#255 Final light bulb moment
set by Zoe, Rob, Brian and friends
The Headscratcher team sat brainstorming ideas for the final problem in this iteration of New Scientist鈥榮 puzzle column. 鈥淲e should probably give it a seasonal flavour,鈥� said Brian. 鈥淪omething about festive decorations?鈥� said Rob.
鈥淲e could base it on the eight lights on my mantelpiece,鈥� said Zoe. 鈥淚鈥檝e programmed the one on the left to blink on and off every second. Each of the other lights also switches state every second, but only when all the lights to the left of that light are on.鈥�
鈥淪ounds complicated,鈥� said Alison. 鈥淣ot really,鈥� said Zoe. 鈥淎fter 1 second, light one switches on. At 2 seconds, light two switches on and light one switches off. At 3 seconds, light one switches on and light two stays on. Then light three switches on for the first time and the other two switch off, and so on.鈥�
鈥淪o, from the starting position of no lights being on, how many seconds is it before all eight lights are lit?鈥� asked the others.
And that, dear reader, is the final puzzle in the Headscratcher column. Watch out for New Scientist鈥榮 new puzzle column, BrainTwister, starting next week.
Solution next week
Quick quiz #232
set by Bethan Ackerley
1 The three parts of the hip bone are the ischium, the pubis and what?
2 One of the earliest written uses of the word "cryptograph" is found in which Edgar Allan Poe story?
3 In what year did the Carrington event, the most intense geomagnetic storm in recorded history, take place?
4 What name is given to organisms that thrive in environments with very few available nutrients?
5 In 1952, which two scientists used an axon from a longfin inshore squid to demonstrate the ionic mechanism of action potentials?
Quick quiz #232
Answers
1 The ilium
2 The Gold-bug
3 1859
4 Oligotrophs
5 Alan Hodgkin and Andrew Huxley