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

I'm not sure that it makes any difference; if you write an 's' close to the pin, when the page is rotated the 's' will move in a circle within the circle described by the stationary photographer: if you simulate a stationary squirrel by suspending a blue pen above and just brushing the paper, when the page is rotated there will be a blue circle within the photographer's pencil grey one.

It does make a difference, as the latter represents the actual problem a little more closely.

Agreed!

But irrelevant!

The relevant point is that a pencil is made to draw a circle without moving. The question is, is that "circling"? And the answer, it seems to me, is arbitrary.

I wonder which of us is truly being irrelevant, bearing in mind that your fine example doesn't even include a squirrel.

What I've been trying to demonstrate (albeit somewhat haphazardly) is that, a) your example *does* involve movement, and b) that the effect of moving the ground beneath our protagonists' feet makes no difference to the outcome:

I. If both characters are marked on your sheet of paper [ie each fixed to his own spot on the ground (the closest scenario to the original problem)], the photographer will circle the squirrel as the paper/ground rotates.

II. If the photographer is made static, as in your squirrelless model, when the earth moves the squirrel will describe a small circle within the circle drawn by the photographer, and so be encircled.

III. If the squirrel is static, when the page turns/the earth moves etc the photographer will surely circle it.

Wheels within wheels.

All motion is relative.

We run to stay still.

I don't think there's anything else I can do to the Entry to reflect the complete and utter irrelevance of this entire problem, so is there anything I can do to make it make more sense?

Apart from linking to a tennis-playing blancmange, probably not.

The "Real Problem" section is quite tough to wade through, and I think you may lose a few readers here. It's a complex train of thought, and there's no particularly simple way to present it without diagrams, preferably moving ones.

Ok, I've rewritten it - is it easier to read now?

OK, I've had another quick look. No improvement since last time I looked, six days ago, I'm afraid.


"Camp 1 - the photographer encircles the squirrel by encircling the tree " -- that would be a spurious argument, but it is not the view of camp 1. It's not even the view you go on to explain in the sentences following that one. I'd phrase it as:

"Camp 1 - the photographer encircles the squirrel by encircling an area which at all times includes the squirrel"


"circling meaning to orbit the squirrel as it goes around the tree in a similar way to the moon orbiting the earth" -- this is not a good analogy, because the earth and moon both circle around a single point, called the barycentre of the system. This point is not at the centre of the earth, although it is within the earth.

The subsequent sections, "Going Nowhere Fast" and the ones after it present a completely spurious argument
about relative motion. It has already been pointed out that these arguemtns are completely invalidated by the case where the
squirrel is sitting on the centre of a rotating turntable, and yet you go on to present this as if it were a minor problem, saying
"One slight flaw with this way of thinking"...

That's like saying that a slight flaw in your proof of the existence of God is that the logic is wrong. The "Real Problem" is not that the man and the squirrel are not moving relative to each other, as there are situations where this is true in which the man is undoubtedly circling the squirel and everybody agrees that he is circling the squirrel.

Unfortunately, I don't know what the Real Problem is, because nobody has yet presented anything to suggest that the man is not circling the squirrel other than the spurious "fact" that he is never behind the squirrel.

Perhaps this entry is "going nowhere fast".

One way to proceed, bearing in mind that the consensus seems to be that circling does occur, would be to rename the entry 'The Squirrel Proposition Refuted'.

The scene can be set, the problem described and resolved, and then any counter-arguments can be dismissed one by one.

So the answer to the problem is... a rewrite

I'll have a look at it once I've done some other stuff.

Ok, 1st draft - what do you think?

Alex, I am flattered that you should have taken up my latest suggestion. However, I think it would be prudent to wait for comments from your true peers, the thread's other participants who, like you, have written a great number of highly entertaining entries - I have written precisely nothing (and should probably stick to pointing out typos).

I have the feeling, though, that a break of a few days would set you up to pat this still fascinating entry into shape.

"a break of a few days" - I hope you only mean a break of a few days from the Entry...

Excellent PR work here - great forbearance as well Alex. Keep going.

Someone must have picked this - they must have been eating Tufty's magical Topic bars again

Ok, it's patting into shape time - what do I need to do?

I love it - the whole arguing over varous geographical and mathematical and semantic points

I will have a thorough read soon, but here's something that occurred to me: are you talking about only in 2 dimensional space? Imagine (as was suggested earlier) that the tree trunk gets bigger and bigger...so that eventually both the squirrel and the photographer are walking around the equator, on opposite sides of the earth...

We need a squirrel smiley, really.

No, size doesn't matter! The equator case is the same as the photographer-crawling-on-the-tree-bark case.