by EnergyUnlimited » Sun 27 Aug 2006, 02:59:07
$this->bbcode_second_pass_quote('Montequest', 'T')he Second Law of Thermo Dynamics states that whenever energy is converted from one form to another, there is an energy loss in the form of heat. This is the law of entropy as well, which is a measure of the amount of energy no longer practically capable of conversion to work. Entropy within an isolated system inevitably increases over time. Since it takes work to create and maintain order within a system, the entropy law tells us that, in the battle between order and chaos, it is chaos that ultimately wins.
The only truly isolated system we know of is the universe; or in a laboratory experiment. But there are two other system types: open and closed. The earth is an example of a closed system. It exchanges energy with the universe, but not matter, save the occasional meteorite. Since it is a closed system it's environment is always being degraded by entropy, but the thermodynamic equilibrium with space is maintained by the input of solar radiation.
Living organisms, on the other hand, are an example of an open system, where both matter and energy are exchanged.
As I do agree, that living organisms are open systems, I will still insist, that Earth is still an OPEN system as well.
You see, we are now losing entire
MOON to the space (you know, slowly but still it is going away).
I concentrated on energy exchange in my definition as mass and energy are related (mass is a form of energy).
However if you want to stay with more "traditional" definitions, slow loss of moon is a good enough reason to consider Earth system to be open.
Possible "merger" with a Sun in distant future would add weight to this argument (I know - you may argue that it is Sun, which is closed system and Earth is still not open...but those are academic arguments only).
Metheorities, particles of cosmic radiation, satelites etc would still convince a purist, that Earth is an open system in traditional sense.