There is a popular youtube video of some metal beads being thrown out of a flask, literally hovering out of the container

My question is how detailed a physical explanation of this phenomenon we have?

Question: More precisely, if we used the best available mechanical physics simulator software, and we tried to simulate this behavior, would the software be able to reproduce the effect or not? My guess is not but I would like to know why not.

Or do we have to content ourselves only with handwaved explanations? I am from the school of thought that you don't understand physics until you have a reasonable certainty that you can reproduce the physics in a computer.


It turns out that this is a subject of a recent paper in Proceedings of the Royal Society A and the paper is open access so you can read it for free.

The gist is that the chain isn't really best modeled as a chain but as a linked set of rods. The authors conclude that not only is the chain pulled down by gravity, but it is also being pushed up by the container -- this upward force is what causes the chain to "leap" out of the container. It turns out that the fountain height above the container is linear with the height of the drop. They test their model numerically and get good results.

As a final point, I would take issue with the notion that we cannot understand physics until we can reproduce it in a computer. There could be countless reasons why we can't reproduce something in a computer that have nothing to do with our own understanding of the universe but are instead due to resource limitations. Einstein had no access to computers to reproduce anything in, but it would be hard to say he did not have an understanding of the physics he pioneered.

  • 2
    $\begingroup$ Indeed. And the converse of the last statement also holds: If you put all the laws of physics into your computer and run a perfect simulation that's correct in every detail without worrying about approximations or such, then have you really learned anything at all? $\endgroup$ – user10851 Oct 2 '14 at 0:03
  • $\begingroup$ @ChrisWhite I didn't want to get into philosophy about it, but I don't think we can really use simulations to prove or disprove anything about the universe. At best, we can find results that go against a hypothesis or results that go with it. Which I suppose can be true about experiments as well... science is hard... $\endgroup$ – tpg2114 Oct 2 '14 at 0:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.