Time is an illusion, lunchtime doubly so..........

Is it?

Interesting thing time. Is it an illusion? Or does the flow, arrow of time in any physical sense exist? Or is it just inside our heads? A way of applying a pattern to the random fluttering of the wings of the universe? A pattern which we perceive but is, in truth, just that. A perception.

It seems real. Once an action has occured it seems impossible for it to 'unoccur'. Impossible for the universe to roll itself back to that bifurcation and reiterate down another possible path. It is impossible for us to perceive the multiple possibilities inherent in each quantum event, only one of the infinite possibilities is ever presented to us. Only one 'collapse of the wave function'. Why? What is it that prevents us from seeing each and every tiny forking of the path that the universe takes on the infinite roads to oblivion? Why do we only see the one we're on?

Feynman once postulated, taking the time invariance of quantum mechanical theory as his cue, that a positron (a 'positively' charged electron) is simply a normal electron moving 'backwards' in time. Because of the nature of quantum theory, that whichever way you do the sums, it matters not a jot whether 't' is 't' or '-t', except that with '-t' the charge is 'reversed', it is as valid an explanation of a positron as stating it is a 'seperate' 'particle'. In fact, Feynman, in explaining his diagrams and the resulting 'sum over histories' solutions to QED makes it very clear that you have to take into account the possibility that an electron goes backwards in time, emits a photon, moves forward in time and then absorbs a photon. The same photon? So, at a quantum level at least, time travel is theoretically possible. And yet, beyond that, once we scale up to our macrocosmic level, the level of what our brains perceive, and analyse, and rationalise, it seems impossible.

The desire to go back, reinvent what we are, what we have done, what we have said is rooted deep in our conscienceness. The idea that in some way we could change the present by manipulating the past just as we change the future by manipulating the present. And yet were it possible, we would already have done it but still the present is unchanged. It is the seeming paradox, which turns out not to be a paradox at all. You cannot travel back and murder your grandfather, the act is excluded by your very existence in the present.

Michael Moorcock (I think) once wrote a short story set hundreds of years in the future about 'time travel tours'. Tours back to famous events in history. The individuals are briefed on the exact circumstances, as they are known, so as not to influence in any way the unfolding events as they are known to the future. The central character chooses AD32/3 and witnesses the entrance of Christ into Jerusalem. He is there when Jesus is arrested and is part of the crowd when Christ is paraded, with Barabbas, before the baying mob, ecce homo. Only when he notices the subtle physical changes wrought on homo sapiens by the long years of evolution does he realise that the screaming mob are all time tourists!

So, in a very real sense, there is no linear passage of time, from there to here to where ever; past present and future are all so tightly bound together that it really doesn't matter whether time travel is possible or not. Either way, the present would be as it is and can be nothing else.

In the end the present is all we have, have had or will have. Beyond that only our memories and our hopes can provide comfort.

Thank you to the late, lamented Douglas Adams for the title and for perhaps the most quotable book in the history of the universe, the Hitch-hikers Guide to the Galaxy!