As a follow-up to our recent discussion, Chris Crawford offers a brief summary of the debate between the eminent theoretical physicists Lee Smolin and Leonard Susskind on the topic of cosmic natural selection and Lawrence Rifkin responds.
Yesterday I decided that it might be helpful if I happened to know something about the topic, so I set to work digging up material on this issue. After some digging, I stumbled upon a twenty-year-old exchange of messages between Lee Smolin and Leonard Susskind, his strongest critic. Reading that exchange was most edifying.
The most important lesson I learned is that this question is way over my head. I entered graduate school 50 years ago and I got my master’s and was pretty much up on the physics of the day. In succeeding years I occasionally noted new developments in the world of physics, but didn’t bother to keep up with the hard stuff. You know, in 50 years, physics has come a long way. This really struck home when I considered the fact that 50 years before 1973 was 1923. The physics of 1923 was, by the standards of 1973, primitive. They hadn’t discovered quantum mechanics. Nuclear physics was in its infancy. Little was known about radioactivity. Astronomy was really primitive. So if I compare the difference between 1923 physics and 1973 physics with the difference between 1973 physics and 2023 physics… well, I gotta admit that I’m very much in the dark. You philosophers have one huge advantage over physicists — the ancient philosophers are still relevant.
All this said I have figured out a number of things about Mr. Smolin’s thesis. It is based on a very complicated and very lengthy series of calculations involving string theory, quantum gravity, and all manner of other horrors of modern physics. My impression is that nobody really follows his calculations, because they are so esoteric and rely on a broad range of assumptions and interpretations of recent developments, many of which remain controversial. However, Mr. Smolin was able to establish falsifiability by showing that his calculations relied on assumptions that implied that the largest physically feasible neutron star would have a mass of 1.6 solar masses. He later amended his calculation to show that the largest such neutron star would have a mass of 2.0 solar masses. Then somebody found a neutron star with a mass of 1.96 solar masses and another with a mass of 2.07 solar masses. Technically, that falsified Mr. Smolin’s thesis, but open-minded physicists would be willing to cut him some slack. Still, these discoveries do undermine his hypothesis.
As I understand his arguments, Mr. Smolin is not claiming that his other universes DO exist; he claims only that they COULD exist. Mr. Susskind argues that they CANNOT exist. In the nearly 30 years since he published his hypothesis, it has garnered little support among physicists. From my shallow digging of the material on the web, I suspect that, while a small number of people remain enthusiastic about the hypothesis, the general community of physicists does not find his reasoning compelling.
My overall conclusion is that the hypothesis is entirely speculative, enjoying nothing in the way of empirical support. It relies upon a big hairy mess of calculations and assumptions that only Mr. Smolin seems to grasp in its entirety. It is certainly the antithesis of the desideratum that a scientific hypothesis is ideally clear, simple, and elegant.
Some other observations: the Second Law of Thermodynamics has absolutely nothing to do with the law of conservation of mass/energy, even in its most modern versions.
“Cumulative natural selection is the only theory we know of that is, in principle, capable of explaining the non-designed existence of organized complexity.”
No. The best explanation for non-technical people is Schroedinger’s three-lecture series in Dublin in 1943 entitled “What is Life?” You can download a PDF of the published content by searching on “Schroedinger What is Life? Dublin” Many of its technical details have been corrected by subsequent research (Schroedinger had no way of knowing about DNA), but the fundamental point — that living systems are merely the expression of high quantities of negentropy — is clear.
There is a great deal of modern material explaining how self-organizing systems arise in environments loaded with lots of negentropy. It has always bothered me that this clear and simple explanation of how life arose just doesn’t seem to have penetrated the consciousness of our civilization. Indeed, when you grasp the implications of negentropy, it becomes obvious that the huge quantities of negentropy that the sun pours all over the earth made the development of life all but inevitable.
Reply by Lawrence Rifkin MD
Why is there a universe of matter and stars, and why do the laws of nature allow energy to organize matter into staggering complexity, including life and mind?
My advocacy for cosmological natural selection was to further stimulate the idea that CNS is a powerful and logical scientific hypothesis to explain the existence of complexity and life in the universe as we know it.
Black hole generated variant universes (each its own Big Bang) is Smolin’s proposed mechanism for how CNS may occur. But the mechanism itself is not what I am advocating. (There are other speculative mechanisms, including a Big Crunch cyclic oscillating universe where each bang is a phase transition from a metastable state into another more stable state accompanied by a release of energy, with the laws of nature varying slightly in each round, the ones more conducive to star formation more likely to reproduce variants of those laws). My argument was not for any particular mechanism. It was for the underlying process of cosmological natural selection as a logical naturalistic explanatory foundation. So often in science, the mechanistic explanation and supportive evidence come long after the hypothesis. So arguing against the mechanism does not, to me, make one throw out the underlying idea itself. Will it forever be physically impossible to get contributory empirical evidence for or against CNS? Have we reached a physical limit of what can be known here? We’ve heard that before in the history of ideas. As I wrote, “it will come down to evidence. Our minds expand, while the God of the gaps gasps.”
Modern physics shows that black holes and the Big Bang have common physical attributes. In both, the curvature of space-time approaches the infinite. Our current scientific understanding is that our universe is felt to have emerged from a singularity (the Big Bang) and then formed singularities (black holes). If the singularity that was the Big Bang could create our universe, the hypothesis that the singularities that are black holes produce their own big bangs is certainly intriguing. But, again, the point in my original article and subsequently was to was explore the explanatory power and logic of CNS, not any particular mechanism.
If, as Mr. Crawford suggests, a good scientific hypothesis must be “simple” and “clear,” I suppose quantum mechanics and general relativity were not good hypotheses? In any event, the underlying mind-blowing powerful algorithm of biological natural selection is simple, clear, and elegant! It are the genetic mechanisms, the non-genetic influences, and ecological environments that are complicated. The logic of CNS, right or wrong, is also simple, clear, and elegant. The proposed mechanisms are not.
I agree about the pervasive and fundamental explanatory power of “negentropy” (the idea goes by many names, and involves energy flows, non-equilibrium systems, etc.). I believe Kauffman phrased it something like this: A universe that maximizes entropy at the fastest rate possible will evolve toward a state that is increasingly complex, organized, alive, and intelligent.” The general idea is that complex life optimizes its ability to extract energy efficiently, and therefore facilitates overall entropy production. Disorder is the selection pressure for self-organized systems. All this is hugely fundamental and powerful. A book I highly recommend that explores these ideas is “The Romance of Reality” by Bobby Azarian.
What I believe Mr. Crawford misses is that while “negentropy” likely explains the formation of autocatalytic sets and simple peptides, current evidence suggests that no matter how much or what type of energy is then added, including sunlight, it does not create anything more complex. Simple molecules and nucleic acids are a far cry from the mind-boggling complexity of cells, to say nothing of bodies and minds. The explanation for the formation (not the continuation) of this next level of increasing complexity needs to go beyond an underlying non-equilibrium free-energy explanation. So far, only natural selection (differential replication based on variation and fitness) can explain the coming into being of that more complex scale, phase, and level of non-designed organized complexity.
The existence of the complex laws of nature themselves that allow for the creation of matter and allow for the ability for high-level complex material phenomena to form in the first place, and the apparent exquisite fine-tuning of the parameters of nature that are necessary for these laws and their effects to occur, need a naturalistic explanation beyond the underlying dissipative entropy flow that sustains them.