In the latest issue of Philosophy Now (Issue 124, February / March 2018) I read a review of a book, Experiencing Time by Simon Prosser, ‘a lecturer in philosophy at St Andrews University,’ (Scotland, presumably). The reviewer was Heather Dyke, who ‘has taught philosophy at Otago, NZ and at the London School of Economics’.
I haven’t read Prosser’s book, but I was particularly taken by this quote (albeit out of context): "…if no physical system can detect the passage of time, then neither can the human mind". Basically (according to Dyke), Prosser rejects what he calls ‘A-Theory’ that past, present and future is how time manifests itself and, what’s more, is dynamic in as much as past, present and future keep changing all the time (my italics). ‘B-Theory’ simply states that events are temporally related – some events precede other events but there is ‘no objective distinction between past, present and future, and that time is not dynamic’ (Prosser’s position). I can’t do Prosser justice, but I can use my own philosophical position to critique what Dyke presented.
Prosser came up with a thought experiment, which Dyke only partly expounds upon: “a physical device that could detect whether or not time was passing, and thus tell whether or not A-Theory was true”. According to Dyke, Prosser contends that his detector, which uses ‘light... [to] illuminate when it detects the passage of time’, can’t distinguish between A-Theory and B-Theory, because ‘it will illuminate’ in both cases. This apparently leads him to the conclusion that I quoted above: if time can’t be detected by his ‘device’ then ‘neither can the human mind’.
My own position is that both A-Theory and B-Theory are correct, because B-Theory is just A-Theory without consciousness. Consciousness is the 'time-passing detector' that Prosser claims can’t exist. Consciousness is the only phenomenon that exists in a continuous present, as Erwin Schrodinger pointed out in his prescient book, What is Life?. Schrodinger doesn’t claim that this is a unique attribute of consciousness, but I do. I contend that everything else in the Universe either exists in the past or the future. Only consciousness surfs a wave of time which we experience as a constant now. That is why the concepts of past, present and future have no reference without consciousness; and, on that point, Prosser and I might even agree.
I’ve written a few posts on time, and in one I quoted William Lawrence Bragg:
Everything that has already happened is particles, everything in the future is waves. The advancing sieve of time coagulates waves into particles at the moment ‘now’.
I’m the only person I know who believes that quantum mechanics and classical physics are complementary rather than different versions of the same reality. Schrodinger’s equation is fundamentally a description of a wave function that only exists in Hilbert space, which theoretically can have up to infinite dimensions. Schrodinger’s equation has been superseded by QED (quantum electrodynamics) but the wave function and its phase change with respect to time and the Born mechanism to convert it into probabilities in the ‘real world’ (not Hilbert space) still apply. Also there is no time in Hilbert space, so ‘time’ in the famous time dependent Schrodinger equation can only exist in the classical physics world.
It is for all these reasons that I argue that they are different worlds that happen to interface at what’s called the ‘decoherence’ of the wave function, when the Schrodinger equation no longer applies. That’s right: Schrodinger’s equation only applies in Hilbert space, not the real world, even though time in the real world determines the phase of the wave function.
But I believe Lawrence Bragg (as distinct from his father, William Henry Bragg) provided a clue. Basically, it all makes sense to me if quantum mechanics is the future and classical physics is the past. The Born rule, that gives us the probability of an ‘event’ occurring in the real world (in the future), is mathematically equivalent to running Schrodinger’s equation both forward and backward in time – a point made by Schrodinger himself. Superposition makes perfect sense in Hilbert space if time doesn’t exist. Feynman’s path integral method assumes all paths are possible but most of them cancel each other out and we are left with the most probable path. He demonstrates this most efficaciously when he explains mirror reflection using quantum mechanics (as expounded in his book, QED).
For a photon of light, time is zero, and light is arguably the most commonly known quantum phenomenon that we witness all the time. We know that light has a finite velocity, otherwise, as someone pointed out (Caspar Henderson in A New Map of Wonders), everything would happen at once. A photon of light could literally see the entire life of the universe in its lifetime, which is zero from its perspective. Light is effectively in the future until it interacts with matter, as Bragg inferred.
Einstein discovered, mathematically, as opposed to empirically, that time is fluid, which means it passes at different rates depending on the observer. It’s gravity that ultimately determines the rate of time, because a particle (any particle) in free fall follows maximum relativistic time (as expounded by Feynman in another book, Six Not-So-Easy Pieces). Any deviation from free fall means that time will slow down, and that’s Einstein’s theories of relativity (both of them) in a nutshell.
Now, you may think that if time ‘flows’ at different rates in different locations then they must all have different ‘nows’ but there is no logical reason for that. Quantum entanglement suggests that now can exist across the Universe, even though Einstein himself never accepted that possibility.
In fact, Einstein argued that the now that we all experience is totally subjective – there is no objective now. I think that the finite age of the Universe, along with quantum entanglement, suggests that he was wrong, but others will work that out in the future, one way or another.
But the now that everyone experiences is a consequence of consciousness, because only consciousness surfs on a constant now.
Addendum 1: Loop quantum gravity theorist, Carlo Rovelli, has defined ‘now’ as the 'edge of the big bang', and that is as good a definition of an 'objective now' as you will find. An objective now can be translated or frozen in time like when you take a photograph or the background cosmic radiation, which is 380,000 years after the big bang (or thereabouts). In other words, objective ‘nows’ are relational as opposed to the present which becomes the past as soon as it arrives, except to sentient creatures like us.
Addendum 2: Roger Penrose, whose comprehension and discussion of quantum mechanics makes my ruminations appear simplistic, uses a metaphor of a mermaid sitting between the sea and the land to represent the relationship between QM and classical physics. He consistently talks about QM in 3 phases: U, R and C. U is the evolution of the wave function (described by Schrodinger’s equation in Hilbert Space). R is the 'decoherence' of the wave function, usually in the form of a measurement or observation. And C is classical physics, or the real world, where the detection takes place. U, R and C represent a sequence, which is consistent with my thesis that, relationally, QM is the future and classical physics is the past.
Addendum 3: Carlo Rovelli (refer Addendum 1) has said that ‘at a fundamental level, time disappears’, which is a well known mathematical conundrum in quantum cosmology (refer Paul Davies in The Goldilocks Enigma). My point would be that if you were looking into the future, you’d expect time to disappear.
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