Second Law Of Thermodynamics

Heat will not flow spontaneously from a cold object to a hot object. That really is it. Except if you stop and think about it enough, you realise what it implies: everything - you, me, atoms, the world, the universe - is running down, dying, heading towards the Heat Death?, and there's nothing that can be done about it.

• http://www.secondlaw.com/
• http://www.2ndlaw.com/ continued
• http://www.entropylaw.com/
• http://www.cchem.berkeley.edu/~chem130a/sauer/outline/secondlaw.html
• http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html
• http://timothyplatypus.tripod.com/FaS/anotherhat_first.html song
• http://www.theonion.com/onion3631/christian_right_lobbies.html 'Christian Right Lobbies To Overturn Second Law Of Thermodynamics'

(Further to the above the Second Law of Thermodynamics was abolished in the Soviet Union between the 1940s and 1960s....)

The law can alternatively be phrased as 'entropy cannot decrease', but that definition requires a definition of entropy, which is a bit tedious.

"The supreme law of nature." -- Arthur Eddington

Those who eagerly read the first and third laws of thermodynamics will be a bit disappointed - the first is really just a prequel to the second, and the third is the typical third-in-a-trilogy, being some hopelessly boring rubbish about the entropy of a crystal at absolute zero.

The second law is nice because once you understand it, it's just obviously true; it just says 'things which can't happen don't happen'. It's a bit like the Turing-Church thesis, which basically says 'all computable functions can be computed'.