Monday, January 31, 2011

Maths and vampires

Vampires are in. Indeed, they have been all the rage for the last 200 years, appearing in books, films, comics… Vampires are a craze like aliens, dragons or superheroes --they are an icon of our society. The problem is that some people believe that they do really exist or, at least, they do not dismiss this possibility. For these cases, let’s resort to numbers.
We do not know when vampires first appeared. Some books and films hint at the time of pharaohs, but let’s be indulgent and start in more recent times: all legends accept that in the Middle Ages, castles in Central European woods were inhabited by vampires. Let’s take the year 1200 as the date of birth of the first vampire (quite late, I know, but I am being indulgent again). Then, in 1200, our first vampire flies out at night looking for a fresh neck to suck some dinner. Most legends state that vampires bite and suck the blood of their victims, who in turn become vampires themselves. However, we miss some information: when do vampires feel hungry? Every night, every week, every full moon? Let’s be indulgent again and think of a vampire who needs to be fed only once a year, far from our three meals a day, like the rest of hominids. Then, in the first year (in 1200), our immortal vampire hunts a victim, drinks his/her blood and turns him/her into another vampire, so on 1 January 1201 we have two vampires terrorizing human beings. In the following year there will be 4, because both vampires need to have a meal, and in 1204 we get 8, in 1205 we get 16 and in 1206 we get 32. Every year, the number of vampires doubles so in 1225 this exponential progression makes 16 million vampires for a total population of about 450 inhabitants on the Earth. Let’s go on with numbers. Nine years later, in 1234, vampire population would amount to 8,000 millions, which is far more than the total number of inhabitants on Earth at the beginning of the 21st century. If we go on with numbers until now-a-days, we would need a computer because the total amount of vampires will be greater than the amount of sand grains of our planet. These data clearly demonstrate that the vampire species is utterly unsustainable (even more than the human species). Just imagine the final figures if we assume that vampires have dinner every evening! Last week we said that we cannot create artificial blood yet, so vampires must have a very tough existence… We are what we eat!
Now, after publishing this post against vampires, I will hang a bulb of garlic by my door, just in case my words are too hurting...

  1. One of the main classic sources on vampirism (in French):
  2. Exponential progression: 
  3. Blood donation: 


  1. Oh, you need task C1 which runs 1x per hour, but not the same time as task C? Sure, have it run when “n mod 60 == 1″ (still once per hour, but not the same as C1). help me with math


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