h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Langton's Ant - A3908720
Author: Amy the Ant - U135642

It isn't about ants.

Great idea for an entry!

But I'm confused about something --

If an ant turns to the left and then moves one square forward, how is that moving to the right? Likewise, if he turns to the right and moves one square forward, how is that moving to the left?

For example, if we had a 3x3 grid:

1 2 3
4 5 6
7 8 9

And the ant starts out in square 5, facing 2. He turns to the left, so is still on square 5, but now facing 4. He moves one square forward, so onto square 4. That is one square to the left of where he originally began, from his original perspective.

Umm, I wrote it going one way round and then changed the lefts and rights to suit the computer demo. And I've messed up. Give me a minute .

'At first, we might think we can predict the path the ant.'

This sentence seems incomplete.

Otherwise, nice Entry.

Fixed.

Excellent entry, Amy. I think should definitely be part of the Guide. Remind me in a few days and I will check it for typos, but I didn't see any on a quick read through.

I can't come up with any suggestions for improvement. Explaining mathmatical concepts in words isn't an easy thing. YOu've pulled it off.

NBY

For my own information as much as anyone else's... I don't think 'Life, the Universe and Everything' is supposed to be capitalised. Right?

Although it would be really funny to link those words to their respective directory pages...

I dunno. I'm going to leave the capitals there because I think it has more impact. I'll decide later.

I need a day or so to sort out the links to other EG entries. Incidentally, a search on Langton brings up A447383 and U110704. Is the great man one of us?

If he is, he hasn't contributed.

OK, I've had a more detailed read. The content is fine. It just needs a few typos to be corrected.

infinite white plain --> infinite white plane
divide the plain --> divide the plane
the path the ant --> the path of the ant

Add a full stop after:

GUT to this day

Move the fullstop that is just before the first footnote to just after the footnote:

out.@@@@

becomes

out@@@@.

Thanks, Gnomon.

I can't believe I did the plain/plane thing .

I'll fix them later when I add the links.

Fascinating stuff very well explained, Amy.

One more small slip to fix: 'The ant knows the all the rules of the universe'. Maybe so, but she sometimes includes one too many definite articles in a sentence.

I had heard about this program a few years ago and always had a hard time trying to visualise it. But you seem to have done a good job.

*bows to the Orm*

Fixed

Thanks, GodBen .

I've started putting in the links but hootoo is too slow tonight.

I'm thinking of changing 'chaos theory' to the more accurate (though less exciting) 'complexity theory' so that I can link to A197453 without causing confusion.

I thought this was a bit confusing:

"Watch the ant carefully. It is on a white square, it moves to the square on its left. The ant is now on a new white square. It steps to the left again and does that twice more;"

This to me brings up the picture of an ant just moving to the left 3 steps, so that it ends up at a distance of 3 from where it started. Maybe something like 'turns left and moves one square forward' would be clearer?

Perhaps a link to Conway (has a description of life also) at A2982468?

The last paragraph seems a little off to me, though it's a style opinion. A mathematician with enough experience (any random professional mathematician say) would know enough to have respect for such seemingly simple systems. It isn't as if they would smugly assume that they could destroy it with their brilliance and be embarrassingly brought down by such a small foe.

Looks good otherwise

I think Amy's point is a good one. A mathematician might not be misled, but many scientists, in particular nuclear physicists, think they have a very good grasp of the way the world works, and have been proved wrong on many occasions. They could learn a lesson from this humble automaton.

An excellent Entry. Good length, good idea.

Is there a Langton's Ant simulator anywhere on the net you can link to.

B

She already did: http://www.math.ubc.ca/~cass/www/ant/ant.html

It's fairly cool once it starts to build the 'highway'.