Hey, Vsauce. Michael here.
In 1826 this became the very first photograph
ever taken.
And in 1992, this became the very first image
ever uploaded to the web.
But how many photographs have we all taken,
altogether throughout all of history?
Well, 1000memories investigated this very
question.
They took a look at the number of digital cameras
currently in use, typical usage of a digital
camera, as well as the amount of analog film
and film-developing supplies used by the industry
ever since the 19th century.
Tabulated altogether, they estimated that
we have taken 3.5 trillion photographs, 4
billion of which were taken this year alone.
We are snapping more photographs than ever
before, because of the proliferation of easy-to-use,
affordable digital cameras.
In fact, we take 4 times more pictures per day
than we did 10 years ago.
Or think of it this way.
Today, every 2 minutes, humanity takes more
pictures than we took altogether in the entire 1800s.
Of course, the 1800s were a long time ago.
But if we take every year from the invention
of photography until today, 10% of all of
those images, a tenth of every still image
recorded of our world, was taken in the last 12 months.
That's a lot.
But even crazier is the fact that a fifth
of these images, 20% of them, all wind up
in the same place - Facebook.
Facebook is huge.
But to put it in perspective, you Vsaucers
are huge.
If all of us got together in one place and
claimed independence, we would become the
152nd largest country on Earth.
Right between Guinea-Bissau and 
Trinidad and Tobago.
But Facebook, with is 1 billion users, would
be the 3rd largest country on Earth.
To take a quick, dark detour, of those 1 billion
people on Facebook, it's estimated that 30
million of them are now dead.
And in 100 years, it's estimated that half
a billion of the people on Facebook will be deceased.
Facebook stories offers a really neat tool,
where you click on a country and then see
what other countries most of their Facebook
friends live in.
It's fun to see what countries are most connected
to which others, but this whole thing brings
up the question of degrees of separation.
If you were to take 2 random people on Earth,
how many friend of a friend of a friend of
a friends would you need to connect those
2 people?
Well, in the real world, it's a little difficult
to figure out, because we don't know who's
friends with who and there are a lot of people.
But, luckily, mathematics has come to our rescue.
Watts and Strogatz showed that you could calculate
the average path between any 2 random people
quite easily.
In this equation, the "N" stands for the total
number of people in the population.
And "K" stands for the number of friends each
person has.
If we assume that each person has, say, 30
friends and we assume that 10% of our population
is too young to have actual friends, it turns
out that you can connect any two people on
Earth with only 6.6 connections.
Theoretically.
Of course, in the real world, we don't all
have the same number of friends, we don't
all have 30 friends and isolated groups make
the average much, much higher.
Of course, there are non-real world places,
where these connections are easier to follow.
For instance, Facebook.
Last year, Facebook's data team released two
papers, showing that amongst all Facebook
users at the time, the average distance between
any two random users was only 4.74 friends.
Twitter is even tighter.
It's been shown that any two random users
of Twitter are connected by only 4.67 friends,
though some studies have shown it to be as
low as 3.5.
Numbers like that can make impersonal crowd
seem quite intimate.
But one of my favorite things about crowds
is how smart they are.
Wisdom of the Crowds is a fascinating phenomenon,
where the collective knowledge or guesses
or estimations of a big group of people, when
averaged, are better than one individual person
working alone.
A good example of this is trying to guess
how many jellybeans are in a jar.
Some people will overestimate, while others
will underestimate, but collectively, each
member cancels out the errors of the other
and the group average estimation winds up
being smarter than the sum of its parts.
The BBC's demonstration of this is fantastic,
I've linked it down in the description, it's worth watching.
They had 160 people guess the number 
of jellybeans  in a jar.
The guesses ranged from a few hundred to tens
of thousands, but the average of all 160 guesses
was 4,515, only 5 beans away from the exact answer.
It's amazing to think that in a large enough
group, the errors and shortcomings of everyone
else, no matter how annoying they are individually,
actually can balance and correct our own shortcomings.
It feels good, though a little bit strange
to think that in a group, it's possible for
nobody to be correct, but for everybody to be right.
And as always,
thanks for watching.
