The problem concerns what would happen if such a lawn sprinkler were submerged in water and water were sucked through it, flowing backwards. The possible outcomes are as follows: the sprinkler will spin forward; the sprinkler will spin backward; the sprinkler will not spin at all. There has been much debate in the past century over the solution. Feynman once attempted the experiment, "which ended in a minor catastrophic explosion". In recent years, the experiment has been performed many times, with air as the medium of the sprinkler, demonstrating that the "reverse" sprinkler does spin in the steady state. The University of Maryland also did the experiment on a very low friction bearing underwater and found that the sprinkler did indeed turn very slowly as if being sucked forwards. Although many experiments have been done, the scientific community still debates the validity of them because of the complex forces involved.