The U.S. Patent Office looks askance at claims for certain notorious inventions. Claims of anti-gravity engines and time machines automatically provoke skepticism.
In fact, claims like those provoke official skepticism. Under the law and regulations in the United States, the inventor must claim utility for the invention, and further must teach how to use the invention. Whenever a claimed invention appears to violate known scientific principles (for example, one that claims to yield more energy than it uses), the U. S. Patent Office may require demonstrative proof of the invention’s usefulness and of its operability, often requiring that a working model accompany the patent application.