Huw Price in Medium of Expression:
Lee Smolin likes big targets. His last book, The Trouble With Physics, took on the string theorists who dominate so much of contemporary theoretical physics. It was my engrossing in-flight reading on a trip to the Perimeter Institute a few years ago, where I first met its rather engaging author in person. I thoroughly enjoyed that battle, from my distant philosophical vantage point – “Pleasant is it to behold great encounters of warfare arrayed over the plains, with no part of yours in the peril,” as Lucretius put it (1). But now things are more serious: in Time Reborn Smolin has my team in his sights, and some part of mine is certainly in the peril, if he emerges victorious. Should I now be feeling sorry for the string theorists?
I’ll come back to that question, but first to the dispute itself, which is one of philosophy’s oldest feuds. One team thinks of time as we seem to experience it, a locus of flow and change, centered on the present moment – “All is flux”, as Heraclitus put it, around 500BC. The other team, my clan, are loyal instead to Heraclitus’s near contemporary, Parmenides of Elea. We think of time as it is described in history: simply a series or “block” of events, lined up in a particular order, with no distinguished present moment. For us, “now” is like “here” – it marks where we ourselves happen to stand, but has no significance at all, from the universe’s point of view.
Which side is right? Both teams have supporters in contemporary philosophy, but we Parmenideans claim powerful allies in modern physics, commonly held by physicists themselves to favour the block picture. Einstein is often quoted as one of our champions.