This works well for a marble on top of a superball (you might need to duck!). If the balls are of the same size, one would expect, I think, a Boltzmann distribution in the energies. That's why a few molecules might escape. Of course, that (evaporation)cools off the remaining gas, so even fewer molecules would have the necessary escape velocity. You still need to provide the energy to the gas molecules to get any substantial amount of gas to orbit, I think. Bill -----Original Message----- From: math-fun-bounces+cordwell=sandia.gov@mailman.xmission.com [mailto:math-fun-bounces+cordwell=sandia.gov@mailman.xmission.com] On Behalf Of Henry Baker Sent: Tuesday, August 01, 2006 4:10 PM To: franktaw@netscape.net Cc: math-fun@mailman.xmission.com; gene_salamin@yahoo.com Subject: Re: [math-fun] A modest proposal for carbon sequestration in space No, the pressure won't increase over time, unless the model itself breaks (i.e., by radiating away too much energy, melting the column, or destroying the column with high-speed CO2 molecules, etc.). To get some idea about how this might actually work, see the following web page re stacks of superballs: http://www.physics.gla.ac.uk/~kskeldon/PubSci/exhibits/D12/ I seem to recall a video of this type of demonstration somewhere on the internet, but haven't been able to find it. Needless to say, one model for the CO2 column (or any air column) is a stack of superballs.