Short answers, pulled from the story.
James Prescott Joule performed his experiment in 1845 to prove that heat is a form of energy generated by mechanical work. His paddle-wheel apparatus demonstrated that a descending weight could rotate a paddle in water, raising its temperature and establishing a precise link between mechanical work and thermal energy.
William Rankine coined the term potential energy by the 1850s. This development occurred alongside the formalization of thermodynamics by William Thomson, later known as Lord Kelvin, which created a mathematical framework for understanding energy.
Green plants capture radiant energy from the Sun through photosynthesis and convert carbon dioxide and water into carbohydrates, lipids, and proteins. They store this energy as chemical potential energy within their biological structures.
Albert Einstein proposed the formula E equals mc squared in 1905 to quantify mass-energy equivalence. This equation reveals that 1 kilogram of rest mass equals approximately 9 times 10 to the 16th joules, which is equivalent to 21.5 megatonnes of TNT.
Emmy Noether established Noether's theorem in 1918 to prove that the conservation of energy is a direct mathematical consequence of the translational symmetry of time. This theorem demonstrates that because the laws of physics do not change over time, energy must be conserved.
The second law of thermodynamics states that the system doing work always loses some energy as waste heat, creating a limit to the amount of heat energy that can do work in a cyclic process. This law leads to the hypothesis of the inevitable thermodynamic heat death of the universe where energy is evenly distributed and no work can be performed.