Today is a good day for science.
Recently, I have been inspired by news that astronomers are currently convening in Prague to decide the fate of Pluto, the black sheep of our solar system. This "plucky" little spheroid (yes, one of the "journalists" covering this story used that adjective in describing some elementary school children's attempts to save its historical status) has, for decades now, been the recipient of the astronomical equivalent of affirmative action.
But discovery of other objects in the solar system of comparable size and orbit have called Pluto's status into question. For scientists to be consistent, they would have to allow Pluto's moon Charon, the heretofore-asteroid Ceres, and the newly discovered celestial body nicknamed "Xena" into the planet club. Moreover, dozens or perhaps even hundreds of roughly spherical objects orbiting the sun may be candidates for entry.
Reading about this fascinating shift in long-established facts has reminded me of the wonder I experienced in my youth regarding what I thought at the time was God's creation (or, more accurately, just God; I was pretty pantheistic). About the time of my sophomore year in high school, I really got into cosmology and astrophysics. I thought then that I would surely become some sort of scientist, a geneticist if not a physicist (I was taking biology at the time).
I read popular works, primarily by Stephen Hawking. I read the original version of A Brief History of Time, as well as the illustrated version, and I even made my parents play lectures of his on tape (in his robotic voice and everything!) during at least one family vacation. I saw in a bookstore the other day that he has a new illustrated tome entitled The Universe in a Nutshell which purports to be an update of that first popular book which I so enjoyed.
I see these sorts of adolescent ruminations on the nature of reality as my first stirrings of philosophical interest. My interests in science have shifted--towards evolutionary theory and neuroscience more than anything--but they never completely left me.
In fact, I could quite easily see myself in graduate school for science, were it not for the fact that experimental work never appealed to me. (Also, even though I am fortunate to be mathematically talented, I never really liked the more advanced math that I studied.) I'm too much of a big picture thinker; I wouldn't be satisfied chipping away at one small corner of the universe when there's so much out there that's exciting.
But, as I've said, my interest in cosmology has been rekindled, and I've been spending (too) much time recently perusing Wikipedia. I have to say, it is a fantastic source (as far as I can discern) for popular discussions of theoretical physics, advanced mathematics, and high-concept science-fiction.
I'm feeling lazy, otherwise I'd include links, but I started off looking at Dyson spheres, stellar engines, the Kardashev civilization scale, the anthropic principle, ecumenopoleis (plural form of ecumenopolis, or world-city), and cosmological evolution (what you might call Darwinism for universes). I swear, though, I could spend days reading about these things. They're utterly fascinating, truly a testament to the power of the human imagination and the sublime beauty of our universe.
I think it's no coincidence that I find Spinoza so compelling, given these sensibilities. Even though he is an amazing thinker in terms of human psychology, ethics, and politics, Spinoza is also a big picture thinker. I find some fascinating parallels between Book I of the Ethics and ideas like the infinite universes hypothesis and the anthropic principle. This is huge stuff--I mean, we're talking bigger-than-the-universe stuff.
Consider the following. It's a given that intelligent life is an extremely improbable phenomenon. Given enough time and space, it's bound to happen somewhere in a universe, but only if that universe falls within specific parameters, having certain fixed cosmological constants. Because of how rare it is, it would seem to us that (excluding the possibility of intelligent designer(s), whose existence would itself be even less probable than that of a universe capable of supporting some kind of intelligent life) it's unlikely to arise if only one universe existed. In other words, the fact that we exist seems to lend credence to something like the infinite universes hypothesis.
But, as it turns out, this kind of reasoning is an instance of the inverse gambler's fallacy! As you may know, the gambler's fallacy is this idea that if you've been, say, playing roulette for a long time and 17 hasn't come up yet, that it's due to show up on this particular spin. The error here is that dice (and roulette wheels) have no memory. On any given trial, it's just as likely that 17 will come up if the last 100 spins have not landed there as it would be if say 50 of the past 100 had (improbably) landed on 17.
The inverse of this, also a fallacy, is to think that the occurrence of something improbable means a long history of unsuccessful attempts. So, say I go to a casino and play the slot machine once, hitting triple-7 and winning the big jackpot. I then ask you, is it more likely that this is an old machine that has had many losers before or that it's a brand new machine which had never been used before? We'd be inclined to suppose the former, but unjustifiably so. The probably of hitting 777 on spin #1 is equal to that of hitting 777 on spin #1,000,000.
What does this mean for the universe? Well, the likelihood that life will arise in this universe does not change even if there are millions of non-life-supporting universes "out there" (assuming that universes are closed systems that don't interfere with each other). If this reasoning is correct then, from our perspective, it is no more rational to believe that there are infinitely many universes than to believe there is just one--it's merely an aesthetic preference. That's just so counterintuitive!