Is Gravity Entropy?

The New York Times yesterday had a curious science article suggesting that maybe one way that entropy manifests is as gravity; or, to put it another way, gravity may not be a fundamental force in the universe, but just another way that entropy appears to our experience:

Think of the universe as a box of scrabble letters. There is only one way to have the letters arranged to spell out the Gettysburg Address, but an astronomical number of ways to have them spell nonsense. Shake the box and it will tend toward nonsense, disorder will increase and information will be lost as the letters shuffle toward their most probable configurations. Could this be gravity?

I think I understand exactly what is being suggested, and I think I can put it in simpler terms: imagine that Kobe Bryant leaps to dunk a ball. Leaping to dunk a ball is an intentional act, like making your bed, or taking scrabble letters and spelling out the Gettysburg Address. When Kobe leaps to dunk a ball he moves (locally) from a high entropy state (that is, from a state that he doesn’t want) to a low entropy state (that is, to a state that he does want). But desired order that “goes up” must also “come down.” Over time, Kobe’s entropy will increase (that is, he will return to the floor) in the same way that a bed will go from made to unmade and a scrabble board will go from words to nonsense. In other words, there are a lot more ways that Kobe can be than in the air, just as there are a lot more ways that a bed can be than in the state of what we call “being made,” or that a scrabble board can be than in the state of spelling out the Gettysburg Address. Entropy is derived from the fact that there are a whole lot more ways for things to be “fucked” than “not fucked.” Or, as Yeats so sonorously and wryly put it in his 1921 poem, “The Second Coming”: 

Turning and turning in the widening gyre

The falcon cannot hear the falconer;

Things fall apart; the center cannot hold;

Mere anarchy is loosed upon the world,

The blood-dimmed tide is loosed, and everywhere

The ceremony of innocence is drowned;

The best lack all conviction, while the worst

Are full of passionate intensity.

That’s entropy. And Kobe’s landing somewhere on the court floor after a powerfully determined leap may be a manifestation of that.

Put still another way, gravity may be no more a separate law or force in the universe than that there is a separate law or force of unmade beds, or of scrabble letter dissolution. Kobe Bryant returning to the floor after a jump, ruffled bedspreads, and scrabble words coming undone when left to themselves may all be manifestations of one underlying law: entropy (the second law of thermodynamics).

Here’s how Dr. Erik Verlinde, one of the physicists suggesting that gravity might not be fundamental, puts it in the New York Times article:

Over the last 30 years gravity has been “undressed,” in Dr. Verlinde’s words, as a fundamental force. 

. . . What is new, he said, is the idea that differences in entropy can be the driving mechanism behind gravity, that gravity is, as he puts it an “entropic force.”

In other words, the gravity emperor has no clothes: it has been “undressed” and found to be something that is not fundamental. And Dr. Verlinde thinks that gravity has been exposed as entropy. It may thus be an increase in entropy that we witness when we see Kobe Bryant returning to the basketball court floor, not a law of gravity. 

Dr. Verlinde’s analogy is the kinking of hair on a humid day:

Dr. Verlinde’s argument turns on something you could call the “bad hair day” theory of gravity.

It goes something like this: your hair frizzles in the heat and humidity, because there are more ways for your hair to be curled than to be straight, and nature likes options. So it takes a force to pull hair straight and eliminate nature’s options.

I find this whole idea that gravity might be reduced to entropy fascinating, as it makes gravity no more real (in the ultimate sense) than a flat earth is real. In the 15th century it dawned on humans generally that the apparently flat earth was round; in the 21st century it may dawn on humans that what we take to be a mysterious law of attracting bodies is, in fact, just another manifestation of things going to shit; that is, of entropy.

Have a nice day (if you can). And as you walk about, watch your step. You might trip and fall.