HEFAT2014 10 th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics 14 – 16 July 2014 Orlando, Florida THE PERPETUAL PURSUIT OF PERPETUAL MOTION Ruiz, F. Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL 60616, USA, E-mail: ruiz@iit.edu ABSTRACT We all know that perpetual motion of the 1st or 2nd kind is impossible, but this has not deterred inventors from coming up with new ways to attain this dream. The US Patent Office, for instance, has granted several perpetual motion patents in recent history, against its long-standing policy. Perhaps one of the reasons for this is that inventors are getting more sophisticated. Unbalanced wheels and magnets are giving way to holograms, forcing scientists to make connections between fields that would not have been made otherwise. Perpetual motion of the Third Kind, which seeks to produce infinite exergy rather than infinite energy, has made its appearance, and it seems that new laws of Thermodynamics would need to be added in order to forbid it. This paper studies not only the "science" behind perpetual motion, but also the psychological and philosophical underpinnings of a pursuit that would not go away. INTRODUCTION The dream of perpetual motion has been pursued for as long as man has been able to control fire. Back in the VI century BC, the Greeks dreamed of inextinguishable fire, which would not need to be constantly fed through toil and drudgery. They formed this dream into the myth of Prometheus, a Titan who dared to steal that fire from Zeus himself [1]. As the endless motion of the planets in their orbits (whether around the earth or around the sun is immaterial) began to be discovered, people posited that perhaps it could be tied to something physical on earth, which therefore would no longer require a team of slaves to be maintained in motion. We know today this was not such a far-fetched dream, since this is precisely what tidal power plants do [2]. The ancient mind does not seem to have been averse to the concept of perpetual motion. Aristotle, for instance, conceived of a “primum movens” (ὃ οὐ țȚȞούȝεȞοȞ țȚȞεῖ, in ancient Greek), which provides power for keeping the universe in motion without in turn needing to be powered by anything else [3]. This state of mind continued throughout the Middle Ages. Copernicus seems to have accepted this concept as the source of motion of the planets, though not necessarily as the prime mover of everything that is [4]. This is because medieval theology, and St. Thomas Aquinas in particular, had appropriated the concept of primum movens as an attribute of God himself [5]. This does not mean, however, that machines implementing these ideas were in active development since the power requirements of the time were rather modest. We have to come to the early XVI century and Anthony Zimara to find a theoretical attempt at devising such machine by causing a windmill to drive the bellows that create the wind moving the windmill itself [6]. As Renaissance gave gradual way to Enlightenment, proposals for perpetual motion machines multiplied. These machines can be roughly classified into three groups, depending on the physical principle purportedly harnessed: 1. Water running uphill (or air blowing upwind) 2. Unbalanced wheels and pendulums 3. Magnetic machines These three groups correspond to the forces that were known at the time, before they were quantified and subject to calculus (which had not been yet invented). The machines in the first group implied that a waterwheel could make enough power to run pumps that in turn would raise the water back to its initial height. Those in the second group made use of the fact that a balance would shift if more weight is placed on one plate than on the other; the trick was to move weights between plates in a clever way, much like a cartoon character avoids crashing into the ground by stepping out of a falling elevator in the nick of time. Finally, the mysterious ability of magnets to attract or repel other bodies, often acting against gravity, was too tempting to be left alone. I am not going to provide even a summary list of the machines that were devised, often in good faith, during those three centuries. You can find an excellent account, for instance, in “Perpetual Motion, the History of an Obsession,” by Arthur Ord-Hume [6]. Webpages exist that collect a number of such