[Winstonm]

luke warm, on Jun 12 2008, 05:27 PM, said:

helene_t, on Jun 10 2008, 05:29 AM, said:

luke warm, on Jun 10 2008, 11:16 AM, said:

hey, i'm just sayin'... btw, is there a tendency towards disorder? what is needed for order to occur from disorder?

That disorder is created elsewhere to balance it. For example when a plant grows, the growing plant itself represents growing order but it is balanced by the fact that it uses relatively ordered ultraviolet light for its photosynthesis and returns the energy from the light in the form of relatively disordered infrared light.

i guess i just don't understand it then... it's very hard to imagine the earth, after the BB, becoming "ordered" from its molten state

Isn't it possible that our impressions based on our time frame create self-delusion - that our world and our universe are not so ordered as we would like to believe.

[Gerben42]

Quote

hey, i'm just sayin'... btw, is there a tendency towards disorder? what is needed for order to occur from disorder?

There is no need to look for genie-in-a-bottle answers to this questions and invoke supernatural beings like gods. Good thing we have invented physics to make some sense of an otherwise incomprehensible universe.

A star is just a cloud of hydrogen with at least 1.3 x 10^29 kg that collapsed due to it's own weight.

A planet like the Earth is also round because of gravity. When it cooled down, the heavy stuff (metal) is at the bottom, whereas the light stuff (oxides) is at the top. What is so ordered about the Earth?

[helene_t]

luke warm, on Jun 12 2008, 11:27 PM, said:

i guess i just don't understand it then... it's very hard to imagine the earth, after the BB, becoming "ordered" from its molten state

Q: Did the Earth get more ordered as it cooled and if so does it violate the 3rd law of thermodynamics?

A: It got more ordered and that doesn't violate the 3rd law. Things get more ordered as they cool. The universe as a whole gets more disordered because the heat lost by the Earth diffused into deep space as infrared radiation. The 3rd law applies only to isolated systems, in particular systems that do not lose energy to their environment.

Q: Has more order arisen since BB and if so does it violate the 3rd law?

A: I suppose the universe was extremely ordered in the beginning since all the energy was confined to a tiny universe. However, parts of the universe can get more ordered by losing energy to other parts of the universe, see for example the previous question.

Q: Growing living organisms and populations can build up order without losing energy. Does that violate the 3rd law?

A: No it does not violate the 3rd law, see my previous post.

[luke warm]

ok helene... it's just counterintuitive, that's all... it seems to me that if left alone a non-intelligent object would tend toward disarray (think an abandoned house, or car)

[gwnn]

I hate saying entropy is disorder, since it is just a popular interpretation of a statistical concept. Sometimes it's quite hard to figure out why a particular system is less ordered than another, even though the entropy is clearly higher.

[hrothgar]

luke warm, on Jun 13 2008, 01:20 PM, said:

ok helene... it's just counterintuitive, that's all... it seems to me that if left alone a non-intelligent object would tend toward disarray (think an abandoned house, or car)

As a counter example, think of a pool of water on a very cold day

When water transitions from a liquid to a solid form it becomes much more ordered.

Its perfectly legitmate to complain that a pool of water is not a closed system. However, none of us are arguing that the earth is a closed system...

[han]

Agree with Csaba that order and disorder are poor terms to think about entropy.

It seems like in this thread the word order is used both for low (or high?) entropy and for the abundance of patterns, two very different concepts. Those who would like to increase their understanding of physics (or any science for that matter) should make an effort to understand the words that are used as well as they can.

[helene_t]

Fair point.

Just read Schroedinger's "What is life". He talks about "order" but concedes that he had been criticized for not using the more well-define term "free energy" which would have been more apt in context. He said he would indeed have chosen the term "free energy" if writing for an audience of chemists.

[han]

Well, hopefully he explains what he means by the word "order" and then uses it consistently. If so then there is nothing wrong with that.

[Al_U_Card]

Good article in Scientific American about Time's arrow and entropy and the universe. Helps make sense of it all.

[luke warm]

luke warm, on Jun 10 2008, 11:16 AM, said:

hey, i'm just sayin'... btw, is there a tendency towards disorder? what is needed for order to occur from disorder?

helene said:

That disorder is created elsewhere to balance it. For example when a plant grows, the growing plant itself represents growing order but it is balanced by the fact that it uses relatively ordered ultraviolet light for its photosynthesis and returns the energy from the light in the form of relatively disordered infrared light.

helene, lead me through this, if you will... i'm picturing a violent world with lava covering its surface (and, i suppose, its core) and i'm comparing that to an abandoned house... i can't see how that particular world would produce the growing plant that uses light for photosynthesis any more than i can picture how the house can produce bright yellow shutters on its windows... did the seed that produced that plant evolve from the molten state of the planet, or did it immigrate here from some also-originally-molten universal point? just asking

hrothgar, on Jun 13 2008, 07:01 AM, said:

luke warm, on Jun 13 2008, 01:20 PM, said:

ok helene... it's just counterintuitive, that's all... it seems to me that if left alone a non-intelligent object would tend toward disarray (think an abandoned house, or car)

As a counter example, think of a pool of water on a very cold day

When water transitions from a liquid to a solid form it becomes much more ordered.

Its perfectly legitmate to complain that a pool of water is not a closed system. However, none of us are arguing that the earth is a closed system...

i'm not convinced the pool of water to ice is an apt analogy because once the temperature rises the ice would melt, leaving the water... the abandoned house (or car) can go through any number of environmental changes and, without intelligent intervention, completely deteriorate

[Al_U_Card]

Don't forget that entropy has to do with possibilities and potentials and not just with the randomness or orderliness of the system. When time is added in, it gets pretty systemic. Better just to lie down until your head stops hurting...lol

[helene_t]

It may not be possible to give a simple analogy which makes it easier to understand how living organisms can build up free energy. Anyway, I will give it a try:

Electrolysis of a solution of sodium chloride. The hydrogen gets separated from the chlorine, which represents a reduction of entropy. Obviously, to avoid violation of the 3rd law, the entropy must be rising elsewhere. It is. The energy that comes from the power supply is converted into heat (along with the chemical energy in the chlorine and hydrogen gas).

From a thermodynamic pov I think this is closer to what happens in the growing plant than Richard's example.

[barmar]

It's been said before in the thread, but bears repeating until everyone gets it. The 3rd law only applies to a closed system. The universe as a whole is (assumed to be) a closed system, so the total entropy in the universe is increasing.

But a freezer, living organism, or even the earth is not. Energy flows in and out of these systems, and this energy can be used to produce local reductions in entropy. There's always a balancing increase in entropy somewhere else, which usually appears as heat radiated out of the local system. This is why a refrigerator has a vent blowing hot air.

Left to themselves, most local systems WILL tend towards an increase in entropy. A glass is infinitely more likely to fall and shatter into lots of random pieces than those pieces are likely to reassemble themselves into a glass. To make a glass out of silicon sand requires input of lots of energy (a furnace to melt it together, then some device to shape it). This energy transfer is what allows a local reversal of entropy.