In a recent essay at Aeon, University of British Columbia philosophy prof Evan Thompson recounts a famous 1922 debate between Albert Einstein (1879–1955) and philosopher Henri Bergson (1859–1941) about the nature of time.

As Thompson notes, Einstein understood time as it is represented in his relativity theory: “For the German physicist, the time measured by clocks was no longer absolute: his work showed that simultaneous events were simultaneous in only one frame of reference. As a result, he had, according to one New York Times editorial, ‘destroyed space and time’ – and become an international celebrity.”

What Bergson thought Einstein got wrong

Bergson did not dispute either Einstein’s theory or the need for a frame-of-reference approach to time in science. But as his book Duration and Time, published later that year, revealed, he was sure that there is more to time than clocks — in terms of how humans experience it.

Thompson puts Bergson’s view like this:

We usually imagine time as analogous with space. We imagine it, for example, laid out on a line (like a timeline of events) or a circle (like a sundial ring or a clock face). And when we think of time as the seconds on a clock, we spatialise it as an ordered series of discrete, homogeneous and identical units. This is clock time. But in our daily lives we don’t experience time as a succession of identical units. An hour in the dentist’s chair is very different from an hour over a glass of wine with friends. This is lived time. Lived time is flow and constant change. It is ‘becoming’ rather than ‘being’. When we treat time as a series of uniform, unchanging units, like points on a line or seconds on a clock, we lose the sense of change and growth that defines real life; we lose the irreversible flow of becoming, which Bergson called ‘duration’.

Think of a melody. Each note has its own distinct individuality while blending with the other notes and silences that come before and after. As we listen, past notes linger in the present ones, and (especially if we’ve heard the song before) future notes may already seem to sound in the ones we’re hearing now. Music is not just a series of discrete notes. We experience it as something inherently durational.

Evan Thompson, “Clock time contra lived time,” Aeon, September 30, 2024

Bergson did not think that duration or lived time can be measured because there are no units of measurement that are applicable.

Einstein didn’t see the point of all that. In his 1905 paper on the electrodynamics of moving bodies Thompson tells us, “he claimed to have defined time entirely in objective terms.” But “Bergson argued in the 1922 debate, local simultaneity is always something that is perceived by conscious beings. Clocks don’t read themselves.”

And so the debate continues to this day.

Time, brains, and neuroscience

Thompson points out that Bergson’s concept of duration helps us make sense of the gap, for example, between what neuroscientists report about our brains and what we personally experience in our lives. About the Bergson–Einstein debate, he offers his own view:

The debate that began on the evening of 6 April 1922 and expanded through the 20th century represents a missed opportunity for moving our scientific worldview beyond its blind spot – its inability to see that lived experience is the permanent, necessary wellspring of science, including abstract theories in mathematical physics. In retrospect, we can see that the debate was an unfortunate misunderstanding. Bergson’s and Einstein’s ideas are more aligned than either realised during their lifetimes. By combining their insights, we gain an understanding of something fundamental. All things, us included, embody different durations as they move through the Universe. There is no one time. Through his attempts to show Einstein a hidden world of duration passing beneath special relativity, Bergson continues to remind us of something forgotten in our scientific worldview: experience is the ineliminable source of physics.

Thompson, “Clock time contra lived time”

Parts of the essay were adapted from a book, The Blind Spot: Why Science Cannot Ignore Human Experience (MIT 2024), of which Thompson is one of the authors. The other two authors of Blind Spot are University of Rochester astrophysicist Adam Frank and Dartmouth College theoretical physicist Marcelo Gleiser.

Meanwhile, back in the lab … negative time?

Just when we thought that things were settling down, physicists are reporting that they have found evidence of negative time in a strange experiment. As reported at LiveScience, “Physicists showed that photons can seem to exit a material before entering it, revealing observational evidence of negative time”:

Quantum physicists are familiar with wonky, seemingly nonsensical phenomena: atoms and molecules sometimes act as particles, sometimes as waves; particles can be connected to one another by a “spooky action at a distance,” even over great distances; and quantum objects can detach themselves from their properties like the Cheshire Cat from Alice’s Adventures in Wonderland detaches itself from its grin. Now researchers led by Daniela Angulo of the University of Toronto have revealed another oddball quantum outcome: photons, wave-particles of light, can spend a negative amount of time zipping through a cloud of chilled atoms. In other words, photons can seem to exit a material before entering it. “It took a positive amount of time, but our experiment observing that photons can make atoms seem to spend a *negative* amount of time in the excited state is up!” wrote Aephraim Steinberg, a physicist at the University of Toronto, in a post on X (formerly Twitter) about the new study, which was uploaded to the preprint server arXiv.org on September 5 and has not yet been peer-reviewed.

Manon Bischoff, Jeanna Bryner, “Quantum physicists discover ‘negative time’ in strange experiment,” LiveScience, October 5, 2024

We’ll see what happens with the paper. But remember, Einstein always hated quantum physics specifically on account of the “spooky action at a distance.” This finding would just give him another reason. And yet the quantum world is perfectly good science.

Perhaps the mistake is not realizing that we live in a world full of mysteries that, solved! … lead to further mysteries.