What is your name, affiliation, academic position, and job title?
Tommaso Treu, Physics and Astronomy Professor, University of California, Los Angeles, USA.

What is your journey?
I was born and grew up in Milan (Italy). I studied Physics in Pisa, at the University of Pisa and Scuola Normale Superiore. I got my PhD from the Scuola Normale Superiore. During my graduate studies I spent one year at the Space Telescope Science Institute in Baltimore, MD. I was a postdoc at the California Institute of Technology, and a NASA Hubble Fellow at the University of California Los Angeles (UCLA). I was a faculty member of the University of California Santa Barbara (UCSB) for nine years, before returning to UCLA in my current position.

What is your field of research and/or what project are you involved in?
I am in interested in cosmology, galaxy formation and evolution, and supermassive black holes. Currently, I am trying to figure out (with many others!) what is the fundamental nature of dark matter, what it the expansion history of the universe and therefore what is the universe made of, and how did the first galaxies and black holes formed after the Big Bang.

What are your research plans?
I’d really like to know the answers to the following questions: What is dark matter? What’s the universe made of? How do galaxies and supermassive black holes form? I spend all my available time trying to figure out how to get closer to answering these questions.

How does CosmoVerse fit within those plans?
Cosmoverse is bringing people together to try and find out what is the universe made of. It’s a big problem and I am hoping that by using our collective intelligence and resources we can make progress.

What new skills would you like to learn in the next year?
Where do I start? I feel like one never knows enough… although that’s why this job is so interesting.

What are the most exciting open questions in your research area?
To me, the ones I listed above, but I am sure there are many more.

What advances or new results are you excited about or looking forward to?
The thing I love the most of my job is surprises. There is nothing more exciting than discovering something that you did not expect. We are fortunate that astronomy is a very rich field and surprises are relatively frequent. I am pretty optimistic that, with all the new telescopes and satellites coming on line, there will be plenty of new twists and turns to understand.

What is your view on cosmic tensions? How does your work connect with this open question in the community?
I find it extremely interesting and compelling. What blows my mind is that we are aiming to measure the expansion rate of the universe with 1% precision. This is an incredible precision, if you think about it for a second. Most people don’t even know their own height to this level of precision (or barely)! So I think that we need a lot of independent measurements to be sure we are getting it right. My goal in this context is to use gravitational time delays to measure the expansion history of the universe to this level of precision. This method is independent of all other methods and it is thus particularly valuable.

What role do you think a community network like CosmoVerse can play in developing theoretical astroparticle physics and cosmology?
As the field grows, it is important to find ways to communicate. The more people and ideas that we are able to deploy effectively on solving a problem, the more the chances that we will be able to solve it. Cosmoverse is a great platform for communication and collaboration.

What’s your favourite food? Why?
Being Italian, you are probably not surprised to hear pizza and gelato! The first time I went to Naples and ate pizza there I got Stendhal Syndrome. Fortunately you can now find good Italian pizza even in Los Angeles. That’s very important to me.

What non-physics interests do you have and want to share?
Besides enjoying spending time with my wife and my son, I love traveling, reading, and skiing.  I like to travel to places I have not been to before, preferably off the beaten path, and learn new things, see new places, try new foods (going back to my love for surprises). I read books mostly about history, policy, and economics, to try and understand our world a bit better. And I feel most free and carefree when I am skiing down a mountain.

In your view, what’s the most important challenge that humanity faces currently?
The list is long. Learning how to get along with each other, avoiding violence and conflict, is at the top of my mind these days. The other topic I think often about is sustainability. We humans cannot go on like this. We only have one planet, and we need to take care of it. And we need to take care of each other at the same time.