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

Ok, I've added a sentence pointing out the problem with rotating axes.

Mckay

Good to see a 'real life application' involving squirrels - well sort of Not sure how to add the link though

Entry: The Squirrel Dilemna - A Puzzle - A16967659
Author: Alex "Tufty" Ashman [!] - U566116

For ease of ridiculing the author etc...

And Finally
Another squirrel who thinks a lot about his movements is Tufty, who has been used to teach UK children road safety since the 1950s. He starred in his own public information film of the 1970s, as you can see here.>/P>

Dare you

Ok, though I don't like the look of that closing tag

That's my get-out clause.

I found another page with the Tufty film on the National Archives site, at http://www.nationalarchives.gov.uk/films/1964to1979/filmpage_tufty.htm
I'm not sure which would be the better link. You can download it from this one, but the BBC page is a better read.

I think I'll keep the BBC link

Apologies for disappearing so abruptly. The family geek tells me that the apparent mass attack by viruses and other nasties was in fact nothing more than an indication that our hard disk is failing - somehow, I don't find that very comforting.

Amusing as it was, for a spell, to argue with Gnomon, I can no longer deny that the squirrel moves within the photographer's orbit around the tree, and so is encircled - just as a planet's inner moons, lying within the orbit of those further out, are encircled.

And the stationary photographer circling the twirling squirrel (as it appears from the latter's point of view)?

Sorry to harp, but I still haven't got an answer.

Ok, I've added a bit about that

Well, that covers it, but it doesn't go the next logical step and say "this shows that the question is empty". You still haven't made the necessary distinction between absolute and relative motion. For our purpose absolute means no more than "relative to the background", by which the photographer always circles the squirrel (so long as his radius is bigger; but having brought us here with such a vivid setup, it is a bit thick to suddenly jam the photographer up against the bark). Relative motion introduces (for one thing) a question of time that doesn't apply if one party stays still. You could imagine a radar scanner sweeping around a circular screen, and an object circling inside the screen just ahead of the scanner radius. The radar will never pick up this object, though it is in the circle. In that sense the squirrel appears to stay ahead of the circling photographer's radar, but if you disregard time then it can't escape being inside the photographer's circle.

I find this less than clear: "The problem is that if the photographer were to occupy the same radius circle around the tree" -- occupy is off-putting. There are two ways to occupy a circle, and the general reader will think it means "be inside". You mean "describe the same circle" but that is mathspeak too. You should perhaps bring the squirrel out to circle the tree at the same radius as the photographer.


" . . . as the squirrel, the photographer and the squirrel would be indistinguishable in their motion, and we would have great difficulty trying to reason whether one was encircling the other." -- No difficulty at all. neither circles the other, both circle the tree.

"Placing the photographer on a bigger circle than the squirrel is therefore necessary, and this would allow the photographer's circle to surround that of the squirrel." -- This is just too obvious to mention. And if the squirrel stepped further out, he'd circle the photographer. No problem here, surely?

Mathematicians would go around this by saying something along the lines of:

Without loss of generality, we will assume that the photographer's circle has larger radius than the squirrel's.

Or, as a student I knew once said: "without loss of generosity"

A nice cup of for Recumbentman, more specifically the first paragraph above: I think it summarises quite well the problem. At least, what I perceive the problem to be.

Santé!

It is surprising, but reassuring, to see how much conversation an entry that focuses on seemingly simple conceptual problems generates. I can't help but see it as a largely semantic disagreement, however.

It is amazing how many intelligent people can disagree and still all be right within the context of their chosen definitions; such is the complexity and flexibility of the English language.

I hope this will help:
http://www.thefreedictionary.com/around

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a·round (-round)
adv.
1.
a. On all sides: dirty clothes lying around.
b. In close to all sides from all directions: a field bordered around with tall trees.
2. In a circle or with a circular motion: spun around twice.
3. In circumference or perimeter: a pond two miles around.
4. In succession or rotation: passed the collection plate around; seasons that rolled around each year.
5. In or toward the opposite direction or position: wheeled around to face the attacker.
6.
a. To or among various places; here and there: wander around.
b. To a specific place: Come around again sometime.
7. In or near one's current location: waited around for the next flight.
8. From the beginning to the end: frigid weather the year around.
9. Approximately; about: weighed around 30 pounds; around $1.3 billion in debt.
prep.
1. On all sides of: trees around the field.
2. In such a position as to encircle or surround: a sash around the waist.
3.
a. Here and there within; throughout: on the political stump around the country.
b. In the immediate vicinity of; near: She lives around Norfolk.
4. On or to the farther side of: the house around the corner.
5. So as to pass, bypass, or avoid: a way around an obstacle; got around the difficulty somehow.
6. Approximately at: woke up around seven.
7. In such a way as to have a basis or center in: an economy focused around farming and light industry.
adj.
1. Being in existence: Our old dog is no longer around.
2. Being in evidence; present: asked if the store manager was around.
Idiom:
been around Informal
Had many and varied experiences; been experienced in the ways of the world: a young executive who has been around.

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[Middle English : probably a-, in; see a-2 + round, circle; see round1.]

Adv. 1. around - in the area or vicinity; "a few spectators standing about"; "hanging around"; "waited around for the next flight"
about
2. around - by a circular or circuitous route; "He came all the way around the base"; "the road goes around the pond"
3. around - to or among many different places or in no particular direction; "wandering about with no place to go"; "people were rushing about"; "news gets around (or about)"; "traveled around in Asia"; "he needs advice from someone who's been around"; "she sleeps around"
about
4. around - in a circle or circular motion; "The wheels are spinning around"
5. around - (of quantities) imprecise but fairly close to correct; "lasted approximately an hour"; "in just about a minute"; "he's about 30 years old"; "I've had about all I can stand"; "we meet about once a month"; "some forty people came"; "weighs around a hundred pounds"; "roughly $3,000"; "holds 3 gallons, more or less"; "20 or so people were at the party"
about, approximately, close to, more or less, or so, roughly, some, just about
6. around - in or to a reversed position or direction; "about face"; "brought the ship about"; "suddenly she turned around"
about
7. around - to a particular destination either specified or understood; "she came around to see me"; "I invited them around for supper"
8. around - all around or on all sides; "dirty clothes lying around (or about)"; "let's look about for help"; "There were trees growing all around"; "she looked around her"
about
9. around - in circumference; "the trunk is ten feet around"; "the pond is two miles around"
10. around - from beginning to end; throughout; "It rains all year round on Skye"; "frigid weather the year around"

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It should be obvious that most definitions of 'around' have to do with the path of the viewer, not that which the viewer views or the viewpoint of the viewed. Still, there is room in there to consider that (from the squirrels viewpoint) the photographer never gets 'behind' him - as in 'around back'.

My original suggestion was just to clean up the verbiage to make it clear that getting 'behind the tree and in view of the squirrel was the initial dilemma'.

There's still one little thing which leaves me slightly confused: what is the "dilemma"? Isn't a dilemma a difficult choice, one where both outcomes would result in disaster?

You're quite right, Toy Box -- "choice between two equally unfavourable alternatives", the SOED puts it. So this is at best just a paradox; and some of us don't even see it as that.

The Squirrel Dispute?

Crouching Photographer, Hidden Squirrel?

The Hunt For Red Squirrel?

I've made some changes - hope it's ok now