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Danas bih vam htjela reći poneto
o matematici ljubavi.
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Now, I think that we can all agree
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that mathematicians
are famously excellent at finding love.
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But it's not just
because of our dashing personalities,
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superior conversational skills
and excellent pencil cases.
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It's also because we've actually done
an awful lot of work into the maths
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of how to find the perfect partner.
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Now, in my favorite paper
on the subject, which is entitled,
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"Why I Don't Have a Girlfriend" --
(Laughter) --
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Peter Backus tries to rate
his chances of finding love.
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Now, Peter's not a very greedy man.
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Of all of the available women in the U.K.,
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all Peter's looking for
is somebody who lives near him,
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somebody in the right age range,
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somebody with a university degree,
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somebody he's likely to get on well with,
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somebody who's likely to be attractive,
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somebody who's likely
to find him attractive.
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(Laughter)
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And comes up with an estimate
of 26 women in the whole of the UK.
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It's not looking very good,
is it Peter?
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Now, just to put that into perspective,
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that's about 400 times fewer
than the best estimates
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of how many intelligent
extraterrestrial life forms there are.
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And it also gives Peter
a 1 in 285,000 chance
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of bumping into any one
of these special ladies
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on a given night out.
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I'd like to think
that's why mathematicians
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don't really bother
going on nights out anymore.
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The thing is that I personally
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don't subscribe
to such a pessimistic view.
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Because I know,
just as well as all of you do,
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that love doesn't really work like that.
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Human emotion isn't neatly ordered
and rational and easily predictable.
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But I also know that that doesn't mean
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that mathematics hasn't got something
that it can offer us
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because, love, as with most of life,
is full of patterns
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and mathematics is, ultimately,
all about the study of patterns.
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Patterns from predicting the weather
to the fluctuations in the stock market,
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to the movement of the planets
or the growth of cities.
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And if we're being honest,
none of those things
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are exactly neatly ordered
and easily predictable, either.
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Because I believe that mathematics
is so powerful that it has the potential
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to offer us a new way of looking
at almost anything.
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Even something as mysterious as love.
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And so, to try to persuade you
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of how totally amazing, excellent
and relevant mathematics is,
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I want to give you my top three
mathematically verifiable tips for love.
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Okay, so Top Tip #1:
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How to win at online dating.
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So my favorite online dating
website is OkCupid,
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not least because it was started
by a group of mathematicians.
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Now, because they're mathematicians,
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they have been collecting data
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on everybody who uses their site
for almost a decade.
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And they've been trying
to search for patterns
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in the way that we talk about ourselves
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and the way that we
interact with each other
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on an online dating website.
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And they've come up with some
seriously interesting findings.
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But my particular favorite
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is that it turns out
that on an online dating website,
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how attractive you are
does not dictate how popular you are,
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and actually, having people
think that you're ugly
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can work to your advantage.
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Let me show you how this works.
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In a thankfully voluntary
section of OkCupid,
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you are allowed to rate
how attractive you think people are
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on a scale between 1 and 5.
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Now, if we compare this score,
the average score,
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to how many messages a
selection of people receive,
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you can begin to get a sense
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of how attractiveness links to popularity
on an online dating website.
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This is the graph that the OkCupid guys
have come up with.
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And the important thing to notice
is that it's not totally true
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that the more attractive you are,
the more messages you get.
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But the question arises then
of what is it about people up here
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who are so much more popular
than people down here,
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even though they have the
same score of attractiveness?
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And the reason why is that it's not just
straightforward looks that are important.
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So let me try to illustrate their
findings with an example.
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So if you take someone like
Portia de Rossi, for example,
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everybody agrees that Portia de Rossi
is a very beautiful woman.
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Nobody thinks that she's ugly,
but she's not a supermodel, either.
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If you compare Portia de Rossi
to someone like Sarah Jessica Parker,
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now, a lot of people,
myself included, I should say,
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think that Sarah Jessica Parker
is seriously fabulous
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and possibly one of the
most beautiful creatures
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to have ever have walked
on the face of the Earth.
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But some other people,
i.e., most of the Internet,
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seem to think that she looks
a bit like a horse. (Laughter)
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Now, I think that if you ask people
how attractive they thought
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Sarah Jessica Parker
or Portia de Rossi were,
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and you ask them to give
them a score between 1 and 5,
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I reckon that they'd average out
to have roughly the same score.
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But the way that people would vote
would be very different.
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So Portia's scores would
all be clustered around the 4
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because everybody agrees
that she's very beautiful,
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whereas Sarah Jessica Parker
completely divides opinion.
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There'd be a huge spread in her scores.
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And actually it's this spread that counts.
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It's this spread
that makes you more popular
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on an online Internet dating website.
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So what that means then
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is that if some people
think that you're attractive,
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you're actually better off
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having some other people
think that you're a massive minger.
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That's much better
than everybody just thinking
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that you're the cute girl next door.
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Now, I think this begins
makes a bit more sense
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when you think in terms of the people
who are sending these messages.
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So let's say that you think
somebody's attractive,
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but you suspect that other people
won't necessarily be that interested.
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That means there's
less competition for you
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and it's an extra incentive
for you to get in touch.
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Whereas compare that
to if you think somebody is attractive
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but you suspect that everybody
is going to think they're attractive.
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Well, why would you bother
humiliating yourself, let's be honest?
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Here's where the really
interesting part comes.
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Because when people choose the pictures
that they use on an online dating website,
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they often try to minimize the things
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that they think some people
will find unattractive.
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The classic example is people
who are, perhaps, a little bit overweight
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deliberately choosing
a very cropped photo,
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or bald men, for example,
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deliberately choosing pictures
where they're wearing hats.
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But actually this is the opposite
of what you should do
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if you want to be successful.
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You should really, instead, play up to
whatever it is that makes you different,
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even if you think that some people
will find it unattractive.
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Because the people who fancy you
are just going to fancy you anyway,
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and the unimportant losers who don't,
well, they only play up to your advantage.
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Okay, Top Tip #2:
How to pick the perfect partner.
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So let's imagine then
that you're a roaring success
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on the dating scene.
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But the question arises
of how do you then convert that success
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into longer-term happiness
and in particular,
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how do you decide
when is the right time to settle down?
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Now generally,
it's not advisable to just cash in
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and marry the first person
who comes along
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and shows you any interest at all.
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But, equally, you don't really
want to leave it too long
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if you want to maximize your
chance of long-term happiness.
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As my favorite author,
Jane Austen, puts it,
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"An unmarried woman of seven and twenty
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can never hope to feel or
inspire affection again."
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(Laughter)
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Thanks a lot, Jane.
What do you know about love?
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So the question is then,
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how do you know when
is the right time to settle down
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given all the people
that you can date in your lifetime?
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Thankfully, there's a rather delicious bit
of mathematics that we can use
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to help us out here, called
optimal stopping theory.
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So let's imagine then,
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that you start dating when you're 15
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and ideally, you'd like to be married
by the time that you're 35.
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And there's a number of people
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that you could potentially
date across your lifetime,
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and they'll be at varying
levels of goodness.
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Now the rules are that once
you cash in and get married,
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you can't look ahead to see
what you could have had,
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and equally, you can't go back
and change your mind.
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In my experience at least,
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I find that typically people don't
much like being recalled
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years after being passed up
for somebody else, or that's just me.
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So the math says then
that what you should do
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in the first 37 percent
of your dating window,
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you should just reject everybody
as serious marriage potential.
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(Laughter)
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And then, you should pick the
next person that comes along
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that is better than everybody
that you've seen before.
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So here's the example.
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Now if you do this, it can be
mathematically proven, in fact,
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that this is the best possible way
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of maximizing your chances
of finding the perfect partner.
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Now unfortunately, I have to tell you that
this method does come with some risks.
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For instance, imagine if
your perfect partner appeared
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during your first 37 percent.
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Now, unfortunately,
you'd have to reject them.
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(Laughter)
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Now, if you're following the maths,
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I'm afraid no one else comes along
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that's better than anyone
you've seen before,
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so you have to go on
rejecting everyone and die alone.
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(Laughter)
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Probably surrounded by cats
nibbling at your remains.
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Okay, another risk is,
let's imagine, instead,
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that the first people that you dated
in your first 37 percent
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are just incredibly dull,
boring, terrible people.
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Now, that's okay, because
you're in your rejection phase,
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so thats fine,
you can reject them.
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But then imagine, the next
person to come along
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is just marginally less boring,
dull and terrible
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than everybody that you've seen before.
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Now, if you are following the maths,
I'm afraid you have to marry them
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and end up in a relationship
which is, frankly, suboptimal.
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Sorry about that.
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But I do think that there's
an opportunity here
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for Hallmark to cash in on
and really cater for this market.
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A Valentine's Day card like this.
(Laughter)
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"My darling husband, you
are marginally less terrible
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than the first 37 percent
of people I dated."
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It's actually more romantic
than I normally manage.
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Okay, so this method doesn't give
you a 100 percent success rate,
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but there's no other possible
strategy that can do any better.
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And actually, in the wild,
there are certain types
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of fish which follow and
employ this exact strategy.
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So they reject every possible
suitor that turns up
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in the first 37 percent
of the mating season,
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00:10:53,413 --> 00:10:56,944
and then they pick the next fish
that comes along after that window
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that's, I don't know, bigger and burlier
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than all of the fish
that they've seen before.
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I also think that subconsciously,
humans, we do sort of do this anyway.
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We give ourselves a little bit of time
to play the field,
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get a feel for the marketplace
or whatever when we're young.
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00:11:13,115 --> 00:11:18,023
And then we only start looking seriously
at potential marriage candidates
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once we hit our mid-to-late 20s.
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I think this is conclusive proof,
if ever it were needed,
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00:11:22,716 --> 00:11:27,222
that everybody's brains are prewired
to be just a little bit mathematical.
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Okay, so that was Top Tip #2.
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Now, Top Tip #3: How to avoid divorce.
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00:11:32,730 --> 00:11:35,868
Okay, so let's imagine then
that you picked your perfect partner
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and you're settling into
a lifelong relationship with them.
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Now, I like to think that everybody
would ideally like to avoid divorce,
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apart from, I don't know,
Piers Morgan's wife, maybe?
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But it's a sad fact of modern life
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that 1 in 2 marriages in the
States ends in divorce,
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00:11:56,284 --> 00:11:59,585
with the rest of the world
not being far behind.
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00:11:59,585 --> 00:12:01,684
Now, you can be forgiven, perhaps
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for thinking that the arguments
that precede a marital breakup
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are not an ideal candidate
for mathematical investigation.
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For one thing, it's very hard to know
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what you should be measuring
or what you should be quantifying.
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00:12:13,834 --> 00:12:20,407
But this didn't stop a psychologist,
John Gottman, who did exactly that.
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Gottman observed hundreds of couples
having a conversation
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00:12:25,602 --> 00:12:28,064
and recorded, well,
everything you can think of.
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00:12:28,064 --> 00:12:30,551
So he recorded what was said
in the conversation,
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00:12:30,551 --> 00:12:32,614
he recorded their skin conductivity,
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00:12:32,614 --> 00:12:34,534
he recorded their facial expressions,
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00:12:34,534 --> 00:12:36,874
their heart rates, their blood pressure,
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00:12:36,874 --> 00:12:43,324
basically everything apart from whether
or not the wife was actually always right,
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00:12:43,324 --> 00:12:46,348
which incidentally she totally is.
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00:12:46,348 --> 00:12:49,268
But what Gottman and his team found
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00:12:49,268 --> 00:12:51,772
was that one of the
most important predictors
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00:12:51,772 --> 00:12:53,922
for whether or not a couple
is going to get divorced
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00:12:53,922 --> 00:12:59,022
was how positive or negative each
partner was being in the conversation.
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00:12:59,022 --> 00:13:01,634
Now, couples that were very low-risk
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00:13:01,634 --> 00:13:05,861
scored a lot more positive points
on Gottman's scale than negative.
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00:13:05,861 --> 00:13:08,001
Whereas bad relationships,
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00:13:08,001 --> 00:13:10,793
by which I mean, probably
going to get divorced,
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00:13:10,793 --> 00:13:15,405
they found themselves getting
into a spiral of negativity.
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00:13:15,405 --> 00:13:17,758
Now just by using these very simple ideas,
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00:13:17,758 --> 00:13:20,260
Gottman and his group were able to predict
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00:13:20,260 --> 00:13:23,103
whether a given couple
was going to get divorced
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00:13:23,103 --> 00:13:25,758
with a 90 percent accuracy.
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00:13:25,758 --> 00:13:29,152
But it wasn't until he teamed up
with a mathematician, James Murray,
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00:13:29,152 --> 00:13:31,291
that they really started to understand
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00:13:31,291 --> 00:13:35,601
what causes these negativity spirals
and how they occur.
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00:13:35,601 --> 00:13:37,308
And the results that they found
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I think are just incredibly
impressively simple and interesting.
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00:13:41,667 --> 00:13:46,005
So these equations, they predict how
the wife or husband is going to respond
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00:13:46,005 --> 00:13:47,971
in their next turn of the conversation,
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00:13:47,971 --> 00:13:50,099
how positive or negative
they're going to be.
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00:13:50,099 --> 00:13:51,896
And these equations, they depend on
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00:13:51,896 --> 00:13:54,242
the mood of the person
when they're on their own,
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00:13:54,242 --> 00:13:56,856
the mood of the person when
they're with their partner,
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00:13:56,856 --> 00:13:58,845
but most importantly, they depend on
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00:13:58,845 --> 00:14:01,824
how much the husband and wife
influence one another.
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00:14:01,824 --> 00:14:04,532
Now, I think it's important
to point out at this stage,
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00:14:04,532 --> 00:14:07,852
that these exact equations
have also been shown
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00:14:07,852 --> 00:14:10,498
to be perfectly able at describing
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00:14:10,498 --> 00:14:14,256
what happens between two
countries in an arms race.
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(Laughter)
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00:14:18,194 --> 00:14:21,905
So that -- an arguing couple
spiraling into negativity
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00:14:21,905 --> 00:14:23,819
and teetering on the brink of divorce --
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00:14:23,819 --> 00:14:28,107
is actually mathematically equivalent to
the beginning of a nuclear war.
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00:14:28,107 --> 00:14:30,606
(Laughter)
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00:14:30,606 --> 00:14:33,159
But the really important term
in this equation
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00:14:33,159 --> 00:14:35,877
is the influence that people
have on one another,
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00:14:35,877 --> 00:14:38,900
and in particular, something called
the negativity threshhold.
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00:14:38,900 --> 00:14:40,579
Now, the negativity threshold,
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00:14:40,579 --> 00:14:45,072
you can think of as
how annoying the husband can be
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00:14:45,072 --> 00:14:49,254
before the wife starts to get
really pissed off, and vice versa.
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00:14:49,254 --> 00:14:54,408
Now, I always thought that good marriages
were about compromise and understanding
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00:14:54,408 --> 00:14:57,261
and allowing the person to
have the space to be themselves.
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00:14:57,261 --> 00:15:00,558
So I would have thought that perhaps
the most successful relationships
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00:15:00,558 --> 00:15:04,024
were ones where there was
a really high negativity threshold.
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00:15:04,024 --> 00:15:05,692
Where couples let things go
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00:15:05,692 --> 00:15:08,487
and only brought things up if
they really were a big deal.
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00:15:08,487 --> 00:15:12,023
But actually, the mathematics
and subsequent findings by the team
-
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00:15:12,023 --> 00:15:15,318
have shown the exact opposite is true.
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00:15:15,318 --> 00:15:17,707
The best couples,
or the most successful couples,
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00:15:17,707 --> 00:15:21,519
are the ones with a really low
negativity threshold.
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00:15:21,519 --> 00:15:25,378
These are the couples that don't
let anything go unnoticed
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00:15:25,378 --> 00:15:28,399
and allow each other
some room to complain.
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00:15:28,399 --> 00:15:33,733
These are the couples that are continually
trying to repair their own relationship,
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00:15:33,733 --> 00:15:36,418
that have a much more positive
outlook on their marriage.
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00:15:36,418 --> 00:15:38,516
Couples that don't let things go
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00:15:38,516 --> 00:15:44,426
and couples that don't let trivial things
end up being a really big deal.
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00:15:44,426 --> 00:15:50,023
Now of course, it takes bit more than
just a low negativity threshold
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00:15:50,023 --> 00:15:54,162
and not compromising to
have a successful relationship.
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But I think that it's quite interesting
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to know that there is really
mathematical evidence
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00:15:59,053 --> 00:16:02,480
to say that you should never
let the sun go down on your anger.
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00:16:02,480 --> 00:16:04,188
So those are my top three tips
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00:16:04,188 --> 00:16:07,383
of how maths can help you
with love and relationships.
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00:16:07,383 --> 00:16:09,826
But I hope
that aside from their use as tips,
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00:16:09,826 --> 00:16:13,928
they also give you a little bit of insight
into the power of mathematics.
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00:16:13,928 --> 00:16:18,293
Because for me, equations
and symbols aren't just a thing.
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00:16:18,293 --> 00:16:23,119
They're a voice that speaks out
about the incredible richness of nature
-
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00:16:23,119 --> 00:16:24,929
and the startling simplicity
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00:16:24,929 --> 00:16:29,384
in the patterns that twist and turn
and warp and evolve all around us,
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00:16:29,384 --> 00:16:32,187
from how the world works to how we behave.
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00:16:32,187 --> 00:16:34,485
So I hope that perhaps,
for just a couple of you,
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00:16:34,485 --> 00:16:36,926
a little bit of insight into
the mathematics of love
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00:16:36,926 --> 00:16:40,134
can persuade you to have
a little bit more love for mathematics.
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00:16:40,134 --> 00:16:41,521
Thank you.
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00:16:41,521 --> 00:16:43,815
(Applause)
closed TED
