sexta-feira, agosto 27, 2010

Sistema "aberto" versus sistema "fechado"

Vi este pequeno texto no blog do Bill Dembski, e resolvi colocar aqui tal como foi escrito.

Essencialmente ele lida com o argumento ateu de que a evolução (aumento de complexidade informacional) não viola as leis da ciência porque a Terra é um "sistema aberto" e como tal recebe energia do exterior. Supostamente essa energia teve a capacidade de reverter os efeitos da 2ª Lei da Termodinâmica.

The common sense law of physics

I was discussing the second law argument with a scientist friend the other day, and mentioned that the second law is sometimes called the “common sense law of physics”. This morning he wrote:

Yesterday I spoke with my wife about these questions. She immediately grasped that chaos results on the long term when she would stop caring for her home. – Chaos does not produce life.

I replied:

Tell your wife she has made a perfectly valid application of the second law of thermodynamics. In fact, let’s take her application a bit further.

Suppose you and your wife go for vacation, leaving a dog, cat and a parakeet loose in the house (I put the animals there to cause the entropy to increase more rapidly, otherwise you might have to take a much longer vacation to see the same effect). When you come back, you will not be surprised to see chaos in the house.

But tell her some scientists say, “but if you leave the door open while on vacation, your house becomes an open system, and the second law does not apply to open systems…you may find everything in better condition than when you left.

I’ll bet she will say, if a maid enters through the door and cleans the house, maybe, but if all that enters is wind, rain and other animals, probably not.

This is an application of the main point in chapter 5 of my new book : “If an increase in order is extremely improbable when a system is closed, it is still extremely improbable when the system is open, unless something is entering that makes it NOT extremely improbable.”

For a slightly more technical version of this story, complete with a mathematical analysis of the equations for entropy change, see my video .

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