Dark Science

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On Aug. 21, 1945, physicist Harry Daghlian accidentally dropped a brick of tungsten carbide into a plutonium bomb core at the Los Alamos National Laboratory. The mass went critical, and Daghlian died of radiation sickness.

Exactly nine months later, physicist Louis Slotin was conducting an experiment on the same mass of plutonium when his screwdriver slipped and the mass again went critical. He too died of radiation sickness.

The mass became known as “the demon core.”

The Vanishing Debtor

Alpha approaches Beta, asking for payment of a debt.

Beta: If you had an odd number of pebbles — or for that matter an even one — and then chose to add or subtract a pebble, do you think you would have the same number?

Alpha: No.

Beta: If you had a measure of one cubit and chose to add or cut off some length of it, that measure would no longer exist, would it?

Alpha: No.

Beta: Well now, think of a human in the same way: one human is growing and another is diminishing. All are constantly in the process of change. But what by its nature changes and never stays put must already be different from what it changed from. You and I are different from who we were yesterday, and by the same argument will be different again tomorrow.

Exasperated, Alpha strikes Beta.

Beta: Why are you angry with me?

Alpha: As someone nearby just demonstrated, it was not I who hit you, not I at all, but someone else altogether.

(From a fragment by Epicharmus.)

Newcomb’s Paradox

Flamdor McSqueem is a superintelligent wombat from the planet Zortag. He shows you two boxes. You can choose to take the contents of Box A or the contents of both boxes. He has privately predicted what you will do.

If Flamdor predicted you would choose Box A only, then Box A contains $1 million. If he predicted you’d choose both boxes, then Box A contains nothing. Either way, Box B contains $1,000. What should you do?

Some people reason that Flamdor is very intelligent and his predictions are usually accurate, so it would seem best to choose Box A. Others note that Flamdor has already made his prediction and can’t change the contents of the boxes now, so it seems best to take both boxes.

There’s no correct answer — decision theorists are still arguing about it. What would you do?

Easy

Write down any number:

886328712442992

Count up the number of even and odd digits, and the total number of digits:

10 5 15

String those together to make a new number, and perform the same operation on that:

10515

1 4 5

And keep iterating:

145

1 2 3

You’ll always arrive at 123.

Start Again

THEIR ARE THREE MISTEAKS IN THIS SENTENCE.

Well, wait, there are only two. So there was a mistake of fact. Which means that the sentence really did contain three mistakes. But that means it was true all along … in which case it’s not false … in which case it really contains only two mistakes …

Arguing in Circles

Some years ago, being with a camping party in the mountains, I returned from a solitary ramble to find every one engaged in a ferocious metaphysical dispute. The corpus of the dispute was a squirrel — a live squirrel supposed to be clinging to one side of a tree-trunk; while over against the tree’s opposite side a human being was imagined to stand. This human witness tries to get sight of the squirrel by moving rapidly round the tree, but no matter how fast he goes, the squirrel moves as fast in the opposite direction, and always keeps the tree between himself and the man, so that never a glimpse of him is caught. The resultant metaphysical problem now is this: Does the man go round the squirrel or not?

— William James, Pragmatism, 1907

A Parable

Ernie and Bert are fishing. “I’ll bet you a dollar,” says Ernie, “that if you give me two dollars I’ll give you three dollars.”

Bert agrees and gives Ernie two dollars. Ernie says, “I lose,” returns one dollar and pockets the other.

Ernie goes on to found a successful software company and Bert dies a bitter alcoholic.