by MonteQuest » Fri 14 Jan 2005, 01:08:00
$this->bbcode_second_pass_quote('Xelat', 'M')ontequests use of the law in these and other threads is a terribly terribly terribly incorrect application of the 2nd law. Keith_McClary, Nero and others have the correct understanding. Let's state the crappy version of the law:
Any system which is free of external influences becomes more disordered with time. This disorder can be expressed in terms of the quantity called entropy.
Actually this is one of several versions that are in words. Let us stick with words. I will paraphrase Montequests argument:
Human beings have decreased entropy by creating society and since the entropy of the earth is steadily increasing they face an increase in entropy.
This argument is terrible. Why? The law again:
Any system which is free of external influences becomes more disordered with time. This disorder can be expressed in terms of the quantity called entropy.
The Earth is not a system free of external influences. It approximates a closed system - a system which has energy exchange with the outside but not matter - as has been noted in the the "Tech" thread. If in fact the Earth were free of external influences it's likely life would never have evolved here and it would be a relatively boring place. But the Sun provides substantial energy input to the Earth, and the Earth radiates a substantial amount of energy into space. Thus the concern over greenhouse gases.
On the contrary, I am quite correct in my use of 2nd law. Anyone who has read my posts on 2nd Law knows that I have addressed isolated, closed, and open systems, and their differences with respect to applying the law to them. Xelat does not understand the law sufficiently here, so I will reiterate:
The principle that energy always runs from hot to cold is completely equivalent to saying entropy always increases. In an isolated system like the universe, this is a constant where it is free of external influences as Xelat says. But, in open and closed systems, like living organisms and the earth, entropy can be reversed or reduced at one point, but only with an
even greater increase in entropy somewhere else in the environment. The energy required to create order is
always greater than the energy required for disorder to happen. Entropy applies to everything. No exceptions. Energy cannot be converted from one form to another without a loss of energy in the form of heat. Classic Second Law in an isolated system. In an open or closed system, this loss can be reversed or reduced, but only by
increasing the loss even greater somewhere else. This is what Xelat fails to grasp, as most people do.
Just because the earth is not free of external influences, does not mean that entropy stops increasing, it only means that it can be reduced or reversed by the addition of outside energy, but only with an even greater increase in entropy somewhere else. There are no free lunches. Technology is complex. It requires a lot of energy transfers. In each transfer there is a loss of usable energy creating an increase in entropy that requires even more energy use to deal with the disorder. Look around you at the mess we have made of the earth in order to have our time-saving and labor-saving devices; the loss of species, habitats, climate change--all examples of that increased entropy somewhere else. You cannot avoid starvation by eating your food faster. Entropy is always increasing and one day the sun will die and so will all life here on earth, that is a given. 2nd law leaves us with the following imperative:
Since we can't beat the system(energy cannot be created or destroyed, 1st Law), and we won't have the energy required to hold entropy at bay(reduce or reverse), post-peak, we must reduce our increase of entropy by a power down and a simplification of our use of energy(less energy transfers). We can't have a completely sustainable world due to the limits set by the 2nd law, but we can find a far more harmonious existence with our fragile planet--and, leave more of a share of our finite resources to future generations in the process.
A Saudi saying, "My father rode a camel. I drive a car. My son flies a jet-plane. His son will ride a camel."