How magicians control flip of a coin

livemint.com:

Dynamical Bias in the Coin Toss, Persi Diaconis et al, SIAM Review, 2007) That is, if a coin is tails-up when flipped, it has a slightly higher chance of landing tails, rather than heads—0.51 to 0.49. Now this is so slightly higher that it makes no real difference on a single coin toss, like the one that starts off a tennis or cricket match. But instead, let’s say you have a bet with a friend that depends not on one, but a thousand tosses.

Let’s say the bet is simply that when done, you will have called correctly more often than him. Let’s say you can peer closely to see which face is up before the tosser tosses, and you call that face, every time. In such an experiment, you’re likely to win your bet, because you can expect to call correctly about 510 times out of 1000.

This is what Diaconis and colleagues concluded. And why this slight preference for the starting position? They start by referring to a study that “showed that ... a vigorous flip, caught in the hand without bouncing, lands heads up half the time." But your garden variety coin toss is not usually so neat.

“Naturally tossed coins obey the laws of mechanics," they explain, “and their flight is determined by their initial conditions." The coins also “precess": the coin’s rotation itself changes the nature of that rotation, as the coin flies through the air. This is just normal. Tops precess as they rotate.

So does our planet Earth. This is why the North Pole points at the star Polaris today, but pointed at Alpha Draconis about 5,000 years ago, and will point at Vega in another 13,000 years. In the case of the flipped coin, Diaconis and colleagues took into account its “angular momentum vector"—never mind what that means—and the angle the vector makes with the