Claim: Particle Physics is Stagnating Because of Groupthink

PM: Sorry for the delay. While once-retired, I am still over committed.

Unfortunately, conversations about climate science have a pall over them of connection to various political action advocacy positions. This seems to lead to a good bit of impugning of motives and focusing more on winning of some kind of contest than of improving understanding. It is too bad, but it is what it is for now. Two notions often arise that really should not be unclear. Call the two main “camps” in the conversation Side A, and Side B. Side A is sometimes called the camp of skeptics, deniers, non-alarmists, or whatever, and Side B can contain people sometimes called alarmists, mainstream consensus, or whatever.

Side A often claims that anthropogenic CO2 dominated global warming (let’s call this ACDGW) is not “valid” because it has not been demonstrated in a controlled experiment, and that therefore, ACDGW is not scientifically justified (at least not yet). Side B often claims that the “science” of ACDGW is just “basic physics” and that therefore it is as established as basic physics and anyone who disputes that statement is, well, a scientific simpleton.

It is helpful to be clear when discussing either A or B’s claims about what “science” is or is not. The word “science” sometimes means different things to different people. Focusing on just the physical and life sciences (and mostly physics) it is helpful to distinguish between two general classes of “science.” One could be called basic science and would include physics, chemistry, and biology. Another could be called complex or interdisciplinary science. (But don’t get riled up yet, wait for some explanation, neither is “better” or “worse” than the other).

The central characteristic of basic sciences in this view is that they proceed by (of course constantly making observations) but fundamentally 1) propose a theory of how something works (not why, just how) 2) formulate the theory in non-arbitrary mathematical terms that can predict the outcomes of controlled experiments isolating the “something” and 3) perform controlled experiments and compare the non-arbitrary, previously well defined, predictions of the theory with the experimental outcome. If the prediction and the outcome are close enough, then the theory is, for now, assumed to not be wrong. Other theories, that predict outcomes that can be ruled out by the error bounds of repeated experiments, preferably using multiple phenomena and methods, are assumed to be wrong.

The central difference between basic sciences and complex sciences is that (usually) in a complex science the definition of the problem rules out performing controlled experiments. Astrophysics and cosmology are good examples of this kind of science. Climate science is another. The approach of these sciences is to observe the system (or systems) under study, compare the phenomena that appear to be involved with phenomena from the basic sciences for which there is experimental evidence, and construct a theory that mathematically explains observed behavior and predicts future behavior in terms of results of experiments that can be performed, albeit not on the complete system. A key distinction is that what the theory does is explain current and past observations and predict future observations, but the observations are necessarily not controlled experiments. By definition of the system under study, a controlled experiment is not possible. Nevertheless, a theory is judged better or worse than another theory if it agrees the most with observations, both present/past and future. Because a single or a few definitive controlled experiments are not available to rule out incorrect theories, it can take longer to find a definitive complex theory. For example, in cosmology, working theories have gone from steady-state, to open big bang, to open inflationary big bang, to closed big bang with dark matter, etc. etc. Various alternatives, such as cosmologies in which the “constants” of the universe are functions of the universe itself and change as the universe evolves in time, have taken quite some time to rule out observationally (almost but not quite). In astrophysics, the original notion that a black hole was simply a mathematical oddity, a solution of Einstein’s equations, for an isolated mass in an empty universe, and that it did not represent anything that would occur in reality. That view evolved over the past 60 years or so such that black hole existence currently agrees more with observations than other explanations for a variety of astronomical systems. Another good example is the theory of stellar evolution. Based on the initial mass of a star at formation (assuming a pristine formation) the theory predicts how the star will evolve in time, what its luminosity and spectral output will be, whether and how long it will be a so-called main sequence star, how and when it will depart from the main sequence and become a giant or dwarf, or whether it will follow another path perhaps to an explosive event and collapse to a neutron star or black hole. All of these predictions are based on observations of many stellar objects and computer models that incorporate as much as we know about underlying physics (even basic physics) from experiments performed in labs or other facilities. None of the predictions are experimentally confirmed by a controlled experiment on a forming and evolving star.

In this view, climate science is much more a complex science than a basic science. As such, the insistence that climate science “prove” its theory by experimental demonstration misunderstands this difference within the practice of “science”. From this perspective the insistence (usually by Side A) on experimental proof should not be constantly raised since it is essentially a straw man. Climate science need no more test its theories with experiments (to be considered “valid” in some sense) than should cosmology. It is unlikely (we hope) that we will have the opportunity to interact with a black hole, but the theories describing them are nevertheless constantly tested against observations, as in the recent observations of gravitational waves from what was most likely a collision of black holes.

You point out that Side B often claims that climate science, in particular ACDGW, is just “basic physics,” and hence anyone who disputes its tenets is a scientific simpleton, akin to disputing the validity of Newtonian mechanics and gravity in regimes in which it applies, or relativistic theories when needed. This claim is wrong on several accounts, but mostly it has to do with what the meaning of “is” is (to quote a famous former president). The apparent intended use of “is” in “is basic physics” means to state that ACDGW = basic physics and therefore any quality of validity of basic physics is also held by ACDGW. This equality is false on a number of levels.

First, trivially, if ACDGW = basic physics, then ACDGW would be taught within physics departments as a required course alongside mechanics, stat mech, QM, EM, maybe fluid mech, solid state physics, plasma physics, particle physics, and relativity for undergraduates with more advanced courses in all of these plus perhaps other specialized courses in field theory, math methods, etc. To my knowledge, ACGW or even the broader climate science, is not taught within physics departments but instead finds its home in other departments named things like meteorology and atmospheric science, or earth science, or something else typically with “science” appended and perhaps including oceanic or environmental in the title. On this count, climate science is not basic physics in the way the subjects mentioned above are basic physics and the equality lacks merit.

Second, the equality does not hold since basic physics is a basic science as described above and depends on comparison with controlled experiments for testing its theories. ACDGW can not and does not do so (which is no shame, it is just its nature) and therefore is not equal to basic physics. Period.

Third, ACDGW is not equal to basic physics because some of its fundamental concepts and quantities are peculiar to ACDGW and are not within physics at all. Things like “forcings” and “feedbacks” are much more at home in computer science or perhaps applied numerical techniques and engineering science than in basic physics. To my knowledge forcings and feedbacks are not part of the standard basic physics curriculum. One of the key quantities of interest seems to be the global spatial (and somewhat time) average of local temperature readings. It is often called an average global temperature, or various distinct subsets of it, but in the view of basic physics, the quantity is (as most of Side A is aware) not a temperature at all. In basic physics a global temperature would be (an intensive property of the global system) the differential of the global energy with respect to the global entropy (two extensive properties of the global system). But the global system is a big thing. Even just the global surface is a big thing, extending over land and ocean surfaces with widely varying properties, coupled to immense non-equilibrium thermodynamic systems such as oceans, and geology and atmospheres, including many mechanical sinks and sources and phase changes and on and on. To get a global temperature using basic physics one would need to specify the global energy and entropy and then find the differential of that somehow. It’s not too hard to show, under a variety of simplifying assumptions, that the average of the temperatures of a collection of systems is poorly (often chaotically) related to the temperature obtained from the summed system properties (energy and entropy). But it is even worse, since the sub systems, and likely the whole system, are not in equilibrium and the notion and definition of temperature as described above assumes equilibrium. All of this should not be viewed as a criticism of ACDGW for being wrong or bad for spending so much time with an average of global temperatures. It may be the right kind of thing to follow. But it definitely is not basic physics.

The more correct statement side B could make is that ACDGW “uses” basic physics. But that does not translate the property of validity that goes along with equality to basic physics. Validity needs to be found another way, whatever is best for a complex science. Lots of theories “use” basic physics but are not determined to be valid. All of the various cosmological theories have “used” basic physics, but as some of them made predictions that became harder and harder to contort to fit observations, they were thought to be less and less valid. (At least until they are resurrected by new observations or clever modifications.) Astrology “uses” basic physics to get the positions of the planets and stars and whatever else is part of it, but its predictions are either wrong or so vague as to be impossible to non-arbitrarily confirm the theory.

Summarizing:

1. The fact that ACDGW is not confirmed by controlled experiment does not mean that it is an invalid theory, any more than the current theory of stellar evolution is invalid on that basis. Its validity needs to be judged by the standards of the kind of science it is.

2. ACDGW uses basic physics but it does not equal basic physics. The validity of basic physics says nothing about the validity of ACDGW, which must be judged by the standards of the kind of science it is.

Finally, the issue of validity of a theory comes up. In a basic science, one could view validity as the property that the theories are not shown to be wrong by any of many experiments so far performed. In a complex science, I am not expert, but my guess is that validity would be a result of how many observations show the theory not to be wrong, including future observations. The only difficulty apparent to me is that in the absence of control over the experiment (or observation), it can be difficult to rule out alternative explanations of observations. This process should not be viewed as a flaw in the science, but simply essential to its nature.