In 1159 A.D., a visionary mathematician named Bhaskara the Learned sketched a design for a wheel that contained curved reservoirs filled with mercury. He theorized that as the wheel spun, the mercury would flow to the bottom of each reservoir, creating an imbalance that would keep the wheel turning indefinitely. This concept was one of the earliest designs for a perpetual motion machine—a device capable of performing work endlessly without any external energy source.
Imagine a windmill that generates the breeze it needs to keep rotating or a lightbulb that powers itself. Such devices have long captivated inventors because they promise to revolutionize our relationship with energy. A perpetual motion machine that includes humans as part of its perfectly efficient system could, in theory, sustain life indefinitely. However, the harsh reality is that these machines don’t work.
Perpetual motion machines violate fundamental laws of thermodynamics, the branch of physics that describes the relationship between different forms of energy. The first law of thermodynamics states that energy cannot be created or destroyed. This means you cannot extract more energy from a system than you put into it, ruling out the possibility of a useful perpetual motion machine from the start. A machine could only ever produce as much energy as it consumed, leaving none to power external devices like cars or phones.
Despite this, inventors have proposed numerous ideas, many of which are variations on Bhaskara’s over-balanced wheel, featuring rolling balls or weights on swinging arms. None of these designs work because the moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle. This results in the wheel swinging back and forth like a pendulum until it stops.
In the 17th century, Robert Boyle suggested a self-watering pot using capillary action to keep water cycling around a bowl. However, if the capillary action is strong enough to overcome gravity and draw the water up, it would also prevent it from falling back into the bowl.
Other designs involve magnets, such as a set of ramps where a ball is supposed to be pulled upwards by a magnet, fall back down through a hole, and repeat the cycle. This fails because the magnet would simply hold the ball at the top. Even if it did keep moving, the magnet’s strength would degrade over time, eventually stopping the motion.
Even if engineers could design a machine that didn’t violate the first law of thermodynamics, it still wouldn’t work in the real world due to the second law. This law tells us that energy tends to spread out through processes like friction. Any real machine would have moving parts or interactions with air or liquid molecules that generate friction and heat, even in a vacuum. This heat is energy escaping, reducing the energy available to move the system until the machine inevitably stops.
So far, these two laws of thermodynamics have thwarted every idea for perpetual motion and the dreams of perfectly efficient energy generation they imply. Yet, it’s difficult to conclusively say we’ll never discover a perpetual motion machine because there’s still so much we don’t understand about the universe. Perhaps new exotic forms of matter will force us to revisit the laws of thermodynamics, or maybe perpetual motion exists on tiny quantum scales. What we can be reasonably sure about is that we’ll never stop searching. For now, the one thing that seems truly perpetual is our quest for perpetual motion.
Using materials available at home or in the classroom, try to design and build your own version of a perpetual motion machine. Document your design process, the principles behind your machine, and the challenges you encounter. Present your findings to the class, explaining why your machine does or does not work according to the laws of thermodynamics.
Conduct an experiment to demonstrate the first and second laws of thermodynamics. For example, you could measure the energy input and output of a simple system like a battery-powered motor. Record your observations and explain how they align with the laws of thermodynamics. Share your results in a lab report.
Research a historical attempt to create a perpetual motion machine. Choose an inventor or a specific design and create a presentation that includes the historical context, the design details, and why it ultimately failed. Discuss how this attempt contributed to our understanding of physics and thermodynamics.
Participate in a classroom debate on the topic: “Will we ever discover a true perpetual motion machine?” Prepare arguments for both sides, considering current scientific understanding and potential future discoveries. Use evidence from the article and other reputable sources to support your points.
Write a short story or essay imagining a world where a perpetual motion machine has been successfully created. Describe the impact on society, technology, and daily life. Consider both the positive and negative consequences of such a discovery. Share your story with the class and discuss the implications.
Perpetual – Continuing indefinitely without interruption. – The concept of a perpetual motion machine defies the laws of physics, as it would require energy to be created from nothing.
Motion – The change in position of an object over time. – The motion of the planets around the sun is governed by gravitational forces and can be described using Kepler’s laws.
Thermodynamics – The branch of physics that deals with heat and temperature and their relation to energy and work. – The laws of thermodynamics explain how energy is transferred and transformed in physical systems.
Energy – The capacity to do work or produce change. – Kinetic energy is the energy of an object in motion, which can be calculated using the formula KE = 1/2 mv².
Machine – A device that uses energy to perform work, often by changing the direction or magnitude of a force. – A simple machine, like a lever, can make it easier to lift heavy objects by distributing the effort over a longer distance.
Gravity – The force that attracts two bodies toward each other, proportional to their masses and inversely proportional to the square of the distance between them. – The gravity of Earth keeps us grounded and affects the orbits of satellites around our planet.
Friction – The resistance that one surface or object encounters when moving over another. – Friction between the tires and the road is crucial for vehicles to stop safely and change direction.
Design – The process of creating a plan or drawing to show the look and function of an object before it is built or made. – Engineers must carefully design machines to ensure they operate efficiently and safely under various conditions.
Inventor – A person who creates or discovers a new method, idea, or product. – Thomas Edison, a famous inventor, developed the electric light bulb, which revolutionized the way we use energy.
Universe – The vast, all-encompassing space that contains all matter, energy, planets, stars, galaxies, and the contents of intergalactic space. – The study of the universe helps scientists understand the origins of cosmic structures and the fundamental laws of physics.
