WEBVTT

00:00:00.693 --> 00:00:05.371
Today I want to talk to you
about the mathematics of love.

00:00:05.371 --> 00:00:07.621
I think we can all agree 
that mathematicians

00:00:07.621 --> 00:00:11.597
are famously excellent 
at finding love.

00:00:11.597 --> 00:00:15.045
But it's not just because
of our dashing personalities

00:00:15.045 --> 00:00:19.544
our superior conversational skills,
our our excellent pencil cases,

00:00:19.544 --> 00:00:24.093
It's also because we've done
a lot of work into the maths

00:00:24.093 --> 00:00:26.582
of how to find the perfect partner.

00:00:26.582 --> 00:00:29.875
In my favorite paper on the subject,
which is entitled,

00:00:29.875 --> 00:00:35.121
"Why I Don't Have a Girlfriend", 
Peter Backus tries to rate

00:00:35.121 --> 00:00:37.091
his chances at finding love.

00:00:37.091 --> 00:00:39.457
Now, peter is not a 
very greedy man.

00:00:39.457 --> 00:00:41.542
Of all of the available 
women in the UK,

00:00:41.542 --> 00:00:45.245
all that Peter's looking for is 
somebody who lives near him,

00:00:45.245 --> 00:00:47.076
somebody in the 
right age range,

00:00:47.076 --> 00:00:49.996
somebody with a
university degree,

00:00:49.996 --> 00:00:51.824
somebody he's likely 
to get on well with,

00:00:51.824 --> 00:00:53.900
somebody attractive,

00:00:53.900 --> 00:00:57.168
somebody who is likely 
to find him attractive

00:00:57.168 --> 00:00:59.441
(Laughter),

00:00:59.441 --> 00:01:02.947
and comes up with an 
estimate of 26 women

00:01:02.947 --> 00:01:05.441
in the whole of the UK.

00:01:05.441 --> 00:01:07.962
It's not looking very good, 
is it Peter?

00:01:07.962 --> 00:01:09.469
Now just to put that
into perspective,

00:01:09.469 --> 00:01:12.574
that's about 400 times fewer
than the best estimates

00:01:12.574 --> 00:01:17.089
of how many intelligent
extra-terrestrial life forms there are.

00:01:17.089 --> 00:01:21.676
And it also gives Peter a 
1 in 285,000 chance

00:01:21.676 --> 00:01:23.902
of bumping into any one
of these special ladies

00:01:23.902 --> 00:01:25.838
on a night out.

00:01:25.838 --> 00:01:28.031
I'd like to think that's why
mathematicians don't really bother

00:01:28.031 --> 00:01:30.915
going on nights out anymore.

00:01:30.915 --> 00:01:32.491
The thing is is that I personally

00:01:32.491 --> 00:01:35.254
don't subscribe to 
such a pessimistic view.

00:01:35.254 --> 00:01:37.812
I know, just as well 
as you do,

00:01:37.812 --> 00:01:40.194
that love doesn't 
really work like that

00:01:40.194 --> 00:01:42.764
human emotion
isn't neatly ordered,

00:01:42.764 --> 00:01:45.573
rational, or easily predictable.

00:01:45.573 --> 00:01:48.571
But I also know that that doesn't
mean that mathematics

00:01:48.571 --> 00:01:51.015
doesn't have something 
it can offer us

00:01:51.015 --> 00:01:53.206
because, love, as 
with most of life,

00:01:53.206 --> 00:01:54.961
is full of patterns

00:01:54.961 --> 00:01:59.302
and mathematics is, ultimately,
all about the study of patterns.

00:01:59.302 --> 00:02:01.635
patterns from predicting
the weather,

00:02:01.635 --> 00:02:03.620
to the fluctuations of 
the stock market,

00:02:03.620 --> 00:02:05.160
to the movement 
of the planets,

00:02:05.160 --> 00:02:06.741
or the growth of cities.

00:02:06.741 --> 00:02:10.142
If we're being honest, none 
of those things are neatly ordered

00:02:10.142 --> 00:02:13.094
Or easily predictable, either.

00:02:13.094 --> 00:02:15.000
Because I believe
that mathematics

00:02:15.000 --> 00:02:18.287
is so powerful that
is has the potential

00:02:18.287 --> 00:02:21.631
to offer us a new way of looking
at almost anything.

00:02:21.631 --> 00:02:25.187
Even something as 
mysterious as love.

00:02:25.187 --> 00:02:26.675
And so, to try 
to persuade you

00:02:26.675 --> 00:02:31.236
of how totally, excellent
and relevant mathematics is,

00:02:31.236 --> 00:02:40.720
I want to give you my top three
mathematically verifiable tips for love.

00:02:40.720 --> 00:02:41.939
Okay, so top tip #1:

00:02:41.939 --> 00:02:45.643
How to win at online dating.

00:02:45.643 --> 00:02:49.079
So my favorite 
online dating website

00:02:49.079 --> 00:02:50.154
is OkayCupid,

00:02:50.154 --> 00:02:51.314
not least because it was

00:02:51.314 --> 00:02:53.764
started by a group 
of mathematicians.

00:02:53.764 --> 00:02:55.343
Now because they're 
mathematicians,

00:02:55.343 --> 00:02:57.663
they have been collecting
data on everyone

00:02:57.663 --> 00:03:00.426
whose been using their site
for almost a decade.

00:03:00.426 --> 00:03:01.780
And they've been
trying to search

00:03:01.780 --> 00:03:04.057
for patterns in the way that
we talk about ourselves


00:03:04.057 --> 00:03:05.964
and the way that we 
interact with each other

00:03:05.964 --> 00:03:07.766
on online dating websites.

00:03:07.766 --> 00:03:10.985
And they've come up with
seriously interesting findings.

00:03:10.985 --> 00:03:13.727
But my particular favorite
is that it turns out

00:03:13.727 --> 00:03:16.007
that on an online 
dating website,

00:03:16.007 --> 00:03:17.912
how attractive you are

00:03:17.912 --> 00:03:21.679
does not dictate 
how popular you are

00:03:21.679 --> 00:03:25.391
and actually having people
think that you're ugly

00:03:25.391 --> 00:03:29.210
can work to your advantage.

00:03:29.210 --> 00:03:30.066
Let me show you
how this works.

00:03:30.066 --> 00:03:33.275
Okay, in a thankfully 
voluntary section,

00:03:33.275 --> 00:03:37.645
you are allowed to rate 
how attractive people are

00:03:37.645 --> 00:03:40.022
between 1 and 5.

00:03:40.022 --> 00:03:43.362
And if we compare this score, 
this average score

00:03:43.362 --> 00:03:46.216
to how many messages a
selection of people receive,

00:03:46.216 --> 00:03:49.526
You can begin to get a sense
of how attractiveness

00:03:49.526 --> 00:03:51.854
links to popularity 
on online dating.

00:03:51.854 --> 00:03:53.656
So this is a graph 
that the online

00:03:53.656 --> 00:03:55.687
OkayCupid guys 
have come up with

00:03:55.874 --> 00:03:57.270
and the important 
thing to notice

00:03:57.270 --> 00:03:59.528
is that it's not totally true
that the more attractive you are,

00:03:59.528 --> 00:04:01.080
the more messages you get.

00:04:01.080 --> 00:04:02.522
But the question arises then

00:04:02.522 --> 00:04:07.926
of what is it about people up here
who are so much more popular

00:04:07.926 --> 00:04:09.549
than people down here

00:04:09.549 --> 00:04:12.690
even though they have the
same score of attractiveness?

00:04:12.690 --> 00:04:15.679
And the reason why is that it's
not just straight-forward looks

00:04:15.679 --> 00:04:16.726
that are important.

00:04:16.726 --> 00:04:18.367
So let me try to illustrate 
their findings

00:04:18.367 --> 00:04:19.396
with an example.

00:04:19.396 --> 00:04:23.367
If you take someone 
like Portia de Rossi,

00:04:23.367 --> 00:04:25.599
everybody agrees 
that Portia de Rossi

00:04:25.599 --> 00:04:28.358
is a very beautiful woman.

00:04:28.358 --> 00:04:29.894
Nobody thinks 
that she's ugly,

00:04:29.894 --> 00:04:31.980
but she's not a supermodel.

00:04:31.980 --> 00:04:33.471
If you compare 
Portia de Rossi

00:04:33.471 --> 00:04:36.749
to someone like 
Sarah Jessica Parker,

00:04:36.749 --> 00:04:40.003
now, a lot of people,
myself included,

00:04:40.003 --> 00:04:45.200
think that Sarah Jessica Parker
is seriously fabulous

00:04:45.200 --> 00:04:47.670
and possibly one of the
most beautiful creatures

00:04:47.670 --> 00:04:49.639
to have ever have walked 
the face of the earth.

00:04:49.639 --> 00:04:56.520
But, some other people, 
e.i. most of the internet,

00:04:56.520 --> 00:04:58.528
seem to think that she 
looks a bit like a horse

00:04:58.528 --> 00:05:01.825
(Laughter).

00:05:01.825 --> 00:05:05.038
Now, I think that if
you ask people

00:05:05.038 --> 00:05:07.260
how attractive Sarah Jessica Parker 
or Portia de Rossi are,

00:05:07.260 --> 00:05:10.213
and you ask them to give 
them a score between 1 and 5,

00:05:10.213 --> 00:05:13.374
I reckon that they would 
average out to the same score.

00:05:13.374 --> 00:05:14.849
But the way that people would vote

00:05:14.849 --> 00:05:15.987
would be very different.

00:05:15.987 --> 00:05:17.702
So Portia's scores would
all be clustered around

00:05:17.702 --> 00:05:20.842
the four because everybody 
agrees that she's very beautiful.

00:05:20.842 --> 00:05:23.643
whereas Sarah Jessica Parker
divides opinion.

00:05:23.643 --> 00:05:26.317
There a huge spread
in her scores.

00:05:26.317 --> 00:05:28.389
And actually it's this
spread that counts.

00:05:28.389 --> 00:05:30.865
It's this spread that
makes you more popular

00:05:30.865 --> 00:05:33.255
on online internet
dating websites.

00:05:33.255 --> 00:05:34.226
So what this means then

00:05:34.226 --> 00:05:37.095
is that if some people think 
that you're attractive,

00:05:37.095 --> 00:05:40.473
you're actually better off
having some other people

00:05:40.473 --> 00:05:44.185
think that you're a massive minger.

00:05:44.185 --> 00:05:46.213
That's much better than
everybody thinking

00:05:46.213 --> 00:05:48.494
that you're the cute
girl next door.

00:05:48.494 --> 00:05:50.013
i think that this 
makes a bit more sense

00:05:50.013 --> 00:05:51.607
when you think in terms
of the people

00:05:51.607 --> 00:05:53.368
who are sending 
these messages.

00:05:53.368 --> 00:05:55.738
So let's say that you think
somebody's attractive

00:05:55.738 --> 00:05:57.971
but you suspect that 
other people

00:05:57.971 --> 00:06:00.032
won't necessarily be 
that interested.

00:06:00.032 --> 00:06:02.823
That means that there is 
less competition for you

00:06:02.823 --> 00:06:04.239
and that there's 
an extra incentive

00:06:04.239 --> 00:06:05.532
for you to get in touch.

00:06:05.532 --> 00:06:07.007
Whereas compare
that to if you think

00:06:07.007 --> 00:06:08.353
somebody is attractive 
but you suspect

00:06:08.353 --> 00:06:10.660
that everybody is going 
to think they're attractive.

00:06:10.660 --> 00:06:13.779
Well, why would you 
bother humiliating yourself?

00:06:13.779 --> 00:06:16.884
Here's where the really
interesting part comes.

00:06:16.884 --> 00:06:21.740
People choose the pictures that
they use on an online, dating website,

00:06:21.740 --> 00:06:23.670
they often try to
minimize the things

00:06:23.670 --> 00:06:27.160
that they think people 
will find unattractive.

00:06:27.160 --> 00:06:31.457
The classic example is that people
who are a little bit overweight

00:06:31.457 --> 00:06:35.391
deliberately choosing 
a very cropped photo.

00:06:35.391 --> 00:06:36.678
or bald men, for example,

00:06:36.678 --> 00:06:39.937
deliberatly choosing pictures
where they're wearing hats.

00:06:39.937 --> 00:06:42.792
But this is the opposite of 
what you should do

00:06:42.792 --> 00:06:43.536
if you want to be successful.

00:06:43.536 --> 00:06:46.817
You should really, instead, play
up to whatever it is

00:06:46.817 --> 00:06:48.356
that makes you different.

00:06:48.356 --> 00:06:50.230
Even if you think that 
some people

00:06:50.230 --> 00:06:52.707
will find you unattractive.

00:06:52.707 --> 00:06:53.836
Because the people 
who fancy you

00:06:53.836 --> 00:06:55.584
are just going to 
fancy you anyway,

00:06:55.584 --> 00:06:57.715
and the unimportant
losers who don't

00:06:57.715 --> 00:07:00.497
well, they only play out 
to your advantage.

00:07:00.497 --> 00:07:02.897
Okay, top tip #2: How to pick
the perfect partner.

00:07:02.897 --> 00:07:05.914
So let's imagine then that
you're a roaring success

00:07:05.914 --> 00:07:07.372
on the dating scene.

00:07:07.372 --> 00:07:11.395
But the question arises of
how do you then convert

00:07:11.395 --> 00:07:14.509
that success into 
longer-term happiness

00:07:14.509 --> 00:07:15.186
and in particular,

00:07:15.186 --> 00:07:19.437
how do you decide when is the
right time to settle down?

00:07:19.437 --> 00:07:22.459
Now generally, it's not 
advisable to just cash in

00:07:22.459 --> 00:07:26.772
on the first person who comes along
and shows you any interest at all.

00:07:26.772 --> 00:07:29.969
But, equally, you don't want
to leave it too long

00:07:29.969 --> 00:07:32.661
if you want to maximize your 
chances of longterm happiness.

00:07:32.661 --> 00:07:35.843
As my favorite author, 
Jane Austen put it,

00:07:35.843 --> 00:07:38.061
"An unmarried woman 
of seven and twenty

00:07:38.061 --> 00:07:42.006
can never hope to feel or
inspire affection again."

00:07:42.006 --> 00:07:44.388
(Laughter).

00:07:44.388 --> 00:07:45.694
Thanks, Jane.

00:07:45.694 --> 00:07:49.711
So the question is then,

00:07:49.711 --> 00:07:51.423
how do you know when 
is the right time 


00:07:51.423 --> 00:07:53.356
to settle down given 
all the people

00:07:53.356 --> 00:07:54.265
you can date in 
your lifetime?

00:07:54.265 --> 00:07:56.940
Thankfully, there is a 
rather delicious bit

00:07:56.940 --> 00:07:58.486
of mathematics that
we can use to

00:07:58.486 --> 00:08:00.404
help us out here.

00:08:00.404 --> 00:08:02.284
So lets imagine then,

00:08:02.284 --> 00:08:06.094
that you start 
dating when you're 15

00:08:06.094 --> 00:08:09.723
and ideally, you'd like to be
married by the time you're 35.

00:08:09.723 --> 00:08:12.016
The number of people that you
could potentially date

00:08:12.016 --> 00:08:13.241
across your lifetime,

00:08:13.241 --> 00:08:14.508
and they'll be at kind of varying 
levels of goodness.

00:08:14.508 --> 00:08:17.469
Now the rules are 
that when you cash in

00:08:17.469 --> 00:08:18.271
and get married,

00:08:18.271 --> 00:08:20.832
you can't look ahead and see
what you could have had,

00:08:20.832 --> 00:08:23.812
and equally, you can't go back
and change your mind.

00:08:23.812 --> 00:08:25.352
In my experience at least,

00:08:25.352 --> 00:08:29.674
i find that people don't typically
like being recalled

00:08:29.674 --> 00:08:30.956
years after being 
passed up.

00:08:30.956 --> 00:08:33.360
For somebody else, 
or that's just me.

00:08:33.360 --> 00:08:36.527
So the math says then
that what you should do

00:08:36.527 --> 00:08:39.758
in the first 37 percent 
of your dating window,

00:08:39.758 --> 00:08:45.488
you should reject everybody 
as serious marriage potential.

00:08:45.488 --> 00:08:49.319
And then, you should pick the 
next person who comes along

00:08:49.319 --> 00:08:53.414
who is better than everyone 
that you've seen before.

00:08:53.414 --> 00:08:53.966
So here's the example.

00:08:53.966 --> 00:08:56.078
Now if you do this, it can be
mathematically proven in fact

00:08:56.078 --> 00:08:59.155
that this is the best
possible way of

00:08:59.155 --> 00:09:03.877
maximizing your chances of
finding the perfect partner.

00:09:03.877 --> 00:09:06.059
Now, unfortunately i have to tell 
you that this method

00:09:06.059 --> 00:09:08.682
does come with some risks.

00:09:08.682 --> 00:09:12.632
For instance, imagine if your 
perfect partner

00:09:12.632 --> 00:09:16.226
appeared during your 
first 37 percent.

00:09:16.226 --> 00:09:22.359
Now unfortunately, 
you'd have to reject them.

00:09:22.359 --> 00:09:24.367
Now, if you're 
following the maths,

00:09:24.367 --> 00:09:26.083
I'm afraid that if no one
else comes along

00:09:26.083 --> 00:09:27.640
better than anyone
you've seen before

00:09:27.640 --> 00:09:30.763
so you have to go 
on rejecting everyone

00:09:30.763 --> 00:09:32.143
and die alone.

00:09:32.143 --> 00:09:34.736
(Laughter).

00:09:34.736 --> 00:09:39.617
Probably surrounded by cats
nibbling at your remains.

00:09:39.617 --> 00:09:41.992
Okay, another risk is, 
let's imagine instead

00:09:41.992 --> 00:09:45.117
that the first people
that you dated

00:09:45.117 --> 00:09:51.036
in your first 37 percent are just 
incredibly dull, terrible people.

00:09:51.036 --> 00:09:52.812
Now, that's okay, cause you're in 
your rejection phase,

00:09:52.812 --> 00:09:54.733
so you can reject them.

00:09:54.733 --> 00:09:58.541
But, then imagine that the
next person who comes along

00:09:58.541 --> 00:10:02.879
is just marginally less boring, 
dull and terrible

00:10:02.879 --> 00:10:04.811
than everybody that 
you've seen before.

00:10:04.811 --> 00:10:06.280
Now, if you are following
the maths

00:10:06.280 --> 00:10:09.483
I'm afraid that you have 
to marry them

00:10:09.483 --> 00:10:12.776
and end up in a relationship
that is, frankly, suboptimal.

00:10:12.776 --> 00:10:13.969
Sorry about that.

00:10:13.969 --> 00:10:15.659
But I do think that there's
an opportunity here

00:10:15.659 --> 00:10:18.809
for hallmark to cash in on
and really cater to this market.

00:10:18.809 --> 00:10:20.799
with a valentines day 
card like this:

00:10:20.799 --> 00:10:24.924
"My darling husband, you
are marginally less terrible

00:10:24.924 --> 00:10:27.969
than the first 37 percent
of people I dated."

00:10:27.969 --> 00:10:33.456
It's actually more romantic
than I normally manage.

00:10:33.456 --> 00:10:38.138
Okay, so this method doesn't give
you a 100 percent success rate.

00:10:38.138 --> 00:10:41.441
but there's no other possible
strategy that can do any better.

00:10:41.441 --> 00:10:44.104
And actually, in the wild
there are certain

00:10:44.104 --> 00:10:47.907
types of fish that follow
this exact strategy.

00:10:47.907 --> 00:10:50.676
So they reject every possible 
suitor that turns up in

00:10:50.676 --> 00:10:53.413
in the first 37 percent 
of the mating season,

00:10:53.413 --> 00:10:55.054
then they 
pick the next fish

00:10:55.054 --> 00:10:58.242
who comes along after
that window who is,

00:10:58.242 --> 00:11:02.024
i don't know, bigger and burlier
than all the fish that they've seen.

00:11:02.024 --> 00:11:03.546
I also think that 
subconsciously,

00:11:03.546 --> 00:11:06.651
humans, we sort of 
do this anyway.

00:11:06.651 --> 00:11:10.445
We give ourselves enough
time to play the field,

00:11:10.445 --> 00:11:12.897
get a feel for the
marketplace or whatever,

00:11:12.897 --> 00:11:13.415
when we're young.

00:11:13.415 --> 00:11:15.363
and then we only start 
looking seriously

00:11:15.363 --> 00:11:18.074
at potential marriage
candidates

00:11:18.074 --> 00:11:19.913
when we hit our 
mid-to-late 20's.

00:11:19.913 --> 00:11:21.616
I think this is 
conclusive proof,

00:11:21.616 --> 00:11:22.771
if ever it were needed ,

00:11:22.771 --> 00:11:24.762
that everybody's brains 
are prewired to be

00:11:24.762 --> 00:11:27.616
just a little bit mathematical.

00:11:27.616 --> 00:11:29.477
Okay, so that was top tip #2.

00:11:29.477 --> 00:11:33.540
Top tip #3: How to avoid divorce.

00:11:33.540 --> 00:11:35.868
Okay so let's imagine then that you
picked the perfect partner

00:11:35.868 --> 00:11:40.645
and you're settling into a 
lifelong relationship with them.

00:11:40.645 --> 00:11:42.549
Now, I like to think 
that everybody

00:11:42.549 --> 00:11:50.095
would like to avoid divorce
from Piers Morgan's wife, maybe?

00:11:50.095 --> 00:11:52.475
But it's a sad fact 
in modern life

00:11:52.475 --> 00:11:56.284
that 1 in 2 marriages 
end in divorce,

00:11:56.284 --> 00:12:00.085
with the rest of the world
not being far behind.

00:12:00.085 --> 00:12:01.684
Now, you can be forgiven, perhaps

00:12:01.684 --> 00:12:05.344
for thinking that the arguments
that precede a marital breakup

00:12:05.344 --> 00:12:09.327
are not an ideal candidate
for mathematical investigation.

00:12:09.327 --> 00:12:10.777
For one, it's very 
hard to know

00:12:10.777 --> 00:12:13.834
what you should be measuring 
and what you should be quantifying.

00:12:13.834 --> 00:12:17.217
But this didn't stop a
psychologist, John Gottman,

00:12:17.217 --> 00:12:20.378
who did exactly that.

00:12:20.378 --> 00:12:22.351
He observed, Gottman observed,

00:12:22.351 --> 00:12:25.782
hundreds of couples 
having a conversation

00:12:25.782 --> 00:12:28.164
and recorded well, everything 
you could think of.

00:12:28.164 --> 00:12:30.581
So he recorded what was said 
in the conversation.

00:12:30.581 --> 00:12:32.994
He recorded skin conductivity,

00:12:32.994 --> 00:12:34.534
he recorded their facial expressions,

00:12:34.534 --> 00:12:36.874
heart rates, their blood pressure

00:12:36.874 --> 00:12:43.324
basically everything apart from whether
or ont the wife was always right,

00:12:43.324 --> 00:12:45.188
which incidentally she totally is.

00:12:45.188 --> 00:12:49.268
But what Gottman found, what
Gottman and his team found ,

00:12:49.268 --> 00:12:52.312
was that one of the
most important predictors

00:12:52.312 --> 00:12:53.922
for whether or not a couple
is going to get divorced

00:12:53.922 --> 00:12:59.213
is how positive or negative each
partner was being in the conversation.

00:12:59.213 --> 00:13:01.634
Now couples that were 
very low risk

00:13:01.634 --> 00:13:05.861
scored a lot more positive on
Gottman's scale than negative

00:13:05.861 --> 00:13:08.072
Whereas bad relationship,

00:13:08.072 --> 00:13:10.963
as in, those that are probably
going to get divorced,

00:13:10.963 --> 00:13:15.835
they found themselves getting 
into a spiral of negativity.

00:13:15.835 --> 00:13:17.758
Now just by using these 
very simple ideas,

00:13:17.758 --> 00:13:20.500
Gottman and his group
were able to predict

00:13:20.500 --> 00:13:23.103
whether a given couple
was going to get divorced

00:13:23.103 --> 00:13:25.758
with a 90 percent accuracy.

00:13:25.758 --> 00:13:27.472
But it wasn't until he teamed up

00:13:27.472 --> 00:13:29.406
with a mathematician
James Murray

00:13:29.406 --> 00:13:31.891
that they really started to
understand what caused

00:13:31.891 --> 00:13:35.601
these negativity spirals 
and how they occur.

00:13:35.601 --> 00:13:37.308
And the results that 
they found,

00:13:37.308 --> 00:13:42.807
I think are just incredibly,
impressively, simple and interesting.

00:13:42.807 --> 00:13:44.325
So these equations, 
they predict

00:13:44.325 --> 00:13:46.763
how the wife or husband
is going to respond

00:13:46.763 --> 00:13:48.501
in the next turn
of the conversation,

00:13:48.501 --> 00:13:49.929
how positive or negative
they're going to be.

00:13:49.929 --> 00:13:51.546
And these equations, 
they depend on

00:13:51.546 --> 00:13:53.912
the mood of the person 
when they're on their own,

00:13:53.912 --> 00:13:56.385
the mood of the person when they're 
with their partner.

00:13:56.385 --> 00:13:58.845
But most importantly,
they depend on

00:13:58.845 --> 00:14:02.094
how much the husband and wife
influence one another.

00:14:02.094 --> 00:14:04.372
Now I think it's important 
to point out that at this stage,

00:14:04.372 --> 00:14:08.462
these exact equations have
also been shown

00:14:08.462 --> 00:14:10.498
to be perfectly able 
to describe

00:14:10.498 --> 00:14:14.256
what happens between two
countries in an arms race.

00:14:14.256 --> 00:14:18.464
(Laughter).

00:14:18.464 --> 00:14:20.855
So that an arguing couple,

00:14:20.855 --> 00:14:22.367
spiraling into negativity,

00:14:22.367 --> 00:14:23.789
teetering on the brink of divorce,

00:14:23.789 --> 00:14:28.107
is actually mathematically equivalent to
the beginning of nuclear war.

00:14:28.107 --> 00:14:30.676
(Laughter).

00:14:30.676 --> 00:14:33.159
But the really important term
in this equation

00:14:33.159 --> 00:14:35.877
is the influence that people
have on one another,

00:14:35.877 --> 00:14:36.697
and in particular,

00:14:36.697 --> 00:14:39.420
something called the
Negativity Threshhold.

00:14:39.420 --> 00:14:40.769
Now the Negativity Threshold,

00:14:40.769 --> 00:14:44.519
you can think of as
how annoying

00:14:44.519 --> 00:14:46.192
the husband can be 
before the wife

00:14:46.192 --> 00:14:50.034
starts to get really pissed of, 
and vice versa.

00:14:50.034 --> 00:14:51.988
Now I always thought 
that good marriages

00:14:51.988 --> 00:14:54.596
are about compromise 
and understanding

00:14:54.596 --> 00:14:57.621
and allowing the person to 
have the space to be themselves.

00:14:57.621 --> 00:15:00.388
So I would have thought that

00:15:00.388 --> 00:15:02.856
perhaps the most 
successful relationships

00:15:02.856 --> 00:15:04.024
are the ones where there is a
really high Negativity Threshold.

00:15:04.024 --> 00:15:06.012
Where couples let things go


00:15:06.012 --> 00:15:08.557
and only brought things up if 
there really were a big deal.

00:15:08.557 --> 00:15:12.023
But actually, the mathematics
and subsequent findings

00:15:12.023 --> 00:15:15.318
by the team have shown the
exact opposite to be true.

00:15:15.318 --> 00:15:18.404
The best couples or 
the most successful couples

00:15:18.404 --> 00:15:19.217
are the ones are the ones

00:15:19.217 --> 00:15:21.779
with a really low 
Negativity Threshold.

00:15:21.779 --> 00:15:25.378
These are the couples that don't
let anything go unnoticed.


00:15:25.378 --> 00:15:28.599
They allow each other some
room to complain.

00:15:28.599 --> 00:15:28.863
These are the couples that are 
continually trying to repair

00:15:28.863 --> 00:15:33.813
their own relationship,

00:15:33.813 --> 00:15:36.418
that have a much more positive
outlook on their marriage.

00:15:36.418 --> 00:15:38.516
Couples that don't let things go

00:15:38.516 --> 00:15:42.426
and couples that don't let 
trivial things end up being

00:15:42.426 --> 00:15:44.527
a really big deal.

00:15:44.527 --> 00:15:50.023
Now of course, it takes more than 
just a low Negativity Threshold

00:15:50.023 --> 00:15:54.332
and not compromising to
have a successful relationship

00:15:54.332 --> 00:15:56.970
But i think that
it's quite interesting

00:15:56.970 --> 00:15:59.103
to know that there is really
mathematical evidence

00:15:59.103 --> 00:16:00.440
to support that you 
that you should

00:16:00.440 --> 00:16:02.662
never let you should go
down on your anger.

00:16:02.662 --> 00:16:04.188
So those are my top three tips

00:16:04.188 --> 00:16:05.943
for how maths can help you

00:16:05.943 --> 00:16:07.355
with love and relationships.

00:16:07.355 --> 00:16:09.826
But I hope that aside 
from these tips,

00:16:09.826 --> 00:16:11.721
they also give you
a little bit of insight

00:16:11.721 --> 00:16:13.968
into the power 
of mathematics,

00:16:13.968 --> 00:16:14.953
because for me,

00:16:14.953 --> 00:16:18.897
equations and symbols
aren't just a thing,

00:16:18.897 --> 00:16:20.359
They are a voice 
that speaks out

00:16:20.359 --> 00:16:23.797
about the incredible
richness of nature

00:16:23.797 --> 00:16:25.169
and the startling simplicity
in the patterns

00:16:25.169 --> 00:16:27.314
that twist and turn,

00:16:27.314 --> 00:16:28.872
and warp and evolve
around us.

00:16:28.872 --> 00:16:31.054
From how the world works,

00:16:31.054 --> 00:16:32.557
to how we behave.

00:16:32.557 --> 00:16:33.407
So I hope that perhaps,

00:16:33.407 --> 00:16:34.435
for just a couple of you,

00:16:34.435 --> 00:16:36.906
a little bit of insight into
the mathematics of love

00:16:36.906 --> 00:16:38.112
can persuade 
you to have

00:16:38.112 --> 00:16:40.314
a little bit more 
love for mathematics.

00:16:40.314 --> 00:16:40.991
Thank you.

00:16:40.991 --> 00:16:43.815
(Applause).