Time Travel: A Writer's Guide to the Real Science of Plausible Time Travel

CHAPTER 4 Hyperspace

CHAPTER 4 Hyperspace The three dimensions are all that there are. Aristotle, from his circa 350 B.C.essay "On the Heavens." Much of the modern literature on time machines and time travel is presented in terms of spaces with four, five or even more dimensions . Even if we reduce the count by one (for the nonspatial time dimension), we are still left with more than three dimensions, hyperspace . We shouldn't let the above epigram worry us too much,however , because Aristotle was pretty much a washout as a physicist— recall his famously wrong assertion that the heavier an object, the faster it will fall. His claim about the number of dimensions to space is not yet clearly a similar mistake, but I would bet that a sizeable number of modern physicists suspect it will eventually prove to be. A fundamental biological-topological argument has been advanced for why space could not have less than three dimensions. In all of our common experiences, intelligent life is always found to occur as an aggregate ofa vast number ofelementary cells interconnected via electrical nerve fibers. Each such cell is connected to several others, not allimmediate neighbors, by these fibers. If space had only one or two dimensions, then such highly interconnected cellular networks would be impossible, as the overlapping nerve fibers would intersect, resulting in their mutually shorting one another . Edwin Abbott's 1880 fantasy classic Flatland, then, is fatally flawed on a biological level. 68 Time Travel It might be thought that the three-dimensionalityof space is obvious since we use exactly three numbers to locate a position in space. To quote H.G. Wells, from his 1934 Experiment in Autobiography, "In the universe in which my brain was living in 1879, there was no nonsense about time being space or anything of that sort. There were three dimensions, up and down, fore and aft and right and left, and I never heard of a fourth dimension until 1884 or thereabout. Then I thought it was a witticism." But why three dimensions, and not some other number?As the mystical Russian philosopher P.D. Ouspensky wrote, "By an independent direction we mean ... a line lying at right angles to another line. Our geometry... knows onlythree such lines which liesimultaneously at right angles to one another and are not parallel to each other. Why are there only three and not ten or fifteen? This we do not know." In an 1888 talk to the Philosophical Society of Washington, however, the American scientist Simon Newcomb dismissed the view that space must necessarily be three-dimensional as an "old metaphysical superstition." (Newcomb is of particular interest in time-travel discussions because he is the only real person mentioned in Wells's The Time Machine) The idea of a fourth dimension is viewed by many as simpleminded nonsense. In his 1897 Presidential Address to the American Mathematical Society, Simon Newcomb declared, "The introduction ofwhat is nowvery generally called hyper-space (sic), especially space ofmore than three dimensions, into mathematics, has proved a stumbling block to more than one able philosopher." Even Einstein got into this business of speaking of the spooky nature of hyperspace when he wrote: "The non-mathematicianis seized by a mysterious shuddering when he hears of 'four-dimensional' things, by a feeling not unlike that awakened by thoughts of the occult." To understand just how right Einstein was with his statement, consider the reaction (in 1929) ofone philosopher to general relativity : "We have no doubt in our mind that nobody can understand it (the fourth dimension), including Einstein himself. The incomprehensibility of [the theory's assumptions] is due to their nature. They Hyperspace 69 deal with the fourth dimension ... and the reality oftime and space. They can only be described by a mathematician's hypothesis or by religious faith/' Who could really blame the skeptical philosopher— how could there actually be four spatial dimensions?After all, anybody can see there are exactly three spatial dimensions and that is simply that. For science fiction writers, however, the fourth dimension (and hyperspace, in general) is a major concept in its own right, and it plays an essential part in time travel,too. FOLDED SPACE-TIME AND WORMHOLES And just what is hyperspace? It is a space ofhigher dimension than the one we obviously live in. As already discussed, our universe appears to be a four-dimensional world called space-time. This...