"One of the most profound laws of Universe is the law of conservation of energy that always holds true. There is a fact, or if you wish, a law, governing all natural phenomena that are known to date. There is no known exception to this law-it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call energy, that does not change in manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says that there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or anything concrete; it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same." - Richard Feynman, Nobel Physics laureate and a celebrated physicist.
The concept has been beautifully put forth by one of the most renowned physicists of the last century, Richard Feynman, in the above lines. In fact, describing the concept of energy is a fairly simple task, as it is an integral part of the universe, it's an inseparable part of life. Without energy, there is no existence of the universe. Energy is manifested in every walk of life. Be it supersonic jet planes or merely riding a bicycle, energy is manifested in every act we do.
What is the Law of Conservation of Energy?
The development of numerous theories related to 'energy' occurred in the 19th century, when legends like Lord Kelvin, Rudolf Clausius, and Walther Nernst conceptualized numerous thermodynamics laws that triggered the rapid acceptance of energy to explain numerous chemical processes. Moreover, energy was also established as a mathematical entity after Clausius formulated the law of Entropy. A simple definition would be that, energy can neither be created nor be destroyed, but it can be transformed from one body to the other. This is perhaps the simplest definition of energy conservation that we were taught in our school physics classes.
In higher physics, understanding the energy conservation law could be a bit challenging, owing to numerous other fundamental laws that govern the entire law. Most notably, the Noether's theorem that is on the basis of modern theoretical physics. Discussing the energy conservation law in the light of higher physics is not possible in the limitations of this article; however, the basic essence of conservation law remains the same, being that energy can only be transformed from one body to the other, but cannot be destroyed. For instance, the gravitational potential energy stored in a dam is converted into kinetic energy in the form of moving water, or the chemical energy in a battery is converted into electrical energy. All these are perfect examples of conversion of one form of energy into the other. Even mechanical energy, that is the kinetic and potential energy, always remain conserved in an isolated system. The law of conservation of mechanical energy is based on similar lines, just like the energy conservation laws. Even mass is related to energy, and this revolutionary theory was put forward by the genius Albert Einstein, who gave the mass energy equivalence theorem or E = mc2. Is there any specific law of conservation of energy equation? Well, depending on the system we're considering, there are numerous energy conservation equations. In mechanics, thermodynamics, relativistic mechanics, we've different energy equations, which require one to define the kinetic and potential energies of the respective systems. The most generalized form of energy conservation equation is,
E = T + V, where T = Kinetic Energy, V = Potential Energy and E = Total energy of the system.
In higher physics, there are numerous conditions on this law. In essence, the fact is that, energy conservation is a universal law, and it amazes physicists about the precision of nature's law. They're true in every context and do not change over time.