23/10/13       BLOG 15/  IS ‘NOW’ AN ILLUSION ? 

Summary: Recent comments from physicists highlight the tripartite rift – between Relativity, Quantum Theory, and common perception – in what each implies for the ‘real nature’ of time. 

And since common time perception is the region least scrutinised by science so far, it must seem most likely to hold the answer to better time understanding overall......, 

Two New Scientist Articles

The latest review of time’s current crisis – i.e. scientists’ lack of understanding  about what it all really means – appears in New Scientist - Nov. 2 2013.  This follows fast on an earlier feature (August 5, 2013), which examined the seeming confliction between relativity, quantum theory, causality and free will. It concluded that our understanding of at least one of this quartet must be wrong.  But which one is erroneous remains unresolved so far...

In similar vein the later New Scientist describes recent efforts by physicists and cosmologists to resolve a very old question long known to philosophers.  Is the moment of ‘now’ real in any sense outside of our personal experience? Or alternately is it just an illusion of human consciousness?

This latest feature is by Australian Michael Slezak, who has tutored philosophy at the University of Sydney.  Since this institution  is also associated with the pioneering Centre for Time (founded by Philosopher Huw Price in 2002),  it’s no surprise to find he has special expertise on time affairs.

The Block Universe

First therefore Slezak summarises how most physicists now probably consider reality as essentially timeless, a concept also known as The Block Universe.  This is a very old philosophical idea given new life over the last century, largely through the great pragmatic success of Einstein’s Relativity Theories.

Relativity has always proven to work with total precision wherever it’s been tried.  But it also implies that our labelling of events as Past-Present-Future, is a purely local description, ultimately of no more significance than ‘Here’.  It holds that events of all sorts really lie timeless or coexistent against the background of space-time – and that we merely “‘dis-cover or come across them” as our lives proceed.  

Obviously such an implication must seem in strong conflict with our everyday experience of memory and reality.  Further it conflicts with one of the main tenets of Quantum Theory – the Copenhagen Interpretation which regards the future as essentially indeterminate....  

Time Reversal Common?

Some physicists therefore now concentrate on “the arrow of memory”, perceiving it as the main criterion through which we derive a direction for time.  They seek to explain why it should always seem to work from present to past – and never from present to future - quite exclusively.

In an earlier feature (The Guardian – 27/08/2009) Slezak has written on one such attempt. He summarised an article in Physical Review Letters (Aug 2009) wherein M.I.T. physicist Lorenzo Maccone proposed that the psychological time arrow of one-way memory could be explained through  quantum entanglement.

Maccone invoked symmetry, to suggest that time-reversed effects may occur in reality - and just as often as those others we normally observe.  For example a cup lying smashed on the floor might rise up to reassemble itself from its scattered fragments – and indeed might be doing so in reality just as often as we see it falling down to shatter in the normal way.

Maccone’s hypothesis also can be seen as the latest restatement of much older ones, 
for example those once summarised by Martin Gardner in Scientific American  -  Jan 1967.  Back then early theorists considered time in relation to  whole extraterrestial regions composed of anti-matter, and with all their inhabitants likewise.  If so, their extraterrestial memories might only reflect what we would see as their future, a process they would regard as entirely natural!

This could even be extended to an entire mirror-Universe where events run in the opposite direction to our own, as indeed Sean Carroll has suggested in a more historical context lately (Blog 14).  And more invocation of symmetry might even suggest it’s continuously interacting  with our own like two giant meshed cog wheels.  If so, some natural constraint of biology might keep us forever unaware of this other anti-Universe.

But of course in practice we never see such examples of time reversal, except in backward-running films.  To explain why not, Maccone postulates a very extravagant and ad hoc addition to quantum entanglement. He suggests that all our memories of such time reversal, may be naturally “erased by (quantum) necessity”.

There is of course no hint of evidence for any such ‘quantum necessity’, nor indeed that extensive time-reversal could ever actually transpire.  So Maccone’s argument dpeends on a wholly theoretical extension of entanglement, a notion itself ontologically dubious.   Wherefore It all seems like another metaphysical example of ‘fairy-tale physics’, which author Jim Baggott so deplores on the modern physics scene. (Cf: Blog 13).

In any case Huw Price – former head of the Sydney Centre for Time and now Cambridge Professor of Philosophy – regards Maccone’s argument as circular: his novel extension to quantum entanglement is “assuming the conclusion he wants to derive”.  Nor does it “explain why all observers have the same orientation in time – why don’t some observers remember what we call the future.....?”

Still the fact that Maccone  was published in Physical Review Letters  is just another testament to time’s growing importance on the modern physics scene.  Likewise his particular focus on memory is a very important matter to which I’ll return in Blog 16....

A Growing Block Universe?

In similar vein Mikchael Slezak’s article reports on how South African cosmologist George Ellis again proposes to use Quantum Theory to explain our experience of Now and its resultant memories.   Ellis invokes the quantum Copenhagen Interpretation which regards the future as indeterminate – until one of its various potentialities becomes suddenly transformed into a definite present through observation at the point of Now.

So the present is defined as that  observation instant which divides a real Past from an unreal Future, and which only comes into existence once such an observation is made!

The Ellis approach would also restore a common moment of Now across the Universe:  if it’s twelve noon now here on Earth, is must also be noon out in the furthest galaxy.   This would also seem to imply a sort of growing Block Universe, but one wherein just the past sector is fixed and determinate.  

But otherwise Ellis discards the full Block Universe implied by Relativity.  He quotes Quantum Theory to conclude that  “You can’t predict what will be tomorrow,  so the future can’t be real because its not even fixed yet”

To which Huw Price retorts that even though the future is unknowable to us, it may still exist, like whatever lies on the other side of an intervening hill! 

In addition the Copenhagen dictum invoked by Ellis results in the well known fable of Schrodinger’s Cat, an example of quantum illogic which British astronomer Fred Hoyle long ago reduced to absurdity.  For if you replace Schrodinger’s mythical cat (which is both-dead-and-alive until inspected!),  by a quantum detonator for an atom-bomb placed in London, then the capital is both there-and-not-there until some outside observer decides to look!

Directional Geometry?

In contrast New York mathematician Time Maudlin accepts common notions  of perception without further consideration, contending that “The notion that time passes is absolutely commonplace.”  Though on this one may observe that whether “time passes” by us – or alternatively instead whether it’s we who “pass through time” as implied by Relativity -  is not at all so clear!

In any case Maudlin proposes that all lines of all sorts drawn in space should always be given an arrowhead of direction as a fundamental property.  (Normally they lack this directional quality.)   From which he hopes to develop a whole new kind of geometry in which time direction is always integral.

Relativity Modified?

Ontario cosmologist Lee Smolin accepts common perceptions of time as valid much like Maudlin does, and seeks to integrate them with what physics apparently implies.   But in doing so he discards Relativity’s  Block Universe, reformulating Einstein through the mathematical medium of shape dynamics.  

So where Relativity Theory renders both space and time elastic for observers travelling at different speeds, these new mathematics would just stretch or compress space alone.  Those various observers would then only differ in their estimates of size or distance, while sharing a common or universal moment of Now.

Smolin’s idea would therefore agree with Quantum Theory to this extent of a universal Now.  But it does seem difficult to reconcile  with all those numerous effects of altered clocks and time dilation now readily observable.  And proven to agree with Relativity mathematics over the past 40 years.  

Still Smolin holds that “all that exists is this moment”, which makes the present the most important, indeed singular, aspect of time . So the past can only be real in terms of present records or traces which former events have left behind. And the future likewise in terms of present indicators sugggesting what may possibly occur.

Why time seems to ‘flow’ ?

In contrast to Smolin, California cosmologist Sean Carroll emphasises the marvellous successes of Relativity in so many fields.  So “we shouldn’t attempt to change the Block Universe to explain our experience of time flowing, ...but should concentrate on explaining human experience in light  of what our very successful physics tells”. 

But then to explain Relativity’s related implication of a fixed future, Carroll invokes Quantum Theory’s supposed extensibility into the Multiverse.  This would hold that an infinity of fixed futures already lie waiting before us – but that we can only encounter one of them.

Philosopher Craig Callender agrees with Carroll that physics should hold on to what is already proven to work so well.  So that “(to explain) our apparently aberrant perception of T, does not mean we have to overturn physics or invent a whole new way of geometry”.  And this is a viewpoint commendably parsimonious in contrast to much of what I’ve described above.

As opposed to the modern notion that the future ‘lies ahead’ of us, Callender seems to favour one  Ancient Greek viewpoint which held that the past lies in front of us and the future behind.  A picture perhaps more realistic and appealing than the modern convention in several ways. 

So that while we may seem to be moving “backward into the Future with no clear idea of where we’re heading”, Callender holds that such is merely due to our egocentric need for a continuous identity.   Instead one might regard all the observations of a lifetime as a series of about 3 billion second-long slices, each one “existing motionless” at its respective moment in space-time.  And from them we generate the illusion of time flowing, by combining all these moments into one egocentric and enduring sense of personal identity. 

Or  “because I think I’m identical over time, that’s why time seems to flow, even though it doesn’t”, as Callender concludes.....

In sum, a trichotomy......

Surveying all the foregoing therefore, and at the risk of undue repetition, it’s clear that a trichotomy, or tripartite rift, exists between current time understandings on three disparate frontiers.  The implications from Relativity don’t agree with those from Quantum Theory, and neither agree with what common experience or perception seems to say!

Of these three great conflicting regions in time understanding, it’s clear that Relativity is most soundly based.  Conversely perception must be the weakest,  in fact never really examined so far with rigour remotely comparable to physics experiments.

It’s therefore through a much deeper re-examination (literally a re-search!) of common ordinary temporal perceptions and preconceptions, that the answer to time’s overall enigma is most likely to be found. 

And that is an exercise to which I’ll devote the next few features here......

NEXT BLOG  “Why can’t people ‘Remember the Future’ – Really?”