PBS Space Time Season 2019 Episode 7 The Impossibility of Perpetual Motion Machines

PBS Space Time season 2019 episode 7, titled "The Impossibility of Perpetual Motion Machines," tackles the age-old idea of creating machines that can run indefinitely without the need for external energy input. Throughout history, many inventors and scientists have tried to build perpetual motion machines, but all have failed to achieve it. In this episode, host Matt O'Dowd explores the physics behind the concept of perpetual motion, why it is impossible to build such machines, and the consequences of violating the laws of thermodynamics.

The episode begins by discussing the Law of Conservation of Energy, which states that energy cannot be created or destroyed in a closed system. Therefore, any machine that runs perpetually would violate this law. O'Dowd demonstrates this by showing a toy with a wheel that spins indefinitely due to the shape of the wheel. However, the energy used to initially set the toy in motion comes from an external source.

Next, O'Dowd delves into the First Law of Thermodynamics, which describes the conservation of energy. The law states that the total energy in an isolated system remains constant. Any energy transfer within the system must come from or go to the environment. This law is crucial in understanding why perpetual motion machines cannot work. Any machine that creates energy out of nothing would violate this law.

Moving on, O'Dowd takes a closer look at the Second Law of Thermodynamics, which describes entropy. Entropy is a measure of how much energy is evenly distributed in a system, and it's always increasing. This law explains why heat always flows from hot to cold objects and why it's impossible to create a 100% efficient machine. O'Dowd explains that the more entropy within a system, the less energy there is available for useful work. Any machine that runs perpetually would violate the Second Law of Thermodynamics by reducing the entropy.

The episode then explores a famous example of a supposed perpetual motion machine: the Orffyreus Wheel. Johann Bessler, a German inventor, claimed to have built a wheel that could run indefinitely. He convinced many people of his invention's legitimacy, and some even gave him money to build more machines. However, he was eventually exposed as a fraud. O'Dowd examines the sophisticated mechanism behind the Orffyreus Wheel and shows why it could never run perpetually.

The episode concludes by discussing the consequences of violating the laws of thermodynamics. O'Dowd explains that humans rely on the laws of thermodynamics to survive. Our bodies are in a constant state of energy conversion, and violating these laws could have dire consequences. In the end, O'Dowd stresses the importance of understanding the laws of thermodynamics and how they apply to the physical world.

In summary, PBS Space Time season 2019 episode 7, "The Impossibility of Perpetual Motion Machines," provides viewers with a detailed explanation of the laws of thermodynamics and why it's impossible to build machines that run perpetually. The episode explores various examples of supposed perpetual motion machines, such as the Orffyreus Wheel, and explains why they all failed. O'Dowd stresses the importance of understanding the laws of thermodynamics and how they apply to the physical world, as they are crucial in our daily lives.