The Wednesday Post (10/2/10)

Well Thomo is still away so you’ve still got me. Lucky you.

I found this a little while ago but didn’t write about it because at the time it wasn’t the most interesting thing happening but as I was going through my saved RSS feeds I found it again, and it made me happy.

Peter Backus, a Grad student at the University of Warwick (UK) has used the Drake Equation to determine the chances of him finding a girlfriend. He says that it has been done by others before and that its a pretty obvious thing to apply the equation to but its still brilliant.

The Drake Equation was developed by Frank Drake who was one of the founding members of SETI (the Search for Extraterrestrial Intelligence) in order to describe the chance of finding intelligent life in the universe. Essentially he made a series of assumptions and then assigned them a probability. When combining the probability of two events occurring the probabilities are multiplied and so the more events that need to occur, the smaller the odds they will. An example is flipping a coin. There is a ½ chance of getting heads. But if you flipped the coin twice the chance of getting heads come up both times is ½ multiplied by ½, ¼.

Drake’s Equation looked like this

N = R* x fp x ne x f x fi x fc x L


N = the number of civilizations in our galaxy with which we might be able to communicate
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
f = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time such civilizations release detectable signals into space.

To use his numbers the equation looked like this:

N = 10 × 0.5 × 2 × 1 × 0.01 × 0.01 × 10,000 = 10

So in our entire galaxy, and if we make HUGE assumptions, there might be 10 other sources of intelligent life in the galaxy.

Anyway, back to Backus. He used the same equation but simply changed the meaning of the variables.

N = the number of potential girlfriends
R* = the population of the UK as of 2007 (60,975,000)
fw = the fraction of those people who are women (51% or 0.51)
fL = the fraction of women who live in London (13% or 0.13)
fA = the fraction of women who are ‘age appropriate’ (limited to women aged 24-34, 20% or 0.20)
fU = the fraction of women with a University education (26% or 0.26)
fB = the fraction of age appropriate women, living in London with an University education that he finds physically attractive (estimated at 1/20, 5% or 0.05)
L = the length of time available to have encountered a girlfriend (31 years).

Solve for N. Carry the one. He’s left with N ≈ 10,000. Or in other words, in the entire UK the pool of women the equation predicts for him is limited to 10,000 individuals. But then he adds that he’s only considered it from his perspective, what about hers? By adding the chances of her finding him attractive, being single and getting along with him reduced 10,000 to approximately 26 women. That’s a low number. At least I don’t need to worry, I’m spoken for!


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Filed under James' Corner

5 responses to “The Wednesday Post (10/2/10)

  1. Uwe

    Sorry James not really in anyway related to disease or really biology so you might was well have used the old Boyles Law question which I believe is an urban myth but goes like this:

    The following is supposedly an actual question given on a University of
    Washington chemistry mid-term. The answer by one student was so “profound”
    that the professor shared it with colleagues, via the Internet, which is, of
    course, why we now have the pleasure of enjoying it as well.
    Bonus Question: Is Hell exothermic (gives off heat) or endothermic(absorbs

    Most of the students wrote proofs of their beliefs using Boyle’s Law (gas
    cools when it expands and heats when it is compressed) or some variant. One
    student, however, wrote the following:

    First, we need to know how the mass of Hell is changing in time. So we need
    to know the rate at which souls are moving into Hell and the rate at which
    they are leaving. I think that we can safely assume that once a soul gets to
    Hell, it will not leave. Therefore, no souls are leaving.As for how many
    souls are entering Hell, let’s look at the different Religions that exist in
    the world today. Most of these religions state that if you are not a member
    of their religion, you will go to Hell. Since there is more than one of
    these religions and since people do not belong to more than one religion, we
    can project that all souls go to Hell. With birth and death rates as they
    are, we can expect the number of souls in Hell to increase exponentially.
    Now, we look at the rate of change of the volume in Hell because Boyle’s Law
    states that in order for the temperature and pressure in Hell to stay the
    same, the volume of Hell has to expand proportionately as souls are added.

    This gives two possibilities:

    1. If Hell is expanding at a slower rate than the rate at which souls enter
    Hell, then the temperature and pressure in Hell will increase until all Hell
    breaks loose.

    2. If Hell is expanding at a rate faster than the increase of souls in Hell,
    then the temperature and pressure will drop until Hell freezes over.

    So which is it? If we accept the postulate given to me by Teresa during my
    Freshman year that, “it will be a cold day in Hell before I sleep with you,
    and take into account the fact that I slept with her last night, then number
    2 must be true, and thus I am sure that Hell is exothermic and has already
    frozen over.

    The corollary of this theory is that since Hell has frozen over, it follows
    that it is not accepting any more souls and is therefore, extinct…leaving
    only Heaven thereby proving the existence of a divine being which explains
    why, last night, Teresa kept shouting “Oh my God.”

    • Hi Uwe,
      “not really in anyway related to disease or really biology”
      can i refer you here
      Its our first post that essentially says welcome to DoTW a blog not always about diseases and not always weekly. So there.

      As for the Boyles Law thing, I love that. I saw it a few years ago and thought it was one of the most brilliant de-railments of a scientific proof I have ever seen. Although the womands name tends to change with every telling.

  2. Love it. 26 women is all he can get? That’s ridiculously low! Must be a problem with the equation, surely this means there be more intelligent life out there ‘mongst the stars than merely 10.

    • The numbers are awesome. Personally I love that he calculates the numbers initially to equal 10 thousand women and then has to revise down based on the assumptions that he might not fit the criteria of all the women that fit his, leaving him with 26. Poor guy.

  3. Pingback: The Wednesday Post (7/4/10) « Disease of the Week!

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