A Splitting Headache

Image: Wikimedia Commons

Tom has a crystal ball that shows him the future. One day it shows him a bomb going off in the city. He alerts the authorities, who disable the bomb, saving millions of people. Tom is glad, but he wonders: How can this outcome be logically consistent with the future that the crystal ball had shown him? In that future he saw millions of people die, but in this future they’re still alive. He realizes that when he contacted the authorities the timeline must have split in two. In the original timeline, the bomb went off just as the crystal ball had foretold, and the city’s population did die. But in this new timeline, the authorities defused the bomb and everyone lived.

This understanding seems to explain what has happened, but it leaves a worrying subjective question. If there are two timelines then there are two Toms, both sharing the same history and presumably each realizing that two instances of his identity now exist. “We are familiar with physical things splitting into two, and can accept in principle that they could even be duplicated,” writes Western University philosopher John L. Bell. “But it is extremely difficult to make sense of the idea that an individual consciousness can be so split.”

The doomed Tom might ask himself, “Why am I the doomed Tom?” Objectively the answer is that he’s the Tom who failed to alert the authorities to the coming catastrophe. “But from a subjective point of view he can ask: why was I the Tom who failed to act? Why couldn’t I have been the saved Tom? There seems to be no satisfactory answer to this question.”

In his Philosophy of Mathematics and Natural Science, mathematician Hermann Weyl notes that Leibniz thought he had resolved the tension between freedom and predestination by letting God consider the infinite number of possible universes and assign existence to one of them. “This solution may objectively be sufficient,” Weyl wrote, “but it is shattered by the desperate outcry of Judas, ‘Why did I have to be Judas?'”

(From Oppositions and Paradoxes, 2016.)



This is an excerpt from Kaikhosru Sorabji’s Opus Clavicembalisticum of 1930. The snaky line running through it is a slur (!) encompassing the whole complex passage.

Indiana University information scientist Donald Byrd observes, “It has a total of 10(!) inflection points; it spans three systems, repeatedly crosses three staves (this is also the most staves within a system for any slur I know of), and goes slightly backwards — i.e., from right to left — several times.”

More at Byrd’s Gallery of Interesting Music Notation.



A poor artist is visited by a time traveler from the future. The traveler is an art critic who has seen the artist’s work and is convinced that he’s one of the greatest painters of his time. In looking at the artist’s current paintings, the critic realizes that the artist hasn’t yet reached the zenith of his ability. He gives him some reproductions of his later work and then returns to the future. The artist spends the rest of his life copying these reproductions onto canvas, securing his reputation.

What is the problem here? Kurt Gödel showed in 1949 that time travel might be physically possible, and there’s no contradiction involved in the critic arriving in the artist’s garret, giving him the reproductions, and later admiring the painter’s copies of them — that loop might simply exist in the fabric of time.

What’s missing is the source of the artistic creativity that produces the paintings. “No one doubts the aesthetic value of the artist’s paintings, nor the sense in which the critic’s reproductions reflect this value,” writes philospher Storrs McCall. “What is incomprehensible is: who or what creates the works that future generations value? Where is the artistic creativity to be found? Unlike the traditional ‘paradoxes of time travel’, this problem has no solution.”

(Storrs McCall, “An Insoluble Problem,” Analysis 70:4 [October 2010], 647-648.)

Out of Bounds


If a game is anything, it’s a set of rules. And playing a game requires following these rules. If we take this definition seriously, then a cheater, one who breaks the rules, not only doesn’t deserve to win — he literally isn’t playing the game. University of Waterloo philosopher Bernard Suits writes:

The end in poker is not to gain money, nor in golf simply to get a ball into a hole, but to do these things in prescribed (or, perhaps more accurately, not to do them in proscribed) ways: that is, to do them only in accordance with rules. Rules in games thus seem to be in some sense inseparable from ends. … If the rules are broken, the original end becomes impossible of attainment, since one cannot (really) win the game unless he plays it, and one cannot (really) play the game unless he obeys the rules of the game.

So, strictly speaking, it’s impossible for a cheater to win a game — he can win only by following the rules. “In a game I cannot disjoin the end, winning, from the rules in terms of which winning possesses its meaning. I of course can decide to cheat in order to gain the pot, but then I have changed my end from winning a game to gaining money.”

(Bernard Suits, “What Is a Game?”, Philosophy of Science 34:2 [June 1967], 148-156.)

Foreign Relations


“Such a question as, Why does everything in Spain look Spanish? is one of those apparently idiotic questions that opens up quite unexpected areas of vision.” — Northrop Frye, “Spirit and Symbol,” Words With Power, 2008

Podcast Episode 127: Rowing Across the Atlantic


In 1896 two New Jersey clam diggers made a bold bid for fame: They set out to cross the North Atlantic in a rowboat, a feat that had never been accomplished before. In this week’s episode of the Futility Closet podcast we’ll follow the adventure of George Harbo and Frank Samuelsen, which one newspaper called “the most remarkable event in the way of ocean navigation that ever transpired.”

We’ll also meet some military mammals and puzzle over a thwarted burglar.

See full show notes …

A Premonition


First-Sergeant Thomas Innes Woods, of Company B, was killed on May 8th [1864]. The first time that Sergeant Woods was ever known to ask permission to leave his post on march or in battle occurred this day, after the Regiment’s all-night march to reach Spottsylvania ahead of Lee. When it became evident that a battle was imminent, Sergeant Woods asked Captain H.W. Grubbs for a pass to go to the rear. On his declaring that he was not sick, he was advised by the Captain that under the circumstances he could not be excused, and Sergeant Woods resumed his post at the head of the Company. Shortly after, during a halt by the roadside, Sergeant Woods wrote in his diary the following, addressed to his friend, Sergeant James A. McMillen: ‘I am going to fall to-day. If you find my body, I desire you to bury it and mark my grave so that if my friends desire to take it home they can find it. Please read the Ninetieth Psalm at my burial.’ He was killed early in the battle. His body was found by Sergeant McMillen and others of Company B, the diary being found in his pocket. His request for the Ninetieth Psalm to be read at the grave was complied with.

— Charles F. McKenna, ed., Under the Maltese Cross, Antietam to Appomattox: The Loyal Uprising in Western Pennsylvania, 1861-1865: Campaigns 155th Pennsylvania Regiment, 1910

Hope and Change


Canada’s “victory nickel,” struck from 1943 to 1945, included a special message to stimulate the war effort: Engraved around the rim were the words WE WIN WHEN WE WORK WILLINGLY in Morse Code.

The coin was reissued in 2005 to commemorate the 60th anniversary of V-E Day.

Hear Hear


Where is a sound? If I play a note at the piano, you and I both seem to locate it at the instrument. But we both also know that we perceive the note because the piano sends waves through the air that strike our ears. That would mean that most of our auditory perception is illusion. Is that what we want to say?

Philosopher George Berkeley wrote, “When I hear a coach drive along the streets, immediately I perceive only the sound, but from experience I have had that such a sound is connected with a coach, I am said to hear the coach.” Perhaps the sound lies at our ears, or at our sensation of it, and it’s only our experience of the world that leads us to attribute it to some remote source. But that raises problems of its own. If sound is sensation, then can a sound occur if no one is present to hear it?

Perhaps the answer lies in between: Acoustics tells us that sounds are vibrations transmitted by the air. But vibrations of very high or low pitch aren’t perceptible to human ears. Are these still sounds?

A similar puzzle concerns smells.

A Long Swim


Just an oddity — in Nature, June 5, 1919, Cambridge zoologist John Stanley Gardiner notes that a Fiji harbormaster had informed him of a saltwater crocodile that had landed alive on Rotuma, 260 miles to the north and 600 miles east of the New Hebrides.

“It certainly did not come from Fiji or any lands to the east, as crocodiles do not now exist on them,” Gardiner wrote. “It must indeed have crossed from the west, and covered at least 600 miles of open, landless sea.

“This occurrence is sufficiently remarkable to be placed on permanent record.”