The Beginning of Infinity: Explanations That Transform the World (43 page)

All this holds as much for knowledge written down as for knowledge spoken in person. So there would still be a ‘Socratic problem’ even if Socrates had written books. Indeed, there is such a problem in regard to the prolific Plato, and sometimes even in regard to living philosophers. What does the philosopher mean by such and such a term or assertion? What problem is the assertion intended to solve, and how? These are not themselves philosophical problems. They are problems in the history of philosophy. Yet nearly all philosophers, especially academic ones, have devoted a great deal of their attention to them. Courses in philosophy place great weight on reading original texts, and commentaries on them, in order to understand the theories that were in the minds of various great philosophers.

This focus on history is odd, and is in marked contrast to all other academic disciplines (except perhaps history itself). For example, in all the physics courses that I took at university, both as an undergraduate and as a graduate student, I cannot recall a single instance where any original papers or books by the great physicists of old were studied or were even on the reading list. Only when a course touched upon very recent discoveries did we ever read the work of their discoverers. So we learned Einstein’s theory of relativity without ever hearing from Einstein; we knew Maxwell, Boltzmann, Schrödinger, Heisenberg and so on only as names. We read their
theories
in textbooks whose authors were physicists (not historians of physics) who themselves may well never have read the works of those pioneers.

Why? The immediate reason is that the original sources of scientific theories are almost never good sources. How could they be? All subsequent expositions are intended to be improvements on them, and
some succeed, and improvements are cumulative. And there is a deeper reason. The originators of a fundamental new theory initially share many of the misconceptions of previous theories. They need to develop an understanding of how and why those theories are flawed, and how the new theory explains everything that they explained. But most people who subsequently learn the new theory have quite different concerns. Often they just want to take the theory for granted and use it to make predictions, or to understand some complex phenomenon in combination with other theories. Or they may want to understand nuances of it that have nothing to do with why it is superior to the old theories. Or they may want to improve it. But what they no longer care about is tracking down and definitively meeting every last objection that would naturally be made by someone thinking in terms of older, superseded theories. There is rarely any reason for scientists to address the obsolete problem-situations that motivated the great scientists of the past.

Historians
of science, in contrast, must do precisely that – and they encounter much the same difficulties as the historians of philosophy who address the Socratic problem. Why, then, do scientists not encounter these difficulties when learning scientific theories? What is it that allows such theories to be communicated through chains of intermediaries with such apparent ease? What has happened to the ‘difficulty of communication’ that I stressed above?

The first, seemingly paradoxical, half of the answer is that, when they learn a theory, scientists are not interested in what the theory’s originator, or anyone else along the chain of communication, believed. When physicists read a textbook on the theory of relativity, their immediate objective is to learn the
theory
, and not the opinions of Einstein or of the textbook’s author. If that seems strange, imagine, for the sake of argument, that a historian were to discover that Einstein wrote his papers only as a joke, or at gunpoint, and was actually a lifelong believer in Kepler’s laws. This would be a bizarre and important discovery about the
history
of physics, and all the textbooks about that would have to be rewritten. But our knowledge of physics itself would be unaffected, and physics textbooks would not need any change at all.

The second half of the answer is that the reason why the scientists
are trying to learn the theory, and also why they have such disregard for faithfulness to the original, is that they want to know how the world is. Crucially, this is the same objective that the originator of the theory had. If it is a good theory – if it is a superb theory, as the fundamental theories of physics nowadays are – then it is exceedingly hard to vary while still remaining a viable explanation. So the learners, through criticism of their initial guesses and with the help of their books, teachers and colleagues, seeking a viable explanation, will arrive at the same theory as the originator.
That
is how the theory manages to be passed faithfully from generation to generation, despite no one caring about its faithfulness one way or the other.

Slowly, and with many setbacks, the same is becoming true in non-scientific fields. The way to converge with each other is to converge upon the truth.

The idea of a ‘doppelgänger’ (a ‘double’ of a person) is a frequent theme of science fiction. For instance, the classic television series
Star Trek
featured several types of doppelgänger story involving malfunctions of the ‘transporter’, the starship’s teleportation device, normally used for short-range space travel. Since teleporting something is conceptually similar to making a copy of it at a different location, one can imagine various ways in which the process could go wrong and somehow end up with two instances of each passenger – the original and the copy.

Stories vary in how similar the doppelgängers are to their originals. To share literally all their attributes, they would have to be at exactly the same location as well as looking alike. But what would that mean? Trying to make atoms coincide leads to some problematic physics – for instance, two coinciding nuclei are liable to combine to form atoms of heavier chemical elements. And if two identical human bodies were to coincide even approximately, they would explode simply because water at double its normal density exerts a pressure of hundreds of thousands of atmospheres. In fiction one could imagine different laws of physics to avoid those problems; but, even then, if the doppelgängers continued to coincide with their originals throughout the story, it would not really be about doppelgängers. Sooner or later they have to be different. Sometimes they are the good and evil ‘sides’ of the same person; sometimes they start with identical minds but become increasingly different through having different experiences.

Sometimes a doppelgänger is not
copied
from an original, but exists from the outset in a ‘parallel universe’. In some stories there is a ‘rift’ between universes through which one can communicate or even travel to meet one’s doppelgänger. In others, the universes remain mutually
imperceptible, in which case the interest of the story (or, rather, two stories) is in how events are affected by the differences between them. For instance, the movie
Sliding Doors
interleaves two variants of a love story, following the fortunes of two instances of the same couple in two universes which initially differ only in one small detail. In a related genre, known as ‘alternative history’, one of the two stories need not be told explicitly because it is a part of our own history and is assumed to be known to the audience. For example, the novel
Fatherland,
by Robert Harris, is about a universe in which Germany won the Second World War; Robert Silverberg’s
Roma Eterna
is about one in which the Roman Empire did not fall.

In another class of stories, the transporter’s malfunction accidentally exiles the passengers to a ‘phantom zone’ where they are imperceptible to everyone in the ordinary world, but can see and hear them (and each other). So they have the distressing experience of yelling and gesticulating in vain to their shipmates, who are oblivious and walk right through them.

In some stories it is only
copies
of the travellers that are sent to a phantom zone, unbeknown to the originals. Such a story may end with the exiles discovering that they can, after all, have some effect on the ordinary world. They use that effect to signal their existence, and are rescued through a reversal of the process that exiled them. Depending on the fictional science that has been supposed, they then may begin new lives as separate people, or they may merge with their originals. The latter option violates the principle of the conservation of mass, among other laws of physics. But, again, this is fiction.

Nevertheless, there is a certain category of rather pedantic science fiction enthusiasts, myself included, who prefer the fictional science to make sense – to consist of reasonably good explanations. Imagining worlds with different laws of physics is one thing; imagining worlds that do not make sense in their own terms is quite another. For instance, we want to know how it can be that the exiles can see and hear the ordinary world but not touch it. This attitude of ours was nicely parodied in an episode of the television series
The Simpsons
, in which fans of a fantasy-adventure series question its star:

STAR:
Next question.

FAN
: Yes, over here. [
Clears throat
.] In episode BF12, you were battling barbarians while riding a wingèd Appaloosa, yet in the very next scene, my dear, you’re clearly atop a wingèd Arabian. Please to explain it.

STAR:
Ah, yeah, well, whenever you notice something like that, a wizard did it.

FAN
: I see, all right, yes, but in episode AG4 –

STAR:
[
firmly
] Wizard.

FAN
: Aw, for glayvin
*
out loud!

Because that is a parody, the fan is complaining not about the story itself, but only that there is a
continuity error
: two horses were used at different times to play the role of a single fictional horse. Nevertheless, there are such things as flawed stories. Consider, for instance, a story about a quest to discover whether winged horses are real, in which the characters pursue that quest on winged horses. Though logically consistent, such a story would not make sense in its own terms, as an explanation. One could embed it in a context that would make sense of it – for instance, it could be part of an allegory about how people often fail to see the meaning of what is right there in front of them. But in that case any merit in the story would still depend on how the characters’ apparently nonsensical behaviour was
explicable
in terms of that allegory. Compare that with the explanation that ‘a wizard did it.’ Since a wizard could equally well have been said to conjure
any
events, in
any
story, it is a bad explanation; and that is why the fan is exasperated by it.

In some stories the plot is not important: the story is really about something else. But a good plot always rests, implicitly or explicitly, on good explanations of how and why events happen, given its fictional premises. In that case, even if those premises are about wizards, the story is not really about the supernatural: it is about imaginary laws of physics and imaginary societies, as well as real problems and true ideas. As I shall explain in
Chapter 14
, not only do all good science-fiction plots resemble scientific explanation in this way, in the broadest sense all good art does.

In that spirit, then, consider the fictional doppelgängers in the
phantom zone. What enables them to
see
the ordinary world? Since they are structurally identical to their originals, their eyes work by absorbing light and detecting the resulting chemical changes, just as real eyes do. But if they absorb some of the light coming from the ordinary world, then they must cast shadows at the places where that light would otherwise have arrived. Also, if the exiles in the phantom zone can see each other, what light are they seeing with? The phantom zone’s own light? If so, where does it come from?

On the other hand, if the exiles can see
without
absorbing light, then they must be differently constituted from their originals, at the microscopic level. And in that case we no longer have an explanation of why they outwardly resemble their originals: the ‘accidental-copying’ idea will no longer do: where did the transporter get the knowledge required to build things that look and behave like human bodies, but function internally in a different way? It would be a case of spontaneous generation.

Similarly, is there air in the phantom zone? If the exiles breathe air, it can’t be the ship’s air, because they would be heard speaking or even breathing. But nor can it be a copy of the small amount of air that was in the transporter with them, because they are free to move around the ship. So there must be a whole shipful of phantom-zone air. But then what is preventing it from expanding out into space?

It seems that almost everything that happens in the story not only conflicts with the real laws of physics (which is unexceptionable in fiction), but raises problems within the fictional explanation. If the doppelgängers can walk through people, why do they not fall through the floor? In reality, a floor supports people by bending slightly. But if it were to bend in the story, it would also vibrate with their steps and set off sound waves which people in the ordinary world could hear. So there must be a separate floor and walls as well as an entire spaceship hull in the phantom zone. Even the space outside cannot be ordinary space, because if one could get back into ordinary space by leaving the ship, then the exiles could return by that route. But if there is an entire phantom-zone space out there – a parallel universe – how could a mere transporter malfunction have created
that
?

We should not be surprised that good fictional science is hard to invent: it is a variant of real science, and real scientific knowledge is
very hard to vary. Thus few if any of the storylines that I have outlined make sense as they stand. But I want to continue with one of my own, making sure that it (eventually) does make sense.