Zenith Grant Awardee
Andrew Strominger
Harvard University
Co-Investigators
Project Title
The Nature of Time in Asymptotically de Sitter Universes
Project Summary
The physics community at large has a schizophrenic view on the nature of time. On the one hand it is widely believed that time evolution is deterministic and unitary. On the other it is also believed that the universe began life at the big bang. But if there was nothing before the big bang, unitarity would have to be violated at the initial moment. So something must give. I have put forth an unconventional and speculative proposal concerning this paradox in the specific context of universes of the general type we inhabit which expand forever in the far future. Through a variety of approaches over the last several decades, we have understood in a fairly concrete manner that a spatial direction can emerge in a holographic fashion in quantum gravity, as a scale parameter of the theory living on the holographic plate. But in general relativity, space and time are on equal footings. Therefore it should also be possible for time to emerge holographically. Time evolution would then be realized as a scale transformation in a theory living at future infinity, and the big bang a fixed point of these transformations. The goal of this proposal is to find some kind of concrete picture or toy model in which this can be realized.
Technical Abstract
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.