115 - Craig Callender & Tim Maudlin: Time Travel, Time’s Arrow, and The Block Universe
Jul 16, 2023
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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.
The concept of the block universe challenges static vs. changing perceptions of time.
McTaggart's A and B series of time offer different frameworks for understanding past, present, and future.
The debate between presentism, eternalism, and possibleism lacks clear logical grounds and requires consideration of physics.
Relativity undermines the notion of objective simultaneity and highlights the need for a comprehensive understanding of spacetime.
Deep dives
The Block Universe and Time's Persistence
The concept of the block universe challenges the notions of static and changing. The block universe is not in time, but time is in it. It contains all change and everything that is static. The idea that it is either static or changing is not accurate, as it transcends these concepts. The block universe does not persist through time, as it is a timeless concept. It is important to understand that a single event cannot be static or changing because it does not persist through time.
McTaggart's A and B Series of Time
McTaggart's A and B series of time provide different ways of understanding time. The B series organizes moments based on the earlier than relation and does not reference past, present, or future. On the other hand, the A series orders moments in terms of past, present, and future, using a dyadic structure. These different ways of thinking about time have philosophical implications and can shape how we perceive and discuss time.
Metaphysics and Logical Grounds in the Philosophy of Time
The debate between presentism, eternalism, and possibleism in metaphysics of time does not have clear logical grounds. These perspectives deal with how we conceive of time, existence, and the past, present, and future. Each viewpoint carries its own philosophical implications, but their preference or probability cannot be definitively determined before considering the current understanding of physics. The philosophical conceptions of time should not be reduced to epistemology, but rather considered as distinct disciplines.
Relativity and the Concept of Simultaneity
Relativity challenges the notion of objective simultaneity. Simultaneity is a relative concept and dependent on one's frame of reference. The absence of an objective now throughout the universe in relativity undermines the idea of a fixed and universally agreed-upon present moment. Instead, simultaneity is based on how events are perceived and experienced in different locations. The preferred foliation in physics and the absence of an absolute simultaneity highlights the need for a comprehensive understanding of spacetime and its relation to the concept of time.
The possibility of time travel is a debated topic
The podcast episode discusses the debated topic of time travel. While some argue that time travel is logically impossible, others contend that it is at least metaphysically possible. Time travel stories in science fiction often explore the concept and present various scenarios involving time travel.
Main arguments for and against time travel
The podcast explores the main arguments for and against time travel. On one hand, some argue that time travel is logically inconsistent, pointing to paradoxes such as the grandfather paradox. However, others contend that time travel is logically possible, as demonstrated by consistent time travel stories in science fiction. The debate also touches on the physical plausibility of time travel, with some arguing that it could be allowed within the framework of general relativity.
Challenges and limitations of time travel
The challenges and limitations of time travel are discussed in the podcast. It is noted that while time travel to the future is a natural consequence of the passage of time, time travel to the past poses significant challenges. The issue of causality, specifically the potential for causing paradoxes, is a major concern. Additionally, compatibility with the laws of thermodynamics and the increase of entropy over time is questioned.
The John Bell Institute for the foundations of physics
The podcast includes a pitch for the John Bell Institute for the foundations of physics. The institute aims to bring together philosophers, physicists, and mathematicians to advance research in the foundations of physics. They are currently seeking funds to establish a permanent location for the institute and encourage interested individuals to contribute through their GoFundMe page.
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.
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.
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