The Universe Between – Spoiler

The nature of the Thresholder universe only began to become clear when they sent one of their number – an eighteen-year-old woman named Sharnan – through to the Telcom Laboratories. Sharnan was chosen for the mission for exactly the same reason that McEvoy had sent Gail Talbot though the original Threshold more than a quarter of a century earlier.

It became clear to Hank Merry and Robert Benedict that the Thresholder universe was in reality no different to their own, and that the apparent extra spatial dimension was nothing more than an artefact of viewing it through hyperspace. Robert developed a romantic attachment to Sharnan, and though her and others he learned that the Thresholder universe was only one of an infinite number. He realised that this was the root of the problem.

The Thresholder technology was less advanced than that developed by the Telcom Laboratories team, and their equipment was prone to infinitesimal errors with the critical angles of rotation. The result was that consignments were prone to end up in different universes, where different laws of physics applied. The steel pipes had ended up on a Mars where steel had a melting point below that of water. The Thresholders had realised their error and recovered the steel, but they had then been forced to dump the now molten metal hundreds of miles away from Ironstone for safety. The 61 Cygni colonists had been on a world where the Second Law of Thermodynamics was running in reverse – they were exposed to cold, and instead of cooling down they began to heat up. Once returned to normal conditions of entropy, they began to recover. Less fortunate were the members of the Saturn expedition, who had ended up on a Saturn composed of antimatter.

Hank Merry was able to address the technological issues, and Robert Benedict gradually learned more about the Thresholder world. It was a parallel version of Earth with a very similar history up until November 1963. Before he had had a chance to establish the Joint Conference and so end the Cold War, President Kennedy had been assassinated in “some place they call ‘Texas’” with the consequence that the Thresholders were “still limping along with a ‘United Nations’ or some such thing.