“Information” and indeterminism

To Shannon and Weaver, “information” is a measure of reliable co-variation between states at two separate locations. This co-variation is usually causal, but it might not be. Either way it is a “brute” physical fact, and most importantly it does not have semantic content — in other words, it isn’t true or false, it isn’t part of a linguistic or mental representation of anything, and as such it doesn’t depend on interpretation.

By contrast, linguistic or mental representations such as sentences and beliefs do have semantic “content”, which does depend on interpretation. That interpretation might be tightly constrained; indeed it is often constrained by “indicator” relations (in which representation and subject matter are linked by an “information channel” in the first, non-semantic sense of the word). But interpretation is still an essential part of it, because its “content” is “assigned” in a more or less holistic way, taking account of the larger representation of which it is a part.

In the everyday “semantic” sense of the word, ‘information’ stands for something like “true content”. In other words, it is used to refer to potential knowledge. If you think about it, this is an entirely different concept from that of non-semantic “information” above. It belongs to the “realm of representation” if you like — like beliefs and sentences, and unlike mere co-variation.

Physics makes claims that are themselves true or false, but it does not make claims that say something else is true or false, or whether something else should or should not be believed. In other words, while physics may be a representation of reality itself, it does not say anything about representations. I hope you can see this difference, between semantic “levels”, because it’s vital. It means that the everyday, “semantic” sense of the word ‘information’ does not occur in physics. Similarly, the traditional sense of the word ‘probability’ (meaning “credibility”) does not occur in physics either.

It seems to me that we humans are uniquely susceptible (probably innately susceptible) to the appeal of “immaterial substances”, to specious non-explanations involving the mind (such as “living things were designed by God”), and to the sense that physics is uniquely respectable as a science. This has given rise to a whole brand of non-explanatory, spiritualistic mysticism, one that systematically misinterprets words like ‘information’, ‘probability’, etc., and takes them to have their “semantic” sense, or in other words a sort of “mental” meaning. Under the influence of continental European philosophers and anti-materialist mystics, physics itself is sometimes taken to be a sort of “study of belief” rather than a “study of the physical world”. Some of the claims made by Bohr, Heisenberg and more recent interpreters of this tradition are grossly immodest. For example, Bohr held that “there is no quantum world”. Heisenberg held that “the concept of the objective reality of the elementary particles has ‚Ķ¬†evaporated”. More recently, ND Mermin tells us that “we now know that the moon is demonstrably not there when nobody looks”!

Words can be dangerous, especially familiar words in unfamiliar contexts, because they give rise to false expectations. To illustrate this, consider the EPR experiment, Bell’s inequalities, etc.. It’s one thing to say rather modestly that quantum spin orientation is “indeterminate prior to measurement”, quite another to say that “determinism is false”.

Let’s accept that “spin” orientation is “indeterminate” before “measurement”, and let’s reflect for a minute on those words. First, the “indeterminacy” here is the “indeterminacy” of Hamlet’s sister’s hair-color: it’s the indeterminacy of there simply being “no fact of the matter”, rather than the indeterminacy of “things depending on chance” or of “something intrinsically random” going on. Randomness only enters the picture when “measurement” throws up a series of apparently random values. Thus the word ‘measurement’ is quite misleading here, as what we have is more like a “random number generator”. We are not tempted to say that rolling a die or tossing a coin is a type of “measurement”. Furthermore, these apparently random numbers are correlated in an interesting way between physically separated “generators”, which suggests that they are linked by the “spooky action at a distance” that Einstein disliked so much, which in turn suggests they may not be as “random” as they appear in isolation. That is definitely bad for Einstein, but it is bad for determinism? — I think we have no way of telling. The “indeterminism” in question isn’t the type of indeterminism that is opposed to causal determinism. The “measurement” in question isn’t measurement as it is usually understood, capturing real values. Even the “spin” involved isn’t really spin as generally understood (spinning tops, Earth, etc.). We have good reasons for thinking the quantum world is real, but we haven’t any very clear ideas about the kinds of things that populate it. The values we get from “measurement” (or “interaction” or “generation” or whatever we call it) might indeed forever resist fitting any formal pattern as a matter of principle. Or not, as the case may be. In my opinion, no one can tell. Not yet, anyway.