Time and Experience in Physics and Philosophy [draft]

Below is the introduction of paper I presented at a conference in L’aquila, Italy in April 2019. The conference aimed to revisit important philosophical issues related to the famous 1922 debate between Einstein and Bergson. HERE is the conference site (it is in Italian, so you’ll need to ask Google to translate it for you).

Time and Experience in Physics and Philosophy

“What is Time?” Bergson-Einstein Conference in L’Aquila, Italy April 4-6, 2019

By Matthew D. Segall

“What is time?” Reflecting on this ageless question stretches my imagination in several directions: I first consider the time of my own most direct and intimate experience of being alive: I was born, I live and age, and I will die, necessarily in that biological order. Each year, I watch as winter frost melts to make way for spring flowers. My interest in fundamental physics then leads me to ponder the paradoxes of relativity and quantum theory: I wonder what, if any, significance my personal biography has given the deterministic mechanism and time-reversibility of Nature’s fundamental laws. I reflect on whether my experience of seasonal rhythms is reducible without remainder to the mechanical effect of a slight tilt in the rotation of our dust mote planet as it revolves in warped space-time around a massive ball of radiating plasma. Finally, my incurable philosophical itch compels me to search for some more general metaphysical scheme or wider interpretive context within which the laws of physics might find a place alongside  lived experience.

It is this quest to understand time that has brought us together for today’s conference. Physicists, theologians, businessmen, philosophers, artists—really all thoughtful human beings—have at one point or another been struck by this question and struggled to answer it in their own terms. Nearly a century ago, time was at the center of Einstein and Bergson’s debate in Paris. Centuries earlier, another influential intellect, Ben Franklin, had tried to settle accounts: “Time is money.” Centuries earlier still, Augustine had to confess that he did not know what time is (though he offered a few conjectures). And Plato, as he stared in wonder at the stars above him while inwardly contemplating the perfections of geometry, offered at least a likely story: time is a moving image of eternity.

The passage of time is both inescapably obvious and profoundly mysterious. Nothing gets to the heart of who and what we are more than time. Stars ignite, burn their atomic fuel, and go supernova, creating the heavier elements needed for conscious lifeforms like us to take shape. We are born, we age, we die. Civilizations rise and fall. None of these processes is intelligible in reverse. And yet, there has been a strong consensus among physicists for at least a century that the time of human experience, let us call it “phenomenal” or “lived time,” is, as Einstein once put, a “stubbornly persistent illusion.” Everyday time is not at all what it appears to be. As Augustine admitted, time is plain as day until someone asks us to explain how it works: suddenly, we find ourselves having a hell of a time trying to make any sense of it. A recent New York Times article chronicled the growing controversy (and confusion) about seasonal changes in clock-time, so-called “daylight savings” time.1 Back in the 1920s, changes to local clock-times in US cities like Boston and Detroit led some residents to worry that an extra hour of sunlight in the evening would dry up their gardens and disturb their farm animals. The article quotes Michael Downing, author of Spring Forward: The Annual Madness of Daylight Saving’s Time (Counterpoint, 2005):

“The idea of losing or gaining an hour is itself such a fantastically bad philosophical proposition that nobody knows what they’re talking about…Most people don’t even understand whether moving the clocks forward gives them more sunlight or less sunlight in the morning. They just can’t remember what it does, because it so defies logic.”

As if the time of everyday experience wasn’t strange enough already, in the equations of physics— whether classical, relativistic, or quantum—it doesn’t even matter which direction time flows, if it can even be said to “flow” at all. The one exception, perhaps, is the 2nd law of thermodynamics, to which I return later.

I cannot promise that the paper to follow won’t make an even bigger mess out of time. I can only offer a few potential pathways through the thicket in the hopes of finding some new perspectives on a very old question. I first revisit the crucial bifurcation between natural science and human experience that has informed not only our views of time but so much of modern thought and culture. Alfred North Whitehead will be my principal guide in this endeavor. Along the way I distinguish Whitehead’s process philosophy from Henri Bergson’s understanding of temporality. Though Whitehead affirmed much of Bergson’s critique of scientific materialism, he departs in crucial respects from the Frenchman’s vitalism. Finally, I draw Whitehead into conversation with the work of loop quantum gravity theorist and popular science author Carlo Rovelli. While the convergence is by no means complete, I believe there are some hopeful signs in Rovelli’s professed natural philosophy that align him with Whitehead and thus bring us closer to a philosophical reconciliation between human experience and the Nature known to science.