Thermodynamics

You grew from a single zygote to an adult in just a few years. Do you think that is a violation of thermodynamics? It is not; and for all the same reasons.If you answer this post, please answer the question about the zygote to adult. Do you think that violates the law of thermodynamics?Cheers -- Sylas

Deleted in edit.... Sorry, my point was adequately covered already by others, so I will sit back for now.This message has been edited by Sylas, 02-13-2005 15:09 AM

There are so many things wrong with the thermodynamics argument that one is quite overwhelmed wondering which error to point out.The fact of the Earth being in the middle of an enormous energy flux, flowing from the Sun and then on out into empty space, makes total entropy calculations pretty much irrelevant.One curious side issue is that physicist/chemist Ilya Prigogine coined the term "dissipative structures" for the various complex and subtle patterns that form spontaneously in systems that are held far from thermodynamic equilibrium, and which contribute to dissipating energy that flows through the system (energy dissipation is not a bad way to describe increasing entropy). This is an example in which thermodynamics can drive the emergence of complexity.But there is another point I want to bring up. Evolution is about change of living creatures in a lineage; parent to child. But each new organism is not made by physically transforming the parent. An organism grows by physically transforming the material it ingests.Thermodynamics relates to the physical changes in a system; not in differences between a system and a close copy made from different materials. Growth is where thermodynamics is relevant; not in the differences from parent to child in a long sequence.The thermodynamics argument is analogous to a conversation with the pointy haired boss of a car manufacturer who drops into the engineer's office:Pointy haired boss: Ah, I see you are working on the new model sedan.Engineer: Yes. This new sedan will be 10 km/hr faster than the old one.Pointy haired boss: Isn't that a violation of conservation of momentum?Engineer: (stunned silence)Cheers -- SylasThis message has been edited by Sylas, 02-13-2005 17:35 AM

No worries, Brad; that won't happen. For whatever reason, I simply cannot follow your posts sufficiently well to attempt an engagement.I think, but am not sure, that you operate at a much more sophisticated level. My comments here were addressed at a more simple minded failure to understand thermodynamics.There are indeed some interesting questions relating to thermodynamics and the living world. However, there is simply no basis for saying that thermodynamics conflicts with evolutionary change, including those changes which are an increase in complexity.How much insight can be gained into evolutionary change by application of ideas from thermodynamics is an interesting question. To get any sensible insight, one needs to get over some very straightforward hurdles first. You don't get useful insights from people who simply think in terms of "evolution means increasing complexity; and that is a conflict with the second law". That's wrong.Cheers -- Sylas

I don't get it. How is that not a temporary violation? You seem to confusing the second law with some notion of eventual degradation, that is temporarily violated during growth. That's a temporary violation of your tendency to degradation.The real laws of thermodynamics do not allow for temporary violations. (Quibble; in very small systems and very very short times spans this might not be quite true; but for macroscopic structures and time spans of a minute or more, the laws of thermodynamics are inviolate.)Thermodynamics also admits no exception for designers or intelligence. Designed artefacts are every bit as subject to the physical laws as anything else. Indeed, the laws of thermodynamics were discovered by considering hard physical limits that no designer of engines could overcome.What the second law thermodynamics prohibits is decrease in entropy in systems not tapping into external energy sources.Increase in complexity of systems sustained by a strong energy flux is no problem whatsoever for thermodynamics.

Here are some of the standard expressions of the second law of thermodynamics, taken from the hyperphysics website. These statments are equivalent, in that each form can be derived from the others.

• Heat will not flow spontaneously from a cold object to a hot object. (The Clausius statement 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. (This refers to "closed system", with the notion of being free of external influences.)
• You cannot create a heat engine which extracts heat and converts it all to useful work. (The Kelvin-Planck statement of the law.)
• There is a thermal bottleneck which contrains devices which convert stored energy to heat and then use the heat to accomplish work. For a given mechanical efficiency of the devices, a machine which includes the conversion to heat as one of the steps will be inherently less efficient than one which is purely mechanical.

The Clausius statement of the law does not refer to "closed systems", but to "spontaneous" processes. The Kelvin-Planck statement refers to heat engine efficiency without making reference to closed systems.Cheers -- Sylas(If I have the above wrong, I'm sure there is a physicist in the house to correct me.)

Potential energy is represented as a negative. For example, what is the energy in a body in a circular orbit?Let M and m be the two masses involved, and R be the orbital radius. The formula for the gravitational potential energy of this system is -GMm/R. Note the minus sign. The kinetic energy of motion of GMm/2R; half the magnitude and the opposite sign.The net energy of the system is therefore negative, and can be calculated as -GMm/2RThere is a speculation that the total energy of the universe is zero; although accelerating expansion seems to indicate that this speculation is false; and that there is a net positive energy. Where did it come from? We don't really know; physics has not solved ultimate origins.Cheers -- SylasThis message has been edited by Sylas, 02-17-2005 21:31 AM

I don't think it is really "testable" in the usual sense. It is just a convention, that makes the maths work out nicely. That potential energy reduces as you move into a gravitional well is pretty clear. As you fall, you speed up (more kinetic energy) and also lose potential energy.By convention, the zero for potential energy is when there is no detectable gravitational force, which means objects are far far apart. Using a value other than zero is a bit awkward, since kinetic energy increases without bound as you fall into a point source of gravity.Cheers -- Sylas