On 11/22/2014 1:09 PM, John Clark wrote:
On Sat, Nov 22, 2014 , meekerdb <meeke...@verizon.net <mailto:meeke...@verizon.net>> wrote:> Loschmidt's idea was that an isolated column of gas in a gravitational field would develop a temperature gradient, warmer at the top.
You're right - just a brain slip on my part.
I believe that would be cooler at the top not warmer,. molecules at the top of a column of gas would have more gravitational potential energy than those at the bottom and so would have had to expend kinetic energy to get up that high and become cooler as a result. Virtually everybody agrees that this is not in violation of the second law but there doesn't seem to be a consensus on exactly why it doesn't.
ISTM it's just an laboratory example of what a star was once thought to do. Before nuclear decay was discovered, Lord Kelvin (William Thompson), calculated the life time of the Sun assuming its energy came entirely from gravitational collapse. His estimate was no more than a few tens of millions of years. Darwin estimated that evolution would have required at least an order of magnitude longer. So Darwin seriously considered that Thompson had proven evolution wrong. If he had just looked at it the other way around he might be credited with discovering nuclear energy as well as evolution!
The stars conversion of gravitational energy to radiation doesn't violate the 2nd law because the radiation photon states are much more numerous than the remaining matter states.
Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
