Length of baseball games
In an earlier article, I asserted that the average length of a baseball game was very close to 9 innings. This is a good rule of thumb, but it is also something of a coincidence, and might not be true in every year.

The canonical game, of course, lasts 9 innings. However, if the score is tied at the end of 9 innings, the game can, and often does, run longer, because the game is extended to the end of the first complete inning in which one team is ahead. So some games run longer than 9 innings: games of 10 and 11 innings are quite common, and the major-league record is 25.

Counterbalancing this effect, however, are two factors. Most important is that when the home team is ahead after the first half of the ninth inning, the second half is not played, since it would be a waste of time. So nearly half of all games are only 8 1/2 innings long. This depresses the average considerably. Together with the games that are stopped early on account of rain or other environmental conditions, the contribution from the extra-inning tie games is almost exactly cancelled out, and the average ends up close to 9.

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Messages from the future
I read a pretty dumb article today about passwords that your future self could use when communicating with you backwards in time, to authenticate his identity to you. The idea was that you should make up a password now and commit it to memory so that you can use it later in case you need to commuicate backwards in time.

This is completely unnecessary. You can wait until you have evidence of messages from the future before you do this.

Here's what you should do. If someone contacts you, claiming to be your future self, have them send you a copy of some document—the Declaration of Independence, for example, or just a letter of introduction from themselves to you, but really it doesn't need to be more than about a hundred characters long—encrypted with a one-time pad. The message being encrypted, will appear to be complete gibberish.

Then pull a coin out of your pocket and start flipping it. Use the coin flips as the one-time pad to decrypt the message; record the pad as you obtain it from the coin.

Don't do the decryption all at once. Use several coins, in several different places, over a period of several weeks.

Don't even use coins. Say to yourself one day, on a whim, "I think I'll decrypt the next bit of the message by looking out the window and counting red cars that go by. If an odd number of red cars go by in the next minute, I'll take that as a head, and if an even number of red cars go by, I'll take that as a tail." Go to the museum and use their geiger counter for the next few bits. Use the stock market listings for a few of the bits, and the results of the World Series for a couple.

If the message is not actually from your future self, the coin flips and other random bits you generate will not decrypt it, and you will get complete gibberish.

But if the coin flips and other random bits miraculously turn out to decrypt the message perfectly, you can be quite sure that you are dealing with a person from the future, because nobody else could possibly have predicted the random bits.

Now you need to make sure the person from the future is really you. Make up a secret password. Encrypt the one-time pad with a conventional secret-key method, using your secret password as the key. Save the encrypted pad in several safe places, so that you can get it later when you need it, and commit the password to memory. Destroy the unencrypted version of the pad. (Or just memorize the pad. It's not as hard as you think.)

Later, when the time comes to send a message into the past, go get the pad from wherever you stashed it and decrypt it with the secret key you committed to memory. This gives you a complete record of the results of the coin flips and other events that the past-you used to decrypt your message. You can then prepare your encrypted message accordingly.

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