Vampires and the Anthropic Principle

In debates over the existence of God and man, the existence of vampires rarely enters the discussion. Whether Count Dracula and his kin exist hardly seems to be a relevant concern. But a fascinating paper by a pair of physicists makes me wonder if the existence—or rather the non-existence—of vampires can shed light on one of the popular arguments for the existence for God—the argument from fine-tuning.

In Ghosts, Vampires and Zombies: Cinema Fiction vs Physics Reality , Costas J. Efthimiou and Sohang Gandhi use math and physics to illuminate inconsistencies associated with the popular myths about ghosts, zombies, and vampires. “The fact of the matter is,” they note, “if vampires truly feed with even a tiny fraction of the frequency that they are depicted to in the movies and folklore, then the human race would have been wiped out quite quickly after the first vampire appeared.”

Vampires feed on human blood, which causes the victim to suffer not only from blood loss but also from the indignity of turning into a vampire themselves. Each feeding therefore decreases the human population by one and increases the vampire population by one. If only one vampire where to exist on earth it wouldn’t be long before the entire human population was decimated.

To illustrate this point, the authors of the paper show what would happen if the first vampire made his appearance in the year 1600. They note that the global population of humans at the start of that year is estimated to be 536,870,911. Using the conservative estimate that a vampire would only need to feed once a month, they are able to calculate the effect on the human race.

On February 1st, 1600 1 human will have died and a new vampire born. This gives 2 vampires and (536, 870, 911?1) humans. The next month there are two vampires feeding time a single vampire feds on a single human in the first month, this would create two vampires—and decrease the human population by one and thus two humans die and two new vampires are born. This gives 4 vampires and (536, 870, 911?3) humans. Now on April 1st, 1600 there are 4 vampires feeding and thus we have 4 human deaths and 4 new vampires being born. This gives us 8 vampires and (536, 870, 911 ? 7) humans.

The result is a geometric progression with ratio 2. Since all but one of these vampires was once human, the human population is its original population minus the number of vampires (excluding the original one). So after n months have passed there are 536, 870, 911 ? 2n + 1 humans. As the authors note, the vampire population increases geometrically and the human population decreases geometrically.

This chart shows the vampire and human population at the beginning of each month during a 29-month period.

The authors determine that if the first vampire appeared on January 1st of 1600 AD, humanity would have been wiped out by June of 1602, two and half years later:

We conclude that vampires cannot exist, since their existence contradicts the existence of human beings. Incidentally, the logical proof that we just presented is of a type known as reductio ad absurdum, that is, reduction to the absurd. Another philosophical principal related to our argument is the truism given the elaborate title, the anthropic principle. This states that if something is necessary for human existence, then it must be true since we do exist. In the present case, the nonexistence of vampires is necessary for human existence.

It is this last principle that is particularly intriguing and makes me wonder if it can be applied to the anthropic principle. As Wikipedia explains, “In physics and cosmology, the anthropic principle states that humans should take into account the constraints that human existence imposes on the kind of theoretical universe that can support human life.” The anthropic principle is often stated in a positive way, assuming that certain conditions must be met before human life can exist. At least two dozen demandingly exact physical constants must be in place for carbon-based life to exist on earth, the slightest variation in any of these conditions—even to a minuscule degree—would have rendered the universe unfit for the existence of any kind of life, much less for humans.

But I believe Efthimiou and Gandhi’s paper provides an example of how the anthropic principle can be stated in a negative way. Vampires are a prime example of a class of objects (let’s call them V-class objects) whose non-existence is necessary for the existence of humans. In other words, if humans exist, then it is necessary that V-class objects do not exist since they would have wiped us out long ago. Let’s designate this the V-class principle.

At first glance this seems so obvious as to be unworthy of notice. Since we humans do, in fact, continue to exist, it shouldn’t be surprising that vampires (and other V-class objects) do not exist. But this raises the question of why humans exist and V-class objects do not. Their existence is, after all, as probable (or improbable) as the existence of humans. The obvious answer, of course, is that homo sapiens merely got lucking in the evolutionary process and managed to slip past the obstacles that would lead to extinction.

This is a plausible answer until we consider that to get around the anthropic principle we need to posit something similar to the mulitverse hypothesis. Returning once again to Wikipedia, we find that this theory is,

The concept of other universes has been proposed to explain why our universe seems to be fine-tuned for conscious life as we experience it. If there were a large number (possibly infinite) of different physical laws (or fundamental constants) in as many universes, some of these would have laws that were suitable for stars, planets and life to exist. The anthropic principle could then be applied to conclude that we would only consciously exist in those universes that were finely tuned for our conscious existence. Thus, while the probability might be extremely small that there is life in most of the universes, this scarcity of life-supporting universes does not imply intelligent design as the only explanation of our existence.

Although it seems to be a complex speculation designed to get around the obvious implications of the anthropic principle, this too is possible. But consider what happens when we combine the mulitverse theory, the anthropic principle, and the V-class principle.

The non-existence of any V-class objects is as statistically improbable as the aligning of dozens of independent physical constants that give rise to life. Any universe created by the multiverse generator would need to include both (a) the positive conditions necessary for life (i.e., the fine-tuned laws of nature) and (b) the negative conditions necessary for human existence (i.e., the absence of V-class objects).

The anthropic principle could therefore be restated as claiming that the existence of human life requires both (a) the alignment of several cosmological, chemical, and physical constants and (b) the non-existence of all V-class objects. The probability that each of these stochastically independent events could align precisely as they have—without any intervention—is roughly zero. The evidence therefore points to “fine-tuning” of these conditions.

If it is the case that we have reduced the chance hypothesis to a virtual impossibility, then we are left with the obvious conclusion that the fine-tuning is not apparent, but actual. The fine-tuning implies the existence of a tuner; hence we can conclude that the scientific evidence supports the conclusion that God exists. The fact that vampires don’t exist doesn’t prove that God does, of course, but it does seem to shore up the anthropic principle, making the fine-tuning inference more reasonable and probable than its alternative.

Potential Rebuttals: One argument against this conclusion is that there are vampire killers (e.g., Buffy the Vampire Slayer) who are able to keep the vampire race in check. Clive Thompson runs the numbers and concludes that the precise number of vampires that could exist in a Buffy universe is no more than 512. So the unlikely event that V-class objects like vampires could be held at a steady number would undercut my argument.

A much weaker claim is that vampires don’t necessarily have to turn their victims into vampires sine they can kill them before draining their blood. That method, however, would still decimate the human population—it would just take a few years longer.

The other line of attack would be on my claim that the existence of V-class objects is as likely as their non-existence. This is a Bayesian assumption, but I think it’s reasonable. If it could be shown that this is not definitely the case, however, it would likely prove to be an effective defeater to my argument.