Farewell to Reality

Jim Baggott has written an important book, ‘Farewell to Reality: How Modern Physics Has Betrayed the Search for Scientific Truth‘, which takes a hard look at many modern ideas in theoretical physics, and finds that many of them are not science.

Philosophy of science

Baggott begins with a chapter on basic philosophy of science, identifying six principles that he concludes are important for science.  The most important, I think, are the Fact Principle, which is that scientific knowledge is built on verified empirical facts, the Theory Principle, theories provide explanations for the relationships between those facts, and the Testability Principle, scientific theories should be testable in some fashion.

Another principle that Baggott includes in this chapter is the Copernican Principle, the idea that humans are not at the center of the universe or hold any special place in it.  This a guideline derived from centuries of scientific discoveries, rather than as something that strictly defines science.  While it’s possible we might find evidence that contradicts this principle, to overturn a pattern observed for centuries would require that the evidence be substantial.

Baggott then has a few chapters covering what he call the Authorized Version of Reality.  I think his choice of name here is unfortunate.  It implies that that there is a council of elders or something somewhere deciding what is and is not reality.  A better name might have been the Reliable Version of Reality, or the Experimentally Supported Version of Reality.

The Authorized Version of Reality

Anyway, Baggott runs through the basic science of the Standard Model of particle physics, Newtonian physics, and Special and General Relativity.  These sections are more of a refresher than a tutorial.  For the science I already understood, it was a pleasant summary, but for the areas I wasn’t strong in, mostly particle physics, I quickly found myself lost in the terminology.  While I was somewhat able to follow his narrative, readers completely unfamiliar with these subjects will likely be completely lost.

Baggott points out that, despite its many successes, the Authorized Version of Reality has a lot of flaws.  He discusses the problems in quantum probability, the collapse of the wave function, quantum entanglement, the hierarchy problem, the mysteries of dark matter and dark energy, the need to reconcile gravity with the quantum world, and the fine tuning problem.

On the one hand, Baggott sees the theories that are attempting to move beyond the Authorized Version as heroic attempts to work past these problems.  On the other hand, he returns repeatedly to the principles he starts out with to show why many of these attempts have serious flaws.  He refers to many of the ideas that follow as “Fairy Tale Physics”.


He first looks at Supersymmetry, the idea that there is a symmetry between matter particles and force particles such that they can transform into each other.  If Supersymmetry is true, it might solve the hierarchy problem, identify the particles that make up dark matter, and even possibly provide for a quantum theory of gravity (called Supergravity).  The assumptions behind Supersymmetry would also serve as important foundations for the Superstring and related theories below.

Baggott has some sympathy with Supersymmetry.  He characterizes it as a theory with few assumptions, that if borne out, would explain a great many things.  However, he points out that the few assumptions have not been empirically verified.  Indeed, the failure of the Large Hadron Collider (LHC ) to find expected particles is making the outlook for Supersymmetry appear somewhat bleak.

Because Supersymmetry is so important for the ideas below, many physicists are still holding out hope that evidence for it will be found when the LHC comes back online.  Baggott points out that, due to how much Supersymmetry has riding on it, advocates will likely find ways to tweak the theory for as long as they can, until or unless some evidence is found.

String theory

Baggott then discusses String theory, the idea that elementary particles are actually tiny one dimensional vibrating strings, with each type of particle defined by the string’s vibration resonance.  String theory, Superstring theory, M-theory, and related concepts hold the purported promise of unifying quantum mechanics with general relativity.

Baggott states that Superstring theory and the related theories, need the assumptions of Supersymmetry to be true.  They require the existence of additional dimensions aside from the normal three that we can perceive, with a total of nine dimensions usually considered to be the minimum.  Our inability to perceive these extra six dimensions requires the assumption that they are compacted into a manifold with a size on the order of the Planck length.

Baggott points out that M-theory, the idea that the variants of Superstring theories can be subsumed into one theory is actually not a theory itself, but the prospect of a theory that has not yet been discovered.  He also discusses the concepts of Branes and braneworlds, which are the assumed physical reality described by the mathematics involved in M-theory.

Baggott is scathing in his assessment of these theories, remarking that, “No amount of window-dressing can hide the simple fact that this is all metaphysics, not physics”.  He points out that none of the layered assumptions mentioned above have any empirical evidence.

Multiverses, Mathematical Universe, Holographic Principles, Fine tuning, etc.

A book on problems with theoretical physics would be expected to dress down String theory, but Baggott isn’t finished and proceeds to point out problems with many other concepts often discussed in physics.

He points out that notions such as the Many Worlds interpretation of quantum measurement, the Bubble Universes from eternal inflation theories, the Holographic Principle, the Mathematical Universe Hypothesis, and many other concepts aren’t just not experimentally supported, they aren’t even conceivably testable, which makes them non-scientific.

Finally, Baggott takes on the Anthropic Principle, the idea that the universe appears finely tuned for us.  He points out that these theories are basically metaphysical attempts to counter the Copernican Principle above, that they are often motivated by world views, and that the Anthropic Principle hasn’t really been shown to add anything uniquely productive to scientific investigation.

The danger to science

Baggott mentions multiple times in the book that he does not have a problem with the speculation involved in these theories, but he does have an issue with those speculations being presented with the same authority as what he calls the Authorized View of Reality.  He decries the fact that many of these theories are judged for their aesthetic appeal rather than their correspondence with empirical observations, and notes that many in the physics profession are beginning to question the value of even requiring empirical evidence.

He points out the danger to science’s long term credibility.  If the requirement for empirical testability is allowed to disappear, if the definition of science becomes watered down, it may open the door to many interesting and exciting contemplations, but it will sacrifice science’s reputation for producing reliable and useful knowledge.

Sticking to reliable knowledge, admitting what we don’t know, is frustrating.  That frustration, along with the pressure on scientists to make breakthroughs this year, to publish now, has led physicists to go far beyond the realm of empirical knowledge, into metaphysics.

My take

I read this book because, while I’m not a physicist, I’ve had an uneasy feeling about many of these theories for some time.  I think Baggott is making a crucially important point.  Science has credibility.  It has that credibility because it has a history of producing reliable knowledge, of the type necessary to build technology, cure diseases, and improve life in many ways.

I think by weakening its discipline, science runs the risk of, eventually, becoming irrelevant.

I’ve noticed that the scientists most likely to disparage philosophy are theoretical physicists.  For some time, I suspected that this was because many of them realized that what they were doing was perilously close to, if not outright in, metaphysics, and were defensively attempting to distance themselves.

I hope Baggott’s book has an impact.  It’s a difficult read for a non-physicist, but carries an important message.

26 thoughts on “Farewell to Reality

  1. On the other hand, the theories are a compelling alternative to “God did it.” I suspect that is the base reason for their existence in pop culture rather than strictly scrawled across blackboards in a university.


  2. I’m going to have to read this book, but i think you’ve done an excellent job in this review. Things do get odd at Planck lengths, that we have to admit, and retrocausality has blown everything out of the water. Your warning about the spearhead of physics becoming metaphysics is valid, but its hard not to drift into this grey-on-grey world when effects can indeed proceed the cause.


    1. Thanks! I agree, and so does Baggott actually. He admits early in the book that scientific theories are laden with metaphysics. You can’t get away from it. But there is a difference between a theory that makes predictions that simply can’t be tested yet, and one that makes no prediction that can be tested for centuries, if ever.


      1. Forgot to say, I think Steve makes some excellent points below. These things can’t yet be tested because of the energy levels required. That doesn’t mean they can’t be tested. An important distinction, i think.


        1. Thanks John. Some theories of the universe may never be directly testable in particle accelerators. We might need to observe colliding black holes or some phenomenon that really rips the fabric of the universe to pieces!

          After all, think that we are trying to do here – explain how nature operates from the very smallest lengthscales up to the very highest energies!


          1. As simple as mowing the lawn!

            Steve, did you read Matt Raves post, linked above in one of my comments? I think you’d really enjoy it, and his blog in general. I’m reading his book right now and its exceptional.


  3. Good review of the book. But I think the author is perhaps over-selling his case. Few (if any) theoretical physicists would deny the requirement for testability. The problem is that there is very little (if any) empirical data available at high energies. The LHC has just started to explore the lowest energies at which evidence for supersymmetry might emerge, but we are nowhere near testing quantum gravity theories. We need bigger colliders or more imaginative experiments!

    Does that mean physicists should desist from theorising until evidence emerges? No. Einstein developed his general theory of relativity first and it was tested later. He was guided by mathematical principles.

    Many of the theories discussed are highly speculative. Some may indeed by untestable. But then again, someone may think of a way to test them in the future. It’s the job of theoretical physicists to invent theories. Others will then try to test them.

    Sometimes we are lucky enough to have empirical evidence first and have to devise theories to explain the observations. Sometimes it’s the other way around. Science, like advertising, is 50% a waste of time – the problem is we don’t know which 50% will be wasted.


    1. Thanks. From what I understand, Einstein’s theories still made predictions, some of which were tested within a few years. When you can’t conceive of a way your idea could ever be tested, that seems like a pretty clear sign you’re dabbling in metaphysics. No problem with that, (I do my share of it on this site), but you should be clear that that’s what you’re doing.


      1. Higgs predicted his boson back in the sixties. It took half a century to prove him right. Was he engaged in metaphysics? At the time he made the prediction, it must have seemed impossible to imagine a way of testing his theory.

        String theory and the rest may seem like metaphysics now, but perhaps in a hundred years we’ll all be driving superstring-powered cars and wondering what the fuss was.

        The trouble with string theory now is that it doesn’t make any predictions that can be tested. It just doesn’t make any predictions at all. That’s the real problem with string theory. The other problem is that nobody has thought of a better alternative.


        1. It sounds like we agree that testability is an important criteria.

          The dividing line between scientific theory and metaphysics is really more of a broad spectrum. Were the ancient Greeks engaging in metaphysics when they developed atomism. Certainly. What is metaphysics this century might be science next century. Whether what you’re doing is metaphysics or theoretical science is a judgment call.

          But the further you go beyond conceivable testability, the less grounds you have to say you’re not engaging in metaphysics. Again, I have no particular problem with it. Only when it is presented as solid science, or those who engage in it pretend like their doing something different than metaphysicians.


  4. Theoretical physicist Lee Smolin wrote a similar and controversial book a while back called “The Trouble with Physics: the Rise of String Theory, the Fall of a Science and What Comes Next”. One of his claims was that the physics establishment has given too much support, including financial support, to work on string theory at the expense of more promising (in his opinion) views.

    I don’t think, however, that there is any risk that physics will “fall” or has fallen (as Smolin’s subtitle suggests) or that “science runs the risk of eventually becoming irrelevant”. What seems more likely is that physicists will run up against certain limits as to what they can figure out or experimentally confirm. For example, will our financial resources and technological abilities allow us to keep building bigger and bigger particle colliders? There will still be pressure of various kinds to keep doing theoretical physics, but the distinction between theoretical physics and philosophy of physics or metaphysics might evaporate. Of course, that would be ironic, since physics used to be part of “natural philosophy”.

    Good point about the apparent defensiveness of some physicists. One of the virtues of Smolin’s book, if I remember correctly, is that he discusses the human aspect of these controversies.


    1. Good points. I agree. I’ve often wondered the same thing about particle accelerators. Maybe someday there will be one that circles the solar system. But eventually we just won’t be willing to invest anymore.

      If I read Baggott correctly, he’s fine with metaphysical speculation, as long as it’s identified as such.


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