by Shivam Panda
The laws of thermodynamics come together like a beautiful masterpiece, painted over a decade in the 1900s by a handful of legendary scientists.
Around 1850 Rudolf Clausius and William Thomson (Kelvin) stated both the First Law - that total energy is conserved - and the Second Law of Thermodynamics. The Second Law was originally formulated in terms of the fact that heat does not spontaneously flow from a colder body to a hotter. The third law, however, birthed the demon we now know the be entropy. But why a demon you ask?
In a series of letters written between James Clerck Maxwell and Peter Trait, Maxwell proposed a revolutionary machine. His machine, what we call a perpetual motion machine, would run on the energy it produces. Since it is perpetually in motion, we can build our applications around the system so as to ‘work perpetually’.
However, while physically creating such a machine, he found it in fact did not maintain its motion perpetually. This is when Robert Clausius theorized there was a demon, responsible for always dissipating certain amount of energy into an unusable form. This demon he named as entropy, meaning turning point in Greek.
Entropy was formalized by the father of thermodynamics, Sadi Carnot. He defined entropy as a measure of randomness. This randomness spawned from the evolution of unusable forms of energy, like the heat given off by a tirelessly working engine.
However, the heat used in, say, a steam engine, is not a form of entropy, as this energy does not leave the system and is hence use, in this case, to turn the wheels of a locomotive.
Entropy has since been described as the loos of energy from a system, the randomness of energy in a system, ‘negative’ gain (basically meaning loss) of energy in a system, et cetera. Even in a perpetual machine, there is loss of energy from the system due to friction, or force needed to overcome air resistance.
But how can you lose energy? Isn't it a universal truth that energy has to be conserved?
Well, when the word system is used, it is describing parameters within which the energy remains usable. A system which has a certain boundary described for it, is called an isolated system, meaning we are considering the situation as if there would be no external influence. If at all, there is an external influence, such as keeping a perpetual motion machine in motion by pushing it, then this force you apply is an external influence and hence making the system not isolated. Likewise, when we say ‘lost energy’ we talk about the energy that has been lost by the system, like the brakes warm up after some intense braking.
Whether you know it or not, the world around us is in a constant state of reaction. There are both physical and chemical reactions happening around you at the very moment you read this. There is continuous oxidization of nutrients within you, there is an exchange of gases around you and within you! One of the most important parts of our day is...the day itself. We need daylight for so many things, Vitamin D, plants produce their food thanks to it, the entire biosphere orients its body clock with the sun. But did you know, the reason you're getting all this sunlight and heat, is due to entropy?
Any star's energy production comes from combing two nuclei together. The energy expelled from one such reaction is used to initiate another such reaction, and so and so forth. This chain reaction does not last forever, however. Stars also die. And this is because every reaction in their core expels energy in the form of heat and light radiation. Now consider this. Stars lose their energy to their surroundings. The machines we use to lose their energy their surroundings. The energy we consume from the environment is lost again to the environment in our deaths. All the energy of every system is lost to its surroundings ultimately. Even the theoretical ‘perpetual motion machine’ comes to a stop eventually.
The ‘space’ we see at night, dark cold and lifeless, is nothing compared to what is to come. We see stars, sometimes planets maybe if we look closely, some constellations and distant galaxies. But cosmology, the study of the universe and how it changes through the passage of time, predicts much worse than the large spotted expanse of nothingness we see in the night sky. In a few TRILLION years, the last stars would have died out, leaving cold cores of highly condensed matter. All planetary systems would have been ripped apart by the expansion of the universe, and those still intact would be lifeless, with planets having exhausted cores, producing no more warmth. There will be no production of light and heat from stars, no live planets no galaxies forming, it’ll be an actual dark universe.
The degenerate era (no not the 1970’s) refers to this phase of the universes life. This is the most probable end to the universe. ‘The Thermal Death’ all energy will be randomized, unusable, and difficult to harness. One thing to remember is that even the era in which the big bang occurred, the universe was in a state of maximum entropy, so what may seem like the end, may actually be the start of something great and beautiful.
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