The recent Lykken-Spiropulu anti-SUSY diatribe in Scientific American has sparked some echoes. One of them was published on the NPR website. The piece titled
First, the title is preposterous because, as Gleiser admits, we are waiting for the 2015 LHC run that will probe higher energies and that will have "completely new chances" to find SUSY which are uncorrelated to the null results of the 2012 run. In fact, Maria Spiropulu was hired to search for SUSY and extra dimensions, so if she still works as a CMS member next year, it's likely that the search for SUSY will represent most of her work.
But this [beep] Gleiser repeats many of the laymen's misconceptions about how science works.
The first paragraph says:
Is physics in crisis? An article in the May issue of Scientific American by physicists Joseph Lykken, from Fermi National Accelerator Laboratory, and Maria Spiropulu, from the California Institute of Technology, lay bare an issue that is keeping a growing number of physicists up at night. Will supersymmetry — the hypothetical symmetry of nature proposed some 40 years ago — be proved out? Or should it be archived to history as just another clever idea that didn't prove true?I won't comment on the omnipresent "subtle kicks" into particle physics as such, preposterous fairy-tales about its being in a crisis, and so on. There is no content in these sentences; they only show that their author is hostile towards the hardest discipline of science.
But let me say a few words about the SUSY's being "archived to history". Gleiser thinks that ideas in science are archived as failures if "they don't prove true". But that's just a complete misunderstanding of the scientific method. Ideas in science are only eliminated if they prove false – if they are falsified. If a proof or disproof of an idea doesn't arrive, the idea must still be considered as an option. It is a viable theory. The same point may be said in many words. The absence of a proof isn't a proof of the absence. One simply cannot eliminate an idea or a paradigm that hasn't been falsified.
Actual ideas that have been eliminated – like the phlogiston, the substance identified with heat, or the luminiferous aether – produce general predictions that may be and have been empirically shown to be incorrect. Supersymmetry also makes such general predictions but none of them has been falsified. Instead, what has been falsified are only particular models leading to some particular values of the low-energy parameters etc. But it's just an elementary, childish fallacy to think that by falsifying some representatives of a (more or less naturally or unnaturally clumped) class of theories, one falsifies the whole class. Models just don't "fight for their validity" in this collectivist way. Every qualitatively different theory or model of physics has its own individual "account" and until this account goes to the red numbers, the theory or the model is just a viable option!
Gleiser says that a lot is at stake, reviews some physics of the Standard Model and its limitations, and so on. But he eventually returns to the anti-new-physics comments that seem to be the actual goal of his diatribe.
So far, not a trace of supersymmetry has graced the amazing detectors at CERN. Or the dozens of other experiments spread around the globe hunting for supersymmetric particles raining down from the heavens, something that should happen if they are, indeed, dark matter. Things are not looking good for SUSY.The words "not a trace" may sound dramatic – like if he had something stronger to say than just "SUSY hasn't been found yet" – but needless to say, this "added value" is largely nonsense. If a trace (like a 4-sigma SUSY-like excess: we have surely seen various 2-sigma excesses which were probably/mostly flukes) were found somewhere, it would be very likely that a stronger discovery of the same signal and perhaps related signals would quickly be made as well and soon or later, it would be followed by a similar discovery at the other detector, and so on.
The discoveries of new physics by several experiments are not independent events. The discovery by CMS and by ATLAS are pretty much equivalent things. If one occurs, the other occurs as well, and so on. If a particle is seen in one of the decay channels, it's probably going to be soon in the other dominant channels, too. So the actual "absence of evidence" is more or less just one bit of information.
Gleiser then quotes Nima's comment ending with "That's OK; theorists don't need to be consistent; only their theories do" and apparently criticizes Nima for that:
The question, though, is how long can you keep on changing your story before you realize the story is just wrong? This is the hardship (and the excitement) of research; we don't have a path ahead, we need to forge one. And we are not sure of which direction to take, having only inklings that it could go this or that way.How long? I have already answered this question many times and a science-literate person should know the answer even without my help. A theory in science has to be considered as a viable option up to the moment when it is falsified or at least the moment when the apparent probability of its validity decreases to exponentially small values, like 0.001%, which is not hard if you deal with a theory that is really, demonstrably wrong. SUSY hasn't been falsified and it hasn't been shown to be extremely unlikely so one must still consider it as a possibility, of course. The same will be true even if the 2015 LHC run finds no traces of SUSY. Opinion may evolve quantitatively but there will be no paradigm shift without an actual sharp event – in theory or in the experiment – that would change things qualitatively. A gradual inflow of "not paradigm changing" data from the experiments implies that the theorists are gradually adjusting their beliefs; that's exactly the right thing for them to do and they may behave in this way indefinitely. Only if experimental results are "qualitative", they may force theorists to change their beliefs "qualitatively".
In fact, even in the absence of evidence for SUSY coming from the 2015 LHC run, SUSY will look more likely than not as a symmetry that applies at some scale to most of the compentent particle physicists, so of course that they will continue to study it. Theorists will surely use SUSY all the time because it's essential for formal theoretical reasons but even phenomenologists will study it because it will probably remain the #1 candidate for new physics that may be found at some moment. Only if a more interesting theoretical paradigm is found by theorists, it may supersede supersymmetry at the #1 place in the research of potential new physics.
You just can't treat a theory as a falsified one if it is not actually falsified!
Gleiser also says something that proves that he doesn't have a clue what supersymmetry actually means:
Of course it may be that supersymmetry is a symmetry of nature, but realized at energies well beyond the reach of our current machines. This is what Arkani-Hamed was saying. But if this is the case, we need to change the story quite a lot and redefine what it is that we want supersymmetry to answer. Clearly, it won't do much to help as understand the Standard Model.This is complete bullshit, too. Even if there is no trace of SUSY in the 2015 LHC run, it won't redefine what SUSY is. SUSY is a symmetry generated by Grassmann-odd generators whose anticommutator involves the spacetime momenta (generators of translations), a clever loophole in the (philosophy of the) Coleman-Mandula theorem. SUSY plays many roles in string theory as well as in (equally unproven so far) models of low-energy physics (e.g. a possible full explanation of the lightness of the Higgs, to mention the key example of this category) but those things are just not a "definition of SUSY".
Details about "what SUSY is relevant for" are guaranteed to change as the experimental data eliminate some possibilities. In contrast to Gleiser's misconceptions, there is no "the story" about the detailed character or role of supersymmetry in physics beyond the Standard Model. Instead, there are many scenarios, possibilities, and models and all of those that remain viable are treated as viable options and they are sometimes by studied by some researchers. It's not true at all that all researchers study exactly the same realization of SUSY in particle physics.
The usual Shmoitian junk appears near the end:
Theories need to be consistent. But they also need to be falsifiable: this is where theorists do need to be consistent. If you can't test a scientific hypothesis, what are you doing, exactly?But SUSY is undoubtedly falsifiable. Even the most general form of SUSY is. Measure the particle spectrum up to the Planck scale and if you find out that the fermionic and bosonic states can't be matched in any way that would be compatible with SUSY, SUSY is experimentally ruled out. What Mr Gleiser and similar [beep]s are actually dissatisfied with is that SUSY has not been falsified yet. But it's not a duty for scientific theories to be quickly falsified. On the contrary, the longer they survive, the better for them.
A hostile enough person could say that any accepted theory in science is unfalsifiable, too. Quantum field theory is unfalsifiable. Things are consistent with it but one could perhaps also design some other, non-QFT explanations of all the phenomena. What can I do to falsify quantum field theory as such? Well, this is a silly question. Quantum field theory simply works. In the same way, SUSY and string theory work, too. They represent two overlapping frameworks in which all the known phenomena in Nature may be described. We got very far and the theories are results of quite some progress. So it shouldn't be shocking that it's hard to falsify them. The reason is that there are many true things about them.
The final paragraph is:
Supersymmetry, beautiful as it is, has the annoying feature that it can always be hidden from testing, a slippery fish you can't hold on to. Of course, the ultimate judge of all this is nature itself. But a theory that is always hiding from us serves very little purpose as an explanatory scientific device.It's just not true that a theory of particles and fields that cannot be found at the LHC serves "very little purpose as an explanatory scientific device". The inflaton cannot be produced by the LHC yet it plays an essential role in the scientific explanations of the Universe – and it's a complete coincidence that direct signs of cosmic inflation were found exactly in 2014 (hopefully). The role of SUSY and string theory etc. is analogous to the inflaton. The LHC is not seeing everything about Nature. Scientists – I primarily mean theorists – are using many concepts that are important for the inner logic, coherence, consistence, and simplicity of their explanations but they "cannot be seen". There is nothing wrong whatsoever about this fact. They may explain "what they are exactly doing" but only to those who are actually ready to listen (and who have at least some background to understand).
NPR, why are you giving room to unhinged [beep]s such as Mr Gleiser? It is truly distasteful.