Describe your latest project.
Dark Cosmos is a book about two of the biggest mysteries in science today — dark matter and dark energy. Over the past years and decades, we have learned that the kinds of matter we are most familiar with (protons, neutrons, electrons, atoms and molecules) make up only a few percent of the mass and energy of our universe. My book is about how we came to this conclusion, and about some of the ideas we have regarding what dark matter might be made up of, and why dark energy exists in the quantity it does. To answer these questions, I talk about everything from black holes and neutrinos to extra dimensions of space and other universes.

What inspires you to sit down and write?
Ever since college, I have really enjoyed reading popular science writing. Books by Paul Davies, Kip Thorne and others played a big role in my becoming interested in physics. Unlike most of my colleagues, I still read a lot of popular science books today. After giving a series of physics lectures for the general public, I decided to convert those notes into a book. It was a lot of work, but also a lot of fun.

Have you ever taken the Geek Test? How did you rate?
I haven't taken it, but I suspect I would score pretty high.

Chess or video games?
Both, although I don't have enough time to do either one very well these days.

What do you do for relaxation?
I play guitar in a punk rock band. I don't know if I would call it "relaxing," exactly, but it is absolutely a good time.

If you could be reincarnated for one day to live the life of any scientist or writer, who would you choose and why?
I would want to come back as the physicist who finally succeeds in discovering a Grand Unified Theory or a Theory of Everything. To be the first to witness and understand the blueprint of our universe would be about the most fantastic experience I can imagine. On the other hand, I would not want to come back as a physicist long after that discovery was made. After all, what would be left to do?

What was your best subject in high school? Your worst?
I always loved history, but was also naturally good at mathematics. I was an absolutely terrible language student. My Spanish teacher never understood how I could learn calculus, but couldn't train myself to speak even simple Spanish sentences. I think she assumed that I never studied at all for her class, when in fact I worked harder in that class than in any other.

By the end of your life, where do you think humankind will be in terms of new science and technological advancement?
The most exciting advances are almost always impossible for foresee. That being said, I think we have only seen the beginning of the information age. We are steadily becoming better at sending more information, and more kinds of information, to and from our homes, offices and wherever else we are. In my lifetime, I expect that most people will go to work and school virtually — logging on instead of commuting. If nothing else, this should help to cut down on traffic! And from there, it is not hard to imagine virtual worlds that we can log into. Virtual offices where we work, virtual destinations for vacations, virtual clubs for socializing — the possibilities are limitless.

Which country do you believe currently leads the world in science and technology? In ten years?
The United States is certainly the biggest single contributor to science and technology today, although we should remember not to take this for granted. Investments in education and research have made our technological achievements possible, and neglecting these crucial factors in the future could cause our leading role to diminish. Considering how much our economy depends on technology and innovation, I don't think we afford to neglect science in our public policy.