Let's look again at minilife.nlogo. So, to use this you do Setup; it turns all the cells white.

Now, I can either do what I did before, which is randomize by setting a certain percentage of

the cells to black, or I can edit myself. So I can click on Edit, and I then can click on cells to turn

them black, or I can click again on them to turn them white. And so I can decide what I want to use

for an initial configuration. And you can just try and randomly set cells to black, or you can set

specific patterns. Okay, and then when

you're done with this, you can un-click

on Edit, and do Go 1. Okay what this does -- it doesn't actually update the first time I click on it,

and instead marks as green all the cells that are going to either stay alive or come alive. So you

can see before it updates which cells are
going to go to black.

Okay, I click again, and it actually

does the update. So, just to clarify,
the green is not actually part of

the game of Life, it's just an indicator to show you in this model which cells are going to come alive.

So, let's try that again. All right, so, there we go.

And again, and again, and again.

And notice here, I've gotten to a fixed point,

that is, a configuration that doesn't change.

You could do the same thing again. I'm going to

randomize here, and then if I click Go, the

the Go Forever button,

you'll see it go for a long time,

until it gets to a fixed point, which are

either... I click Go to stop it again.

These are either configurations that don't

change, or that alternate. So for instance,

this one here, this column of three

black cells, at the next time step, that goes

to a row of three, and the next time step, that

goes to a column of three. So that's a "period two"

structure -- you could think of it as a kind

of attractor. You may not know that the game of Life has its own sort of research community associated

with it, people who try and investigate what kinds of patterns you can make in the game of Life that

have interesting properties. We're going to talk about some of those patterns in a little while,

but let me show you one particularly

famous simple one. Okay, I'm going to set up

and then I'm going to click -- oops, I have to edit --

click here, here, here, here, here. This is a pattern,

and let's see what this does.

Okay, we Go once, and check it out! It's the same

pattern, but it's moved down,

and to the right. Let's look at it

going faster... oops, that's

a little too fast... and what you can see

if I speed it up a little bit,

is this pattern is what's called a "glider."

It glides down, keeping its shape.

And it turns out you can build up

very interesting patterns using gliders.

Now, it's time for another quiz.

This time you need to download

minilife.nlogo, and for the first question,

you create a glider, and the question is

how many generations does it take

for the pattern to recreate itself in the

same orientation, but one cell

down and to the right?

The second is for you

to set up this

configuration of two

gliders about to collide,

and run it until they collide

and the pattern becomes stable,

and the question asks you what happens?