Richard Feynman’s Nontoxic Ant Ferry

RICHARD FEYNMAN, CALTECH’S Nobel Prize winning physicist (1965; quantum electrodynamics), was a Princeton University graduate student during the early years of World War II when foraging ants crawled in his bay window and spurred development of an ant control device that did not kill the creatures. It was not quite as momentous as the proverbial apple conking Isaac Newton on the head in 1666 and waking him up to gravity. But according to, Feynman’s “analysis of the behavior of ants involves some of the same ideas that were central to his work in theoretical physics.”

On a more mundane note, Feynman recounts the experience in his 1985 book, Surely You’re Joking, Mr. Feynman!: “In Princeton the ants found my larder, where I had jelly and bread and stuff, which was quite a distance from the window. A long line of ants marched along the floor across the living room. It was during the time I was doing these experiments on ants, so I thought to myself, ‘What can I do to stop them from coming to my larder without killing any ants? No poison; you gotta be humane to the ants!'”

Interesting sentiments coming from a man who worked on the Manhattan Project in New Mexico to help develop atomic energy into the bombs dropped on Japan to end World War II. But, of course, the goal of the Manhattan Project was to build the bomb ahead of Hitler’s scientists working in Europe. Peace and freedom were envisioned at the end of the atomic trail.

“One question that I wondered about was why the ant trails look so straight and nice,” wrote Feynman in his oft-reprinted 1985 book. “The ants look as if they know what they’re doing, as if they have a good sense of geometry. Yet the experiments that I did to try to demonstrate their sense of geometry didn’t work. Many years later, when I was at Caltech and lived in a little house on Alameda Street, some ants came out around the bathtub. I thought, ‘This is a great opportunity.’ I put some sugar on the other end of the bathtub, and sat there the whole afternoon until an ant finally found the sugar. It’s only a question of patience.”

Today we know that ants are putting down a pheromone trail, and that over time the trails most frequented (i.e with food at the end) get a stronger dose of pheromone while the pheromone disappears from the least-wandered trails. Feynman’s observations are called Ant Logic or Ant Colony Optimization by those who, in or out of the bathtub, today study the trail-following process, oftentimes using virtual ants in computer simulations for Internet routing, robotics, and business and travel solutions.

Apparently, via pheromone trails between their nest and food resources, in their everyday life ants have mastered a workable solution to what is called The Traveling Salesman Problem, which the web site of the same name (abbrev. TSP) calls “one of the most intensively studied problems in computational mathematics.”

Planning the best route between a hundred cities for a traveling rock band or the quickest path for sending data packets among thousands of Internet nodes on the Worldwide Web can apparently overheat and exhaust modern computers. In a chapter titled “Ant Logic” in The Perfect Swarm, book author Len Fisher says: “To calculate the optimal route that Ulysses might have taken between the 16 cities mentioned in The Odyssey, for example, requires the evaluation of 653,837,184,000 possible routes.” That works out to “ten thousand billion calculations” for a relatively simple travel problem.

Fortunately, Nobel Prize-caliber calculations were not needed to disrupt ant trails and humanely protect Feynman’s Princeton larder or Pasadena home. ANT FERRY was the name Feynman gave to his least-toxic ant removal device: “I made a lot of little strips of paper and put a fold in them, so I could pick up ants and ferry them from one place to another,” wrote Feynman in Surely You’re Joking, Mr. Feynman!.

“What I did was this: In preparation, I put a bit of sugar about 6 or 8 inches from their entry point into the room, that they didn’t know about. Then I made those ferry things again, and whenever an ant returning with food walked onto my little ferry, I’d carry him over and put him on the sugar. Any ant coming toward the larder that walked onto a ferry I also carried over to the sugar. Eventually the ants found their way from the sugar to their hole, so this new trail was being doubly reinforced, while the old trail was being used less and less. I knew that after half an hour or so the old trail would dry up, and in an hour they were out of my larder. I didn’t wash the floor. I didn’t do anything but ferry ants.”

No Nobel Prize is needed to obliterate ant trails and naturally protect larders without toxins or even killing any ants. However, the patience, the extra hour, may be outside the modern mindset. Nonetheless, thank you Mr. Feynman for what your colleagues call a PROOF of CONCEPT.


5 Responses to Richard Feynman’s Nontoxic Ant Ferry

  1. Milford Hufana says:

    I have been checking out many of your posts and it’s nice stuff. I will definitely bookmark your website.

  2. […] Richard Feynman’s Nontoxic Ant Ferry, dogs chasing birds away from trees laden with fruit or nuts is more a proof-of-concept awaiting […]

  3. Faz says:

    Ants farm aphids for milk – how cool is that! Feynman was also cool.

  4. […] fascinating. Unfortunately, unlike Richard Feynman, I haven’t had the time to set up Ant Ferries as a method of discouraging the ants from returning – my daughter and wife are patient, but […]

    • joelg5 says:

      A very thoughtful blog: on ants, algorithms et al. In a world where people are less in a rush, one could sit, think, meditate, reflect and perhaps like Feynman win a Nobel Prize. Perhaps a Peace Prize for letting humans and ant species share the same planet with less pesticidal warfare.

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