Physics 1

I’m reading some books on the latest developments in physics — something I do every once in a while. I’m interested in learning about the latest developments in string theory, brane theory, etc — the latest accounts of the “ultimate” structure of the universe; and I’m interested in how the strange anomalies that astronomers continue to make — about the age and size of the universe, the degree of its expansion, and so on — can be explained (most recently, in terms of “dark matter,” “dark energy,” and other such strange concepts). I’m interested, too, or perhaps above all, in the philosophical implications of all this.
There are several points that need to be mentioned, as I begin.
First: although the explanations that pop science books give is never of the same depth as the understandings of the scientists themselves, this is especially true with theoretical physics and cosmology. Because things like quantum mechanics, together with more recent developments like string theory, cannot be understood in “layman’s” or intuitive terms. Things like the uncertainty principle, wave/particle duality, and quantum superposition are so profoundly counter-intuitive — although everything we know tells us that they are true and real — that they are not graspable at all in words, images, or logical concepts. To put it differently, they are only comprehensible as very high level mathematical abstractions. Since I — like the overwhelming majority of human beings — do not understand the math, I am simply not capable of understanding quantum mechanics.
Which means that, to a large extent, I am incapable of judging what’s told to me in the books I’m reading on theoretical physics. I accept what I’m told about quantum mechanics, because quantum effects are really experienced in the physical world, just as much as “classical” physical effects (which I can comprehend) are really experienced. But even if I have an idea about how quantum computation might work, I still can’t grasp what a quantum superposition (the cat in the box being both alive and dead) actually means.
In particular, when scientists disagree (as major physicists currently do, on many matters) my only grounds for deciding between them are aesthetic or metaphysical ones. I am not able to follow the reasoning on the basis of which the scientists themselves argue out their positions; nor can I understand the criteria which could lead one to concede the argument to the other.
(For what it’s worth, the scientists and mathematicians who do understand these matters, do so only at this highly abstract mathematical level; they remain as incapable of grasping it intuitively as anyone else. It’s often said that great physicists, like Einstein, somehow have an intuitive grasp of the math and of the concepts they come up with. But Einstein himself is as good an example as any of the fact that it is humanly impossible to “translate” such mathematical/theoretical intuition back into other, more commonplace terms or frames of reference. Einstein had as much trouble as anyone else in grasping the real implications of relativity and (even more) of quantum mechanics.)
That’s the first problem. The second one, perhaps equally serious, is that physicists themselves seem to be reaching the point where mathematical consistency and elegance seem to have become more important than empirical verification. This is a point that was made particularly strongly by John Horgan in his 1996 book The End of Science. Horgan says, basically, that theoretical physics has gone into the deep end, or “jumped the shark”: it has reached a point where it has become concerned with “speculations [that] cannot be empirically verified” (p65). There is no way that we can ever actually know whether or not the universe is made of 9-dimensional strings, or attached to multidimensional membranes, or whether or not what we call the universe is only one of many, created in innumerable “Big Bangs.” String theory and its kin are no longer making verifiable or falsifiable predictions, the way general relativity and quantum mechanics both did. Instead, the claims for such theories are that, if we solve all their equations, then the theories and facts we already know about the universe come out right.
In other words: there will never be any empirical evidence either in favor of, or against, the existence of six tiny folded-up dimensions in addition to the three spatial dimensions we experience on a regular basis. The claim is rather that, if we start from the postulate of those extra dimensions, then we can derive the laws of quantum mechanics and relativity (as we already know them without any recourse to the extra dimensions). This is supposed to be a good thing, because it saves physics from the embarrassment that, as they are currently formulated without string theory, quantum mechanics and general relativity logically contradict one another — even though they both work, in the sense that they both have been verified, and have measurable consequences in overwhelming numbers of circumstances.
String theory claims to resolve the contradiction; and physicists therefore claim that it describes the ultimate nature of reality. But this is both logically dubious (because it leaves open the possibility that some entirely different theory, making entirely different claims, which nobody has thought of yet, might also resolve the contradiction and mathematically generate the same observed results with regard to gravity and subatomic particles), and metaphysically shaky (since what it claims as “ultimate reality” not only cannot ever be observed, but has no pragmatic consequences whatsoever).
Horgan therefore suggests that what the string and brane theorists are doing is aesthetics, metaphysics, or theology, rather than science.
My feeling about this is that two out of three ain’t bad (I have little use for theology). But if theoretical physicists are really engaging in metaphysics and aesthetics, then we need to think about the philosophical assumptions embedded in, and the philosophical consequences of their arguments: something that they themselves are not very good at doing, since they tend to be ignorant of the history of philosophy (the occasional reference to Leibniz or Spinoza notwithstanding), and to assume that their mathematics gives them a philosophical authority, when they talk about such things as space, time, and why things are the way they are. They often tend to be quite philosophically naive.
So even though I don’t understand most of what the physicists are saying, I think it’s important for us to try to think through these issues, rather than accept their assertions at face value — since, in certain contexts, the physicists may well not understand the presuppositions and implications of what they are saying, either.