without having to leave your own home or deal with other people?

Well, you might be in luck. You can already download an Ebola virus

genome.

Right here on the Internet, right now. And if you're willing to wait

a few years for 3D bioprinting technology to progress

a little bit, you can just acquire one then, submit the genome to it

and ta da! All you can print Ebola.

Or anthrax or whatever it is you wish to mass-produce at home

to wipe out humanity.

Are humans going to go extinct

soon? Will human extinction be

anthropogenic? That is the result of human

action. Or will it be one of the good old-fashioned kinds

of extinction Earth's history knows pretty well?

The Global Catastrophic Risks Survey, issued by Oxford University's

Future of Humanity Institute placed our risk of extinction

before the year 2100 at 19%.

Now, you might be thinking "whatever, blah blah blah armageddon".

"It'll be okay, humans are too smart

to go extinct." Maybe you're right.

But it's difficult to predict the distant future

with a lot of certainty. What's really cool though

is that if you embrace that uncertainty, a simple argument

can show that human extinction soon is actually

more probable. It's called the Doomsday

argument. Imagine a giant

urn that contains either 10 balls

numbered 1 to 10, or a million balls

numbered 1 to a million. Now, you don't know

which is the case, but you are allowed to pull out

one ball. You go ahead and do that

and it is ball number 4.

That's pretty strong evidence in favour of the 10 ball condition

because drawing a four from a set of 1 through 10

is a one in 10 chance. But drawing four from a million different numbers

is a one in a million chance.

By analogy you are also a numbered

ball. You are a human who knows

approximately what your birth number is.

It's probably somewhere around 100

billion. That's how many other humans

were most likely born before you were.

Importantly, you didn't get to decide which birth number

you would have. So, just like the number for a ball,

you are a random sample from the set of all humans

who will ever live. The Doomsday argument points out

that from 200 billion people there's a 50 percent chance that a randomly chosen

person,

like you, would be born in the first one hundred billion.

Whereas if there will be 10 trillion humans,

there's only a one percent chance that any given human,

say you, would happen to be born within the first

100 billion. Either you are special

and lucky to be born so improbably early in the story of humanity

or your birth number is to be expected

because there will not be tens of trillions of humans.

Human extinction will be sooner

rather than later. But before you become

too convinced that the end is nigh, keep in mind that the Doomsday argument is

not

uncontroversial. One problem it might have

is a reference class problem. Are you really a

random sample from the set of all humans who will ever

be born? Well, if you believe that in the not so distant future

humans will be quite different than they are today.

For instance, there'll be full of more 3D printed

organs. The mere fact that right now there aren't very many humans

with that trait could be evidence that you aren't a random sample from the

set of all humans,

just from the set of all humans like

you, like does around you. Those born

earlier in human history. Also

the Doomsday argument doesn't consider the likelihoods

of actual threats or human advantages

over those threats in the future. It just assumes that

we don't know which way the balance will lie; that

human extinction soon and human extinction

later are equally likely. But maybe you don't believe that.

Maybe you are convinced that human ingenuity will

always stay one step ahead of any extinction event

thrown at it. You could be right,

but there's reason to doubt that optimism.

For example, the Fermi paradox.

If it is likely that intelligent life forms in our universe are capable

of living for billions

and billions of years, where are they?

Why are the skies so silent? Perhaps

it is because extinction level threat events are just

too common for intelligent life anywhere

to ever catch up.

So,

does this mean we should just give up?

The Voluntary Human Extinction Movement think so.

Founded in 1991, its supporters believe that

humans are a negative influence

on Earth and always will be. Thus

we have a moral obligation to just stop reproducing

right now and fade away. But what would

a computer do? In a way, that's

kind what Tom 7 did. He created a program that plays video games.

The program came up with novel techniques and strategies for playing

games and even exploited glitches

humans didn't know about, or at least

hadn't told it about. He also had the program play other games,

like Tetris, which I think is relevant

to our question. The computer struggled to figure out what to do.

You see, the computer wasn't programmed to consider future repercussions far

enough ahead

to notice that stacking Tetriminos in certain ways

made a big difference. On one run, when faced with

imminent demise, the computer did something

eerie. Rather than

lose, and receive a 'game over',

it just paused the game. For

ever. Tom 7 describes the computer's reasoning

like this: "The only winning move

is to not play." And that's right.

If you pause a game for ever

you will never lose that game. But you'll also never

win that game or achieve a high score.

Now, we might not know what achieving a

sentient life high score in this universe

means or whether or not we're capable of achieving one.

We might also sometimes panic

when the future looks bleak. But if we keep playing

and keep learning, chances are we could eventually

figure it out and start playing

really well.

So, thanks for continuing to play, for being here.

And as always,

thanks for watching.