|Julius von Mayer, James Prescott Joule thermodynamics
Conservation of energy
In an isolated system, total energy is conserved, although it may be converted from chemical energy to kinetic, potential, heat, light, and sound.
Although not the first to discover the relation between heat and mechanical work, Julius von Mayer was the first to publish a clear quantitative relation between them, having discovered that in hotter weather his patients’ blood was a deeper red. * Meanwhile, James Prescott Joule built an apparatus that mechanically transferred gravitational potential energy of a weight into heat and kinetic energy of water churned by the weight.
Einstein showed the equivalence of energy and mass, and we now know that mass may be converted to energy; therefore, we speak of the conservation of mass-energy, except for systems without time translation symmetry, in which case even perpetual motion happens.
Potential energy Perpetual entropy Hypothesized ocean Actualized emotion Imperpetual motion Intellectual commotion