thermodynamics - Connection between entropy and energy - Physics Stack Exchange
Why hot tea always cools down but never gets hotter by itself? Whether energy flows from a hot object to a cold one or vice-versa, energy remains conserved. The first law of thermodynamics asserts that energy is conserved during any process. The three Notice in Table 1 that the units for entropy, equation, require. The simulations we describe here establish a relationship between the Kolmogorov–Sinai entropy and the energy dissipated as heat from a NE.
It's easy enough to keep the temperature constant you make the change isothermally, i. It's also easy enough in principle to keep the entropy constant you make the change adiabatically and do it very slowly. But generally, in most practical situations, if you try to change one of the other variables you'll also end up changing the energy a bit as well.
For example, if you change the volume of a system you do work on it, and that changes the energy. But this is a mere practical issue - it's certainly possible in principle to change the entropy of a system without changing its energy. Thermodynamics is often thought to be mostly about energy, but when you really get down to it, the role played by energy is no different from that played by any other conserved quantity. Out of all the extensive quantities, the only really special one is the entropy, since it isn't conserved.
Why heat increases entropy (video) | Khan Academy
So for me, the above rearranged version of the fundamental equation is more fundamental than the "fundamental" one. Another, somewhat unrelated point is that entropy only increases over time on average. For very small systems there are fluctuations, which mean that the entropy can temporarily decrease all by itself.
But how can degraded energy, or its hierarchy, or the process of degradation be truly represented? There seems to be a contradiction between the first and second principles. One says that heat and energy are two dimensions of the same nature; the other says they are not, since potential energy is degraded irreversibly to an inferior, less noble, lower-quality form--heat.
Statistical theory provides the answer.
Entropy (energy dispersal)
Heat is energy; it is kinetic energy that results from the movement of molecules in a gas or the vibration of atoms in a solid. In the form of heat this energy is reduced to a state of maximum disorder in which each individual movement is neutralized by statistical laws.
Potential energy, then, is organized energy; heat is disorganized energy. And maximum disorder is entropy. The mass movement of molecules in a gas, for example will produce work drive a piston. But where motion is ineffective on the spot and headed in all directions at the same time, energy will be present but ineffective.
One might say that the sum of all the quantities of heat lost in the course of all the activities that have taken place in the universe measures the accumulation of entropy.
One can generalise further. Thanks to the mathematical relation between disorder and probability, it is possible to speak of evolution toward an increase in entropy by using one or the other of two statements: These equivalent expressions can be summarized: In breaking the vicious circle of repetitiveness in which the ancients were trapped, and in being confronted with biological evolution generating order and organizationthe concept of entropy indirectly opens the way to a philosophy of progress and development see: At the same time it introduces the complementarity between the "two great drifts of the universe" described in the works of Bergson and Teilhard de Chardin.
The image of the inexorable death of the universe, as suggested by the second principle, has profoundly influenced our philosophy, our ethicsour vision of the world, and even our art.
The thought that by the very nature of entropy the ultimate and only possible future for man is annihilation has infiltrated our culture like a paralysis.
This consideration led Leon Brillouin to ask, "How is it possible to understand life when the entire world is ordered by a law such as the second principle of thermodynamics, which points to death and annihilation?