Farewell to Reality (3 page)

The contemporary physicist and philosopher Bernard d'Espagnat called it ‘veiled reality', and commented that:

… we must conclude that physical realism is an ‘ideal' from which we remain distant. Indeed, a comparison with conditions that ruled in the past suggests that we are a great deal more distant from it than our predecessors thought they were a century ago.
³

At this point the pragmatists among us shrug their shoulders and declare: ‘So what?' I can never be sure that the world as I perceive or measure it is really how the world is ‘in reality', but this doesn't stop me from making observations, doing experiments and forming theories about it. I can still establish facts about the shadows — the projections of reality into our world of perception and measurement — and I can compare these with similar facts derived by others. If these facts agree, then surely we have learned something about the nature of the reality that lies beneath the shadows. We can still determine that if we do
this,
then
that
will happen.

Just because I can't perceive or measure reality as it really is doesn't mean that reality has ceased to exist. As American science-fiction writer Philip K. Dick once observed: ‘Reality is that which, when you stop believing in it, doesn't go away.'
⁴

And this is indeed the bargain we make. Although we don't always openly acknowledge it upfront, ‘reality-in-itself' is a metaphysical concept. The reality that we attempt to study is inherently an
empirical reality
deduced from our studies of the shadows. It is the reality of observation, measurement and perception, of things-as-they-appear and of things-as-they-are-measured. As German physicist Werner Heisenberg once claimed: ‘… we have to remember that what we observe is not nature in itself but nature exposed to our method of questioning'.
⁵

But this isn't enough, is it? We may have undermined our own confidence that there is anything we can ever know about reality-in-itself, but we must still have some
rules.
Whatever reality-in-itself is really like, we know that it must exist. What's more, it must surely exist independently of perception or measurement. We expect that the shadows would continue to be cast whether or not there were any prisoners in the cave to observe them.

We might also agree that, whatever reality is, it does seem to be rational and predictable, within recognized limits. Reality appears to be logically consistent. The shadows that we perceive and measure are not completely independent of the things-in-themselves that cause them. Even though we can never have knowledge of the things-in-themselves, we can
assume
that the properties and behaviour of the shadows they cast are somehow determined by the things that cast them.

That feels better. It's good to establish a few rules. But don't look too closely. If you want some assurance that there are good, solid scientific reasons for believing in the existence of an independent reality, a reality that is logical and structured, for which our cause-and-effect assumptions are valid, then you're likely to be disappointed. To repeat one last time, reality is a metaphysical concept — it lies beyond the grasp of science. When we adopt specific beliefs about reality, what we are actually doing is adopting a specific
philosophical position.

If we accept the rules as outlined above, then we're declaring ourselves as
scientific realists.
We're in good company. Einstein was a realist, and when asked to justify this position he replied: ‘I have no better expression than the term “religious” for this trust in the rational character of reality and in its being accessible, to some extent, to human reason.'
⁶

Now, it's one thing to be confident about the
existence of an independent reality, but it's quite another to be confident about the existence of overtly theoretical entities that we might want to believe to exist in some shape or form within this reality. When we invoke entities that we can't directly perceive, such as photons or electrons, we learn to appreciate that we can't know anything of these entities as things-in-themselves. We may nevertheless choose to assume that they exist. I can find no better argument for such ‘entity realism' than a famous quote from philosopher Ian Hacking's book
Representing and Intervening.
In an early passage in this book, Hacking explains the details of a series of experiments designed to discover if it is possible to reveal the fractional electric charges characteristic of ‘free' quarks.
^*
The experiments involved studying the flow of electric charge across the surface of balls of superconducting niobium:

Now how does one alter the charge on the niobium ball? ‘Well, at that stage,' said my friend, ‘we spray it with positrons to increase the charge or with electrons to decrease the charge.' From that day forth I've been a scientific realist.
So far as I
'
m concerned, if you can spray them then they are real.
⁷

This brings us to our first principle.

Having established what we can and can't know about reality, it's time to turn our attention properly to science.

The scientific method

In 2009, Britain's Science Council announced that after a year of deliberations, it had come up with a definition of science, perhaps the first such definition ever published: ‘Science is the pursuit of knowledge and understanding of the natural and social world following a systematic methodology based on evidence.'
⁸

Given that any simple definition of science is likely to leave much more unsaid than it actually says, I don't think this is a bad attempt. It all seems perfectly reasonable. There's just the small matter of the ‘systematic methodology', the cold, hard, inhuman, unemotional logic engine that is supposed to lie at the very heart of science. A logic that we might associate with Star Trek's Spock.

The ‘scientific method' has at least three components. The first concerns the processes or methodologies that scientists use to establish the hard facts about empirical reality. The second concerns methods that scientists use to create abstract theories to accommodate and explain these facts and make testable predictions. The third concerns the methods by which those theories are tested and accepted as true or rejected as false. Let's take a look at each of these in turn.

Getting at the facts

The first component seems reasonably straightforward and should not detain us unduly. Scientists pride themselves on their detachment and rigour. They are constantly on the lookout for false positives, systematic errors, sample contamination, anything that might mislead them into reporting empirical facts about the world that are later shown to be wrong.

But scientists are human. They are often selective with their data, choosing to ignore inconvenient facts that don't fit, through the application of a range of approaches that, depending on the circumstances, we might forgive as good judgement or condemn as downright fraud. They make mistakes. Sometimes, driven by greed or venal ambition, they might cheat or lie.

There is no equivalent of a Hippocratic oath for scientists, no verbal or written covenant to commit them to a system of ethics and work solely for the benefit of humankind. Nevertheless, ethical behaviour is
deeply woven into the fabric of the scientist's culture. And the emphasis on repetition, verification and critical analysis of scientific data means that any mistakes or wrongdoing will be quickly found out.

Here's a relevant example from contemporary high-energy physics. The search for the Higgs boson at CERN's Large Hadron Collider has involved the detection and analysis of the debris from trillions upon trillions of protons colliding with each other at energies of seven and, most recently, eight trillion electron volts.
^*
If the Higgs boson exists, then one of the many ways in which it can decay involves the production of two high-energy photons, a process written as H → γγ, where H represents the Higgs boson and the Greek symbol γ (gamma) represents a photon.

About three thousand physicists have been involved in each of two detector collaborations searching for the Higgs, called ATLAS and CMS.
^**
One of their tasks is to sift through the data and identify instances where the proton—proton collisions have resulted in the production of two high-energy photons. They narrow down the search by looking for photons emitted in specific directions with specific energies. Even so, finding the photons can't be taken as evidence that they come from a Higgs boson, as theory predicts that there are many other ways in which such photons can be produced.

The physicists therefore have to use theory to calculate the ‘background' events that contribute to the signal coming from the two photons. If this can be done reliably, and if any systematic errors in the detectors themselves can be estimated or eliminated, then any significant excess events can be taken as evidence for the Higgs.

On 21 April 2011, an internal discussion note from within the ATLAS collaboration was leaked to a high-energy physics blogger. The note suggested that clear evidence for a Higgs boson had been found in the H
→
γγ decay channel, with a signal thirty times greater than predicted.

If this was true, it was fantastic, if puzzling, news. But it wasn't true. The purpose of internal discussion notes such as this is to allow the exchange of data and analysis within the collaboration before a collective, considered view is made public. It was unfortunate that the note had been leaked. Within just a few weeks, ATLAS released an official update based on the analysis of twice as much collision data as the original note, work that no doubt demanded many more sleepless nights for those involved. There was no excess of events. No Higgs boson — yet.
^*

As ATLAS physicist Jon Butterworth subsequently explained:

Retaining a detached scientific approach is sometimes difficult. And if we can't always keep clear heads ourselves, it's not surprising people outside get excited too. This is why we have internal scrutiny, separate teams working on the same analysis, external peer review, repeat experiments, and so on.
⁹

This was a rare example in which the public got to see the way science self-regulates, how it uses checks and balances in an attempt to ensure that it gets its facts right. Scientists don't really like us looking over their shoulders in this way, as they fear that if we really knew what went on, this would somehow undermine their credibility and authority.

I take a different view. The knowledge that science can be profoundly messy on occasion simply makes it more human and accessible; more Kirk than Spock. Knowing what can go wrong helps us to appreciate that when it does go seriously wrong, this is usually an exception, rather than the rule.

No facts without theory

The process of building a body of accepted scientific facts is often fraught with difficulty, and rarely runs smoothly. We might be tempted to think that once we have built it, this body of evidence forms a clear, neutral, unambiguous substrate on which scientific theories can be
contrived. Surely the facts form a ‘blank sheet of paper', on which the theorists can exercise their creativity?

But this is not the case. It is in fact impossible to make an observation or perform an experiment without the context of a supporting theory in some shape or form. French physicist and philosopher Pierre Duhem once suggested that we go into a laboratory and ask a scientist performing some basic experiments on electrical conductivity to explain what he is doing:

Is he going to answer: ‘I am studying the oscillations of the piece of iron carrying this mirror?' No, he will tell you that he is measuring the electrical resistance of a coil. If you are astonished, and ask him what meaning these words have, and what relation they have to the phenomena he has perceived and which you at the same time perceived, he will reply that your question would require some long explanations, and he will recommend that you take a course in electricity.
¹⁰

Facts are never theory-neutral; they are never free of contamination from some theory or other. As we construct layer upon layer of theoretical understanding of phenomena, the concepts of our theories become absorbed into the language we use to describe the phenomena themselves. Facts and theory become hopelessly entangled.

If you doubt this, just look back over the previous paragraphs concerning the search for the Higgs boson at CERN.

This brings us to our second principle.

So how do scientists turn this hard-won body of evidence into a scientific theory?

Theory from facts: anything goes?

The naïve answer is to say that theories are derived through a process of
induction.
Scientists use the data to evolve a system of generalizations, built on abstract concepts. The generalizations may be elevated to the status of natural patterns or ‘laws'. The laws in turn are explained as the logical and inevitable result of the properties and behaviour of a system of theoretical concepts and theoretical entities.