The Mystery

Lateral thinking is a powerful tool for solving seemingly unsolvable problems or mysteries. The kernel idea behind is consciously letting loose of any unconscious prejudice and bias, and considering all logically possible scenarios and options when analyzing the problem, notably including even the highly improbable ones.

Please  consider the following mystery from the book “The Pilot Who Wore a Dress: And Other Dastardly Lateral Thinking Mysteries” by Tom Cutler:


The Scenario

Bob and Jim are brothers. Bob was born in Hastane Maternity Hospital, near Drumroos in Scotland, at 8.15 a.m. on April Fools’ Day 1976. Jim was born in the same place, just seven minutes later. Their mum remembers the day not only because of the happy occasion of their births but because of the Jovian-Plutonian gravitational effect that astronomer Patrick Moore reported would happen that day. Jupiter is the largest planet in the solar system, with a mass of about two and a half times that of all the other planets glued together. Pluto on the other hand is so small that in 2006 it was reclassified as a dwarf planet. Moore told listeners to BBC radio that as Pluto passed behind Jupiter at 9.47 that morning, a powerful combination of the two planets’ gravitation would decrease the gravity on Earth. People were told that if they jumped in the air at exactly the right time they would stay up longer than normal and briefly feel as if they were floating. Shortly after the appointed time hundreds of listeners telephoned the BBC to report that they had indeed felt the effect. One woman said that she and some friends had been ‘wafted’ from their chairs and ‘orbited gently around the room’. Not that you cannot orbit around a room when you’re inside it, but never mind. Of course, the whole thing was an April Fools’ hoax by the mischievous Patrick Moore. Although Jupiter is very massive it is also a very very long way away. At its closest to Earth the planet has a gravitational pull only about the same as that of a Renault Twizy on an old man standing a couple of feet away. The gravitational attraction of Pluto is even less. It’s about the same as a marble 100 yards away from you. Which means that even the combined gravity of the two distant planets is far too small to cause a person to become lighter or float while jumping. It’s a good job that gravity is such a weak force, or the gravitational pull of Bob and Jim’s obstetrician would have caused the tide to go out in their mum’s cup of tea.


Problem to Solve

Jim and Bob were born at the same place in the same hour of the same day of the same month of the same year, and to the same mother. Yet they are not twins. How can that be?

Juerg Gutknecht
A propos Juerg Gutknecht 29 Articles
Jürg Gutknecht started his professional career in Computing when he joined the real-time systems programming group at Swissair. From 1970 and while being employed by IBM as a working student, Gutknecht studied Mathematics at the ETH Zurich, from where he graduated in 1977 with a PhD. After an employment as a professor of Mathematics at the Kantonsschule Heerbrugg in the Swiss Rheintal, Gutknecht joined Niklaus Wirth’s Lilith/ Modula research team in 1981 and, in 1985, after a sabbatical stay at the Xerox-PARC Research Laboratory in California, he was appointed Assistant Professor and later Full Professor of Computer Science at ETH. Together with Wirth, Gutknecht developed the Oberon programming language and the Ceres personal workstation. His esearch interests are in the area of programming languages, compilers, concurrency and component-oriented systems design.

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