Jesse

Yeah, that's a good point...the greater freedom of molecules in a liquid might offset the other factors I mentioned, and make it so that there are more possible microstates that give a living organism than there are microstates that give a rock. It would be nice to see some numbers, but as I said it's hard for me to imagine how you'd calculate the entropy of an organism--you might just have to settle with calculating the entropy of a soup made up of all the same molecules in an organism without regard for their spatial arrangement.

Goober

Yes, and the entropy of an organism relative to a rock is not relevent to the total change in entropy of a process where an organism becomes a more complex organism.

That is what the 2nd law argument is based on as it applies to evolution. No one is claiming organisms come from rocks. It doesn't even apply to abiogeneis because RNA does not come from rocks either.

To work out whether a process violates the second law we need to know what the process is, and you have defined no process here. Rocks to DNA is not a process that anyone is postulating.

If you were talking about the process where DNA (or RNA) is generated from dNTPs or NTPs, or how dNTPs or NTPs are generated from simpler compounds, then you could discuss how the 2nd law applies to the process. But I can't see how the relative entropies of rocks and DNA has anything to do with the 2nd law argument.

What is the rock made of? How big is it? How do you determine what mass of rock is equivalent to a DNA molecule to make the comparison? All of your things are poorly defined and you do not have a clear process which you are considering, which is why any argument based on these lines is not going to hold water.

Which does not matter to the 2nd law. The 2nd law does not care where the entropy changes occur. If you don't consider entropy changes elsewhere, then you will get the wrong result. Which is why the 2nd law argument against evolution is wrong.

Jesse

Goober:
Yes, and the entropy of an organism relative to a rock is not relevent to the total change in entropy of a process where an organism becomes a more complex organism.

That is what the 2nd law argument is based on as it applies to evolution. No one is claiming organisms come from rocks. It doesn't even apply to abiogeneis because RNA does not come from rocks either.

To work out whether a process violates the second law we need to know what the process is, and you have defined no process here. Rocks to DNA is not a process that anyone is postulating.

If you were talking about the process where DNA (or RNA) is generated from dNTPs or NTPs, or how dNTPs or NTPs are generated from simpler compounds, then you could discuss how the 2nd law applies to the process. But I can't see how the relative entropies of rocks and DNA has anything to do with the 2nd law argument.

What is the rock made of? How big is it? How do you determine what mass of rock is equivalent to a DNA molecule to make the comparison? All of your things are poorly defined and you do not have a clear process which you are considering, which is why any argument based on these lines is not going to hold water.

But modig wasn't making a 2nd law argument, and I don't think he/she was even saying that the entropy of a person vs. the entropy of a rock was directly relevant to refuting the 2nd law argument. You're correct in the sense that even if the entropy of an organism turned out to be vastly lower than that of a rock, it still wouldn't support the 2nd law argument, because the low entropy of an organism would still be the product of a process that increased the total entropy of the universe. So it doesn't really matter whether the entropy of organisms is very low or if it's pretty average, the 2nd law argument is wrong either way. But my impression is that modig's comments about organisms vs. rocks were meant as more of a side note, to illustrate the idea that it's a mistake to equate low entropy with "order" or "complexity".

modig

As Jesse pointed out, I'm not really talking about the 2nd law argument directly. I'm interested in this more for the understanding of Entropy than anything, but also because I'd like to be able to say something like:

"Since a rock of comparable mass and temperature has less Entropy than an organism, shouldn't you be complaining about the formation of rocks on earth as well?"

And yes, it's more of an example of the common misunderstanding that people get when they are told that entropy is a measure of "disorder" than anything else. I've given up trying to refute the 2nd law argument, as nobody who buys it understands enough thermo to judge the refutation. I'm trying out just getting them to admit that they don't actually know what entropy or the 2nd law of thermodynamics is beyond something containing the statement "order goes to disorder" and that they personally have no way of knowing which argument is correct because of this.

simian

Assuming the rock is limestone (CaCO3, calcite form), S=22.2 cal/ºmol at 25ºC

Water, which should constitute about 70% of an living item, S=45.38 cal/ºmol

Both the above values are from the 56th Edition of the CRC Handbook of Chemistry and Physics.

Assuming a plant, I would say the remainder would be glucose, mostly in a polymerized form (cellulose or starch), with a small amount of protein. I can't find the entropy values for glucose, at least right now (keep in mind entropy may be less than 0).

And, yes, entropy can be calculated for open systems. Like a mass balance or energy balance, a control surface must be defined and the entropy of anything (solid, liquid, gas, photons, etc) must be accounted for. Yes, it can be complicated, but it can be done.

Simian

Goober

Sorry, I thought you were referring to the 2nd law argument. It sounded like that was the misconception that you were referring to. Disregard most of what I said. I see the point of what you're trying to do now, highlight their ignorance of the concept by pointing out the absurdities that their flawed understanding generates. That's a good idea, actually, much easier than trying to educate them.

As simian rightly pointed out, water has a higher molar entropy than water, and water would be the most common molecule in a living organism. But in addition to that, living things also are made up large numbers of complex molecules like proteins and DNA. Larger molecules tend to possess larger molar entropies, so yes, a rock would unqestionable have less entropy, and much less entropy at that.

No, the molar entropy of glucose must be positive. All entropies of substances must be greater than zero except for ions in solution, which can be negative because they have a quirky way of defining the zero point for entropy.

Peter Soderqvist

Living DNA represent low entropy becuase its micro states are not so many!
Hence, a dead body (macrostate) have a huge quanity of microstates, but not so with a living one, because the organism will end to live if you change, or alter its micro states, for instance, put the neurons in the leg, and cells from the leg into the head. A dead body can sustain this altering of micro states, but not a living one. The reason is simple, there is so many more ways to be dead than there is to be alive. Boltzmann’s Entropy = k log W, or Schrodinger’s S = k log D. Disorder = Ways. A living human body need also its 37.0 degrees in order to live, and it also need to preserve both its temperature, and its water fluids from the environment, because this water will end up in the environment when the organism is dead, and the body’s temperature with the same degrees as the environment too, this is equilibrium, known as maximum entropy!

I cannot respond to reply, because I am on holyday!