Subtitles section Play video
-
I think we can all agree that mathematicians are well known for being extremely popular
-
with the opposite sex. But it's not just because of our dashing personalities and superior
-
pencil cases. Oh no. It's also because we've have done an awful lot of work in the mathematics
-
of, how to find the perfect partner. In my favourite paper on the subject, entitled
-
"Why I don't have a girlfriend", Peter Backus tries to work out his chances of finding love.
-
In particular, he is looking for single women who live near him in the UK, are of the right
-
age range, have an university degree, are likely to be attractive, and he is likely
-
to get in well with. And the total he comes up with is 26 in the whole of the UK.
-
Now to just put that in perspective that's 400 times fewer than the best estimates of
-
how many intelligent extra-terrestrial life forms there are. And it gives him a 1 in 285,000
-
chance of meeting one of these 26 ladies on a given night out. It's not looking very good
-
is it Peter? Now I don't prescribe to this frankly pessimistic
-
view. I think there is a lot of people you can have a successful relationship with if
-
you want to. But given all the people you'll date throughout your life time, how do you
-
know when is the right time to settle down? Of course it isn't wise to cash in the first
-
person who shows you any interest, but equally if you want to be truly happy you can't leave
-
it too long. As my good friend Jane Austin says "An unmarried woman of seven and twenty
-
can never hope to feel or inspire affection again." Yeah, thanks a lot Jane, what do you
-
know about love? But the thing about dating is that once you've
-
made up your mind, you can't go back and change it. Typically people aren't that happy being
-
recalled later after being passed up for somebody else. So many people should you date before
-
you decide to settle down? Now, if only there were some kind of a mathematical
-
formula for a dating strategy that we could use to help us. Oh wait, there totally is!
-
And its called optimal stopping theory. So, let's say you start dating at about 15
-
years old and ideally you'd like to settle down at 35. And the rules are you can't see
-
ahead of what you could've had once you settle down and you can't go back and change your
-
mind. So the theory says that in the first 37% (or 1 over e) of your dating time, you
-
should reject everybody as serious marriage material. And after that period has passed
-
you should pick the next person that comes along that is better than everybody else you've
-
seen before. And if you do that it can be mathematically proven that you're maximising
-
your chances of picking the perfect partner. So this method has been observed in the wild.
-
So certain types of fish will reject any suitor who comes along within the first 37% of the
-
mating season and then pick the next male fish that comes along that's bigger and burlier
-
than all of the rest. But you could also use this strategy when
-
you're looking to buy or rent a house. Say you got three months in which to look for
-
a house. You should spend the first month (30% of the time window) just getting a feel
-
for the market, going to see houses but never cashing in on any of them. And after that
-
period has passed you then pick the first house that comes along that is better than
-
everything else you've seen before. Now this method does come with risks, it doesn't
-
guarantee that you'll get the perfect partner, it just gives you your best chance of finding
-
them. You could, for instance, be really unlucky and have your perfect match appear within
-
that first 37% window when you're rejecting everybody. And if that's the case, unfortunately
-
the maths says that you'll grow old alone probably be surrounded by cats.
-
Or let's say you got really unlucky and the first 37% of the people you dated were just
-
incredibly dull and boring and terrible people. And that's ok because you're still rejecting
-
all of those people. But let's say the next person that comes along is still really dull
-
and boring but marginally less terrible everybody you'd seen before. If you're following the
-
maths and marry that person you'd just be in a relationship that was suboptimal. Sorry
-
about that. But if everybody followed this strategy then
-
one in three people who do, they can settle down in the knowledge that maths says they'd
-
done the very best they can.