A month ago, one of the greatest scientific experiments of the world yielded tantalizing results, regarding one of the unsolved mysteries of physics. It is all about the question how particles gain their mass. The story is rather exciting, most of all for the involved physicists, whose models predict that this is supposed to happen through the Higgs mechanism.
The collisions of protons in the LHC are supposed to create a particle that is predicted to exist, if the mechanism works the way physicists think it should. The particle itself would remain elusive, even if the theory is right. It would be highly unstable and disintegrates into other particles, W-Bosons, with a certain amount of energy. Those bosons are what the scientists at CERN hope to see.
Last month, CERN announced that several of such particles had been detected and statistical analysis showed a 99% certainty, that this was not just down to mere coincidence. CERN called the finding ‘tantalizing’ and remained cautious to announce that the long sought-for proof of the theoretical models had been found.
Had CERN been the IPCC, it would have called the discovery of the Higgs particle, a virtual certainty. And with this sentence I am crossing the Rubicon. Be warned. There be dragons on the other side of the break.
The story of the Higgs didn’t end last month, even though it seemed virtually certain, according to the statistics. Further measurements contradict the earlier enthusiasm and while the statistical confidence now stands at 95%, the mere fact that it has fallen is an indication that the signal is a fluke. That’s not new to the physicists, who are now reviewing all the ways in which those bosons that they found earlier could have been created in their particular setup without the Higgs. Nature put it this way:
It is not entirely unexpected, adds Joe Incandela, deputy spokesperson for the CMS. “The veterans who have been in the trenches know that in the early goings there are often things that are unclear,” he says.
There is good reason why 99% certainty was not enough to call it quits. Statistics is no use in telling what the cause of certain results is. All it can do, under very special circumstances, is to provide an analysis of one very common and inevitable cause of your observations matching your theory – random noise.
What it cannot do, is to tell whether the mechanism that is supposed to produce your observation, is actually the mechanism that was at work. In the case of the LHC experiments, the observed w-bosons were not actually generated through the Higgs mechanism in the way it was described but some other process. This process was not random noise and hence not initially caught by the statistical analysis.
Statistical analysis, by its nature, must allow for certain deviations from the predicted result. If there is a process going on during the observation period, that produces results similar to the predictions, the initial results will seem to imply a very high certainty that the observation was not down to chance. But once more data has been collected, the subtle deviations between the proposed process and the one actually at work will show deviations that can no longer be reconciled by blaming them on chance alone.
That is why the standards for certainty in particle physics, before a new discovery is announced, is 5 standard deviations. Or a likelihood of 99.9999% of the observation not being down to chance.
This is done under the presumption, that most of the subtle effects and deviations that can be expected when treating on territory so far unknown to science, will come to bear and be identified before such a high level of confidence can be attained.
Moreover, there is the fact that scientists are human beings. They have ambitions, they have a certain amount of trust in their theories and, as all human beings, they are not perfectly objective in setting up the observations or evaluating their results. The physicist Richard Feynman (incidentally a particle physicist) was very aware of those faults and the difficulty of dealing with them.
In a famous lecture he held in 1974, he went to great lengths to show just how important it is, that a scientist must acknowledge his own fallibility and show all the ways in which he could be wrong:
I would like to add something that’s not essential to the science, but something I kind of believe, which is that you should not fool the laymen when you’re talking as a scientist. . . . I’m talking about a specific, extra type of integrity that is not lying, but bending over backwards to show how you’re maybe wrong, [an integrity] that you ought to have when acting as a scientist. And this is our responsibility as scientists, certainly to other scientists, and I think to laymen.
This is why the physicists were so (seemingly) incredibly reluctant, despite 99% statistical certainty, to just go ahead and say: See there, we found it, the science is settled.
I applaud CERN for their modesty in announcing their results. Despite the pressure of having to justify billions of dollars spent on one of the largest science projects this planet has ever seen – they kept their calm. Instead of triumphal rhetoric, even Nature had to concede:
For now, physicists are only willing to call them ‘excess events’, but fresh data from two experiments at the Large Hadron Collider (LHC) are hinting at something unusual — and it could be the most sought-after particle in all of physics.
Keep in mind (and here is one of the dragons I was talking about), that all this happened after an observation that the IPCC would have talked about as a “virtual certainty”.
The contrast between such modesty among particle physicists and the rhetoric associated with climate science is stark. In its fourth assessment report, the Intergovernmental Panel on Climate Change agreed upon the following:
- use of “virtual certainty” (or virtually certain) conveys a greater than 99% chance that a result is true
- “extremely likely” (greater than 95% chance the result is true)
- “very likely” (greater than 90% chance the result is true)
- “likely” (greater than 66% chance the result is true),
- “more likely than not” (greater than 50% chance the result is true),
- “unlikely” (less than 33% chance the result is true),
- “very unlikely” (less than 10% chance the result is true), and
- “extremely unlikely” (less than 5% chance the result is true).
(Update) Please note the systematic contortions in this use of language and its implications. While the IPCC report has numerous claims of “virtual certainty”, there is not even the possibility for the authors of the IPCC reports to express something like virtual impossibility (flawed as it would be), for lack of allowed language describing such a concept.
There is also not a single finding, in which scientist came up with the conclusion, that something was “less likely than not” (33%-50% chance of being true) but a lot that were “more likely than not”. However, not getting such a result among hundreds of inquiries in unbiased research is … well, a “virtual impossibility”. (/Update)
After continued experiments and observations, the statistical certainty of the excess bosons in the LHC being caused by the presence of Higgs particles, is still technically at about 95% – but no physicist would call this “extremely likely”. In fact, the implication of the confidence falling to a mere 95% is that the observation was probably a false alarm.
I can see none of this modesty, that is the result of many disappointments, false alarms, fraudulent claims and other hard-won experience in the struggle to find out how nature works, anywhere in the publications of the IPCC. The vocabulary used is a gross misrepresentation of what such confidence means in the practical experience of scientific discoveries. (And that is before considering such atrocious expressions as “extreme weather events” that resulted in perfectly arbitrary attributions of any and all somewhat unusual weather events to be ascribed to climate change.) I also have trouble finding it in other publications concerning climate change and its effects.
So please understand my reluctance (and sometimes, admittedly, open hostility) towards the claims made in the climate change debate and most of all the claims about the certainty of the findings.
There are enough reasons to reduce the use of carbon based fossil fuels. Be it the fundamental scarcity of fossil fuels; the unavoidable environmental damage associated with their use and extraction; or their price that will inexorably rise as the world is industrializing, which will hamper the economies of the industrialized countries unless they reduce their dependence upon them. (Which is something I have alluded to in one of my comments on the Economist fora and will discuss here in some later posting).
The current display of overconfidence in the results of climate science not only hurts the credibility of science in general today – but the backlash against science that can be expected when core assumptions turn out to be wrong, can proof to be extremely destructive.
Science must not be swayed by public rhetoric and moral panic. Science is about those things that we can know with such utmost certainty, that we can build upon them. Uncertainties and areas of scientific ignorance must find adequate expression and must not be swept under the rug of rhetorics in the way the IPCC tried to institutionalize.