Farewell to Reality (46 page)

12

Just Six Questions

Defining the Destination at the End of a Hopeful Journey

As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.

Albert Einstein
¹

I've found it hard to reach this point without my head filling with all kinds of homilies about journeys and destinations. I set out with the intention to provide you with at least an entertaining journey, one that I trust you have travelled hopefully. These are serious issues, and I still hope to persuade you that there's quite a lot at stake. But I also hope I've been able to make my points in a way that you've found enjoyable, with a minimum of po-faced proselytizing.

We've now arrived at our destination, and it's incumbent on me to try to wrap things up as best I can and give you some sort of definition of precisely where we are. In thinking about how best to do this, I considered providing you with some kind of summary, but this seemed to involve simply repeating all my main points, and I'm conscious that I've done that a couple of times already.

Instead, I figured it would be more interesting to anticipate some of the questions that might now be lurking at the back of your mind, and try to answer them as best I can.

I've thought of six.

If fairy-tale physics isn't science, what is it?

This is a very good question (and thank you for asking). As I've tried to explain, when there is no longer an attempt to ground theoretical
developments by forcing them to relate to the hard facts of empirical reality, the result is metaphysics. Therefore, the easy answer to this question is to declare that fairy-tale physics is metaphysics.

But this won't do. I went to great lengths in Chapter 1 to explain that reality (in its broader, non-empirical sense) is a metaphysical concept and that it is extremely difficult, if not impossible, to eliminate all the metaphysical elements from what we would have no difficulty in accepting as perfectly legitimate science. Philosophers of the logical positivist persuasion had a go at this in the 1920s and 1930s, and failed.

I'm not a professional philosopher, but it seems to me that the root of the problem lies in what we tend to demand from a description or explanation of the physical world if it is to be acknowledged as satisfying and meaningful.

Just what does it mean to comprehend or understand something? We might argue that we understand something when we have grasped the rules governing its properties and behaviour and can use these rules to manipulate the present or predict the future.

But there are rules, and then there are
rules.
We demand descriptions based on rules of the kind that convey insight and
understanding.
If we strip all the metaphysics from science — all the stuff we can't prove by reference to the facts but nevertheless believe to be contingently true (in the spirit of the Veracity Principle) — then what we are left with is a rather vacuous instrumentalism. Theories then serve a simple purpose. They are instruments that we use to relate one set of empirical facts to another, but in a way that conveys no real understanding.

I want to illustrate why I don't think this is very satisfactory by reference to a famous allegory devised by American philosopher John Searle. Searle formulated his ‘Chinese room' thought experiment to attack some assumptions regarding artificial intelligence, but it will serve our purposes here to help us recognize what we mean by ‘understanding'.

Searle sits on a chair in an empty room. We slip him pieces of paper beneath the door carrying questions written in Chinese which require simple, single-word answers. Searle doesn't speak Chinese, but he has a handbook titled
Empirical Rules for the Interpretation of Chinese Characters.
The rules described in the handbook tell him how to interpret the characters without providing a translation. They are rules of the type ‘if
then
. By blindly following the rules, Searle can select quite sensible answers in a way that does not contradict previous answers.

He slips his answers back to us beneath the door. From our perspective, he is having an intelligent conversation with us, in Chinese.

But Searle doesn't
understand
Chinese. He is just a computer, following an algorithm. To have an intelligent conversation with the universe, we need more than mechanical algorithms or instrumental rules that allow us to manipulate the present or predict the future. We need a
structure:
we need to understand the letters, the vowels, the words, the grammar and syntax. We need to understand the basic elements of reality — light, matter and force, space and time — and how these elements combine together to construct the poetry of the universe.

Metaphysics is an inherent and perfectly natural part of the language we use in our dialogue with nature. Eliminate it completely and the language becomes devoid of real meaning. We find we can no longer hold a sensible conversation in it.

The logical positivist programme was doomed. The philosopher A. J. Ayer, the positivist movement's English spokesman, was obliged to develop a grudging acceptance of metaphysics. He observed that: ‘The metaphysician is treated no longer as a criminal but as a patient …'
²

But even though our scientific dialogue has metaphysical elements, this is still a dialogue that is about real, empirical things. It concerns effects that we interpret in terms of the properties and behaviour of photons or quarks or electrons: their spin properties, their quantum wave-particle duality, as manifested in the observations we make and the experiments we perform. It concerns the curvature of spacetime in the vicinity of the sun. It concerns the quantum ripples in the CMB radiation. The dialogue has metaphysical elements (such as photons or quarks, or …), but of course it is also rich in empirical content.

In fairy-tale physics, we lose sight of the empirical content, almost completely. Yes, of course there are references to photons and quarks and electrons, spacetime curvature and quantum ripples, but these are broadly qualitative, not quantitative, references. And we get a lot more besides — sparticles, hidden dimensions, Kaluza—Klein particles, branes, many worlds, other universes, and so on. These new theoretical entities come also in references that are broadly qualitative, not quantitative. If there is one theme underpinning contemporary theoretical physics, it seems to be an innate inability to calculate
anything,
with the not-so-apologetic caveat: well, it still might be true.

I'm no big fan of out-and-out empiricism, but Scottish philosopher and arch-sceptic David Hume's oft-quoted passage seems particularly relevant here:

When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume of divinity or school metaphysics, for instance, let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion.
³

The issue, then, is not metaphysics per se. The issue is that in fairy-tale physics the metaphysics is
all there is.
Until and unless it can predict something that can be tested by reference to empirical facts, concerning quantity or number, it is nothing but sophistry and illusion.

But aren't theoretical physicists supposed to be really smart people?

Another good question. You don't get to be a professor of theoretical physics at Stanford, Harvard or Princeton, or any leading academic institution anywhere in the world, if you're an intellectual lightweight. These are
very
smart cookies. So how can I claim they've got it all wrong?

Well, obviously
they
don't think what they're doing is wrong. As far as they're concerned, this all makes perfect sense. We know the authorized version of reality can't be right. Attempts to solve its problems lead to mathematical structures that suggest all kinds of bizarre things. Okay, we have no empirical proof for these things, but we're faced with a choice. Either we give up and just admit we don't know (which is regarded by many as a rather lame response), or we push on past the demand for empirical proof and explore the structures in a lot more detail, perhaps in the hope that
something
will turn up which will allow us to connect the mathematical structures back to reality.

I actually don't have a problem with this. We should be glad that those few theorists pursuing quantum field theory in the 1950s and 1960s stuck with their programmes, against the odds that prevailed at
the time. The ‘bootstrap' model was the more popular theoretical structure, and the contributions of quantum field theorists were generally dismissed as irrelevant. In 1964, Peter Higgs had problems publishing the paper in which he outlined what would become known as the Higgs mechanism (and in which, in a subsequently added footnote, he predicted the existence of the Higgs boson). He later wrote:

I was indignant. I believed that what I had shown could have important consequences in particle physics. Later, my colleague Squires, who spent the month of August 1964 at CERN, told me that the theorists there did not see the point of what I had done. In retrospect, this is not surprising: in 1964 … quantum field theory was out of fashion …
⁴

Here's my problem. For how long do we continue to suspend our demand for empirical proof? Ten years? Thirty years? A hundred years? The assumption of electro-weak symmetry-breaking caused by the Higgs field allowed Steven Weinberg to predict the masses of the W and Z particles in 1967. The Higgs mechanism was therefore a theoretical device that was arguably justified when these particles were discovered at CERN in the early 1980s, almost twenty years after the theory had been written down.

But even this is indirect evidence, at best. The existence of the Higgs field can only really be betrayed by observing the Higgs boson. If the new particle discovered at CERN in July 2012 is indeed the Higgs boson, then almost fifty years have elapsed since this particle's invention.

We have obviously had to learn to be patient. But at least the Higgs mechanism was progressive — it solved some problems and made predictions for which there was some hope of providing a test sometime in the not too distant future. SUSY has made some predictions, of a sort, but these are not so far supported by data emerging from the LHC. SUSY is failing the test. Superstrings/M-theory and the various multiverse theories have made no really testable predictions at all.

At what point do we recognize that the mathematical structures we're wrestling to come to terms with might actually represent a wrong turn, like the bootstrap model?

Once we ease off on our demands, once we abandon the checks and balances afforded by a proper adherence to the scientific method, we train a whole generation (perhaps that should be generations) of theorists to believe that a soft approach to empirical proof is not only perfectly acceptable but even
necessary
to continue to publish research papers and advance their careers.

Now this is where it all gets
really
interesting. What happens when some really clever people decide that it's okay to abandon the checks and balances? After all, they say, we're all grown-ups. We're all smart cookies. According to a strict interpretation of the rules, this is maybe not acceptable. But hey, rules are made to be broken. If we just relax the rules even by a little bit, then all manner of new and exciting things become possible.

This shift in value-set can be overt or it can be quite subtle. Irrespective of its subtlety, such a shift can lead inexorably to the development of what I call a Grand Delusion (with Capital Letters, intended to Emphasize its Profound Importance).

There are plenty of precedents for Grand Delusions throughout history.
*
And ‘cleverness', it seems to me, is almost a prerequisite. The best example of a recent Grand Delusion that I can think of is the one that led some very clever people in the global financial sector to think that they could relax the rules on financial risk, thereby discovering that all manner of new and exciting things become possible.