(Roughly) Daily

Posts Tagged ‘measure theory

“Oops, I did it again”*…

(Roughly) Daily has contemplated game theory a number of times (e.g., here). The Generalist Academy offers a particularly poignant example…

Football [or, as it’s called in the U.S., soccer] has a lot of strange rules – like Ted Lasso, I still don’t understand exactly how the offside rule works. But the basic game is pretty simple: get the ball into your opponent’s goal, and prevent them from getting the ball into your goal. Scoring a goal against your own side is a rare and accidental embarrassment. Usually.

The qualification round for the 1994 Caribbean Cup had some unusual rules. No match could end in a draw; if the teams were tied at the end of regular time, they would go into sudden death extra time. But! Any goal scored in extra time would count as two goals. This was presumably done because this tournament, like many, used goal difference to break ties in the qualifying groups. (Goal difference = total number of goals they’ve scored minus the number of goals they’ve conceded.) So that extra time “golden goal” would give a team an edge in the overall competition. Little did the organisers know that it would also lead to one of the strangest football games ever seen…

A truly remarkable match: “Own-Goal Football,” from @GeneralistAcad.

* Britney Spears (Songwriters: Martin Max / Rami Yacoub)

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As we work backwards, we might send carefully-calculated birthday greetings to Félix Édouard Justin Émile Borel; he was born on this date in 1871. A mathematician (and politician, who served as French Minister of the Navy), he is remembered for his foundational work in measure theory and probability. He published a number of research papers on game theory and was the first to define games of strategy.

But Borel may be best remembered for a thought experiment he introduced in one of his books, proposing that a monkey hitting keys at random on a typewriter keyboard will – with absolute certainty – eventually type every book in France’s Bibliothèque Nationale de France. This is now popularly known as the infinite monkey theorem.

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Written by (Roughly) Daily

January 7, 2023 at 1:00 am

“No structure, even an artificial one, enjoys the process of entropy. It is the ultimate fate of everything, and everything resists it.”*…

A 19th-century thought experiment that motivates physicists– and information scientists– still…

The universe bets on disorder. Imagine, for example, dropping a thimbleful of red dye into a swimming pool. All of those dye molecules are going to slowly spread throughout the water.

Physicists quantify this tendency to spread by counting the number of possible ways the dye molecules can be arranged. There’s one possible state where the molecules are crowded into the thimble. There’s another where, say, the molecules settle in a tidy clump at the pool’s bottom. But there are uncountable billions of permutations where the molecules spread out in different ways throughout the water. If the universe chooses from all the possible states at random, you can bet that it’s going to end up with one of the vast set of disordered possibilities.

Seen in this way, the inexorable rise in entropy, or disorder, as quantified by the second law of thermodynamics, takes on an almost mathematical certainty. So of course physicists are constantly trying to break it.

One almost did. A thought experiment devised by the Scottish physicist James Clerk Maxwell in 1867 stumped scientists for 115 years. And even after a solution was found, physicists have continued to use “Maxwell’s demon” to push the laws of the universe to their limits…

A thorny thought experiment has been turned into a real experiment—one that physicists use to probe the physics of information: “How Maxwell’s Demon Continues to Startle Scientists,” from Jonathan O’Callaghan (@Astro_Jonny)

* Philip K. Dick

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As we reconsider the random, we might send carefully-calculated birthday greetings to Félix Édouard Justin Émile Borel; he was born on this date in 1871. A mathematician (and politician, who served as French Minister of the Navy), he is remembered for his foundational work in measure theory and probability. He published a number of research papers on game theory and was the first to define games of strategy.

But Borel may be best remembered for a thought experiment he introduced in one of his books, proposing that a monkey hitting keys at random on a typewriter keyboard will – with absolute certainty – eventually type every book in France’s Bibliothèque Nationale de France. This is now popularly known as the infinite monkey theorem.

source

Paradoxically…

Suppose there is a town with just one male barber; and that every man in the town keeps himself clean-shaven: some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber obeys the following rule: He shaves all and only those men in town who do not shave themselves. Under this scenario, we can ask the following question: Does the barber shave himself?

From Epimenides’ Paradox to the Omnipotence Paradox, more fun-with-logic at “Brain Twisting Paradoxes.”

As we return to first principles, we might wish a carefully-reasoned Joyeux Anniversaire to Félix-Édouard-Justin-Émile Borel, a mathematician and pioneer of measure theory and its application to probability theory; he was born in Saint-Affrique on this date in 1871.  Borel is perhaps best remembered by (if not for) his thought experiment demonstrating that a monkey hitting keys at random on a typewriter keyboard will– with absolute certainty– eventually type every book in the Bibliothèque Nationale (or, as oft repeated, every play in the works of Shakespeare, or…)– that is, the infinite monkey theorem.

Borel (image source)

 

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