There were two magnificent timepieces on the wall, and they both chimed on the hour.  I suppose I must have sat there all afternoon, because I can remember hearing them several times.  It was a shame, I recall thinking, that the really friendly proprietor hadn’t managed to set his clocks to the right time.  Every hour, one would chime, and then, thirty seconds later, the other would follow, as surely as night follows day.  

He was talking to a young chap in cycle gear, who asked him how you could prove that the first chime wasn’t actually the cause of the second, seeing as the one followed the other as regular as clockwork. The old man had replied to the effect that it was impossible to prove that any events are linked together in any sort of causal relationship at all, that really events are like “beads on a string” (that’s what he said), and only appear connected because they share the same frame of reference.  

Like I said, it was rather interesting, although not necessarily the sort of conversation you’d want to be part of yourself.  He then went on to say – and bear in mind that I could only hear it because he’d said it first – that the whole idea of cause and effect depends on being able to say which way time is going. Obvious enough, you may think, particularly as these two clocks in the café consistently rotated clockwise, and after all, it would appear that the notion of time works well enough for everyday purposes.  

But my mathematically-inclined neighbour went on to insist that this fortuitous state of affairs only seemed natural because most people’s perspectives are so interminably local.  Suppose instead you were to consider, he said, two observers a very long way apart, then the true perplexity of time becomes apparent. Suppose you have two men – any two would do apparently – and let’s just say for the sake of argument that one’s in St John Under the Rock, and the other’s in Uzhgorod – but it could just as easily be Sidmouth or Florac – and suppose there were two explosions which took place at some distance from both of them – let’s just say one in Prague and the other in Kosice, but it doesn’t really matter (except to the people there).  Now it may well be that our friend in St John hears the Prague explosion before the one in Kosice, whereas his colleague in Uzhgorod perceives the Kosice event first.  Both are correct – who can judge between them?  Information takes time to travel, which gives each of us a different perspective on what order things happen in.  

Of course, although these six towns inhabit different political universes, geographically they are allegedly quite close.  But suppose Florac and Uzhgorod were repositioned at opposite poles of the Milky Way, so that they were as far apart astronomically as they are in reality.  Now they won’t even be able to see each other in the present; they will both (at the same time) see what the other was like 100,000 years ago, for that is how long it takes a photon of light to travel right across the Milky Way.  

But even this isn’t the real problem with cause and effect, I learned.  We’re all of us moving – whether by bike or by train, or simply through the universe in general, he said - and of course (of course!) time passes more slowly the faster you go, at least from the point of view of those left stranded on the station.  Time and place cannot be discussed in isolation from each other, and so talking about the order in which distant events occur simply doesn’t mean anything.  

The cyclist had choked on his tea at this point I think – but I’m not imputing any causal relationship here.