The search of a perpetual motion machine has kept inventors occupied for centuries comment on this statement.

Explanation

For centuries, scientists have been trying to fabticate machines which can generate perpetual motion. The statement is perfectly true. However, their attempts have not met with success so far. Theoretically, there can be generally be three types of perpetual motion machines:
(i) A machanism which would produce machines with efficency more than 100%. This would violate first law of thermodynamics.
(ii) A device that would extract heat from a source and convert it completly into other forms of energy. For example, an ocean liner that uses from the ocean in populsion. This would violate the second law of thermodynamics.
(iii) A meachanism by which energy dissipation could be eliminated cent per cent. superconductors provided a genuine example of this type. When some current is made to flow through a superconductor, energy loss is zero and it would keep on flowing undiminished. But the current can do not work? so all the attempts are futile.