Mechanical energy swing because of the work done by the pendulum to oppose these non-conservative forces. That the loss of mechanical energy in a system always resulted in an increase of the system's temperature has been known for a long time, but it was the amateur physicist James Prescott Joule who first experimentally demonstrated how a certain amount of work done against friction resulted in a definite quantity of heat which should be conceived as the random motions of the particles that comprise matter. This equivalence between mechanical energy and heat is especially important when considering colliding objects. In an elastic collision,
Feathers: The Evolution of a Natural Miracle "as synthesis goes, it is gracious, funny, persuasive and wide ranging." Peter Forbes, in a review published by "The Guardian", stated that Hanson's "enthusiasm is infectious", particularly for a topic Forbes found "alluring". "The Economist" published a review which also described Hanson as having "infectious enthusiasm" and stated, "Mr Hanson's unpretentious style makes what is essentially an excellent scientific work into an enjoyable read for the ignorant and uninitiated." Irene Wanner, in a review published by "The Seattle Times", highlighted Hanson's analogies, calling them "apt" and helping to "simplify complex concepts". "Kirkus Reviews" described "Feathers" as a "delightful ramble through