Xref: utzoo sci.bio:3862 sci.chem:2449 sci.physics:15389 sci.misc:4547
Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!sun-barr!olivea!orc!inews!cmdnfs!bhoughto
From: bhoughto@cmdnfs.intel.com (Blair P. Houghton)
Newsgroups: sci.bio,sci.chem,sci.physics,sci.misc
Subject: Re: Osmosis - the cause at the molecular level.
Message-ID: <923@inews.intel.com>
Date: 10 Nov 90 20:31:51 GMT
References: <1990Nov6.235518.8507@alchemy.chem.utoronto.ca> <839@inews.intel.com> <richard.658194844@fafnir.la.locus.com>
Sender: news@inews.intel.com
Organization: Intel Corp, Chandler, AZ
Lines: 57

In article <richard.658194844@fafnir.la.locus.com> richard@locus.com (Richard M. Mathews) writes:
>bhoughto@cmdnfs.intel.com (Blair P. Houghton) writes:
>>If the contact plugs a hole then it plugs traffic in both directions.
>
>I'm not sure I agree.  This would be true if the molecule plugs the
>hole for some length of time, but not if a point on the molecule just
>bounces off of the membrane.
>
>Say that when a water molecule hits the membrane, it has a certain
>probability of passing through.  If it approaches from the opposite
>side as the other molecule and gets there just before the other molecule
>bounces, it will be able to pass through the membrane before striking
>the other molecule.  Similarly, if it gets there just after the bounce,
>it will be able get through.  Water molecules on the same side of the
>membrane as the other molecule, on the other hand, will be excuded from
>that neighborhood of the membrane for a short time.  Put another way,
>the pressure of the water on one side will be able to push the plug
>out of the way, but the water on the same side as the plug will be
>blocked.

Someone made a perpetual motion machine based on that
principle; they put a particle in a box like so:

        +--------------------+
        |    /    /  . /     |
        |    |    |    |     |
        |\==================\|
        |    |    |    |     |
        |   /     /    /     |
        +--------------------+

The '/' are one-way valves made by doors loaded with
extremely-light-k springs that are also perfectly
eleastic.  Brownian motion of the particle would eventually
carry it from one partition to the next.  If hit that
partition in the passable direction (here clockwise) it
might get through (with some tiny probability) or it might
not; but, it definitely would not if it were moving in the
impassable direction (here anticlockwise).  Close the
system so no energy enters or leaves.  Then the particle
must, with some tiny probability, pass around the box in a
clockwise direction.

Note that the impossibility of perfect elasticity
and near-quantum energetics of the springs have no bearing
on the reasons this can't work.

It has more to do with the fact that the particle is
equally likely to cause the doors to open backwards
as it is to get through them forwards.

I'd prefer that someone who remembers who
invented this look up this thing and tell us
what the actual analysis was.

				--Blair
				  "Mu?"