Perpetual Motion Machines

 What are Perpetual Motion Machines?

A perpetual motion machine is a theoretical machine that can do work indefinitely without an energy source. So basically, it is an infinite energy source. It is impossible for these machines to operate in the real world as they would violate the first or second law of thermodynamics, but more on that later.

Why do we need perpetual motion?

A machine that can sustain motion without any input has been the greatest dream of engineering. Just imagine if a machine that produces more work than inputted. We could use a small one to power a bigger one and so on, and so on, and so on. We could start with a grain of sand and would be able to rotate the whole earth around.

Some examples: 

One such example is the Bhāskara's Wheel which was invented in 1150 by an Indian mathematician, Bhāskara II. He tried to create a hypothetical perpetual motion machine. His plan was to make an overbalanced wheel that would continuously fall over itself, causing it to roll continuously. His variation consisted of curved or tilted spokes partially filled with mercury.  Once in motion, the mercury would flow from one side of the spoke to another, forcing the wheel to continue the motion, in constant dynamic equilibrium.

There are many different types of this unbalanced wheel, some use heavy balls as the weight, and some use long rotating spokes     

Another such machine is the Capillary Bowl, also known as the self-filling bowl— which theorizes that the capillary action would keep water flowing in the tube. However, since the cohesion force that draws the liquid up the tube holds the droplet from releasing into the bowl, the flow is not perpetual. 

Other examples can be a:

1. Self-powering windmill, which comprises a windmill using its own wind energy to rotate the windmill again forever.

2. Self-powering lamp, which would use its own light to power a solar panel which powers the lamp again forever.
   

3. Self-flowing waterfall, which uses waterfalls' potential energy to rotate a turbine which in turn pushes the water up against the waterfall forever.
   

4. Self pulling car, which uses a magnet to pull itself forward forever
   

In theory, all of these ideas and examples look possible, but as we go deeper, they get impossible. 

Why are these machines not possible?

To understand why these machines are not possible, we will have to learn about thermodynamics. Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. In particular, it describes how thermal energy is converted to and from other forms of energy and how it affects matter. There are four laws of thermodynamics in total, but for the sake of simplicity, let’s look at the 1st and the second one as perpetual machines mainly violate them.

The first law of thermodynamics says that, in a closed system, energy can neither be created nor destroyed and can only change its form, i.e. being conserved.

The Second Law of Thermodynamics says that processes that involve the transfer or conversion of heat energy are irreversible. The Second Law also states that there is a natural tendency of any isolated system to degenerate into a more disordered state. So in simple words, It states that as energy is transferred or transformed, more and more of it is wasted. This means, there can never be 100% efficiency and therefore no infinite energy source.

So how do perpetual machines violate these laws?

A perpetual motion machine that produces work without the input of energy, means 100% efficiency. This kind of perpetual machine would have energy that is never wasted and never degenerate into a disordered state, thus violating the second law. Additionally, the more energy is transformed, the more of it is wasted. Another type of perpetual motion machine does more work than putting in, i.e. more than 100% efficiency. In other words, it would get something from nothing. It thus violates the first law of thermodynamics: the law of conservation of energy.

 

Therefore a perpetual motion machine is not only impossible but also implausible.

 

Thus the only thing perpetual is stupidity.