Q: Why be so critical? Those writers just failed to say that they or somebody
else was messing things up. What's this got to do with entropy?
A: That's not a minor omission! It's like a guy outside a bank telling you (as police were running toward you two), "Look at all this money that the nice bank teller shoved at me" and JUST FAILED TO SAY, "I had a gun pointed at him." Don't you think the gun had something to do with the money-shoving?
As I said a minute ago, reading statements like these in books gives many people who aren't as sophisticated as you a strange idea about entropy: it's a mysterious force that makes ordinary things jump around and is at work to mix up the world. That's total balderdash.. Every one of those authors was writing about the second law of thermodynamics and entropy
BUT "they left out the gun"!
That's most frequent error of scientific as well as popular writers -- even texts "leave out the gun" when they start talking about the ordinary world getting mixed up and "going toward disorder". It's people who mess up desks and dorm rooms (and much of the environment), it's hurricanes and tornadoes that tear houses and trees to pieces and scatter the bits; it's earthquakes that can even fracture a concrete freeway and topple a whole building. What's common to all those examples? Energy getting spread out, of course. Energy of ATP in human muscles, energy of air flow in hurricanes, energy of earth movement in earthquakes. As a result of those kinds of processes, solid things get scattered all over and mixed up. The objects do NOT, by themselves, become disordered or random. There isn't any "tendency of objects to become disorganized" in nature any more than bank tellers have a "tendency to give money to robbers" -- without a gun. Energy flow of many kinds is the driving force, the gun, for the world's macro objects becoming disorderly.
The reason so many authors make this mistake of saying "things are tending toward disorder" is their over-extending the basic behavior of internally energetic, mobile molecules and atoms all the way to totally immobile macro objects. We have already seen that those microparticles at 1000 miles an hour clearly tend to be as random and disorderly as they can be. But if they are "boxed" in static macro objects, whether in the stones of an Egyptian pyramid, or in the cardboards of a card deck in Los Vegas, or in the clothes and books and papers in a dorm room, they can't magically move those whole "boxes" they're in! Solid things, whether cards, stones or clothes, will stay exactly in the place that they are, at any moment in time, unless some adequate* energy flow from outside them forces them to move a little or a lot.
If the initial arrangement of things was in some pattern or orderly, when the things are forced to move they will be pushed to different places and become more disordered. Things don't have any tendency in themselves toward macro disorder; the energy flow that moves them is the cause of disorder. That's no indication that nature "doesn't like order". It's just that statistically there are many more billions (or quadrillions) of arrangements that are what we call "disorderly" than there are of the few dozens or hundreds that we call neatly patterned. A technical statement would be:
Whenever an adequate* amount of energy flows through a system of objects, it tends to scatter them. (The energy flow, if adequate*, can break bonds and disperse the resulting object parts.) They will be strewn to random, statistically probable locations consistent with all applicable factors of the objects and their flight paths or those for their fragments. In this process the concentrated energy in the energy flow becomes spread out or dispersed in imparting kinetic energy to the objects; its entropy is increased by such spreading out. Unless the original objects (or an appreciable part of them) are ground into a fine powder, their energy and their entropy contents are essentially unchanged a short while after the process of movement and scattering has stopped. (This time period allows any temporary heating effects to come to equilibrium with the local atmosphere after the energy flow ceases.)
*"Adequate" here means coupled (of the type and frequency that can interact with the object, necessary) and large enough to disrupt the existing arrangement of the object in its locale (sufficient).
Maybe the most dramatic example possible is what happens in a violent windstorm. After a tornado or a hurricane has devastated a town, the shattered houses and scattered wreckage are tragic sights. In seconds powerful winds have made random the most treasured and complex patterns that individuals have carefully created over many years. Ironically, the entropy change is not in all the shocking visible devastation. It is not in the destruction of our human patterns, not in their change from orderly things to disorderly things. The thermodynamic entropy change is invisible in the sense that it is in the dispersal of energy from the concentrated energy source -- the awesome whirling winds that have just passed have spread out some of their kinetic energy in spatially moving objects (an entropy increase in the winds) along with a lesser decrease (energetically) in temperature due to making the previously relatively calm air of the town more turbulent and it is slightly warmer.
—> Next <— Back Home —>> Last