Posted by Davis Lansdstrom (195.92.194.14) on June 12, 2002 at 10:21:16:
In Reply to: Re: Second law + evolution posted by Scott Ellis on June 11, 2002 at 11:29:15:
The link that you posted was interesting to read, but a little metaphysical/philosophical.
The concept of increasing entropy/dissorder/decay has been something that has historically allways been used inappropriately in metaphysics and philosophy. These subjectivists and anti-reductionists will try to apply the second law to concepts like human nature, psychology, economics and the irreversibility of human progress and then try to link it to such concepts as universal entropy death and irreversable large scale entropy , but such a connection can never be made as thermodynamics is mathematical and deals with energetics and simply can not apply in any sense to the above mentioned concepts, except in the most abstract context, but this is not scientific. Creationists try this one out, they say: 'Evolution is order out of dissorder, this contradicts the second law of thermodynamics that says that dissorder can only come from order' You will also hear them saying: 'Before the fall (When Eve ate of the tree of knowledge), the second law was probably not in opperation, as it is the universal law of death, decay and dissorder, it probably came into being when God put the curse on Adam, Eve and subsequent generations, one of the factors of the curse being that there will be death in the world.' You can see how they have distorted the second law to make it fit in with the Bible. It is similar with these philosophers and metaphysicists who twist the concepts embodied in the second law to try to make it fit concepts like those mentioned previously.
I disagree with the idea that the sun is a gravity driven perpetual motion machine, it has been demonstrated that the sun is nuclear fusion powered and that mass/energy as per general relativity accounts for it's long life.
Suns are created in two ways either they are forged in or near to a supernova event, or more commonly they form because enourmous amounts of matter combine under gravity and over come the pressure that is preventing them from doing this, the end result is a pressure build up (yes due to the collective gravity of the gas) in the core of the gas that initiates nuclear fusion, the fusion is a chain reaction process that will 'spread' throught the gas and hey presto, you have a star. I believe that the energy that the gasses must have in the first place to combine comes from the creation energy of those atoms, and the reason they 'clump' is because they expend potential energy under the influence of gravity as a conservative force. Secondly the energy for fusion comes from the binding energies, it is simply a case of 'overcomming the activation energy' (To borrow from Chemistry), this will result in chain reaction. The energies released from fusion are energies given to each atom upon their creation just after the big bang. I agree that gravity holds stars together but I can not see how it could contribute in any way to the net energy out put of the star, stars are simply highly efficient fusion engines that are capable of reclaiming a percentage of their fuel mass from the energy they produce and are capable of fusing alot more than just hydrogen, hence the long life, you your self said that they die. As for entropy, the star increases the entropy of the universe with it's highly entropic EM and particle emmisions, as the star gets older more 'ordered' substances are formed within it like carbon, silicon and eventually iron, the entropy is paid off to the environment still because the star increases in size and entropic out put, so stars do not violate thermodynamics, I don't think.
As for systems from which spontanious order arrises, here is a good chemical one.
Take that material photographers use, Hypo, it is a hypersaturated solution that has been loaded with crystals, (I am not sure what chemical) put a few grains of salt in there and the hypo will immediately be covered with a thick crystal layer. The solution is holding more matter than it is able to, the salt grains provide a 'condensation nucleus' for the crystals in solution. In order for the cryst
sun is a perpetual motion machine, then so is Life, which is intimately coupled with the sun's energy/entropy flow. And I think it is important to realize that the whole process is started and constantly driven by the action of gravity.
: For those that would argue that the sun is not a PMM, since it only burns for about 10 billion years, of course you are technically right. To my mind, though, what constitutes a PMM has more to do with practical human purposes than exact definitions. Something that produces energy for 10 billion years is a PMM as far as human beings are concerned...
: Finally, Davis, I want to ask you a question. Acknowledging that Life does not violate the 2nd Law in the broadest sense, isn't it still peculiar that Life results in such persistent local decreases in entropy? Are there other examples of natural systems that cause perpetually self-sustaining local decreases like this?
: Order can and does arise spontaneously during certain natural transfers of energy. For example, ice crystals forming on a window pane:
: http://www.student.oulu.fi/~ktikkane/eJARJ.htm
: But as far as I know, none of these naturally occurring local decreases are self-sustaining in the same way that Life is.
: You mentioned the example of a refrigerator, but to my mind, a refrigerator is anything but a natural occurrence. As a product of the human mind, refrigerators seem like natural extensions of our own low entropy, like all the other order that we create and maintain on this planet.
: Best,
: Scott
:
: : As an evolutionary biologist by profession, I feel that I must clear up one thing Scott.
: : The process of evolution is not a violation of the second law of thermodynamics at all.
: : The second law of thermodynamics deals with the model concept of a closed system at time (lets say) 1, possesing a quantity of energy in isolation made to do work, the entropy of that system will increase to the point where the initial quantity of energy will be unable to perform the same work at time (lets say) 8.
: : This is because of an increase in 'dissorder' in the system, but more specifically because that system is irreversable, despight the fact that it is closed and isolated, it is still coupled with time and the universe, hence the closed system (at time 8) could never restore (regenerate) its self to the same entropic state that it was at time 1.
: : The initial and final states of the system are different entropically, hence the Second law of thermodynamics joke: 'You can never break even'
: : HOWEVER, if we were to take this system and energetically couple it to another system (make it open), then we could use the output of the coupled energy source to create a local reduction in entropy by performing work on the system, the entropy in the system that was orrigionally colsed will decrease and will remain decreased (depending on the amount of work being done on that system by the coupled source system) HOWEVER this entropy reduction comes at a cost, there HAS to be a pay off of entropy somewhere along the line, that pay off is either to the systems evironment (depending on the degree of 'openness') or it occures in what ever process is driving the coupled source system.
: : I shall give two examples to illustrate the above:
: : 1.The evolution of life - some evolutionary lineages since the precambrian have indeed increased in complexity. If we take a life form to be a system, we immediately see that it is by no means isolated, it is energetically coupled to the system of earth's environment, which in turn is energetically coupled to the sun, the decrease in entropy on earth that allows for increasing complexity evolution, is 'paid off' with an increase of entropy of the sun. I suggest that you look up Ilya Prigogine, who won a Nobel prize in 1977 for a mathmatical description of this very process.
: : 2.A fridge 'violates' the second law about as much as evolution does. The third law of thermodynamics informs us