Science Forums 2

[Shubee]

Originally Posted by CraigD

I think Shubee misreads chapter 9 “Maxwell’s Demon” of “Mr Tompkins in Paperback”. ... The story doesn’t account an instance of such an vastly unlikely event occurring, but the professor incorrectly believing that he, Tomkins, and Maud had witnessed such an event, when actually a real (and invisible, and quite charming) Maxwell’s demon had caused it to happen.

CraigD, your mangled misrepresentation of the story of Maxwell's Demon (pp. 72- 76) is terribly misleading. First off, George Gamow's highly imaginative story is just a story. And in that story, the fantastically improbable really happens. This is clear from the fact that the professor basically says how lucky the three of them are to see an event that will probably never happen again in the whole history of the universe.

The structure of the story is obvious from these excepts:

Apparently forgetting he was talking to a man who knew practically nothing about physics and not to a class of advanced students, the professor rambled on, using such monstrous terms as ‘generalized parameters’ and ‘quasi-ergodic systems’, thinking he was making the fundamental laws of thermodynamics and their relation to Gibbs’ form of statistical mechanics crystal clear. Mr Tompkins was used to his father-in-law talking over his head, so he sipped his Scotch and soda philosophically and tried to look intelligent. But all these highlights of statistical physics were definitely too much for Maud, curled up in her chair and struggling to keep her eyes open. To throw off her drowsiness she decided to go and see how dinner was getting along.

‘Does madam desire something?’ inquired a tall, elegantly dressed butler, bowing as she came into the dining room.

‘No, just go on with your work,’ she said, wondering why on earth he was there. It seemed particularly odd as they had never had a butler and certainly could not afford one. The man was tall and lean with an olive skin, long, pointed nose, and greenish eyes which seemed to burn with a strange, intense glow. Shivers ran up and down Maud’s spine when she noticed the two symmetrical lumps half hidden by the black hair above his forehead.

‘Either I’m dreaming,’ she thought, ‘or this is Mephistopheles himself, straight out of grand opera.’

Maud is obviously dreaming at this point. And what happens in Maud's dream is obviously a mix of learning physics based on the professor's ramblings about statistical thermodynamics and Maxwell's demon and what she learns from the demon directly.

What is the purpose of the demon in Maud's dream?

‘As a matter of fact, I came here of my own accord to show your distinguished father I am not the myth he believes me to be. Allow me to introduce myself. I am Maxwell’s Demon.’

‘Oh!’ breathed Maud with relief, ‘Then you probably aren’t wicked, like other demons, and have no intention of hurting anybody.’

‘Of course not,’ said the Demon with a broad smile,’ but I like to play practical jokes and I’m about to play one on your father.’

‘What are you going to do?’ asked Maud, still not quite reassured.

‘Just show him that, if I choose, the law of increasing entropy can be broken.’

Coincidentally, just as Maud awakens from her dream, the content of the dream, i.e., the demon's strategy to violate the second law of thermodynamics, is seen to parallel reality. And that coincidence, however you want to interpret it, parallels perfectly the professor's statement: "Here I was telling you about statistical fluctuations in the law of entropy when we actually see one!"

Of course this is just a story. I never suggested that this story was based on an observation of the second law of thermodynamics actually begin broken! I simply referred to this story as genuinely indicating a sincere belief by physicists in statistical fluctuations in the law of entropy. The point of the story is that violations of the second law of thermodynamics can happen! That was George Gamow's meaning and I backed it up with unquestionably accurate physics that somehow magically exists in Wikipedia.

Originally Posted by CraigD

I think Shubee misreads chapter 9 “Maxwell’s Demon” of “Mr Tompkins in Paperback”. It’s an exploration of statistical temperature fluctuations in gas (or liquids) and the old thought experiment/question/paradox of Maxwell's demon. These ideas are all classical, not quantum mechanical.

Also, despite being amusing and educational, the professor incorrectly describes Maxwell’s demon, ...

George Gamow simply recreated the original story of Maxwell's demon by giving it a quantum mechanical twist. That's the meaning of this demon using a tennis racquet. I believe it's clear that my quantum mechanical interpretation agrees perfectly with George Gamow's obvious intent.

‘And now, if you will excuse me, it is time for me to start my practical joke on the old, self-assured professor.’
So saying, Maxwell's Demon left Maud perched on the edge of the ice crystal, like an unhappy mountain climber, and set about his work. Armed with an instrument like a tennis racquet, he was swatting the molecules around him. Darting here and there, he was always in time to swat any stubborn molecule which persisted in going in the wrong direction. In spite of the apparent danger of her position, Maud could not help admiring his wonderful speed and accuracy, and found herself cheering with excitement whenever he succeeded in deflecting a particularly fast and difficult molecule.