Second Law of Thermodynamics

Some independent research from one of our RGS Physics pupils:

the second law

All natural and technological processes proceed in such a way that the availability of the remaining energy decreases. In all energy exchanges, if no energy enters or leaves an isolated system, the entropy of that system increases. Energy continuously flows from being concentrated, to becoming dispersed, spread out, wasted, and useless. New energy cannot be created and high-grade energy is being destroyed. An economy based on endless growth is unsustainable.

– Muse, ‘Unsustainable’

The Muse album ‘The 2nd Law‘ is named for the second law of thermodynamics, and while it would be easier to explain hidden meanings behind this album title, I’m meant to be writing about physics.

The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems spontaneously evolve toward thermodynamic equilibrium—the state of maximum entropy. This definition immediately throws up some questions, namely what do all the funny words mean?

Starting at the beginning, thermodynamics is the branch of physical science concerned with the interrelationship and interconversion of different forms of energy and the behaviour of systems in terms of basic quantities such as temperature and pressure (Collins English Dictionary). And that is as simple as it seems to get. Results of thermodynamic calculations are essential for fields of physics and chemistry.
According to, Entropy is a function of thermodynamic variables, such as temperature, pressure or composition, that is a measure of the energy that is not available for work during a thermodynamic process. An increase in entropy means that the quantity of energy that cannot do work increases. Entropy describes the limitations on the amount of thermodynamic work that can be delivered to an external system by a thermodynamic process.
An isolated system is one where no matter nor energy can enter or exit. The only possible known isolated system in existence is the universe, therefore they are hypothetical concepts and not actuality.


When an isolated system reaches thermodynamic equilibrium there can be no changes in energy or matter, meaning that all the energy in the system is unavailable for work. There is no net flow of matter or energy, no phase changes and no unbalance potentials. This is like an electrical cell that has been discharged. Within the cell itself there is energy however it is not useful as it cannot be converted into electrical energy and it is difficult to extract, similar to an isolated system.

Following the principles through leads you to the conclusion that if the universe truly is an isolated system, at some point or another in time the whole universe will reach a state of thermodynamic equilibrium as every last star converts its supply of hydrogen, flickers and fades into darkness. Obviously this would take billions upon billions of years to happen but it is theoretically possible.

Thermodynamics is a complicated and confusing area and I don’t think I could understand it to its fullest extent yet, and now as an added bonus I’ve picked holes in my previously ignorant taste in music.

Collins English Dictionary


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