Chas A. Egan, Charles H. Lineweaver calculated how run-down the universe is as things disappear into the ultimate run-down state of black holes (where you can’t do any work with what gets sucked in). Unlike previous calculations, they included freakishly big ones ( a billion times the mass of the sun) rather than the average (10 million times the mass of the sun) which account for most of its run down-ness: entropy.
The new results for entropy in Boltzmann units are: early universe (10^88); now (10^104); maximum (10^122).
(BTW entropy units are joules per kelvin – can someone remind me are the units of temperature itself, energy, or is it unitless)
Ron Cowen has a good summary of the paper at Science News, where he mentions the following:
“Entropy quantifies the number of different microscopic states that a physical system can have while looking the same on a large scale. For instance, an omelet has higher entropy than an egg because there are more ways for the molecules of an omelet to rearrange themselves and still remain an omelet than for an egg”.
Entropy is surely about macrostates vs microstates, if we had a name for a particular arrangement of molecules in an omelet, it would have high entropy. We don’t, there are many ways to smash an egg and still call it an omelet, so they are low entropy.
Does this mean that entropy is meaningless? No, but it means that it is relative to a particular system. The amount of potential work that can be done by system A on B depends not on some absolute measure of the free energy of A, but how much of that free energy is useful to B.
There is a relationship between the energy exchange between systems and information exchange, so the above paragraph could describe a relationship between two systems where the meaning of A was not absolute, but relative to B. One person’s high entropy omelet is another persons’ very special low entropy omelet with a name.