Re: Planet Densities

James Rogers (
Tue, 12 Nov 1996 11:04:13 -0800

At 10:57 AM 11/12/96 -0500, you wrote:
> Newton's Second Law of TD says that 'in a closed system, it can
>only degenerate into a state of lower complexity.'

Thermodynamics (or at least the recognition of thermodynamics) came a couple
hundred years after Newton.

>With Earth open to
>the sun's energy, and its great density and moderate temperature
>facilitating the most fluid of systems, Life has the best chance of
>forming and/or continuing. (By "most fluid," I mean the "triple point"
>between boiling point and freezing point provides more range for liquids
>to exist due to higher pressure.)

The "triple point" of a compound is the temperature/pressure range that
allows the existence of 3 of the 4 possible phases. The "triple point" for
water is well outside the range of what most organisms would call
"comfortable" since the pressure is significantly below 1.0 atmosphere and
the temperature is below the normal freezing point of water.

This aside, I think you are generally correct. Liquids generally have the
smallest range of any phase. For a system to take advantage of the unique
properties of water, it requires that the system be well suited for the
semi-perpetual existence of liquid water. Ice isn't conducive to life and
very hot water/steam is extremely destructive to organic compounds.

-James Rogers