Farewell to Reality (47 page)

Lending money has always been a bit of a gambler's game. But banks and sub-prime mortgage lenders found that they could substantially grow their businesses by rewriting the rules on risk assessment and concealing the nature of this risk by salami-slicing the debt and selling it on to a multiplicity of other institutions through ‘collateralized debt obligations' and other complex financial instruments.

At the heart of this new financial wizardry was Chinese mathematician David X. Li's Gaussian copula function. Li was lauded as the ‘world's most influential actuary'. His function was used to model complex risk
with a minimum of fuss and with apparent accuracy. It was applied by the banks and the mortgage lenders to set prices for their collateralized debt obligations.

Suddenly it became possible to lend money to institutions and individuals who would previously have been deemed high-risk borrowers. The value-set changed. Lending became more and more predatory, and the result was a property boom.

Those of us with investment savings accounts and pension funds enjoyed it while it lasted. We welcomed an unprecedented period of economic growth. But we were all conspirators in a conspiracy not of our devising. Our financial institutions applied their new theoretical structures and made hay while the sun shone. In the UK, the Labour government's Chancellor of the Exchequer Gordon Brown played whore to the financial sector, declaring the end of boom and bust. It really did seem as though the ‘City' (meaning the financial centres of major cities around the world) had figured out how to make money out of money in ways that benefited many, harmed nobody and would continue for ever.

Alas. It was a Grand Delusion. There finally came a day of reckoning in October 2008. No matter how elaborate the theoretical structures or how complex the financial instruments, nothing could change the rude facts of empirical reality.
*
An awful lot of money had been lent to people who would never pay it back. It was as simple as that. The boom turned to bust.

We had all received a rather stark lesson in the cost of allowing mathematical models to run too far ahead of the empirical facts: ‘Li's Gaussian copula formula will go down in history as instrumental in causing the unfathomable losses that brought the world financial system to its knees.'
⁵

Now, I don't wish to underestimate the intellectual capabilities of theoretical physicists, who, I'm sure, are a lot smarter than actuaries, bankers and mortgage lenders. But it does seem to me that if a relatively small number of very smart people in the financial sector can delude themselves in a way that almost brought down the entire world economy, and which four years later still threatens to cause some
European countries to default on their sovereign debts, then it's surely possible that a few theorists can delude themselves about what qualifies as science?

Okay, but in the grand scheme of things is there any real harm done?

Of course, arguing about whether M-theory, the multiverse and other products of fairy-tale physics are metaphysical rather than scientific structures offers something of an entertaining distraction, but you might think this is hardly earth-shattering when measured (for example) against the misuse of a mathematical function to price collateralized debt obligations. After all, what does it matter if a few theorists decide that it's okay to indulge in a little self-delusion? So what if they continue to publish their research papers and their popular science articles and books? So what if they continue to appear in science documentaries, peddling their metaphysical world views as science? What real harm is done?

I believe that damage
is
being done to the integrity of the scientific enterprise. The damage isn't always clearly visible and is certainly not always obvious. Fairy-tale physics is like a slowly creeping yet inexorable dry rot. If we don't look for it, we won't notice that the foundations are being undermined until the whole structure comes down on our heads.

Here are the signs.

The fairy-tale theorists have for some time been presenting arguments suggesting that the very definition of science needs to be adapted to accommodate their particular brand of metaphysics. The logic is really rather simple. Developments in theoretical physics have run far ahead of our ability to provide empirical tests. If we hang our definition of science on the Testability Principle, then we have a problem — this stuff clearly isn't science.

But if it isn't science, we forgo the opportunity to explore the vast richness afforded by the mathematics. This richness is compelling, as it feeds an innate human desire to concoct stories about our universe and our place in it. Something has to give.

So, in
The Hidden Reality,
Greene writes:

Sometimes science does something else. Sometimes it challenges us to reexamine our views on science itself. The usual centuries-old scientific framework envisions that when describing a physical system, a physicist needs to specify three things … First are the mathematical equations describing the relevant physical laws … Second are the numerical values of all constants of nature that appear in the mathematical equations … Third, the physicist must specify the systems' initial conditions … The equations then determine what things will be like at any subsequent time … Yet, when it comes to describing the totality of reality, the three steps invite us to ask deeper questions: Can we explain the initial conditions — how things were at some purportedly earliest moment? Can we explain the values of the constants — the particle masses, force strengths, and so on — on which these laws depend? Can we explain why a particular set of mathematical equations describes one or other aspect of the physical universe?
⁶

This all seems very reasonable. But at what point does asking ‘deeper questions' about the ‘totality of reality' take us across the threshold from physics to metaphysics? At what point do we run up against the limits of science's capability to answer these deeper questions?

To be fair, the history of science is a history of continually and consistently pushing the boundaries into domains in which it might have been thought that science could or should have no answers to give. To the surprise of many, there were indeed answers to be found. And these were answers that were found to be rooted in empirical reality.

But in fairy-tale physics there are no answers, there are only untested and untestable speculations. Greene continues:

Collectively, we see that the multiverse proposals … render prosaic three primary aspects of the standard scientific framework that in a single-universe setting are deeply mysterious. In various multiverses, the initial conditions, the constants of nature and even the mathematical laws are no longer in need of explanation.
⁷

Don't get me wrong. I'm all in favour of pushing the boundaries; of probing the limits of scientific enquiry. I'm fundamentally interested in
answers to deeper questions about the totality of reality. But I personally prefer rigorous answers that
mean
something. I prefer answers that I can regard either as scientifically true or capable in principle of yielding answers that might one day come to be regarded as true.

Greene wants to give me these answers (basically, telling me that in the anthropic multiverse no answers are necessary, or all answers are possible) by insisting that we extend the definition of science to include speculative theorizing of the fairy-tale kind. We must give up our checks and balances. We must abandon the Testability Principle and adapt our understanding of what it means for something to be scientifically true.

Susskind argues along similar lines. In
The Cosmic Landscape,
he writes:

Frankly, I would have preferred to avoid the kind of philosophical discourse that the anthropic principle excites. But the pontification, by the ‘Popperazzi', about what is and what is not science has become so furious in news reports and internet blogs that I feel I have to address it. My opinion about the value of rigid philosophical rules in science is the same as Feynman's [‘Philosophers say a great deal about what is absolutely necessary for science, and it is always, so far as one can see, rather naïve, and probably wrong.']
⁸

The term ‘Popperazzi' is a reference to the Austrian philosopher Karl Popper, whose principle of falsifiability continues to be popular among scientists as a working definition for what constitutes a scientific theory. According to this view, a scientific theory is one that is in principle capable of being falsified by an observation or an experimental test. Unfortunately, falsifiability has long since lost credibility among philosophers of science.

In fact, ‘Popperazzi' is also a not-so-veiled reference to theorist Lee Smolin, who has sought to use Popper's principle of falsifiability to argue that the anthropic principle is not science. Susskind and Smolin have publicly debated these issues, for the most part arguing at cross-purposes.
⁹

It is unfortunate that Smolin used falsifiability as a criterion with which to question the scientific authenticity of the anthropic principle, since falsifiability is open to attack and not easily defended. But at the
heart of Susskind's argument there appears to lurk a reluctance to commit to ‘rigid rules', no matter what their origin.

By the way, I think that Susskind's use of Feynman's words in support of his argument is rather disingenuous. Feynman was no great fan of philosophy, but he understood well enough what science is. He was also extremely sceptical of the string theory approach. Another oft-quoted Feynman observation is that: ‘String theorists don't make predictions, they make excuses.'
¹⁰

I think we have to be quite concerned about where these attempts to change our outlook on science might lead. Softening our position and letting in all manner of speculative metaphysics may give some theorists a stronger sense of justification for what they're doing, but what other consequences might follow?

If we're going to abandon the ‘rigid rules' and change the definition of what it means for something to be scientifically true, then what definition should we use? That it is rigorously mathematically consistent and ‘coherently' true? But why stop there? If we're no longer demanding that scientific theories should establish a correspondence truth with elements of empirical reality, then, surely, anything goes? Why wouldn't we then regard astrology as true? Homeopathic medicine? Intelligent design?

We can see where this leads. If scientists can set themselves up as the high priests of a new metaphysics, and continue to preach their gospel unchallenged through popular books and television, then the credibility of all scientists starts inexorably to be eroded. Why should we take any of them seriously?

The really worrying thing is that the scientific community seems caught in two minds about all this. While there are many physicists prepared to take the tellers of fairy tales to task, this is extremely sensitive ground. It is hard to criticize fairy-tale physics without being perceived to be criticizing science as a whole. And at a time when science is on the defensive against a resurgent and increasingly voluble anti-science rhetoric, is it really helpful to be throwing rocks at a few theorists? With the boat already rocking, physicists think twice before jumping up and down in it.

What do the philosophers have to say about all this?

Hmm. Another interesting question. We might have imagined that these rather striking developments in theoretical physics would have attracted a lot of interest from the philosophy community. After all, the fairy-tale physicists appear to be challenging the very definition of science, and this is something on which philosophers of science might have been expected to have a ready opinion.

In fact, almost a century of intellectual endeavour and argumentation appears to have led the philosophers further and further away from a consensus on science and the scientific method. As Greek philosopher Stathis Psillos, an authority on scientific realism, commented in a personal note to me:

I share your concerns [regarding] the [current] state of [the] philosophy of science. There is nothing like a consensus on scientific method, explanation, causation, laws and all other key concepts and issues in the philosophy of science. Actually, it seems that if there is anything like a growing tendency it is for pluralism. When it comes to the metaphysics of science, it seems the tendency is to go back to Aristotelianism — and here is where things go bizarre really, since the connection with the current scientific image of the world is thinner than ever.
¹¹

In broad terms, the pluralism that Psillos mentions refers to the very different perspectives held by contemporary philosophers of science. Some, like Psillos himself, argue for a form of scientific realism. Others favour a form of post-positivist empiricism, retaining the negative attitude towards metaphysics and denying that scientific theories progress towards a literally true representation of an independently existing reality. The empiricist believes that the purpose of science is rather to provide us with theories that are adequate for the task of relating one set of facts to another. We should accept as true only what these theories have to say about those things that we can see directly for ourselves. But we should not believe that the unobservable entities that the theories describe (such as photons, quarks or electrons) are in themselves real and that the theories are literally true.

Yet others argue that scientific theories are social constructions, that their interpretation and acceptance as ‘the truth' are no more than conventions, achieved through consensus within the community of people engaged in scientific activity in any particular generation. For sure, these constructions might collectively offer a more
reliable
interpretation of nature than those afforded by superstition or religious mythology, but they are constructions nonetheless.