JON CARROLL

Let us, dear friends, once more into the swamp of the 2007 Xmas Quiz. I asked: "Which point on earth is closest to outer space? Hint: It's not the top of Mount Everest." A day later, I answered: "The point on earth closest to outer space is Mount Chimborazo in Ecuador. The earth is an oblate spheroid that sticks out in the middle, like a beach ball that's been sat on. Thus, a mountain near the equator is closer to outer space."

Objections poured in. As I read the critiques, I realized I was quite a bit above my pay grade. So I turned to an actual board-certified astronomer, the invaluable Andrew Fraknoi, who was kind enough to answer me over the holiday week:

"Since earthly things are a bit 'below my department' (badda bing), I consulted a colleague who is a planetary scientist before answering you, just to be sure my instincts were right.

"We agree that, alas, your critics are right. We generally define the beginning of space as the distance above the Earth's surface where the atmosphere drops to a pressure less than some amount. The amount doesn't matter - for some purposes we define it as less or more, but it is always so little that an unprotected Chronicle reader would die.

"The only thing that matters is the distance from the surface to this point where there is not so much air any more. And that would, indeed, be the same above the equator or a higher latitude. Had the question been worded in the alternative way you mention [a reader had suggested 'Which point on earth is farthest from the center of the earth?'], your answer would have been correct ...

"In other words, what tripped you up was that the definition of space goes with the thickness of the atmosphere, which changes little, not the radius of the Earth, which is indeed different at the poles than the equator.

"When I was first learning to be an astronomy teacher, my biggest fear was that I would be asked a question that I could not answer or would make a mistake in answering. One mentor suggested that the easiest way to deal with such questions was to assign them for homework to the whole class - that would deter students from ever asking a question again. But a far wiser mentor said that not knowing everything was being a great role model for one's students, for it is not how much you know but how smart you can be in working toward an answer that is the hallmark of a great scientist.

"Science is a self-correcting, ever evolving field of knowledge, where people often pool their results and thinking for the common good. So your interaction with your readers is a great example of this. How's that for getting you off the hook?"

Much appreciated, although I've been on that hook so long it feels like home to me.

I also asked: "What is the shortest international border in the world?" I said it was the border between Gibraltar and Spain at 1.2 kilometers. Oh, there were many objections. Some thought the border between Italy and the Vatican City, or between the U.N. headquarters and the United States, might be shorter, but both are longer (although not by much).

But those suggestions bring up an interesting question: What precisely is an international border? The embassies of every nation are, for legal purposes, on the soil of that nation, but does the perimeter of any of them constitute an international border? Then the game would be "find the smallest embassy," and that would be boring.

But we do have two real alternative possibilities. The first is the border between Morocco and the Spanish territory of Peñón de Vélez de la Gomera, which comes in at a low, low 87 meters. The territory was until recently an island, and is now connected to the mainland with an artificial sand strip. Does its new status as a piece of the continent (a part of the whole) matter?

But the winner is the Sovereign Order of Malta, with a border of less than 50 meters - it's basically a building on the Via Conditti in Rome - which has independent diplomatic relations with 96 countries and permanent observer status at the United Nations. Does that count as an international border? I'm saying yes.

Finally, I alleged that "a record 21 co-inventors received the original patent on the computer." Not so fast, said Harry Henderson, author of the Encyclopedia of Computer Science and Technology. It really depends on what your definition of the "first" computer is. He listed some claimants to the throne:

"Harvard Mark I: automatic, digital, but not electronic (used relays); Zuse Z3 - programmable and general purpose but not electronic (used relays); Colossus - electronic, but special purpose (for cracking codes) - not Turing complete; ENIAC - electronic and general purpose, Turing complete (Turing complete means able to compute any computable function, and equivalent to a universal computer or Turing machine).

"So if the criterion is 'programmable digital electronic universal computer,' the winner is ENIAC."

The ENIAC patent was the subject of a complicated patent suit, so there is obfuscation. It appears, though, that the original patent was issued to just two people.

We may be through with God, but God isn't through with jcarroll@sfchronicle.com.

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/01/07/DDF9U8SMQ.DTL

This article appeared on page E - 8 of the San Francisco Chronicle