Theoretical physicist Alan Lightman suggests that our universe is one of many possible variations, leaving physicists at a cosmological dead end. Lightman’s latest book is The Accidental Universe: The World You Thought You Knew.

Alan Lightman: For centuries scientists and especially physicists have believed that we would be able to show why our universe is as it is as a necessary consequence of certain fundamental principles and laws. Like finding – having a crossword puzzle with only one solution, the given certain very fundamental principles like the law of conservation of energy, that there would be only one self-consistent universe allowed. And that has been sort of the holy grail of physics and we have been pretty successful in showing such things as why snowflakes have six-sided symmetry, why raindrops are round, why the sky is blue as necessary consequences of a small number of physical principles.

What has happened in the last ten years or so – or 15 years - is we now believe – when I say we, I mean most theoretical physicists – now believe that our universe is just one of a vast number of universes all with very different physical properties. And all of these different universes originate from the same fundamental principles. So there’s not one solution to the crossword puzzle. There are many solutions to the crossword puzzles. In that case there’s no possibility of explaining why our universe is a necessary consequence of the fundamental principles. There are many, many different possibilities. Some of these other universes might have 17 dimensions. Some of them might have planets and stars like ours. Others may have just an amorphous field of energy with no planets and stars. Some of them might allow life like our universe. Some of them may not allow life. And our universe is just one lucky draw from the hat.

In which case we are accidental. We are an accidental universe. And so the historic mission of science, and especially physics, to show that we are – our universe is the unique result of a certain set of fundamental principles – that historic mission is no longer feasible. It’s no longer possible. This conclusion makes theoretical physicists extremely unhappy because it means that a lot of our mission is an illusion. But that may be the way nature is.

Directed / Produced by Jonathan Fowler, Elizabeth Rodd, and Dillon Fitton