Your first book, The Fabric of the Cosmos, is by Brian Greene, one of the world’s leading physicists. In it, he explores the idea of what reality is.

I almost didn’t put this book on my list because Brian certainly doesn’t need the publicity. But I think this is his underappreciated book. His first book, The Elegant Universe, was specifically about string theory – a particular attempt to reconcile gravity and quantum mechanics. This book takes a step back and looks at foundational issues such as: What is space time? What is quantum mechanics? How do they play well together and what are the problems of having them play together? I like it because it is an extremely well-written book. It covers a lot of deep issues that don’t get attention in a lot of other places, such as the nature of time, the nature of space. It really gives its readers a profound understanding of the universe.

This book is less about theories and more about the basics?

Yes, he isn’t propounding any specific controversial theories in this book. I think that he takes a very legitimate attitude, because we don’t understand a lot right now. We have ideas, we know certain things about how the universe works and there are other things we don’t know. He takes a tour through the issues.

Which of the issues that he explores interests you most?

The single issue that interests me the most is the arrow of time – why the past is different from the future. There are various ways that we can observe that. You remember the past, you don’t remember the future. But these differences can’t be found anywhere in the fundamental laws of physics as we know them. Brian’s book puts that issue front of centre, and it was very helpful to me when I was writing my own book on that issue.

Next up is Alan Guth’s The Inflationary Universe, which attempts to explain some of the unanswered questions behind the Big Bang.

Alan Guth is one of the leading theoretical cosmologists today, and I was actually a postdoc at the Massachusetts Institute of Technology where Alan was when he was writing the book, so I was there on the ground floor. He is one of the most meticulous and careful thinkers that we have in cosmology. His great contribution, when he was quite young, was the idea of the inflationary universe – a way that you could take an incredibly tiny smooth patch, as small as you can imagine it being, and it can expand at a tremendous rate, create energy, and grow into something like the Big Bang. Almost every discussion of early universe cosmology today starts from inflation – trying to make inflation work or trying to improve on it with something better. His theory has set the agenda for theoretical cosmology for the last 30 years and here is the man himself explaining it to you.

Did you help him with his work if you were there when he was writing the book?

We were working together, writing papers, but they weren’t about inflation so I didn’t influence the book. Alan is someone who takes incredible care in trying to make things clear. So even though he discusses some of the deepest issues that we have in early universe cosmology, you are rarely going to find such a careful explanation of what we know and what we don’t.

Evalyn Gates’s Einstein's Telescope: The Hunt for Dark Matter and Dark Energy in the Universe is another book which explores how the universe was made.

That’s right, so after two more theoretical books I thought it would be a good idea to have a more down-to-earth book that really looks at how we know all of these wonderful things about the universe. All of the books I chose are fairly recent. There are classic books on cosmology, but the field has changed so much over the past few decades that you really need to read the more recent books.