remember the day when, at the age of 7, I realized that I wanted to figure out how reality worked. My mother and father had just taken us shopping at a market in Calcutta. On the way back home, we passed through a dimly lit arcade where a sidewalk bookseller was displaying his collection of slim volumes.
I spotted an enigmatic cover with a man looking through a microscope; the words “Famous Scientists” were emblazoned on it, and when I asked my parents to get it for me, they agreed. As I read the chapters, I learned about discoveries by Antonie van Leeuwenhoek of the world of microscopic life, by Marie Curie about radioactivity, by Albert Einstein about relativity, and I thought, “My God, I could do this, too!” By the time I was 8, I was convinced that everything could be explained, and that I, personally, was going to do it. Decades have passed, and I am now a theoretical physicist.
My job is to work out how all of reality works, and I take that mission seriously, working on subjects ranging from the quantum theory of gravity to theoretical neuroscience. But I must confess to an increasing sense of uncertainty, even bafflement. I am no longer sure that working out what is “real” is possible, or that the reality that my 7-year-old self conceived of even exists, rather than being simply unknown.
Perhaps reality is genuinely unknowable: Things exist and there is a truth about them, but we have no way of finding it out. Or perhaps the things we call “real” are ca.