If I had, in my sixth life, any concerns that it was unfitting for a should-be professor to spend most of his time arguing with an undergraduate student rather than sitting in silence at high table with his peers, those concerns had vanished with my further acquaintance with Vincent. His complete lack of interest in my supposed status had cultivated a complete apathy towards it on my part too, and of all my colleagues he seemed the only one with the remotest interest in the unfashionably modern ideas with which I tormented 1940s academia.
“Our impossible time traveller has, in the ten seconds he spent in the past, inhaled eight litres of air, one part oxygen to four parts nitrogen, exhaled eight litres of air in which the carbon dioxide content has been marginally increased. He has stood upon a muddy patch of ground in the middle of nowhere, and the only creature which observed his passage is a startled sparrow which has now taken flight. Beneath the soil a single daisy has been crushed.”
“Ah, but in that daisy!” I intoned, for this was a regular rant of Vincent’s.
“Ah, but in the sparrow!” he retorted. “The sparrow took flight in alarm, and the falcon which was diving to eat it is now diverted, and the falconer has to run further afield to reclaim his bird, and in running further afield—”
“Sees the master’s daughter in flagrante with the butcher’s son!” I lamented. “And catching them so unprepared, cries out, ‘You rascals!’ at which all intercourse ceases and the daughter who should be pregnant is not at all—”
“And does not have her child!”
“And that child does not have a child, being, as it is, not born—”
“And a hundred generations later our brave traveller finds himself no longer in existence because his ancestor was caught with the butcher’s son and so, being non-existent, he cannot return in time to prevent his own birth by the startling of a sparrow, and so, therefore, is born, and so he can return and prevent his birth and… Are we to posit God?” blurted Vincent suddenly. “Is that the only way out of this trap?”
“God?” I queried.
“We are to suppose,” he retorted, dumping his surprisingly spry though hardly nimble frame back down in my second-favourite armchair, which now bore the imprint of his body well into its cushions, “that there are only two solutions to this paradox? That one–the universe, finding itself unable to sustain this great burden on its being, simply ceases to be? Or that two–the universe, finding itself still somewhat confused, fixes itself in a way beyond our ken and which, by its express interest in the events of our time traveller, rather does imply conscious structure and thought more than a mere amalgamation of matter might be expected to provide. Are we to posit God?”
“I thought we’d concluded that this hypothesis was impossible.”
“Harry!” snapped Vincent, throwing his hands up into the air. “How long have we sat here?”
“I assume you query not some imposed measurement of time, rather how long since you first walked into my rooms to refute my errors?”
“Whenever,” he replied, “we come close to the thorny uncertainties of this life, whenever we bring into question the notion of what if, you retreat from the argument like a cocker spaniel from a bulldog’s bone!”
“I see no point arguing on a subject upon which, by all scientific measurements of the time, we cannot gather any data that might give us an answer,” I replied.
“We cannot measure gravity, not in any practicable sense,” retorted Vincent, his face settling into something of a sulk. “We cannot say how fast it is, or even what it is, yet you believe in it as much as—”
“Through observable effect.”
“So you limit our debates based on the tools available?”
“A scientific argument must have some degree of data, some… some sniff of theoretical basis behind it; otherwise it’s not a scientific argument, it’s a philosophical debate,” I replied, “and therefore hardly my department.”
Vincent gripped the arms of his seat, as if only that solid presence would prevent him springing up in rage. I waited for the tantrum to pass, “A thought experiment,” he said at last. “You will at least tolerate that?”
I gestured vaguely over the lip of my glass that, just this once, I might be open to the idea.
“A tool,” said Vincent at last, “for the observation of everything.”
I waited.
There seemed nothing more.
“Well?” I asked at last. “I’m waiting for the development of the argument.”
“We accept the existence of gravity not because we can see it, or touch it, or say with any great certainty what it is, but because it has observable consequences which can be predicted through consistent theoretical models, yes?”
“Yesss…” I concurred, waiting for the snag.
“From observable effects, we deduce non-observable consequences. We observe that an apple falls and say, ‘It must be gravity.’ We watch the refraction of light through a prism and declare it must be a wave–and from that deduction more deductions follow on behaviour and effect, amplitude and energy. So, by very little effort you can quickly theorise your way to the very bottom of things based on rather crude observable effect, as long as it fits the theory, yes?”