Wednesday, May 26, 2010

Life-Unfriendly Design

I listened to May 1, 2010 episode of Unbelievable? while I was mowing the lawn today, and as always it was a valuable experience. The non-Christian guest was Stephen Law, a philosopher at the University of London, and one of my favorite bloggers. The topic was about Science and God, although they ranged quite a bit farther, because both Dr. Law (Great name! Don't you expect him to be a masked vigilante, fighting crime with twin .45s and an insight into epistemology?) and the Christian guest, Dennis Alexander, made the standard digressions this kind of show always has.

One thing that came up in life was that old saw that the universe is well-suited to life. This is one of those big lies that people repeat but never think about.

Yeah, sure. The universe is suited to life, because there is life in it. Great. But the universe is suited to life in the same way that a grand piano is a deadly weapon.

Look at the universe. By which I mean, continue reading this blog, but think about looking at the universe. Everywhere you see, there is life, from the deepest ocean depths to the tops of the highest mountains. Humans, the life that you probably find most important, is everywhere you can see.

Of course, you're being very biased when you think that. You only think that life in general and humans in particular are so common is because you're a human and you live with other humans. Likewise, it's very, very difficult for you to go where there is no life; it takes $20 million dollars to travel to the International Space Station, and even then you'd still be surrounded by life.

Let's take a step back. How well suited to life is the universe, really? Let's put some numbers on it...

The earth is about 6.371 million meters in diameter, or with a radius of around 3.186 million meters or so. Of course, not all of this area is amenable to life; once you get up too high and too low the earth is as inhospitable as Venus or Mars.

As a rough estimate, let's say that there is a hundred meters up or down that can support life. Since the formula for the volume of a sphere is 4/3 π r^3, we know that the volume of the earth's biosphere is the volume of the outer sphere a hundred meters up (with a radius of 3,186,100 meters) minus the volume of the inner sphere a hundred meters down (with a radius 3,185,900).

This gives the total volume of space that can support life as:

1.354773 * 10^20 m^3 (outer) - 1.354518 * 10^20 m^3 (inner)

(For those concerned with the number of significant digits, yeah, I counted more of them than I should for this back-of-the-envelope calculation. That's part of my point...)

Doing the subtraction, we find that the total volume of the earth's biosphere is:

2.55 * 10^16 m^3

(And for those of you who aren't familiar with scientific notation, 10^16 means a 1 followed by 16 zeros. This rough estimate for the total volume of the earth's biosphere is 25,500,000,000,000,000 cubic meters.)

Now let's compare this to something else. The known universe has a diameter of 8.80 * 10^26 m, which means its volume is a whopping 3.57 * 10 ^ 90 m^3. When we divide the volume of life by the total volume of space that the theists' god supposedly created, we find that the ratio between the livable space in the known universe and the universe itself is 7.1 * 10 ^ -65. This is an absurdly small number. How small?

Let's pretend that the entire known universe is the size of the earth. The habitable space would have a volume of 5.8 * 10 ^ -44. That's about the size of an atomic nucleus. Out of the entire earth.

As another idea, imagine that you had to appear at random at some point in the universe. What's the chance that you'll land in someplace you can survive? Well, you'd have to pick up a deck of shuffled cards and deal a royal flush to yourself. Then you'd have to pick up another deck of cards and deal another five cards at random and get another royal flush. And you'd have to keep doing that 21,599,999,999,999,999,999,998 more times, getting a royal flush each time. In a row.

If the Christian's god put together this entire universe and only managed to make that little space suitable for life, I'd say he's either failed at creating a universe that's friendly for life or he's doesn't care that much about life and cared more about empty universes.

Some of you out there might be saying that I'm ignoring the possibility of life on other planets, and I have, so far (mostly because the Christians' god doesn't mention them). Let me give the benefit of the doubt, though. Let's say that each star has enough life-friendly volume to make up two earth (that is, every star has two fully-formed biospheres the same size of earth). This is insanely favorable; as far as we know, our star only has one biosphere, and most stars around the galaxy just aren't capable of supporting life, even if you did put it there. But I'm making this argument as favorable to the Christians as possible. Since there are one sextillion stars in the universe (that is 10^21), the amount of habitable space sky-rockets up to 5.1 * 10 ^37 m^3. The ratio of life-supporting to life-destroying space becomes 1.43 * 10^-43. We have gone from having to deal 21 sextillion hands of poker (each getting a royal flush) to dealing around 21 quadrillion hands of poker (each getting a royal flush). Congratulations: that's made no difference at all.

"But wait!" Dr. Dennis Alexander said. "Perhaps God needed to make the universe this inefficient! If the universe were the size of the solar system, it would only last a week."

After all, the theist might say, if god made the universe the size of the universe he described in his bible, then no stars would ever condense to make helium and the heavier elements necessary for life! If the entire universe were the filled with warm, comfortable space suitable for life, the entire thing would collapse into a black hole in the order of days!

Of course, no real theist could make that claim. Once you start thinking like that, you become...

Well, I'll go into that next time!

Duke York

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