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Zenith Grant Awardee

Lee Smolin

Perimeter Institute for Theoretical Physics


Project Title

Physical and cosmological consequences of the hypotheses of the reality of time

Project Summary

The question of whether time is real or an illusion lies at the root of several of the most fundamental unsolved problems in physics and cosmology today. These include the problem of quantum gravity, which is the problem of unifying the physics of the quantum with the physics of spacetime, the problem of the interpretation of quantum mechanics and the problem of how the laws of physics, which are observed to govern our universe, were selected. In this proposal we investigate the consequences for these problems of the hypothesis that time is real and part of the fundamental organization of nature.

Technical Abstract

We propose to investigate the consequences for several issues in fundamental physics and cosmology of the hypothesis that time is real and fundamental. This is to be contrasted with the view popular among some physicists, cosmologists and philosophers, that time is not fundamental, but is emergent from a timeless fundamental physics. To motivate this hypothesis we analyze the key successes and failures of several approaches to quantum gravity. We argue, from this evidence, that the hypothesis that time is real may offer a new avenue to resolving several of the most persistently unsolved issues blocking a successful quantum theory of gravity. However, if this is correct we have to address the apparent conflict between the hypothesis of the reality of time with the spacetime diffeomorphism invariance of general relativity and the lorentz invariance of special relativity. Approaches to this are discussed, including unimodular gravity, and deformed special relativity. We also address foundational problems in quantum mechanics, as a global time is needed by any framework in which quantum mechanics is derived as an approximation, suitable for small subsystems of the universe, from a deeper, cosmological theory.

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