8 Super Simple Ways To Explain Complicated Science

8. Entropy = Tangled Headphones

The Tricky Bit Entropy is a principle of thermodynamics used to measure the number of microstates in a thermodynamic system. One of the main things we hear about entropy is that the second law of thermodynamics forbids the entropy of an isolated system from decreasing. That is, in an isolated system, the number of microstates can only ever become more, not less. The Simpler Way People are often tempted to think of entropy as an unstoppable march towards disorder, but actually, a better way to think about it in terms of probabilities and nature's preference to adhere to the most probable outcome. A pair of headphones are a great example. It is a well-known first world problem that, no matter what your headphones look like when you put them in your pocket, they will have tied themselves in knots by the time you take them out. This is nothing to do with them "willfully" becoming more disordered, it's just that, whilst there is one way for them to be "ordered" (i.e. untangled) there are a probable infinite ways of them being tangled. Therefore, the probability of them remaining untangled is miniscule. Another way to think about it is to imagine that I'm feeding you through a woodchipper. In your "pre-woodchipper" state, you are made up of a certain configuration of molecules that makes you, "you". In your "post-woodchipper" state, there are an infinite number of ways that you can be "not you", but only one way that you can. Equally, I can't feed your mangled remains through the woodchipper in reverse and get you back, because that would mean a decrease in entropy. Of course, it is technically possible that the woodchipper will spray out your molecules into a perfect "you" shape, but the chances against it are so astronomically minute that you're much more likely to remain a "not you" pile of pulp.