Interviewing Katherine Freese: Dark Matter, Inflation and Star Trek

Last thursday we took the chance to interview Katherine Freese, who visited the Faculty of Physics and gave a speech in the Sala Darwin about her work.

She is a theoretical physicist and a George Eugene Uhlenbeck Collegiate Professor of Physics at the University of Michigan in Ann Arbor. She is known for her work in particle physics and astrophysics.

Freese was one of the first to suggest ways of discovering dark matter, and her work decisively ruled out MACHO dark matter in favor of WIMPs. She developed an original model known as "Cardassian expansion", in which dark energy is replaced with a modification of Einstein's equations.

She has also worked on the beginnings of the Universe, searching for new successful inflationary theories, and even studied the ultimate fate of life in the Universe.



When did you decide to investigate in your field and why?

There are many pieces to this question. My parents were molecular biologists, so the idea of having a scientific career just seemed natural. For a lot of people, I guess, especially for girls, it may sound a bit strange but for me it never did. Then, after studying Physics, I was working on a high energy physics experiment at Fermilab, outside of Chicago. Twice a week I came to the city to take a course in cosmology with David Schramm, and it was my favourite part of the week; so I'm always telling people that I switched from measuring dark current (when you unplug a photon tube and see if there is current off going) to dark matter and dark energy. He was a very inspiring man, so I got very excited about this work with the smallest particles explaining the biggest propierties of the Universe.

Could you explain your model of the early Universe?

I have a model of inflationary cosmology called Natural Inflation, which is a specific model of inflation trying to match the data. One of the things you have to match is, as I explained in my talk before, the idea of galaxy formation coming from small inhomogeneities, a little more dark matter here than there. From the details of this perturbations you can learn the specifics of different inflationary models. So my model is making predictions and we will see if it matches data or not. That is coming in the next five years so I'm very excited about that.

How optimistic are you about new discoveries in your field during this century?

Very optimistic, of course. Look at last hundred years! A hundred years is a long time. You got a lot of scientists, very smart people so, yes, we will figure out dark matter, I think. And dark energy probably.

You have also proposed a model known as Cardassian Expansion, in which dark energy is replaced with a modification of Einstein's equations. Could you confirm that the word Cardassian comes from Star Trek?

Yes! Yes, the idea is that Cardassians are very funny looking but they are made of the same stuff that we are, just like in my dark energy model, and their goal is the accelerated expansion of their evil empire. And that's where I got the name from.

The topics that you cover in your book, The Cosmic Cocktail: Three Parts Dark Matter, aren't really covered in the news or do not appear in mainstream media. What do you think is the best way to spread science?

Good question... I don't know, I tried to write a book hoping that somebody would read it! Honestly, I think that a lot of people watch documentaries on TV, and I think that is a really good way. Maybe podcasts, but you have to be already interested to look for them.

You were director of the Nordic Institute for Theoretical Physics. What were your responsibilities as director?

I became director almost five years ago and I held that position from 2014 to 2016.The Nordic Institute has five permanent faculties, some assistant professors, 20 post-docs and a lot of programs. You have to manage all these programs. People all over the world applied to those programs, I also contacted with people and told them " Hey, you should do a program"... And then, of course, there is a committee that decides which program is chosen.

How would you explain your field of investigation to someone who had just started studying physics?

I’m trying to figure out what the universe is made of. We only understand five percent, which usually shocks the hell out of people. It’s a bizarre and amazing thought.

Last year almost 33 percent of the people that started studying physics were women here in Valencia. What do you think it should be done to increase that percentage?


If I knew… Encouragement, mentorship, starting the younger the better. I don’t really know the Spanish situation. Maybe there’s fifty percent and then they lose interest. You have to find where the drop occurs and try to work with those people. It’s usually a question of self esteem. Make sure they don’t lose their interest if they want to do it, help them with some guidance and some encouragement, wherever the break is. I don’t know where is in Spain, but in the USA is often the first year of college where we lose a lot of women. The first year is so brutal that they give up. They’re just like: Oh my god I’m not doing this. And eventually they do something else.



And for the last question: what would you rather to have a coffee and a debate with someone who thinks the Earth is flat or someone who thinks the Earth is hollow?


Hollow. Do you know why? Because those flat Earth people are also mixing it with a religious paradigm. But the hollow Earth people must be really weird people. It must be Jules Verne fans, you know the center of the Earth, right? They must be quite wild people, more interesting to talk to.