Posted: 14 August 2011 Updated: whenever: whatever
If you like, you can let me know what you think about this. But if you're not willing to have your comments posted on here, along with my response, don't bother me. For contact, use cdoswell_#_earthlink.net -- use the email hyperlink or cut and paste, replacing _#_ with @.
My inspiration for this essay comes from a podcast interview with Dr. Richard Carrier. In his interview, Dr. Carrier made some statements I wanted to check out. Hence, I did some calculations (see below). If you find them challenging, you can skip them because, in essence, what I found is that Dr. Carrier’s statements were correct.
If the "known universe" is a sphere with a radius (r) of 23 billion light years (lyr), that's a sphere with a volume [(4pi/3) r3] of 5.097 x 1031 lyr3. Note that the scientific notation 103 = 1000, whereas 10-3 = 1/1000 = 0.001. Thus, 1031 is 1 followed by 31 zeroes!
1 lyr = 6.78 x 1012 mi = 10 x 1012 km = 10 x 1015 m (ten trillion) = 1016 m.
1 lyr3 = 2.032 x 1038 mi3 = 1039 km3 = 1048 m3
Therefore, the known universe encompasses a volume of 5.1 x 1079 m3. That's 51 followed by 78 zeroes!
Now, consider a good-sized single-family home in America, having a surface area of 2000 ft2. If we assume the interior of the house is at a height of 10 feet, that means a volume of 20,000 ft3. Converting that to metric units, it occupies a volume of 550.661 m3.
Next, consider the volume of a proton (one of the particles within the nucleus of an atom) - modern estimates put its radius at 0.842 x 10-12 m, which means if it's a roughly spherical shape, it occupies a volume of 2.5 x 10-36 m3. The ratio of the volume of a proton to the volume of a house is, therefore, given by (2.5 x 10-36)/(5.50661 x 102) = 0.454 x 10-38. That’s 454 preceded by 39 zeroes to the right of the decimal point!
Consider the volume of the planet Earth: it has an average radius of about 6370 km = 6.37 x 106 m. Therefore, its volume is 2.585 x 1020 m3. Earth is a habitable planet (although the inhabited part is mostly within a spherical shell from 10 km above to 5 km below the surface - an issue I'll ignore for the sake of simplicity). If we were to assume that all the habitable planets in the known universe together occupied the volume of 10 trillion (1013) Earths, then the habitable fraction of the volume of the known universe would represent the following ratio of that volume: [(2.585 x 1033)/(5.097 x 1079)] = 0.507 x 10-46. That's 507 preceded by 47 zeros to the right of the decimal point. [If the uninhabitable volume of the Earth were excluded, this ratio would be even smaller, being divided by a factor of about 250.]
So: the volume of 10 trillion habitable planets (that on the average are "Earth-sized") would occupy a fraction of the volume within the known universe that was one-one hundred billionth the fraction of the volume occupied by a single proton within a good-sized home in America. This is the confirmation of comments made by Dr. Carrier in his interview on the podcast. So if we could shrink the known universe to a volume of a decent-sized American home, the habitable volume within it would be considerably smaller (by a factor of 100 billion) than the volume of a single proton within that home. In fact, it would take 100 billion of those volumes to equal the volume of that proton within that home!
Note: The number of atoms involved is pretty huge, also. Every human body comprises roughly 1027 atoms - 1 followed by 27 zeros!! Imagine the number of atoms for everything on Earth: 1050 atoms - 1 followed by 50 zeros! Current estimates for the number of atoms in the known universe lie somewhere between 1078 and 1082 - less than a "googol" of atoms (10100), but still an enormously large number!
Of course, no one knows the number of habitable planets within the known Universe, which could be many times larger (or smaller) than 10 trillion. At this point in the history of science, it's impossible to know that number, but the Universe is a big place, and life seems to be able to thrive in some pretty hostile environments on Earth (temperatures near the boiling point of water, temperatures well below the melting point of water, highly alkaline and acidic water, very thin air, etc.)! The number seems at least plausible to me, but I certainly can't claim it's very accurate. You can substitute your own guess and see how it changes the numbers.
The rest of that mind-bogglingly vast volume occupied by the known Universe is completely uninhabitable by any lifeform we can imagine: the deep vacuum of space, the volume occupied by stars and their coronas, black holes, extremely hot and cold planets, planets bathed in toxic radiation, planets with extremely poisonous or corrosive atmospheres, planets with no atmosphere, very thin clouds of gas and dust particles, etc. No matter how accurate my guess of the equivalent of 10 trillion Earths actually turns out to be, nothing is going to alter the fact that "islands" capable of supporting the development of life are stupendously rare in the universe! Making the number much smaller simply reinforces this basic idea of the rarity of life-benevolent places. Making the number much larger increases the probability of finding life elsewhere in the universe, rendering the idea that all this was made just for us humans even less plausible.
Some religious believers claim that this Universe seems just about perfectly "designed" for the occurrence of life: if the key physical constants (like the speed of light, Planck's Quantum Constant, etc.) were just a little different, life might not be possible at all. They see this as an argument in favor of the conscious design of the Universe by a creator-deity. But if we consider the preceding, the Universe we know is dominated overwhelmingly by a pervasive hostility to life. There are very few places in the Universe where life is even remotely possible – barring the existence of very strange lifeforms we might not be able to recognize as living that could survive in interplanetary space, within stars, or on what we now see as very life-hostile planets.
This very same argument can be used, of course, to argue that life here on Earth could in fact be the only life in the entire Universe. After all, it seems that habitable domains in the vast emptiness of the Universe are pretty few and far between. However, the discussion herein has been developed assuming that there are 10 trillion habitable planets! While this is, of course, not an infinite number, it's pretty large. With that many places where life is at least possible, what fraction of such places might actually harbor life? With 10 trillion chances, given the rapidity with which life arose here on Earth and its known tolerance for hostile environments, it seems quite likely that there are many, many worlds with life of some sort on them. The very idea that the vast cosmos was created simply as a backdrop for humans on their backwater planet circling a common type of star in the outskirts of an ordinary galaxy is quite a stretch! With so many possibly inhabited worlds, the argument that the Universe was designed solely for humans by a powerful deity fades into implausibility - Bayesian logic makes it an extremely unlikely possibility.
Since the truth about life on other worlds is not yet known, all we have are probabilities, not yes/no answers. With the logical foundation of Bayesian probability, science can estimate the likelihood of life existing on other worlds and, in a nutshell, the available evidence is massively in favor of it. The probabilities are such that life on other worlds is more likely than not. The confirmation of life on other worlds eventually will knock humanity from their presumed (and clearly self-assigned) lordship of the living universe, just as astronomy has removed the Earth we inhabit from the center of the physical universe.
The Universe appears pretty much as if it were "designed" without any grand design at all, and certainly is hostile to life throughout the overwhelming majority of its immense volume! Life is a low probability event within the universe on the average, for sure, but the Universe is a very big place that's been around for a very long time. Far bigger and far longer than most religious believers can comprehend and far more interesting than what is described in any of the "sacred texts" of the world’s major religions. Within that stupendous volume of space and time in which life is mostly impossible, tiny islands of life are not only possible, but likely. Of course, we know for certain that on our microscopic island of Earth - the one place we know in detail - life is a reality, not just a possibility.
The pursuit of scientific understanding has provided, so far, quite a dramatic story of our position in the universe. By the account of science, we're beings made up of atoms created from the raw stuff of the Big Bang, hydrogen, in stars. We're a part of the universe, come to life and able somehow to contemplate its place in the universe. If the universe can create this living embodiment of itself in one tiny corner of the incomprehensibly huge volume it now occupies, would it not simply be conceit that says all this was created for us puny humans by some all-powerful being for mysterious reasons of its own?
The scientific story of the universe is an incredibly rich, entirely nonfictional accounting of stars and planets in all their complex variety, emerging from the relatively simplicity of physical laws that govern everywhere in an identical fashion. Although the scientific story is as accurate as fallible humans can make it, it certainly will not remain static in the future, as new science gains new insight. We’re learning that complexity is not limited to the province of conscious thought, but can develop from the application of relatively simple principles: gravity, conservation of momentum, the equivalence of matter and energy, and so on. The story of the mythical deity producing things out of nothingness by mere thought seems stilted and threadbare in comparison, devoid of insight and plagued with a profound ignorance of how things really work. Is a wave of a god's metaphorical hand any sort of explanation? Does it provide a satisfactory framework for an adult understanding? No. Only the mind of an ignorant child could be satisfied with such an answer!
Our universe and even our own Earth, we're discovering, is not a paradise focused on making life wonderful for the enjoyment of human beings. For the most part, it's downright hostile to any life. The universe's hostility isn't the result of conscious malevolence, but rather flows from the universe's indifference, ticking along by means of laws we're just lately coming to comprehend. We aren't even the equivalent of flyspecks on the immense palette of the universe, and our role in that universe is trivial beyond anyone's comprehension of triviality. But nevertheless, we're still an extremely tiny part of the grand process, however miniscule our role may be. We have a cosmic connection to all that exists because of our shared heritage, that primeval hydrogen gas that emerged from the Big Bang. The cosmic design is codified in the laws of nature, not the commandments of some mythical being we dreamed up to explain things before we learned how find explanations by scientific means.
The existence of a universe in which we can exist and have managed, eventually, to begin to learn of the way the universe works, just is not likely to be the result of the whims of a deity postulated to have infinite capabilities (but for some reason, has a need for the worship of finite human beings it created). As noted, the existence of our universe hinges on the values of some key physical constants. It's true that had those numbers been slightly different, the universe as we know it wouldn't exist, and so we wouldn't exist either. Many believers choose to see this as a sign of conscious design for our benefit - the foundation of the argument that provoked this essay. Science can't offer much in the way of answers to why those numbers are what they are. Unlike religion, science always chooses to eschew making up explanations for things not yet understood. Such issues remain open until someone can offer a plausible explanation and tests the validity of that hypothesis against observations. This is not a sign of the weakness of scientific insight. No, it's a strength, not a weakness! We scientists are not so arrogant as to claim we have the answers to everything, unlike religions.
When an argument is fundamentally untestable, science doesn't offer to even try explaining it away to its adherents. The argument asserting the universe is so perfectly designed for life that it could only have come about by the action of an infinite, loving, and benevolent deity remains out there in the sphere of human ideas because it lives in a realm of metaphysical philosophy, untouchable by any logic or experimentation. You can believe unfounded, unbridled speculation if you choose to ignore any evidence to the contrary and be satisfied when accepting ideas by interpreting evidence in a way that always supports your beliefs, no matter what that evidence really shows. That the universe is manifestly hostile to life seems to indicate that this deity simply isn't all that benign. The controlling tendrils of religious belief provide weak and shallow minds with a version of the universe that believers in mythology find reassuring. If you find comfort in the delusion that the entire colossal universe was made just for you, then I'm unlikely ever to change your mind, no matter what arguments my rationality can muster. If you decide that logic and evidence are incapable of contravening the teachings of those who would have you follow them and obey their dictates, then there's little chance anything I say is going to alter your beliefs. Should you be pleased that I have no wish to convert the unwilling, then, I only ask that you do me the same favor! And praying for me is a patronizing insult, so don't bother with that, either!