115 - Craig Callender & Tim Maudlin: Time Travel, Time’s Arrow, and The Block Universe

Jul 16, 2023

Craig Callender and Tim Maudlin, leading philosophers of science and physics, join Robinson to delve into the philosophy of time, discussing the reality of the past, present, and future, the direction of time, and its relationship to relativity and quantum mechanics. They explore the A-Theory and B-Theory of time, concepts like presentism, eternalism, and the four-dimensional view of time. They also touch on non-locality in quantum mechanics, measuring time in relativity, and the purpose of theorizing about time travel. Plus, they discuss the compatibility of time travel with physics and make a pitch for the John Bell Institute for the Foundations of Physics.

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INSIGHT

Foliation Helps Explain Quantum Nonlocality

Bell's theorem proves local causality cannot explain certain quantum correlations observed experimentally.
Introducing a foliation of spacetime simplifies modeling the causal non-locality required by these quantum phenomena.

INSIGHT

Superluminal Signaling Could Reveal Foliation

If superluminal signaling were possible, we could empirically identify a preferred foliation of spacetime.
Current quantum mechanics forbids superluminal signaling under standard assumptions.

INSIGHT

Clocks Measure Proper Time in Relativity

In relativity, clocks measure proper time, the length of their path through spacetime.
Proper time is invariant and independent of reference frames, explaining what clocks truly measure.

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Craig Callender is Professor of Philosophy and Co-Director of the Institute for Practical Ethics at UC San Diego. Tim Maudlin is Professor of Philosophy at NYU and Founder and Director of the John Bell Institute for the Foundations of Physics. Craig and Tim are leading philosophers of science and physics. Craig also appeared on episode 73, in which he and Robinson discussed pseudoscience and conspiracy theories. Tim was a guest on episode 46, which covered laws of nature, space, and free will, and episode 67 with David Albert, which was all about the foundations of quantum mechanics. In this episode, Craig, Tim, and Robinson delve into the philosophy of time, touching on the reality of the past, present, and future, the direction of time, its relationship to relativity and quantum mechanics, and time travel. Craig and Tim have both written on time. Check out Craig’s book What Makes Time Special? (Oxford University Press, 2017) and Tim’s book Philosophy of Physics, Volume 1: Space and Time (Princeton, 2012). If you’re interested in the foundations of physics—which you absolutely should be—then please check out the John Bell Institute, which is devoted to providing a home for research and education in this important area. At this early stage any donations are immensely helpful.

Craig’s Website: https://www.craigcallender.com

Tim’s Website: www.tim-maudlin.site

The John Bell Institute: https://www.johnbellinstitute.org

OUTLINE

00:00 In This Episode…

01:12 Introduction

04:43 The A- and B-Series of Time

21:20 Presentism, Possibilism, and Eternalism

42:03 Foliations in Time

57:39 Foliations of Time in Quantum Theory

01:03:30 Superluminal Signaling

01:11:56 The Direction of Time

01:35:24 Philosophy and Time Travel

02:03:07 The John Bell Institute

Robinson’s Website: http://robinsonerhardt.com

Robinson Erhardt researches symbolic logic and the foundations of mathematics at Stanford University. Join him in conversations with philosophers, scientists, weightlifters, artists, and everyone in-between.