Idiot question

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Okay, I'm not an idiot, but can someone explain to me (in common layman's terms) what entropy is? And it's relation to life?
 

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  • #2
Okay, I'm not an idiot, but can someone explain to me (in common layman's terms) what entropy is? And it's relation to life?
It is the movement from order to disorder, in laymens terms. It has no bearing on life as scientifically it is only valid in closed systems, if it were valid it would show that life is a sort of reverse entropy, from disorder to order, and its commonly touted by creationists as evidence that evolution is flawed as it does not fit in with the laws of thermodynamics. This is of course a scientifically flawed claim, but that doesn't seem to stop it being used for propaganda purposes.

http://en.wikipedia.org/wiki/Entropy

For over a century and a half, beginning with Clausius' 1863 memoir "On the Concentration of Rays of Heat and Light, and on the Limits of its Action", much writing and research has been devoted to the relationship between thermodynamic entropy and the evolution of life. The argument that life feeds on negative entropy or negentropy as put forth in the 1944 book What is Life? by physicist Erwin Schrödinger served as a further stimulus to this research. Recent writings[citation needed] have utilized the concept of Gibbs free energy to elaborate on this issue. Tangentially, some creationists have argued that entropy rules out evolution.[45]

In the popular 1982 textbook Principles of Biochemistry by noted American biochemist Albert Lehninger, for example, it is argued that the order produced within cells as they grow and divide is more than compensated for by the disorder they create in their surroundings in the course of growth and division. In short, according to Lehninger, "living organisms preserve their internal order by taking from their surroundings free energy, in the form of nutrients or sunlight, and returning to their surroundings an equal amount of energy as heat and entropy."[46]

Evolution related definitions:

* Negentropy - a shorthand colloquial phrase for negative entropy.[47]
* Ectropy - a measure of the tendency of a dynamical system to do useful work and grow more organized.[30]
* Syntropy - a tendency towards order and symmetrical combinations and designs of ever more advantageous and orderly patterns.
* Extropy – a metaphorical term defining the extent of a living or organizational system's intelligence, functional order, vitality, energy, life, experience, and capacity and drive for improvement and growth.
* Ecological entropy - a measure of biodiversity in the study of biological ecology
 
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  • #3
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Still confused. Are there more layier laymens terms we can use?
 
  • #4
Still confused. Are there more layier laymens terms we can use?
Not really does this help?

Wiki also.

There are many ways of stating the second law of thermodynamics, but all are equivalent in the sense that each form of the second law logically implies every other form (Fermi, 1936). Thus, the theorems of thermodynamics can be proved using any form of the second law and third law

The formulation of the second law that refers to entropy directly is due to Rudolf Clausius:

In an isolated system, a process can occur only if it increases the total entropy of the system.

Thus, the system can either stay the same, or undergo some physical process that increases entropy. (An exception to this rule is a reversible or "isentropic" process, such as frictionless adiabatic compression.) Processes that decrease total entropy of an isolated system do not occur. If a system is at equilibrium, by definition no spontaneous processes occur, and therefore the system is at maximum entropy.

Also due to Clausius is the simplest formulation of the second law, the heat formulation:

Heat cannot spontaneously flow from a material at lower temperature to a material at higher temperature.

Informally, "Heat doesn't flow from cold to hot (without work input)", which is obviously true from everyday experience. For example in a refrigerator, heat flows from cold to hot, but only when aided by an external agent, i.e. the compressor. Note that from the mathematical definition of entropy, a process in which heat flows from cold to hot has decreasing entropy. This is allowable in a non-isolated system, however only if entropy is created elsewhere, such that the total entropy is constant or increasing, as required by the second law. For example, the electrical energy going into a refrigerator is converted to heat and goes out the back, representing a net increase in entropy.

A third formulation of the second law, the heat engine formulation, by Lord Kelvin, is:

It is impossible to convert heat completely into work.

That is, it is impossible to extract energy by heat from a high-temperature energy source and then convert all of the energy into work. At least some of the energy must be passed on to heat a low-temperature energy sink. Thus, a heat engine with 100% efficiency is thermodynamically impossible.
If not could you outline exactly where you are stuck? I'm not sure what level you are at so I can't really give it any more simply than: in a system that is closed the "objects" in such a system will lose energy and thus become more disordered by the processes in such a medium. A closed system means there are no energy sources from outside the system, eg the sun to the Earth, where Earth is the system.
 
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  • #5
DaveC426913
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You leave the binder of your manuscript on the counter. You've numbered all the pages to keep them in order.

Your rival sneaks in and rearranges one or two pages.

When you return, you can tell very easily that some pages are out of order. In fact, any change in the page order is immediately obvious. In fact, every change, even the smallest change, is uniquely distinguishable from every other change. Your book has very low entropy.

Your rival sneaks in again but this time thoroughly shuffles all your pages.

In this new state, no page is next to its neighbour. At this, point whether small changes are made to page order or large changes are made to page order, it doesn't really matter. One change is indistinguishable from another. Your book has high entropy.

When the universe ages and dies, everything will be distributed somewhat evenly. Moving molecules around, say switching two molecules - even switching countless billions of molecules - will make virtually no difference. Entropy will be near maximum.
 
  • #6
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So life is in a sense, simply highly organized molecules that happen to create energy in order to sustain said organization? Like a perfect storm or something?
 
  • #7
So life is in a sense, simply highly organized molecules that happen to create energy in order to sustain said organization? Like a perfect storm or something?
Given that they don't reflect entropy, they are exactly what can happen when the papers are organised by an external person; despite people throwing them into disorder, sooner or later no matter how much disorder there is, if there is more of an outside influence that creates order, the papers will become more ordered.

Nice analogy DaveC. :smile:
 
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  • #8
DaveC426913
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Nice analogy DaveC. :smile:
Please, credit where credit is due. Brian Greene is a brilliant, brilliant writer.
 
  • #9
Please, credit where credit is due. Brian Greene is a brilliant, brilliant writer.
Indeed apologies to Brian Greene, an inspired description.
 
  • #10
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Still confused. Are there more layier laymens terms we can use?
Entropy is another word for confusion--- but with a quantitative slant.

So in fact you do already understand it; you could say that your state of mind when you are confused is one with high entropy! Entropy is an abstract descriptive term invented by physicists long ago to measure how confused simple systems can get. It is an abstract concept rather than a "thing", such as a dog or a star. When applied to the state of a gas, entropy is simple to define. When applied to the Universe it turns out that there are problems.
 
  • #11
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Entropy ~ number of ways in which a system can arrange itself.

(Actually it's just related to this quantity... entropy = k*log(ways) ...)

Picture a "way" as a particular arrangement of positions and momenta for all the gas particles in a box of gas.

Gas confined to half a box ~ fewer ways.
Gas expanding to fill the whole box ~ more ways.

Therefore: 2nd law says gas expands. Whoosh.
 
  • #12
DaveC426913
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Entropy is another word for confusion--- but with a quantitative slant.

So in fact you do already understand it; you could say that your state of mind when you are confused is one with high entropy! Entropy is an abstract descriptive term invented by physicists long ago to measure how confused simple systems can get.
The trouble is, that's an ambiguous and rather vague definition. Suggesting it is synonymous with 'confused' is unhelpful.
 

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