Sunday, April 29, 2018

Quote Of The Day: Tim Maudlin On Block Time

Tim Maudlin via Quantum Magazine
Tim Maudlin is a philosopher of science who is often cited as a critic of the popular view in science and philosophy known as "block time," which is just another way of describing eternalism: the view that all moments of time—the past, present, and future, are all equally real and ontological. But it's not so clear that Maudlin outright denies the block universe conception of time. In an interview he gave with Quantum Magazine last year, he seems to affirm block time, but mistakingly thinks it denies change.

A popular misconception of the block universe is that time or change isn't real. But this is just a figure of speech. In the block universe time and change are definitely real. What isn't real, however, is the flow of time and change. There is no flowing of one moment to the next coming into and out of existence in a block universe since all moments exist, but there are definitely distinct ontological states of what exists at different times. This is what time and change are in a block universe: it's the fact that the same events do not exist uniformly throughout the spacetime block. But this often gets misconstrued as "time and change doesn't exist at all" by many scientists and even by many well-intentioned eternalists, and due to that, many people reject the block universe because it seems so self-evidently true that time and change exist. (For an explanation of the experience of the flow of time in a block universe, see here.) I will let Maudlin explain in his own words his issues with this complicated linguistic aspect of block time upon being accused of bucking the the trend. For all his experience on time, he too seems to get tripped up by this.
You don’t sound like much of a fan of the block universe. 
There’s a sense in which I believe a certain understanding of the block universe. I believe that the past is equally real as the present, which is equally real as the future. Things that happened in the past were just as real. Pains in the past were pains, and in the future they’ll be real too, and there was one past and there will be one future. So if that’s all it means to believe in a block universe, fine.
People often say, “I’m forced into believing in a block universe because of relativity.” The block universe, again, is some kind of rigid structure. The totality of concrete physical reality is specifying that four-dimensional structure and what happens everywhere in it. In Newtonian mechanics, this object is foliated by these planes of absolute simultaneity. And in relativity you don’t have that; you have this light-cone structure instead. So it has a different geometrical character. But I don’t see how that different geometrical character gets rid of time or gets rid of temporality.
The idea that the block universe is static drives me crazy. What is it to say that something is static? It’s to say that as time goes on, it doesn’t change. But it’s not that the block universe is in time; time is in it. When you say it’s static, it somehow suggests that there is no change, nothing really changes, change is an illusion. It blows your mind. Physics has discovered some really strange things about the world, but it has not discovered that change is an illusion.

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