🚀 go-pugleaf

In article <1993Jan4.225818.8575@cssc-syd.tansu.com.au>, mos@cssc-syd.tansu.com.au (Michael O'Sullivan) writes...
>rf@cl.cam.ac.uk (Robin Fairbairns) writes:

>I missed the past discussion. I have tried the spoon trick with a bottle
>of beer, and it did work. The beer was not flat 24 hours after the spoon
>was put in. I don't think it would last for days, but the spoon definitely
>prolonged the beers carbonated life (so to speak). I too want to know,
>how does it work?

	The October 1991 issue of Physics Today contained an article titled
	"Throught a Beer Glass Darkly" which described in detail the formation
	of beer bubbles and the subsequent physics of same.

	In terse mode, "bubbles begin as invisible clusters or microbubbles
	of CO2 molecuees that grow on rough spots, called "Nucleation sites..."
	(very similar to the formation of raindrops around dust particles.)
	This explains why some people pour a little salt or sugar into their
	beer to create more foam.

	Also it is noted, "CO2 molecules collect at the nucleation site until
	the resulting bubble reaches a critical size and is able to break
	away..."

	The hypothesis is very simple. The spoon must interfere with the
	nucleation process. Hypothesis expansion follows:

	A/ Spoon collects bubbles (we've all seen this,) and slows down the
	   rate of bubble formation by trapping the bubbles due to increased
	   surface tension.

	B/ Spoon collects bubbles, and resultant supply of microscopic dust
	   particles which are sources of nucleation. (Normally after bubble
	   bursts, dust particle drops down, becomes source of another bubble,
	   but particle adheres to spoon, no longer is active nucleation site.)

	Ok folks, now what?

   Frank R. Borger - Physicist    __       Internet:  Frank@rover.uchicago.edu
Michael Reese - Univ. of Chicago |___      Phone : 312-791-8075 fax : 567-7455
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