28 February 2010
Maxwell's demon: Hoyle's steady state
As an inevitable extension of this law, cosmologists speak of the "heat death" of the cosmos, in which what is left of the world is mostly nothingness, punctuated perhaps by whatever irreducible particles may remain, which simply drift further and further away from one another, without interaction, without heat, and of course without life.
If the world has that as an end, then presumably the world also had a beginning. The law of entropy naturally suggests the cosmogony of the Big Bang -- though as a matter of the history of science there was a period of contention as that implication worked itself out. Most notably, Fred Hoyle, Thomas Gold, and Hermann Bondi developed an elaborate steady-state theory in the 1940s, that would accomodate the expanding universe by having new matter pop into existence, so that the density of the universe remains constant over time. According to this theory as they and others developed it through the 1950s and 1960s, the new matter would be mostly hydrogen, and would be in such small amounts that it would not be directly detectable: roughly one hydrogen atom per cubic meter per billion years, with roughly five times as much dark matter.
Such a creation rate, however, could allow for the fact that all human-scale observations support the second law, while it allows for a subtle re-setting of the clock of time on the Big Scale involved, re-creating the differences, the disequilibria, that the unchecked operation of the 2d law of thermodynamics would destroy.
How did matter pop into existence, on that scale or any other? From a philosophical point of view, Hoyle etc. replied that this question is not more or less difficult than "how did the Big Bang happen"? One begs the universe all at once, or one begs it in pieces over the everlasting run of time. We are beggers in the matter of Being in either case. It is simply the old "why is there anything rather than nothing?"!
Yet this atoms-popping-into-existence stuff makes for an unattractive theory without more. That (perhaps even more than the background cosmic radiation, which has been called the echo of the Big Bang but could well have other explanations) has been the real drawback. If the popping is supposed to take place within the observable universe, it should be ... well ... observable.
Consider a thought experiment that goes back to one of the greatest physicists in history. James Clerk Maxwell spoke of a hyptothetical "demon" who could defeat the 2d law:
"If we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are as essentially finite as our own, would be able to do what is impossible to us. For we have seen that molecules in a vessel full of air at uniform temperature are moving with velocities by no means uniform, though the mean velocity of any great number of them, arbitrarily selected, is almost exactly uniform. Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower molecules to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics...."
Notice that Maxwell is not bringing God into the picture here -- he is thinking as a secular scientist, and is specifying that the demon is as "essentially finite" as we are. But the demon works at a different level, a micro-level.
Notice also that while Hoyle et al sought to limit the Second Law to the human scale by escaping toward a much Bigger Picture, where humanly undetectable violations thereof can become important ... Maxwell follows the opposite strategy. He seeks to limit the Second Law to the human scale by escaping toward a much Smaller Picture, where an intelligent being can work molecule by molecule.
And now we bring in nanotechology, the development of a molecule-by-molecule, indeed atom-by-atom, variety of engineering accoring to which humans may yet create robots that can in term act as does Maxwell's hypothetical demon.
Ah, am I suggesting, by making this connection, that humans have a cosmic role to play by inventing Maxwellian demons that will enable the cosmos to avert heat death? No ... not exactly. That would have an unnecessarily arrogant sound to it. There is no reason to believe that life exists only on this planet, or that the intelligent beings here have a unique role.
Perhaps through the everlastingness of time, intelligent creatures have developed on myriad planets, and that in many of these cases they reach a point at which they develop a nanotechnology capable of beating the 2d law in their localities. And perhaps, the collective effect of all these independent nanotechnological/civilized planets is to keep re-setting the clock. Perhaps intelligent life on sporadically located planets has the same effect that Hoyle sought to model through this random popping into existence of hydrogen atoms he hypothesized.
The alliance of Hoyle and Maxwell moves in both directions at the same time, for the tiniest of scales may give us a crucial clue to what is happening on the largest.
Knowledge is warranted belief -- it is the body of belief that we build up because, while living in this world, we've developed good reasons for believing it. What we know, then, is what works -- and it is, necessarily, what has worked for us, each of us individually, as a first approximation. For my other blog, on the struggles for control in the corporate suites, see www.proxypartisans.blogspot.com.