Rochebelle High School (in Quebec, some part of French Canada) where I did the BI program in 1999-2004, Cegep de Ste-Foy (that’s like a post high school/pre-university college we have in French Canada) in 2004-2006, McGill University for my undergrads in 2006-2009, McGill University again for my Masters degree in 2009-2011, and I’ve been in Cambridge for my PhD since 2011. The coming year I’ll be a visiting PhD student in Stanford, USA.


B.Sc. (Hons) in Maths and Physics, M.Sc. in theoretical physics

Work History:

I worked as a cashier in a small grocery store while in high school and Cegep (which is a 2-year pre-university college). I was a research assistant over the summers during my undergrad. In grad school, I worked in the undergraduate labs in McGill, and I am now working as a supervisor for undergrads in Cambridge. I also went to teach cosmology in China for a month in 2012.

Current Job:

PhD student in Applied Maths and Theoretical Physics (but really I’m a physicist and I do cosmology)


DAMTP, University of Cambridge

Me and my work

I try to understand what happened in the first billionth of a billionth of a billionth of a millionth of a second in the history of the universe, just after the Big Bang (something called inflation).

By looking at the galaxies in the sky, we know that our Universe is in expansion.

To understand what this means, you can think about a raisin bread baking in the oven. As the bread raises, the dough inflates and the raisins get further and further away from each other. The important point is that they move away from each other NOT because they are moving through the dough, but because the dough ITSELF between all the raisins is inflating.

Something very similar is happening in our Universe right now. You can think of the raisins as galaxies in the Universe, and the inflating dough as space between galaxies. So this means that, just like the bread, the Universe is expanding, which means galaxies are constantly moving further and further away from each other, not because they are moving through space, but because space itself is constantly expanding. (One consequence of this is that the further a galaxy is from ours, the faster it seems like it’s moving away from us, because there is more space that is expanding.)

Ok. Now, if we start running the clock of the Universe backwards, it means that the further back in time I go, the closer galaxies were to each other. And if I go far enough in the past, all the galaxies (or, more precisely, the stuff – mostly a gas called hydrogen – they are made of) were all clumped together in a very hot and dense soup. If I go even further back in time, all that soup was contracted at the same point, with basically no space at all. That is the beginning of the Universe, something called the Big Bang (currently, scientists don’t really understand what happens there).

Just after the Big Bang, there was a very short period (about 10^-33 seconds, or a billionth of a billionth of a billionth of a millionth of a second) where space was expanding crazily fast (exponentially, to be precise). It’s as if the raisin cake raised so much that it filled the whole observable Universe (literally). This short period of exponential expansion of space is called inflation.

My work is about inflation. How did it happen? Why? How did it stop? How did it shape and influence the Universe we live in today? What are its consequences that we can still observe?

My Typical Day

Most of the time, it involves writing pages and pages of equations, and trying not to miss a minus sign! I also get covered in chalk explaining my current confusion to other scientists over some coffee…

Lately, I feel like there hardly are any typical days. Next week, I am going to Paris for a conference. For the past month I have been in sunny California, visiting the physics department at Stanford University. Before that, I was in Cambridge for a month, the month before I was in Montreal, visiting McGill University, and the list goes on… I’ve travelled across a ocean about every 3 months since I became a PhD student, and I’ve been on most continents. This is one of the best things about what I do: I get to see the world and meet people from everywhere on the planet. These days, I am getting ready to move across the Atlantic to Stanford, in California, where I will be a visiting PhD student next year.

Regardless, the research routine looks about the same on every continent (that is, if I’m not attending a conference!). The first thing I do in the morning is to have a coffee. A serious coffee. Before that I’m not human (believe me, you don’t want to know what I am). While I have my delicious coffee with my breakfast, I check my emails and look at the ArXiv, which is the website where all the new scientific papers from all scientist across the world appear everyday. It’s very important to sat updated with the research that is being done!

I then bike (or walk, or take the train, depending where I am) to work. Once there, the first thing I do is to feed my office physicist fish. Yes, I have a fish tank in my office, full of fish that help me work out my hardest problems. (Actually, they don’t talk much; I mostly stare at them, but somehow it seems to help thinking a lot!) Here they are, in my office in Cambridge:

The goldfish is Quark, there are three minnows called the 3 Neutrinos (because they are really small and hard to distinguish), and three very funny bottom feeders called the Joeys (they are the observers, so everything remains classical). Actually, they are not in Cambridge anymore, they just moved to California (yes, on the plane).

I usually spend my mornings looking at equations, doing calculations, coding on my computer, and getting confused when things don’t work. Then, in Cambridge, at 11 am everyday we have tea and coffee with all the members of the department (but, of course, I always have coffee). That a great opportunity to discuss recent scientific papers, various nerdy physics gossips, and everybody’s work. I usually attack someone with questions about my work for help, and that is always a great opportunity to get covered in chalk.

In the afternoons during term-time, I usually spend my time teaching (which is also a great way to get covered in chalk), marking, or preparing my classes. If I’m not teaching, I do things like reading recent papers, applying for different things (like funding…), discussing with my supervisor, asking questions to other members of the department, or having Skype meetings with my collaborator (who are based a bit all over the planet).

Around 4-5pm it’s time for coffee again (just writing this makes me want to have coffee…), and then I go back to staring at my equations for a couple of hours, until I’m so starving I have to go home and eat, or, if I was clever and brought dinner with me, until I get too tired or so stuck that it’s no use going on. At that point, my desk usually looks like this:


Once I get home, I Skype with my husband for couple or hours (that is, if I’m not in California, where he is currently doing a postdoc). Then I go to bed watching something funny or a BBC documentary (I really like the BBC Horizon, they are amazing!).

What I'd do with the money

I want to send everyone who participated in the zone a gift!

I want to send everyone in the zone either a copy of  ‘A brief history of time‘ by Stephen Hawking, or ‘The evolution of physics: the growth of ideas from early concepts to relativity and quanta’ by Albert Einstein and Leopold Infeld.  They are both absolutely amazing, mind-blowing books about cosmology, physics, the laws that make the Universe work the way it works, and how we know about it. And they do all that without invoking more complicated maths than just adding, subtracting, multiplying, and dividing, whitout compromising on the scientific accuracy and the depth. The second one, in particular, isn’t very well-known, but it makes an amazing job at explaining how ideas develop in science, and how scientific think when they invent new, revolutionary theories.

I also want to save some of the money so send a number of copies of Chinese-translated versions to the university I visited in China back in 2012, in order to make small, modest steps in giving students the resources to learn by themselves, to be inspired to pursue their science passion further, to understand how science works and is done.

I read those books when I was still in school myself. They were given to me by an outreach program in an institute for theoretical physics, in Canada (the Perimeter Institute), and they fascinated me so much I am still doing physics today. For me it’s sort of a ‘pass it on’.

My Interview

How would you describe yourself in 3 words?

coffee, bicycle, blueberries

Who is your favourite singer or band?

I like a lot of French Quebec music, but it’s unlikely you know about it… Alpha Rococo, Louis-Jean Cormier, Pierre Lapointe, Jean Leloup, Yann Perreau

What's your favourite food?

This is really difficult, because I love so many types of food. If I have to pick just one I’d say blueberries, or any dish that involves shrimps (but not together!!)

What is the most fun thing you've done?

I really like traveling with my (pedal) bicycle, and usually I go for epic adventures. For my first trip, two of my friends and I went from Montreal to Florida in one month, for a total distance of about 3000 km, with nothing but three bicycles, a tent and camping material, little money, and a lot of enthusiasm. The year after I traveled in Italy for a summer school in Trieste and I brought my bike along. I went for day trips in Slovenia, and after the school I went from Bologna to Nice in France and back. The year after, I went in biking in Belgium and Germany. But the most fun bicycle trip of all was last year, for my honeymoon: we went biking across Portugal, from Faro to Porto. My big and crazy dream is one day to travel from Paris to Beijing on my bike. We’ll see how that goes, and if I manage to do it before I turn 80 years old!

What did you want to be after you left school?

I knew already I wanted to be a theoretical physicist, but I realized that only at the very last moment (I explain how in a later question). Before that, I had absolutely no idea, and honestly I found it a bit terrorizing.

Were you ever in trouble in at school?

Not really. I’ve always been more or less a good student, and the few times I wasn’t I managed not to get caught ;)

What was your favourite subject at school?

I loved anything that involved understanding the ‘why’ of things. Usually, that meant I liked subjects where I had a good teacher. I remember absolutely loving my 20th century history class, maths some years (but not others…), my second biology class, and most of my physical sciences classes.

What's the best thing you've done as a scientist?

In 2012, I spent a month in Linyi, a “small city” in China (cities are not really small in China I guess), where I was teaching inflationary cosmology to undergrads for a summer school. It was really inspiring and motivating to see lights shine in the eyes of students as they were understanding the story of the universe I was telling them. I felt it was a big honour for me to get to teach them such fascinating ideas. They were there, just asking to learn, but had never had the chance to be properly be taught physics deeper than just the step-by-step equations crunching. I felt it was a big responsibility to try to inspire them, to light that fire in them, and make them believe in their capacities; because some really had what it takes to become good physicists, but without tremendous strength to fight the odds, they were just born in a place with almost zero opportunities in academia.

What or who inspired you to become a scientist?

I remember very clearly being 15 in my first physical sciences course, and finally understanding how electricity works after being extremely frustrated for months because the whole thing just didn’t make any sense. That was the most amazing feeling, like a light shining in my head and suddenly everything was crystal clear. At that point, I still didn’t know that I wanted to be a theoretical physicist – I didn’t know such a thing even existed! My first contact with advanced physics happened a year later, in 2004, at the International Summer School ISSYP (held at the Perimeter Institute, in Canada). Over there, I was exposed to first-class scientists and international researchers, and that gave me a chance to share my passion for science. This conference profoundly modeled my view of the scientific world. But there is one life lesson I learnt I could have never learnt in textbooks, that is, learning that the people who are doing such research are humans like everyone of us. They aren’t necessarily super humans, they’re just normal people like everybody else who are simply deeply interested. This breaks the perception that only genius super heroes are capable of doing research in this field. So I decided that’s what I wanted to do in life.

If you weren't a scientist, what would you be?

I’d like to try scientific journalism, that way I would still learn lots of fascinating things everyday. I’d also like to open my own bakery, but that’s more of a vague and crazy dream.

If you had 3 wishes for yourself what would they be? - be honest!

1) be able to speak all the languages in the world 2) have an awesome memory that doesn’t forget the things I don’t want to forget 3) have 3 more wishes!! :)

Tell us a joke.

Why can’t you trust an atom? They make up everything.

Other stuff

Work photos:

myimage6 myimage3 myimage4

While I discover tons of amazing places on my bike, I also witness amazing physical phenomena, like this:

How many rainbows can you see? Do you know why this happens?

I also get to see things like this 😀 :


COOL (random) THINGS:
The scale of things:

Various Things in the Universe (yes, neutron stars are about the size of a marathon!)

The Solar System

Youtube science stuff:


Minute Earth



Physics documentaries:

Atom with Jim Al-Khalili (3 parts, really good – mainly the last!!)

Everything – Nothing with Jim Al-Khalili (part 1 Everything, part 2 Nothing. REALLY amazing!!)

Connections with James Burke (3 series, the first is from the 70s but it’s AMAZING)

Interesting reading:

Sean Carroll’s blog (I could have linked to many, but I read this one most often)

Funny/ways to procrastinate: