What follows is a continuing and enlightening discussion between two distinguished interlocutors about cosmological natural selection.
Cosmological Natural Selection: A Critique Part 2 – by Chris Crawford
Thank you for your comments, Dr. Rifkin. I am in a weak position, not having read any of the source material, so my comments are unavoidably speculative. Still, I cannot imagine any possible evidence for what happens inside a black hole; the entire notion of an “event horizon” does render physically impossible any actual evidence. I realize that there have been a great many attempts to determine the internal state of a black hole from strictly mathematical calculations and a variety of assumptions. Particularly interesting have been the efforts to determine the information content of a black hole as well as its internal entropy. But these remain entirely speculative, as they cannot be based on any empirical evidence.
You argue against my claim that other universes are meaningless (because they cannot affect us) by pointing out that the future cannot affect us, either. In other words, these other universes are no less meaningless than our own future. But there’s a crucial distinction that your argument misses: our future is, to some extent, predictable, and, to an even greater extent, subject to anticipation. A man who jumps off a cliff has not died yet, but his future is clear enough as to be meaningful to him. We know that the sun will eventually exhaust its reserves of hydrogen and go through changes that will result in the destruction of earth; that is meaningful to us even though it is billions of years in the future. We can use our knowledge of the current state of the universe to make meaningful statements about some aspects of our future.
But we can never see beyond the event horizon of a black hole. We can never have any idea of anything in those universes. Indeed, we cannot even know that such universes exist. We have lots of fascinating speculations — and that’s all we have. No data — just speculation.
And by the way, the very notion that a black hole could somehow spawn a universe does grossly violate the conservation of mass/energy. We put a few stars’ worth of mass into a black hole and an entire universe of zillions of stars spews out of the other side? Why shouldn’t it spew forth an immensity of candy bars, thundering herds of unicorns, or a teenage boys’ fantasy of millions of large-breasted nubile nymphs?
You argue against my suggestion that other universes might produce other forms of life by noting that my suggestion “… is not consistent with what current biology or physics now supports.” That’s certainly true — but it misses my point. Yes, another universe with different values of the fundamental constants would not produce life just as we know it. Indeed, even a universe with exactly the same values of the fundamental physical constants would not produce the same life we have. See Steven J. Gould’s discussion of the highly contingent nature of life on earth, especially his observations that the evolution of Homo Sapiens was dependent upon a wide range of accidents unlikely to be replicated in an imaginary replay. In other words, the evolution of Homo Sapiens was a fluke. Consider, for example, the ramifications of a certain small asteroid arriving in the vicinity of the earth 65 million years ago one second later than in a previous history. We’d have a dinosaur in the White House.
Lastly, I want to emphasize that this entire discussion runs beyond the extremes of speculation. We are arguing over what kind of hats angels might wear, or whether ghosts can have pimples, or how long leprechauns grow their hair. There is absolutely nothing in the way of empirical information to work with.
Reply by Lawrence Rifkin MD (author of the original post) – Part 2
Evidence for scientific theories can support or disprove. Cosmological natural selection is amenable to falsification. So even if it forever continues to be the case that it would be “physically impossible” to scientifically obtain any kind of empirical evidence for what happens inside a black hole, a lack of positive confirmatory evidence does not by itself render a falsifiable theory purely speculative.
As for the conservation of mass/energy, the second law of thermodynamics only holds for an isolated system. It is not known if it holds for our universe as a whole. Or if what happens inside a black hole is an isolated system.
As for meaning, I suppose it comes down to definitions. I would say a world of branching or oscillating universes conducive to life, and the possibility that life could continue forever is meaningful – powerfully so.
Of course, if we ran the movie of life again on Earth, the specific outcomes would be different (although there is evidence for some convergent evolution trends). That is not the point. The point is if the physical parameters of the universe were slightly different, life (indeed, emergent complexity), itself would itself be unlikely, at least according to most physicists.
The explanation for why the laws of the universe allow for organized complexity and life is perhaps the biggest and most wondrous question of all. Cumulative natural selection is the only theory we know of that is, in principle, capable of explaining the non-designed existence of organized complexity. It may not be true, but it is not purely fanciful. As I wrote in my article, “If evidence proves any one of the cosmological alternatives—or an entirely new idea altogether—we will embrace reality, no matter where it leads.” For many, supernatural explanations, the “well if we weren’t here we couldn’t ask,” the “we can never know,” and the “it just happened to happen” explanations don’t satisfy. I suspect Darwin might agree?
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 Mr. Smolin and Mr. 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 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.
Enjoying the exchange. I think even *good theory* is only as good as consistent, empirical verification. Should it blow up; break down or fall apart, it falls back into the realm of speculation, at least for that moment;under those circumstances and conditions. I am neither mathematician nor physicist. That admitted, I have wondered why there are philosophies of many other arts, sciences and disciplines. Now, I understand the schema. My continuing education is refreshed.
Keeping score, I would offer this: Rifkin, 1; Crawford, 1. Neither contestant is likely to win. But, that is not the point, IMHO.
thanks for the comment Paul.