Paul Halpern - Five Way Interview

Paul Halpern is a professor of physics at Saint Joseph's University and the author of 18 popular science books, including Collider, Flashes of Creation, The Quantum Labyrinth, Einstein's Dice and Schrödinger's Cat, and Synchronicity. He is the recipient of a Guggenheim fellowship and is a fellow of the American Physical Society. He lives near Philadelphia, Pennsylvania. His latest title is The Allure of the Multiverse.

Why science?

Science embodies humanity’s longstanding passion to understand its world and to probe its frontiers.  Ancient peoples looked to the stars and strived to decipher celestial patterns, with the aim of not only predicting astral occurrences, but also trying to comprehend the fundaments of nature and how it affects human lives.  As science developed, humankind’s knowledge of the world and its vital laws grew, along with a greater sense of its barriers and limitations. Interest in multiverse ideas bears on the question of whether or not science is willing to intuit what lies beyond those frontiers, without the prospect of direct observation, with the goal of potentially obtaining a more complete theory of the measurable, observable universe.

Why this book?

Noting the increased mention of the term “multiverse” in the media, I set out to learn everything I could about the history of the topic, and current controversies surrounding it.  In my research, involving numerous interviews and looks at oral histories, I was struck by the stark contradictions in physicists’ views of what is genuine science and what is simply too wild to be discussed.  For example, some researchers dismiss eternal inflation, but advocate instead for the collision of membranes in a higher dimension. Such judgements often seem to be a matter of taste, rather than strict rules about direct measurability.

You present a balanced view in the book: what is your own position on the MWI, a multiverse driven by eternal inflation and the string theory landscape?

My personal view on multiverse theories is that we must strive to exhaust all testable possibilities before reluctantly taking steps that involve elements that are not directly detectable.  Therefore, regarding quantum measurement, it would be wonderfully if scientists developed a complete portrait of spontaneous localization of observables that explain measurements of parameters as distinct as spin and position, yet we are not there yet.  In lieu of that, the MWI has value as a potential alternative.  Similarly, if cosmologists proved that inflation occurs only once, for our own universe, there would be no need for a bubble multiverse.  However, on the contrary, as Andrei Linde showed, inflation seems to be relatively simple to trigger.  Finally, while I think we should remain open-minded to string theory, we must also continue to explore models of quantum gravity that don’t necessitate such a mind-boggling large landscape of possibilities.

What’s next?

I am currently preparing a talk about J. Robert Oppenheimer, John Wheeler, and the golden age of general relativity for the April Meeting of the American Physical Society.  The talk will be in a session honouring the work of the accomplished astrophysicist and historian of science Virginia Trimble, who recently won the Pais Prize for the History of Physics.

What’s exciting you at the moment?

I am thrilled that the history of science and culture has been honoured by recent films such as Oppenheimer and Maestro, both of which I enjoyed very much.  I would very much like to see an increased emphasis in society on scientific and cultural achievements, including greater recognition of new artists and musicians who are blazing novel trails in their fields. 

Photograph © St Joseph's University

Interview by Brian Clegg - See all of Brian's online articles or subscribe to a digest free here