When I proposed ten tenets of a new “religion” around life a few months back, the first tenet on the list said:
The universe is not here for us, or because of us, or designed to lead to us. We are simply here because we can be. It would not be possible for us to find ourselves in a universe in which the rules did not permit our existence.
While simply stated—perhaps to the point of being obvious—it is shorthand for a fundamental principle that has become a wedge issue among professionals who seek to understand the nature of the universe we live in, and the rules by which it operates. In this post, I will elaborate on the meaning and the controversy behind this deceptively simple statement.
The Schism
As a form of entertainment accompanying my journey through astrophysics, I witnessed a schism develop at the deepest roots of physics and cosmology. In brief, many physicists pursue a common quest to elucidate the one logically self-consistent set of rules by which the universe works: a Theory of Everything (ToE), so to speak. In other words, every mystery such as why the electron has the mass that it does, why the fundamental forces have the behaviors and relative strengths they do, why we have three generations of quarks and of leptons, etc. would all make sense someday as the only way the universe could have been.
An opposing camp allows that some of these properties may be essentially random and forever defy full understanding. Those in the ToE camp see this attitude as defeatist and point out that holding such a belief might have prevented discovery of the underlying (quantum) order in atomic energy levels, the unification of electricity and magnetism, reduction of a veritable zoo of particles into a small set of quarks, or any number of other discoveries in physics. Having self-identified in the “defeatist” camp, I knew for sure that the purists were just plain wrong about my position stifling curiosity to learn what we could. Our end goals were just different. I was content to describe the amazing universe—figuring out how rather than why it worked—and didn’t need to find a “god” substitute in an ultimate Theory of Everything (a big ToE).
The counter-cultural viewpoint I hold sometimes goes by the name The Anthropic Principle, simply because it acknowledges the fact that we humans are here—so that whatever form physics takes, it is constrained by this simple and incontrovertible observation to produce conditions supporting life. It amounts to a selection effect that would be insane to pretend isn’t manifestly true.
Scientists are perhaps too well trained to remove humans from the “equation,” and I can definitely get behind the spirit of this practice. After all, the history of science has involved one demotion after another for human importance: Earth is not the center of creation; the sun is not the center of the universe (the universe doesn’t even have a center)—or even the center of our galaxy; moreover, our galaxy is not special among the many billions. Ironically, even through the Anthropic moniker seems to attribute special importance to humans, the core idea is actually the opposite, translating to the ultimate cosmological demotion: our universe isn’t even special: a random instance among myriad possibilities. Yet, I suspect the name itself is a barrier for many scientists, as it seems superficially to describe an idea built around humans—which is a non-starter for many.
I can definitely sympathize with this reaction, as an avowed hater of human supremacy—a sworn enemy of the Human Reich. Don’t get me wrong: I’m not a misanthrope. I love humans, just not all at once on a destructive, self-aggrandizing rampage. Yet for all my loathing of anthropocentrism, I am fond of the Anthropic Principle. What gives?
Basically, I have to ignore the unfortunate label. A rose by any other name is still a rose. I propose using a less problematic name that gets to the same fundamental point: The Biodiversity Principle. I’ll explain what the principle is (by any name), and eventually how it relates to modernity and the meta-crisis as a compatible foundation for long-term sustainability.
The Fine Tuning Problem
Step one is to admit that our universe is pretty amazing. Not only did it last for more than a microsecond, but it has gone on long enough for a lot of interesting things to develop. It expanded rapidly enough to avoid a Big Crunch due to gravitational zeal, yet not so fast as to prevent atoms from finding each other to form stars, planets, and all the rest. Its set of particles—and more importantly the relationships between them—were sufficient to make stable atoms and fill out a periodic table that leads to a rich chemistry landscape. It has every appearance of a Goldilocks universe.
None of this had to happen. By this, I mean that altering physics a little bit would have prevented some key emergent properties. The physics purists are already rejecting the premise of the previous sentence, but I’ll return to their concerns in the next section. A book by John Barrow called The Constants of Nature explores the consequences of having a different mass ratio between the electron and proton, or a different ratio of strength between electromagnetism and gravity (unaccountably forty orders-of-magnitude different in our universe), a different strength of the strong nuclear force, or a different cosmological constant (the “natural” value is 120 orders-of-magnitude larger than what we observe), among others. What he finds is that some of these things appear to be “fine-tuned,” which drives physicists mad. Fine tuning means that something seems to be “just so” and intolerant of much variation before things break. Fine tuning carries with it the unwelcome implication of design or intent. The hard-nosed physicist suspects some underlying principle explains the result, so that it could not have been any other way. Otherwise, it seems the only option is to throw up one’s hands and say that God made it that way, which is not a typical conclusion in most physics publications, or one that I tend to offer.
What Barrow showed was that a number of physical measures don’t have to be much different than they are—sometimes only a few percent off, which is very tight compared to the orders-of-magnitude of variation that might have emerged—for things like chemistry to be wrecked (e.g., no stable atoms; no carbon).
Similarly, the number of extended spatial dimensions matters. Why is it three? One or two could probably not do anything interesting (like life). More than three is too many for stable orbits and atoms (too many for my brain, for sure). Just as in the Game of Life, the simple rules on a two-dimensional grid found a sweet spot where lots of emergent complexity could manifest, but changing the rules and space tends to break it.
We can quantify our ignorance in terms of the number of “arbitrary” parameters in the Standard Model of physics that cannot be derived but must simply be measured—irritating theorists that knuckle-dragging experimentalists are the best source of info. The list comes to a couple dozen underivable parameters, or more if adding cosmological parameters and gravity (more background here). Most of the constants are masses, but also force strengths and “mixing angles.”
So, if we imagine the range of possibilities for the various constants as a “parameter space,” and throw a dart randomly, we’re exceedingly unlikely to hit the small patch that represents our physics (universe) or one that is even capable of producing similar results. The dart is likely to land on a place that either blows itself apart too fast for stars to form, or falls back on itself before anything “good” can happen. It might lack the nuclear properties to make stars. It might lack stable atoms to make chemistry (thus life). In short, the vast majority of the parameter space is barren and frikin’ awful.
But our dart hit the sweet spot! Was it guided? Is there actual fine tuning going on by the hand of a creator?
What Believers Say
The “true blue” physicist rejects the premise. To them, it makes no more sense to speak of a parameter space for these constants/strengths than it would to speak of different possible values for the number 2. In this view, only one logically-consistent framework exists, and that framework demands that the set of values (the “dart”) lands precisely where it does—without freedom to do otherwise. We just haven’t elucidated the underlying truths yet, and need to keep the faith rather than throw in the towel just because it’s hard.
But let’s be crystal clear here. This rigidity/insistence is based on no actual evidence that a deeper connection defines these constants. It’s a belief; a faith; a religion (pot calling the kettle black, here—I have my beliefs, too). Sure, we can look in the rear view mirror and see plenty of examples where mysteries were resolved and a synthesis achieved. I could never rule out further advances in understanding, but lack faith in mastering the whole enchilada. Admittedly, I might also cast my objection to the “one-and-only” physics notion on religious grounds. If the only way physics could have manifested makes a universe that creates life, then that’s pretty spooky (designed? destined?) and I should go back to church—which I don’t want to do. The point is, it comes down to a matter of faith/belief no matter what the position.
My discussions with believers on this topic quickly hit an impasse. A key point is that our physics seems just right to lead to life, and small variations destroy that capability. “But you don’t have the freedom to vary physics.” Yes, but if that’s so, the apparent fine tuning seems all the more problematic: the idea that the one way it could be found this island where stars, galaxies, chemistry, and life can work is pretty crazy, right? “But there is no island if things can’t vary. I don’t see your point.” Clearly not.
Acknowledging loads of individual exceptions, the schism between the ToE types and the heretics tends to split along generational lines. Historically, this might be understood as a natural consequence of the heyday of particle physics in the mid-to-late 20th century. This period saw a growing menagerie of particles condense to a very small number of quarks and leptons in various arrangements, accompanied by the formation of the Standard Model. Moreover, the weak nuclear force was merged with electromagnetism as a significant step toward Grand Unification: two of four fundamental forces are now consolidated. The number of generations of particles and nature of the forces were understood to emerge from group-theory symmetries underlying our universe (its “vacuum state”). Things were coming together, and it was exciting! If you were a physics graduate student in those days, the path toward unification seemed clear.
My generation saw the opposite trend. The Standard Model suffered a weight gain (literally, and in number of parameters) when neutrinos were discovered to have mass. Dark matter and dark energy ripped cosmology apart, so the trend was one of added confusion—and more measured parameters—rather than a continued trend of reduction.
String Theory Comes Untied
String theory came charging in to solve everything, dazzling mortals with its shiny, spiky math. The idea was that all particles were the same thing deep down: a bit of “string” whose vibrational modes produced the particle and force properties we observe. In other words, the Standard Model parameters would turn out to represent different ways of wiggling, and would have a mathematical description so that the result could only be one way! Moreover, gravity would be naturally incorporated without the pathologies plaguing efforts to combine the Standard Model and General Relativity, which are fundamentally incompatible, as formulated. Sounds like just the thing!
The wrinkle (literally, as you’ll see), was that string theory needed more spatial dimensions than just our three in order for the vibrational modes to acquire the rich spectrum required to represent observed particles, forces, and associated symmetries. In fact, it needed ten. Never mind the obvious truth that we live in a world of three spatial dimensions. That’s three macroscopic dimensions, you see. But we can “roll up” the extra dimensions into cyclic structures, like a spider web filament that looks one-dimensional to us, but has a second dimension wrapping around the circumference under magnification.
Fine: it’s not how we might want things to go, but if that’s the price of answering all mysteries, then we can probably swallow it like we’ve swallowed so many other bizarre ideas that experiments (nature, really) ultimately forced down our throats—like relativity and quantum mechanics. Despite the impression many are under, humans did not invent the rules of physics any more than we invented the fact that two plus two equals four. We simply asked nature how it works and struggled to comprehend the answers.
Where things fell apart was in describing the numerous topologies with which one could roll up (“compactify”; wad up; wrinkle) these dimensions. For example, compactifying two dimensions can take the form of a sphere, a torus (donut), a donut with two holes, or three, or any number. Now take 7 extra dimensions and…oh my! Not only is the topology (called Calabi-Yao manifolds) relevant, but the various radii describing the various loops and holes need to be specified. Each variant constitutes a different vacuum state, or universe. Each has its own unique laws of physics, which emerge from how these spaces are tangled and therefore how strings can vibrate within these manifolds. As a consequence, the symmetries that govern the way the forces work or the number of generations of particles relate to these seven-dimensional topological pretzel configurations, while particle masses and force strengths relate to the radii of curvature (as my understanding goes).
Some string theorists began to quantify just how many possible “vacua” are embodied in this topological explosion, coming up with 10500. Just because you understand the numbers 10 and 500 does not mean you truly have any intuition for 10500. There are only 1027 particles in your body, and 1080 atoms in the universe (out to our causal horizon). Even having 1080 universes of 1080 atoms each is “just” 10160 atoms. 10500 is staggeringly huge. It is, notably, much larger than ONE, which was the original target of string theory: the ONE logically-consistent way physics can be. Oops. They overshot a little.
So, this new development, dubbed the Cosmic Landscape (see book by Leonard Susskind), tore the string theory community apart. As an aside, whether or not the basic string theory approach is correct is an open question, and one that may never be resolved. I don’t have a strong opinion either way.
But Pairs Well With…
To me, this unraveling development was not just okay, but exciting. While feeling like a depressing defeat to the ToE believers, for me it opened a multiverse of possibilities that one could explore. What’s better than one universe? 10500! Maybe we could identify which Calabi-Yao folding we inhabit. Maybe we could understand how likely/common our kind of universe is, and the dynamics involved in a new universe settling into a particular vacuum state. This is why I never understood the attitude of the believers that giving up on a ToE showed a lack of curiosity that would have suppressed discovery. They don’t get me at all. I guess we’re after different things. They want deus ex physica, while I’m satisfied with learning about the actual universe as it is presented to us—in all its messiness. I now believe I understand the situation better in the context of Iain McGilchrist’s The Master and His Emissary: I’m less driven by a need for certainty and reliance on a model, and just jazzed to live in an incredible world that we can learn more about. The ToE folks want to live in the tidy model, and if they can’t have it then the world is disappointing and meaningless. Their loss! (To me, free will goes similarly: those who believe in it are unwilling to see the point of living in a universe without it, even though it’s actually just fine without the mental hangup!)
In any case, a parallel development in cosmology pointed more and more to an inflationary epoch in the early universe—efficiently resolving a number of otherwise problematic observations. Most inflationary frameworks permit arbitrarily many causally disconnected “bubbles” of spacetime to erupt into existence: one of which we call the Big Bang that created our expanding pocket of spacetime. What’s permitted happens. Just try and stop it!
And really, one is an odd number. If one, why not more? Zero is perfectly reasonable and ubiquitous: we are not surprised to find zero pink elephant unicorns, but if we found one, we would instantly suspect the existence of more. In the context of our universe why would we mentally (artificially) limit the phenomenon to just one instance? So, if inflation is a correct description of how our universe started—as multiple lines of evidence suggest—then our universe is likely one among uncountably many in a multiverse, and our particular one acquired the physics it did based on which of the 10500 Calabi-Yao manifolds and associated parameters popped out, by chance.
Our particular universe happens to have what it takes to go for billions of years, forming stars, galaxies, planets, chemistry, carbon, and even life!
So, an inflationary multiverse pairs well with a string theory “landscape” to produce any number of possibilities. What a relief! My Sundays remain free! Let a trillion trillion trillion … flowers bloom (or fail to bloom).
The Biodiversity Principle
Now we have arrived at the motivation for calling the multiverse-embracing, landscape-friendly cosmology The Anthropic Principle. We humans are here, so we have the kind of universe that can lead to us. We could not have found ourselves in any other kind of place. It’s a painfully obvious statement of truth, almost not even worth pointing out.
Similarly, it is no coincidence that we find ourselves on the one planet we know to be capable of supporting life. Of course that’s where we’d find ourselves. Astronomers don’t tear their remaining hair out wondering why Earth is a perfect 150 million kilometers from a G2 star. It just happened that way, and with 100 billion stars in the galaxy and 100 billion galaxies, it’s going to happen somewhere (pause to reflect on the fact that 1022 stars is a tiny number in “landscape” terms).
It appeals to me that the multiverse-landscape is the ultimate Copernican demotion. It rankles the ToE believers, but all such revolutions rankle the practitioners of the day. They’ll probably never accept it, and in this case we probably won’t have strong evidence either way. We can never see direct evidence for other universes, as we’re causally disconnected. We might possibly learn more about the likelihood of their existence—by confirming inflationary cosmology, or finding evidence for compactified extra dimensions—but even those developments are not guaranteed.
Thus, I find myself in the peculiar position of being an anti-human-supremacist who embraces the anthropic principle in cosmology. But the real point is that we necessarily find ourselves in the sort of universe capable of creating life that evolves into amazing biodiversity. This is why I now adopt the Biodiversity Principle as a way to say the same thing with an emphasis on life rather than the tiny subset that humans represent. Homo sapiens is one of about 10 million species on Earth right now, occupying less than 0.01% of Earth’s history, while Earth is one of probably billions of life-bearing planets in the universe. We’re not the main point, but one element of something rather amazing that our universe is capable of supporting.
Modernity and the Meta-Crisis
Gee, all of that might fool a reader into thinking I’m still an astrophysicist, despite my abandonment of that life. What does it have to do with the topic I find most compelling to think about these days?
In a word: humility. The Biodiversity Principle is the ultimate refutation of specialness. The universe was not designed for us, or to lead to us, or even to lead to life. It could have gone loads of different ways, and maybe only had a 1 in 10100 chance of being capable of supporting life (essentially zero chance, for all intents and purposes, yet still resulting in 10400 possible configurations for life, so immense is the 10500 starting point).
The Biodiversity Principle therefore requires no explanation for why our universe is “just so.” If it can happen, it will somewhere (in some universe), and ours is obviously one where it did, as must be the case. The tendency among scientists is to ignore or discount our (life’s) presence, but that’s a little weird, isn’t it? Such thinking makes the enormous—and disturbing—assumption that we would pop out of whatever universe physics decided it had to cook up. It’s a blind spot.
The Biodiversity Principle acts to de-center humans, and frees us up to admire and enjoy the luck we have. It shifts focus to the more-than-human world, so that we might treasure the biodiversity we witness and are a part of—and then perhaps act like it!
I also see this “we’re not special” mentality as being in opposition to the fanciful notions of free will and consciousness as “special,” transcendent provisions of humans (scientists are finding otherwise). Get over yourselves, I say! Why can’t we be content that we get to be a part of this ride?
The Biodiversity Principle elegantly removes a problematic sense of purpose (teleology, for those who prefer fancy words). If humans get it in their heads that modernity is somehow “supposed” to happen in our universe (rather than that it happened simply because it could), then we make poor choices and are not as easily convinced that we should abandon modernity. Recognizing the incalculable value of biodiversity as something extraordinary that our universe happens to allow might foster a sense that we should prioritize its long-term health over the usual short-term concerns of modernity and human supremacists.
A repeat of the first of ten tenets I proposed has more complete context now:
The universe is not here for us, or because of us, or designed to lead to us. We are simply here because we can be. It would not be possible for us to find ourselves in a universe in which the rules did not permit our existence.
When constructing this tenet, I had exactly the topic of this post in mind, and now perhaps it is more clear what I meant by it. I hope it is also more clear how this topic ties into the thread I’ve been on lately. Belief in the Biodiversity Principle is an important foundation in my approach to life (enough so that it was the first tenet in my list), and I can’t easily tell how necessary it is in order to possess the rest of my worldview. At least I can see the connection, and recommend trying it on. We are tiny, but we’re here, as a matter of luck. Now, don’t squander that luck in a fit of false self-aggrandizement.
