The Nature of Time in physics, philosophy, complexity, neuroscience and Liebniz

I ventured down a series of paths today, no doubt related, but with no quick and easy way to tie them together.  So I decided to invite you to look with me and let your mind play.

I started with a couple of talks at a recent at a recent Foundational Questions Institute conference on the Nature of Time.

I listened first to a panel made up of neuroscientist David Eagleman, physicist Paul Davies, philosopher Tim Maudlin, and mechanical engineer and computer scientist Raissa D’Souza who is currently most involved with models of complexity.  It is an interesting discussion that begins with Paul Davies’ observation that there is nothing in the equations of physics that says that this moment, the present, is special. There is nothing that conveys the now of our experience.  In modern physics, time is not specifically represented.  Tim Maudlin took note of the fact that now it is physicists, not philosophers that say some of the strangest things about time, but that he will make the more straightforward claim that time exists, that it has a direction, that we are objectively getting older, and that our task is really to understand how things are related to each other.  Raissa D’Souza is interested in the local ordering of emergent properties. For her, time is characterize by the increasing complexity of systems, or their increasing interdependence.  Mathematics itself only came up once in this discussion and it was the philosopher who brought it up, making the argument (I think?) that we need to be careful to distinguish between mathematical possibilities and the properties of physical things.  I didn’t hear enough from him to be sure, but I think he is of the mind that mathematics is a  tool applied to the description of our reality rather than a strategy for unraveling some of the illusions of our experience.

David Eagleman, the neuroscientist, got my attention when he answered a question from the audience.  The question was whether time, like solidity, might one day be understood as not being a fundamental property of the world, but rather as one that is built up in some way from more fundamental fragments.  Eagleman found the question interesting given that our sense of time is thought of as a meta-sense. It is so named because different aspects of our notion of time – duration, temporal order, something called rate of flicker, and simultaneity – actually happen through different neural mechanisms. While they normally work in concert, and produce a unified experience, they can be teased out from each other and separated.

The group did address the fact that, in physics, words like entropy, force, energy or work have very precise meaning, distinct from the common use of these words, and that there was also some difference in how they were used to describe macroscopic events versus quantum mechanical ones.  Eagleman, wanting to say something about the macroscopic energy efficiency of the brain, near the end said something like ‘we’re mobile creatures and if you want to simulate the brain, you need to simulate the stomach because we’re driven by hunger..’  I would agree, and I am intrigued by the fact that hunger has brought us to some of the most enigmatic riddles of our experience.  Eagleman is of the opinion that time itself was calculated internally with respect to how much energy the brain felt itself using.

I then listened to the talk given by Julian Barbour. He mentions early in his talk that Newton got it wrong and Leibniz got it right.  I’ve recently spent time exploring the Leibniz view of the world, and today tried to search out what he said about time, specifically.  I found a nice discussion on the Internet Encyclopedia of Philosophy, where the author uses the structure of virtual realities as a metaphor for the mathematician’s metaphysical ideas. I think it works nicely.  For Leibniz, space and time were the physical representations of ideal relations, and not things in themselves.

Take the analogy of a virtual reality computer program. What one sees on the screen (or in a specially designed virtual reality headset) is the illusion of space and time. Within the computer’s memory are just numbers (and ultimately mere binary information) linked together. These numbers describe in an essentially non-spatial and temporal way a virtual space and time, within which things can “exist,” “move” and “do things.” For example, in the computer’s memory might be stored the number seven, corresponding to a bird. This, in turn, is linked to four further numbers representing three dimensions of space and one of time–that is, the bird’s position. Suppose further the computer contains also the number one, corresponding to the viewer and again linked to four further numbers for the viewer’s position, plus another three giving the direction in which the viewer’s virtual eyes are looking. The bird appears in the viewer’s headset, then, when the fourth number associated with the bird is the same as the viewer’s fourth number (they are together in time), and when the first three numbers of the bird (its position in virtual space) are in a certain algebraic relation to the number representing the viewer’s position and point of view. Space and time are reduced to non-spatial and non-temporal numbers. For Leibniz, God in this analogy apprehends these numbers as numbers, rather than through their translation into space and time.

This site also explains this about the Leibniz perspective:

Leibniz argues that it would be a great waste of possible perfection to only allow living beings to have bodies at that particular level of aggregation with which one is phenomenally familiar. (Perhaps Leibniz was understandably impressed by the different levels of magnitude being revealed by relatively recently invented instruments like the microscope and telescope.) Leibniz writes:

“Every portion of matter can be thought of as a garden full of plants, or as a pond full of fish. But every branch of the plant, every part of the animal, and every drop of its vital fluids, is another such garden, or another such pool. […] Thus there is no uncultivated ground in the universe; nothing barren, nothing dead.”  (Monadology, §§67 & 69)

Barbour’s talk presents what he calls shape dynamics, where shape, identified as the only intrinsic property of something, leads the theoretical construction. I won’t try to capture it here.  But it will likely be the subject of another post.

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