Original sentence: Also, sometimes physicists will discover "apparent" perpetual motion in thought experiments.Because the principles of thermodynamics are so well established, serious proposals for perpetual motion machines are met with disbelief on the part of physicists, which makes a discussion of the merits of the proposal difficult if not impossible.Physicists may try to test their knowledge of physics by proving, without using thermodynamics, that a proposed perpetual motion machine cannot work.Serious discussions of perpetual motion usually occur only when dealing with the topics of open systems, aether theories, free energy, and vacuum energy.Such "paradoxes" expose misunderstandings of the meaning of accepted physical theories and are considered quite instructive.There is a exceedingly remote chance that the accepted laws of physics are wrong, but a lot of evidence is needed to regeneralize these
Edited sentence: It is also generally accepted that talking about perpetual motion machines causes prejudices and a serious discussion cannot take place because of such prejudices.Serious discussions usually occur only when dealing with other topics (such as open systems, aether theories, and free energy).There is a exceedingly remote chance that the accepted laws of physics are wrong, but a lot of proof is needed to regeneralize these