Zenith Grant Awardee
Craig Callender
University of California, San Diego
Co-Investigators
Project Title
What Makes Time Special
Project Summary
There is a gap between what we might call the 'manifest' and 'scientific' images of time. Physics sees time as like space. Yet experience regards them very differently: we behave as if the future is unreal, the present special, and time fundamentally directed. These features affect the way we live our lives; for instance, we dread future pain but feel relief when pain is past. Hence there is a significant gap between time as represented by experience and by physics. Closing this gap is the goal of my research. My work shows that time in physics is surprisingly different than space, even when united into spacetime — despite conventional wisdom. In a very precise sense, physics is able to tell better narratives (make better predictions and explanations) in the timelike direction than spacelike directions. Our macroscopic environments then latch onto this difference to make a representation of time as different than space most natural. By looking at an interdisciplinary mix of fields, including cognitive science, evolution, and philosophy of time, I explain why we believe that there is a common now and also why we care more about the future than past.
Technical Abstract
There is a gap between what we might call the manifest, and scientific, images of time. Time as we represent it in ordinary experience is commonly characterized as having a privileged present, a preferred direction and even a flow; however, you will not find any of these notions in contemporary fundamental physical theory. My research attempts to breach this gap in two ways. First, by investigating mathematical physics, I find the major features that distinguish the timelike from spacelike directions of spacetime. Using a novel difference — the asymmetry of informative strength — I show that this difference goes some way toward linking together the distinctive aspects of what makes time physically special. Second, by investigating philosophy, cognitive science and evolution, I show how it makes sense for creatures like us evolving in environments as we find them to mistake their egocentric (past, present, future) division of time for an objective division of time. I develop this idea in detail for why we believe there is a common now and why we have such markedly differing attitudes, beliefs and emotions toward the past and future.
QSpace Latest
PressRelease: Precision experiment puts pressure on quantum collapse theories
Quantum mechanics, the theory governing the microscopic world, is famously counterintuitive. A particle can exist in a superposition of multiple states, such as different positions, until a measurement is performed. At that point, the wavefunction describing that particle appears to ‘collapse’ to a single outcome. This puzzle lies at the heart of the measurement problem, famously illustrated by Schrödinger’s cat, suspended between life and death until observed. The XENONnT detector, which was designed to be sensitive to rare physics events, has tightened constraints on one family of possible solutions to the measurement problem, known as ‘collapse theories.’ The work, which was partially funded by FQxI, was reported in Physical Review Letters in March 2026. Image credit: XENON Collaboration.