MAKE: Blog: Feynman and ants

Feynman and ants

800Px-Meat Eater Ant Feeding On Honey02
LanBo, the folks who distribute the gel-based ant habitats have a fun story about a DIY ant experiment from the famously curious physicist Richard Feynman -

"I wanted to see how long it would take the other ants to get the message to go to the 'ferry terminal'. It started slowly, but rapidly increased until I was going mad ferrying the ants back and forth." After a while, he started taking the ants from the sugar to a different spot. None of them went back to the original starting place, which would have returned them to the sugar. They followed one another, but not to the sugar.

Feynman did other experiments with ants. In one, he laid out glass microscope slides and got ants to walk back and forth on them to some sugar. When he rearranged the slides or replaced an old one with a new one, the ants got confused and couldn't figure out how to reach the sugar. "It was pretty clear, from rearranging the glass slides that the ants left some sort of trail." He concluded.

He tried to figure out whether the trail indicated which direction to take to the sugar or only that an ant had been on the slide already. He also wanted to know how long the trail lasted. "I tried at one point to make the ants go around in a circle, but I didn't have enough patience to set it up." He wrote.

More than ten years later, after he had worked on a number of important projects, including the Manhattan project, Feynman was still wondering about ants. He was frustrated because the experiments he had done to demonstrate the ants' sense of geometry had not worked. He still wondered, "Why do ant trails look so straight and nice?" By this time he was teaching at the California Institute of Technology.

Feynman and ants - Link.

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Comments

Oldest comments listed first.

Posted by: stm31415 on November 5, 2007 at 6:46 AM

Yay Feynman stories!

As I understand it, the lines are relatively straight because the ants leave pheromones both when leaving to find food and when returning with it. To see how that works, imagine a food source, A, and an ant-source, B.

B b' A

b''

C

An ant (b'') who travels through point C while looking for the food has to go further than an ant who goes straight (b') --- both on the way there, and on the way back. Pheremone trails decrease in strength over time; so the trail of the ant who comes and goes fastest will always be the strongest -- all subsequent ants will follow the path of b'!

The same ting will happen even if the difference in path-length is very small; so the path of b'' would eventually get ti's corners cut until it was straight, anyway.

No innate sense of geometry; just some neato emergent behavior.

Posted by: stm31415 on November 5, 2007 at 6:49 AM

Ooh. ASCII-art failed. Sorry!

Diagram:

B-------------------b'.....................A
..\
....\
......b''

.............C

Posted by: volkemon on November 5, 2007 at 3:43 PM

Feynman rocks. For anyone 'not in the know', he was a brilliant funny man.

WELL worth googling him...I will try to return with some links.

Posted by: Joel on January 14, 2008 at 9:40 PM

I would like to make an ant habitat in my daughters room. 4x8 lexan or plexi with gel 2 or 3 inches thick. Is this possible, any links?, better ideas?

Seems obvious that ants might use rudimentary pher trails now, but initial trails, social skills are important and fascinating. Thanks J.D.

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