We've had a few posts about the sessions at the Setting Time Aright meeting covering questions about memory, choice, free will and the end of civilization, entropy, and...electric fish. But as yet we haven't really wrestled with the hardcore questions about time: Does time exist? Is it fundamental or emergent?
Well here they are. As an intro, watch this after-dinner debate in which Tim Maudlin argues that time is an illusion, while Julian Barbour contends that time is real. Yes, you read that correctly, Julian argues _for_ time, and Tim argues _against_ it. I should add that this is a mock debate: the evil masterminds at FQXi forced the speakers to argue against the ideas they famously hold. (If the picture sways a bit occasionally, it's because the debate was filmed on board the ship and it was a little rocky that evening.)
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That was a mock debate, so don't hold the speakers to the opinions they express there. But there was also a serious session dedicated to the existence of time, featuring Barbour and Maudlin, again, and George Ellis. (By the way, if you're wondering why, when the camera pans round to show the audience, everybody is looking in different directions, it's because there were screens displaying the talk slides located on every wall.)
First up: George Ellis. If you followed our essay contest on the Nature of Time or have read the FQXi profile of his work, you'll already know that Ellis wants to save time. He argues that although the block universe view of time that comes out of relativity seems to indicate that time is an illusion--with past, present and future all existing on equal footing--that model is wrong. He proposes modifying the standard block universe picture to include a flow of time--an emergent block universe--which exploits the irreversibility inherent in quantum wavefunction collapse to distinguish a closed past from an open future:
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Julian Barbour picks apart conceptions of time in relativity, differentiating between Einsteinian relativity, in which each observer splits time and space apart differently, and Machian relativity (more here), in which the positions of objects are defined relative to each other, at a given instant.
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Tim Maudlin also defended time. At the start he clearly sets up the distinction that forms the basis of his discussion: Is time not real? Is the space-time manifold real, but any distinction between time-like, space-like and light-like directions in it not real (Einstein's view)? Is the time-like, space-like, light-like distinction real, but emergent (e.g. defined to be the direction of increasing entropy)? Or is the distinction real and fundamental--the naive everyday view that we take for granted (Newton's view)? Maudlin argus that time and its arrow are real and fundamental and that to see it, we have to change the mathematics we traditionally use to view the structure of space-time. This is one of the most mathematically meaty talks of the entire conference, so sit back and enjoy:
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Finally, as a sneak peak at the Universe session, which I'll blog about later, it's worth looking at Craig Callender's talk -- especially if you're interested in novel ways to slice up the block universe:
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He doesn't get into the crossover aspects of his work trying to recover time's directionality by invoking evolutionary biology and cognitive science here, but in this article, "Evolving Time's Arrow" he talks about more about that.