Andy, just to clear up one point of possible confusion–entropy isn’t a form of energy. Entropy measures disorder. Energy will flow spontaneously from systems at a high temperature (greater disorder) to systems at lower temperature (lower disorder) with a corresponding increase in the total entropy of the combined systems. You can’t get energy to go spontaneously from a high temperature to a lower temperature (as in a refrigerator) without doing work on the two systems from the outside. If the universe is finite (which I believe) and doesn’t expand to infinity, then eventually temperatures will equalize, black holes will swallow up all matter and the total entropy will get to its maximum value.
Yep. If I can pick a nit, which I think is really a profound point, on this:
I take it for granted given your background that when you say “Entropy measures disorder”, you mean, implicitly “Entropy measures
thermodynamic disorder”, and you assume your readers are making that connection. In practice, though, these kinds of explanations create all sorts of problems for readers who don’t make that connection.
It’s important to point this out because it steers complaints about entropy being at odds with biological development because they see biological structures as “ordered” in an complexity-sense, not a thermodynamic (energy available for work) sense.
You have likely heard the pedagogy of the “messy room”. A neat bedroom, with all the shirts folded, and hung on hangars, and all the socks matched and put neatly in drawers, and all the toys cleaned up and put in their bins, is “ordered”. But if we just let “life happen”, that room tends to become “disordered”, a mess, with toys on the floor, socks strewn about and the bed unmade. And this, it is offered, is an example of understanding entropy.
That’s actually a counterproductive example, as people then think (reasonably) that the bedroom going from neat to messy
is an example of disorder and a change in entropy in the technical sense. It is not, and the messy room with toys and clothes strewn about and a messy bed has no significantly different entropy than that same room in “perfectly neat” arrangement. If we burned both rooms completely and measured the heat we could generate from the incineration of both, we’d likely find nearly the same amount of extractable energy. That’s not a perfect test, but a valid one.
All of which to say, “disorder” is a VERY tricky word to understand. Scientists and researchers get it, because it’s a term of art they must use in technical applications. But for many of us non-scientists, we seize on the errant idea that disorder is something like going from a clean room to a messy one. Thermodynamic entropy is a tendency that goes one way in the aggregate, and in that narrow sense,we can say that a young boy’s room has a natural tendency towards messier (for most boys, anyway), but over and over again I find this becoming a problem for creationist thinking, the idea that “disorder” and “order” in the “macro arrangement” and non-thermodynamic sense has some attachment to the Second Law of Thermodynamics.
It doesn’t.
So I don’t disagree with anything you said (and it was well said) but wanted to add the stipulation that this is strictly applied to thermodynamics, not to the “order” of biological structures. I can feel the “a messy room is a rise in entropy” thing coming on, here – not from you, though.
-TS
