Editor's pick: Theory proposes, the world disposes
I take issue with the critique of the role of experiment in theoretical physics by Jim Baggott and Daniel Cossins (27 February, p 38). May a physicist be allowed to set the record straight? The concept of supersymmetry was not “conceived as an elegant way to plug holes in the standard model” of particle physics. It was first noted by string theorists and then applied to supergravity. Had Albert Einstein not discovered relativity, then supersymmetry would force us to invent it.
Most string theorists share the view that in the long term the test of a good theory is experiment. The jury is still out on the multiverse, for example. It is those who claim already to know whether or not our universe is unique who are being unscientific – as are those who claim to know what can and can't one day be tested.
Baggott and Cossins write that “theoretical physicists have grown increasingly comfortable plucking theories out of thin air… The Higgs boson is a case in point.” But the Higgs was proposed in 1964 and discovered in 2012, in one of theory's greatest triumphs. And let's not forget gravitational waves, first proposed in 1916, whose discovery 100 years later confirmed the existence of black holes – which were .
Social intelligence all the way down
Aviva Rutkin focuses on the wrong sort of human behaviour when comparing human and artificial intelligence (19 March, p 20). The human brain is not designed to be good at chess, Jeopardy or Go.
Even object manipulation is not one of our fortes. It is the things we do socially that a machine will find very hard to match. Making sure granny is offered the last cucumber sandwich at a tea party, or ceasing to discipline a child when you sense you may go too far, for example. When machines can model human behaviour in groups, in all its recursive splendour, only then will we have a real challenge on our hands.
First class post
Until the poachers come through and kill them. Will they have some sort of protection?
Sara Mains Palkovich about plans to reintroduce extinct species to Europe (26 March, p 8)
Ingredient-free marketing works
Shannon Fischer's description of the power of placebos is fascinating (12 March, p 32). It chimes with my having heard the marketing manager for a big-brand painkiller saying that the more you advertise the stronger the drug becomes – and that its effects kick in within 5 minutes, which is pharmacologically impossible.
How would loyalty cancel a stench?
You report a finding that body odour produces less disgust when attributed to a member of the smeller's group, and Stephen Reicher's comment that because loyalties can affect a core biological response that shows how powerful and malleable group identities can be (27 February, p 20). I find it more interesting that a “core biological response” can be affected by psychosocial events. I wonder whether this is a basis for the placebo effect.
Is doping partly mind over matter?
In recurrent furores over doping in sports, I have not noticed any consideration of the role of the brain in performance as outlined in James Witts's informative article (30 January, p 38). Could any improved performance of an athlete on a performance-enhancing drug not be due, at least in part, to a mental change?
Having worked on many clinical trials, I propose one for athletes in which half of the test group is on the real drug and half on a placebo, no one knowing which. Sadly, I find it difficult to imagine top athletes agreeing to participate in such a study.
A bump passing in the quantum night
I am as excited as anyone about the possibility of a new particle being discovered that would shake up our understanding of the universe (5 March, p 30). But I am a little alarmed that it turns up at exactly six times the mass of the Higgs boson.
To me it seems more likely that it is an artefact of statistical analysis, and might turn out to be, to put it in musical instrument terms, a harmonic of the Higgs. I fear that it will just fade away like the Cheshire Cat, leaving nothing behind but an enigmatic, vanishing smile. Of course, the idea of a harmonic might just be plausible if we visualise it in terms of string theory.
Fusion reactors are all difficult
David Hambling mentions a new breed of leaner, meaner nuclear fusion reactor, including the “affordable, robust, compact” ARC device (30 January, p 34). But the claims for ARC include rapid dismantling and re-assembly of the lining and the shell of the “doughnut” in which fusion takes place. These need to be replaced as the flux of neutrons from the reaction makes them radioactive and thus weakens them.
I can report from experience that this replacement will require a very big “hot cell” containing complex equipment for remote handling of the radioactive parts.
The ARC designers including a tank of molten fluorine-lithium-beryllium salt (FLiBe) in the shell. This will involve solving the problem of welding replacement segments of the tank to irradiated metal in the adjacent segments. And there are issues of toxicity and long-lasting radioactive contamination of the FLiBe. ARC's claimed “plug-and-play” flexible configuration is only theoretical: the more radioactive it becomes, the more difficult it will be to reconfigure it to the extent claimed.
How to detect an absent neutrino
Matthew Chalmers describes the neutronless double beta decay and the difficulty of detecting it (13 February, p 30). It is already very difficult to detect the presence of a neutrino.
So how can we be sure we have detected the absence of a neutrino? How can researchers be sure that they have observed a double beta decay without a neutrino, instead of one with two of them? Can there be sufficiently precise measurement of the momentum of the detected particles to be sure that no momentum is carried away by the neutrinos of an ordinary double beta decay?
How to detect an absent neutrino
An intriguing cover line: “Once in 100 trillion trillion years – we're about to see the rarest event in the universe” (13 February), though the article (p 30) says it may happen every 1025 years.
Mornington, Victoria, Australia
The editor writes:
• Neutrinoless double beta decay (NDBD) does emit electrons, whose energies and directions of motion can be measured accurately enough to discriminate it from other decays. And the article reported the lower limit on NDBD half-life, established as 1025 years, though the full range now being investigated stretches up to 1027 years.
Nudge theory and regulation practice
Your leader “A nudge too far?” makes some interesting points but perpetuates the idea that the work of the UK Behavioural Insights Team uses a solely “evidence-based” approach (12 March, p 5). As you rightly point out, nudges are seen as a replacement for legislation. It would therefore be appropriate to compare the outcome of a “nudge” with the likely outcome of regulation.
That is not what the trials do. The biggest nudge in the UK was the which attempted a voluntary approach to health issues around food, alcohol and the workplace by getting pledges from manufacturers, retailers and employers. These were viewed by most public health experts as totally ineffective. Instead, there have been calls for the government to introduce regulation such as compulsory labelling and minimum alcohol pricing. The deals have all now been abandoned by the government and a sugar tax has been announced.
Nudge theory has its place, but to state that it is evidence-based is a stretch when, in the UK, its application is underpinned by an ideological assumption that regulation is inherently negative. The evidence is that regulation can be far more effective than behavioural interventions, as shown by a range of public safety and health laws, from seat-belt use to workplace smoking.
Shocking timing in obedience trial
Andy Coghlan reports a modified version of the infamous Milgram experiment on obeying orders, in which participants were asked to estimate the time lapse between pressing a key and hearing a tone, in milliseconds (27 February, p 14).
My estimate is that the best that I could do would be to report to the nearest 250 milliseconds. Did some reported estimates really go to three significant digits?
Turramurra, New South Wales, Australia
The editor writes:
• built on earlier work showing that the perceived time delay (not necessarily the actual delay) correlates with a sense of agency or control. Participants were indeed asked to make use of all possible numbers between 0 and 1000 milliseconds.
For the record
• This one is : it was of the California Institute of Technology who observed that, seen from the Oort cloud, the sun appears so small that you could completely block it out with the head of a pin (19 March, p 30).
• Delila Gasi-Tandefelt and her colleagues are taking blood samples from men with advanced prostate cancer in sequence, not at fixed intervals (19 March, p 38). And Bert Vogelstein and colleagues make strands of DNA that mirror their target mutation, and tag these with a fluorescent marker so that they can detect any bits of mutated DNA that stick to their bait.
• A bass-ic mistake: the song of lonely Whale 52 has recently deepened from 52 Hz to 47 Hz (19 March, p 30).