A machine that can seemingly run with no energy supply – it is an idea that has already been obsessed over by many, including Leonardo da Vinci. The idea is known as perpetual motion. A perpetual motion machine is a device that performs its work without any external source of energy. As work is physically a form of energy in itself, this means that a perpetual motion machine would need to be able to create energy out of nothing.
Such a device, however, would violate the basic properties of our universe – principally the law of conservation of energy. This law states that in an isolated physical system (such as a perpetual motion machine) energy can neither be created nor destroyed; it can only change from one form of energy to another.
But there is also a “perpetual motion machine of the second kind”. This idea violates the second law of thermodynamics, which describes the direction that energy transformation takes and dictates that the most probable sequence of transformations always leads towards a state of greater disorder, or greater entropy. It follows from the second law of thermodynamics, therefore, that heat cannot be transferred from an area of lower temperature to an area of higher temperature if no work is performed.
The apparent instances of perpetual motion that emerge every now and then in reports today are of this second kind. They are not truly isolated systems and are often subtly connected with their surroundings, from which they draw energy. If they were to be completely isolated from the outside world, they would remain motionless.
Dr Susann Beetz answered this question on the basis of the column written by Prof. Ulrich Walter of the Technische Universität München for the N24 portal (http://www.n24.de/n24/Kolumnen/Prof-Ulrich-Walter-Wissenschaft/d/4419706/kann-es-ein-perpetuum-mobile-geben-.html).