Heisenberg’s work in particle and quantum physics highlights two alternative approaches to science: observation based, or theory based. This has important implications for the climate alarmist-skeptics debate. Is there a climate equivalent of Heisenberg’s Matrix Mechanics, which by escaping the dead hand of reductionism, opened the way to true insight into quantum physics? This PBS Space-time video by Matt O’Dowd nicely shows the important insights of Heisenberg in seeking understanding of physical reality.

Werner Heisenberg in 1925, while trying to interpret new discoveries about atomic electron orbits, took a bold and unconventional approach of building a theory strictly limited to measureable parameters, rejecting the reductionist approach of trying to build a model world view of hypothetical particles and forces operating serenely down to the smallest scale.

Niels Bohr affirmed Heisenberg’s philosophy by asserting that what mattered in a physical system were the measureables. Only the measureables. Not imagined structures and machinations that could not be seen. Unobservable details, according to Heisenberg and Bohr, are irrelevant and meaningless.

For a decade or so the science establishment ignored Heisenberg and Bohr as deniers of extreme reductionism, which was (and still is) the ruling science paradigm. The grail-quest continued for a detailed model of the inner workings of atoms; an all-singing all-dancing self contained model of reality – like a climate model – with lots of moving parts.

However early quantum theory and the origins of what would become quantum field theory, was plagued by problems that eventually would vindicate the approach and alternative paradigm of Heisenberg and Bohr. Infinities cropped up. Problems were especially severe regarding the atomic nucleus. Scattering experiments revealed hitherto unknown structure within protons and neutrons, but the forces necessary to explain nuclear structure ran to infinity or to values breaking space-time. Attempts to build a nuclear model from the scattering experiments failed. This forced physicists to return to the ideas of Heisenberg and Bohr.

Heisenberg had not been idle in the meantime, and had constructed a theory that discarded the grail-quest of a model of internal nuclear structure, involving in his theory only the observed entities entering and leaving the scattering experiments. Nothing more.

This humbling simplicity was offensive to the naturally pompous academic mind – but it worked. Heisenberg had formulated a scattering matrix – the S Matrix, which mapped the probabilities of all outcomes of an experimental particle collision. Heisenberg’s approach with the S Matrix was to ignore the non-observable entities and treat the measured S matrix as itself the fundamental reality.

But the full realisation of the value of Heisenberg’s paradigm would come a generation later, in the 1960’s and 70’s as physicists acknowledged a roadblock in the path of a mechanistic-reductionistic understanding or model of the nucleus. Heisenberg’s S-matrix theory was finally applied to the nucleus in a serious way.

One of the first fruits of the S-Matrix approach was obtained by Steven Hawking who applied it to the study of black holes. This would lead to the discovery of black hole Hawking radiation. Another scientist who applied it was Gabriele Veneziano who was trying to solve the difficult problem of the strong nuclear force. Veneziano also applied the S-Matrix but went one step further, bringing in the element of (Euler) topology. Linked to this was the representation of particle properties as frequencies of oscillating elements – or “strings”. Regardless of one’s positive or negative attitude to string theory, it has made the notable achievements of reconciling general relativity and gravity with quantum physics. And also having gravity emerge spontaneously from its theoretical architecture. Some string proponents such as Ed Witten, in answer to the question “what did string theory every predict?” reply “gravity”.

S-matrix theory is not of course the be-all-and-end-all of physics, and it became somewhat sidelined after the 1970’s in favour of the reductionist hubris of mechanistic particle based quantum theories. However S-matrix continued to be fruitful every time it was applied. One notable exponent of it was Geoffrey Chew – who led theoretic developments based on S-Matrix and the associated “bootstrap” theory to lay the foundations of quantum gravity. Ed Witten, a leading string theorist, would develop the S-matrix approach into the “holographic principle”, a multidimensional theory in which space-time is a lower dimensional (e.g. surface) projection on a higher dimensional (e.g. volume) reality. The holographic principle solves the “black hole information paradox” associated with the event horizon.

In the hands of the Iranian born Princeton scientist Nima Akadi-Hamed, S-Matrix theory has developed into the “Amplituhedron”, a geometric structure which simplifies the calculation of particle interactions (Heisenberg would have loved it!) Like Heisenberg’s original S-Matrix approach, the Amplituhedron dispenses with the uniqueness of particles and their locations – these things are emergent, not fundamental. Again wonderfully subversive of reductionism. The Amplituhedron is one of the most exciting and promising current theoretical developments in physics (needless to say, Ed Witten is a fan!)

What has any of this to do with climate science?

The implication of the S-Matrix story for climate science is that, even in the exact sciences, reductionism is not the only game in town. Mainstream climate science is rigidly reductionist and massively inductive, seeking to embody all its claimed understanding of climate in hugely complex general circulation models. This is analogous to the particle based standard model type approach in physics. Of course, this approach is not without its successes, some spectacular. But Heisenberg, Bohr, Hawking, Chew, Witten, Arkani-Hamed and others have convincingly shown that an alternative more deductive approach can also be highly fruitful and powerful, often in a more efficient way. By analysing observables only in an interpretive matrix, solutions arise to otherwise intractable problems. This shows that reductionists cannot claim a monopoly on fundamental reality. What they intuitively imagine to be fundamental, may be only emergent.

And never forget philosopher of science Karl Popper’s exhaustive demonstration that, in the end, science has to be more deductive than inductive. That induction’s appeal is illusory as it represents nothing more than the reprocessing of one’s predjudices.

Climate history provides us with the equivalent of an “S-Matrix”. What goes in? What comes out? Inputs to earth’s climate include continental rearrangement and changes in ocean circulation, mountain uplift, volcanic activity, the evolution and spread of bacteria, algae, animals and plants, solar and orbital variations. What comes out? Climate, in its 4-dimensional history. The approach of climate skeptics is more akin to the observation based S-matrix. A matrix linking inputs with outputs seeking to understand how they are linked. Milankovitch’s discovery of the subtle orbital forcing of the glacial-interglacial cycle is an example. A real causative mechanism. No whiff of CO2.

On the other hand, the alarmist hypothesis that CO2 is causing warming during a glacial period that is somehow harmful, is the opposite – reductionist, inductive and mechanistic. It sees computer models as the underlying reality and climate observations are simply altered into forced agreement with the reductionist models. Where CO2 alone is insufficient to explain warming, positive feedbacks such as with water vapour are invoked that are analogous to dark matter and dark energy needed to make cosmological models work.

So the observation based approach like the S-Matrix, and the reductionist inductive models, come to conflicting conclusions about the workings of climate and the status of CO2. For the mainstream mechanistic community, the science is settled, and carbon doom is nigh. On the other hand, the sceptical position is Heisenberg’s uncertainty. Time will tell which side is right.