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Entropy Vs. Life

  1. Aug 13, 2005 #1
    We don't know how cells or bacteria were created which is a highly orginazed chunk of matter. But if it arose randomly from a soup of necessery indegrients, would that violate the second law of thermodynamics which says the entropy increases with time.

    The probability of the "soup" to create a perfect square of molecules would be no different than to create a cell. In time, the perfect square disappears but the cell lives on by picking up other molecules and dividing. So the order begins at the microscopic level.
     
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  3. Aug 13, 2005 #2
    I do not know the immediate answer to your question, but let me point out that the second law of thermodynamics is not quite as strict as most physical laws. It's more of a guideline. An overwhelming amount of the time, the entropy of a closed system will increase with time, but there is a miniscule possibility that a closed system's entropy can decrease.
     
  4. Aug 13, 2005 #3
    The simple answer is that life pays for its order by increasing the rate at which the Universe in general is being disordered. So light from the sun is captured by a forest and then released at a much lower temperature than it would have been off bare rock.

    This kind of perspective changes life and other dissipative structures from a surprise to a necessity. Structures that are better at disposing of entropy gradients are likely to be favoured by nature. Some would call this the basis of a fourth law of thermodynamics. A controversial area still of course.
     
  5. Aug 13, 2005 #4
    I quote from ZapperZ's journal, which I think answers your question:

    [09-05-2004 07:33 AM] - Imagination without knowledge is Ignorance waiting to happen - Part 2
    https://www.physicsforums.com/journal.php?s=&action=view&journalid=6230&perpage=10&page=10
     
  6. Aug 14, 2005 #5

    russ_watters

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    The 2nd law says entropy for a closed system increases with time. The entropy of that "soup" could still be increasing while the first proto-cells were forming.
     
  7. Aug 14, 2005 #6

    Moonbear

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    As others have pointed out, living organisms are not a closed system and require continuous inputs of energy from the environment to maintain internal order (homeostasis). The majority of this energy is provided by the sun through photosynthesis in which the photosynthetic organisms convert the sun's energy into chemical energy. Then photosynthetic organisms are consumed by non-photosynthetic organisms to extract the chemical energy and use it for themselves.

    So, you need to consider the sun as part of the system of life on Earth and the loss of energy from the sun that accompanies the use of that energy to maintain order by living organisms.
     
  8. Aug 14, 2005 #7

    Bystander

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    "Organized," "order," and "low entropy" are NOT synonyms, never have been synonyms, and never will be synonyms. Entropy is the integral of dq/T from 0 K to the temperature of interest for the system of interest. The change in entropy associated with the formation of chemical compounds is the entropy of the compound minus the entropies of the elements comprising the compound; this is nearly always greater than zero (can't think of any exceptions off the top of my head). The entropies of mixing compounds to form solutions, cell walls, micelles, and other biological structures is also positive.

    Anyone who asserts that "highly organized" structures such as living cells are also "low entropy" entities ain't been near a thermo book in his/her/its life, or is engaged in fraud.
     
  9. Aug 14, 2005 #8
    Living organisms are dissipative structures (Nobel Prize for Chemistry for Prigogine on 1977). They are studied from a "generalization" of thermodynamics.

    dS = diS + deS

    diS > 0 for disissipative phenomena. If system is isolated deS = 0 and then dS = diS > 0

    If system is open dS =/= diS. On a dissipative structure

    dS = diS + deS

    with |deS| >> |diS|

    and dS = diS + deS << 0

    that is the system self-organizes.
     
    Last edited: Aug 14, 2005
  10. Aug 14, 2005 #9

    This is one of more commons errors of physics literature.

    Of course the second law of thermodynamics is a strict law. It is so strict as Newton ("rational") laws of mechanics.

    This typical error on interpretation of second law is the basis of the completely wrong article published in physical review letters some years ago:

    and was invalidated by several authors including Juan R. (CPS:physchem/0309002).
     
  11. Aug 14, 2005 #10

    Q_Goest

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    There are many examples of processes in nature that reduce entropy locally, only to increase entropy elsewhere. Take water vapor for example. The evaporation of water increases enropy, but the condensation of water is a local decrease in entropy. So water vapor that forms into rain droplets is actually a decrease in entropy for the water.

    There's nothing special about local decreases in entropy, it happens all the time without the help of life.
     
  12. Aug 14, 2005 #11

    selfAdjoint

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    Exactly, and just as Newton is not true in the more general case of high speeds, so the second law is not true in the general case of open systems, where its hypotheses are violated:

    In every closed system the entropy is non decreasing
     
  13. Aug 14, 2005 #12

    Gokul43201

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    Glad you brought this up. I've always wanted to ask an ID proponent to point me to literature quoting the value of [itex]\Delta S^o_f ~(human~being)[/itex].

    But note here, that the relevant entropy change is not for formation from the elements but rather from H2O, O2, CO2 and N2 (primarily).
     
    Last edited: Aug 14, 2005
  14. Aug 15, 2005 #13

    Bystander

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    ... and?

    Your homework for the day: count translational, rotational, internal rotational, and vibrational degrees of freedom contributing to the heat capacities of a system of n amino acids, n(NH2-R-CO2H), in aqueous solution; synthesize an n-peptide from the n amino acids; count the contributions to heat capacities of the products; note the absence of any change in total heat capacity; configure the peptide in any "active" arrangement you wish (prion, enzyme, whatever), using the water from the condensations and additional water from the original solution if necessary; count contributions to heat capacity; integrate the difference in heat capacities between the configured peptide and that of n amino acids in solution.

    The "relevant" entropy change is between smaller reactant molecules and larger product molecules. Losses of translational degrees of freedom, and "locked" configurations appear as increases in product heat capacities relative to the sum of reactant heat capacities; hence, an increase in product entropy.

    Edit: Addendum: Would everyone please note that this process takes place in a "closed system." i.e., there is NO necessity to flounder about defining open, closed, and isolated systems and the second law statements applying to such.
     
    Last edited: Aug 15, 2005
  15. Aug 16, 2005 #14
    You are completely misguided.

    1) appealing to strictness of second law i was (it is obvious for anyone with a minimum knowledge) rebating the popular but wrong idea of physics literature that Newton laws are laws of nature whereas the second law is a "statistical" law.

    2) I newer said that Second law was absolute. In fact, in my papers and preprints i newer said that. For example in (CPS: physchem/0309002) I said

    3) The second law is perfectly valid in open systems. You say is completely wrong. Has you heard about the thermodynamics of open systems guy?

    I recomend to you very, very, very old literature on the topic. See, for example, famous Prigogine monograph Introduction to thermodynamics of irreversible processes 1955.

    Prigogine received the Nobel Prize for chemistry 1977 for his work in open systems, specially dissipative structures.

    AS already SAID in post #8


    The second laws read

    diS > 0 for disissipative phenomena and

    diS = 0 for equilbrium phenomena.

    If, and only if, the the system is isolated (no "closed" like you incorrectly say) the deS = 0 and then dS = diS > 0 or dS = diS = 0.

    That is entropy S is non decreasing (*).

    If system is non isolated (e.g. open) then dS =/= diS, and

    dS can be positive, negative, or zero in function of external flows of matter and energy.

    In living systems (mature) the ss aproach can be used and the production of entropy by metabolic processes is almost cancelled by external flows of entropy (mainly expulsion of residue by cells metabolism) and dS = 0.

    Therefore, the living body maintain its structures (its order) "forever".

    (*) Note that i did not say that was valid elsewhere. Your "in every closed system the entropy is non decreasing" is also wrong when one studies small (nano) systems.

    However, and this was the error of Wang et al paper i cited, that does not imply a violation of the second laws. Precisely the result obtained by Wang et al are compatible with the second law until the second order in perturbation series of thermodynamic fluctuations theory.
     
    Last edited: Aug 16, 2005
  16. Aug 16, 2005 #15

    Gokul43201

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    When one says the above, there is an implicit statement that the change is measured in the limit of a large number of particles or over large timescales.
     
  17. Aug 16, 2005 #16
    I'm sorry but i cannot agree.

    If one say "every" that mean "every". Precisely the error of interpretation of the second law was the basis for wrong claims of Wang et al paper and subsequent gulash of news and others on APS, Nature news, BBC science news, and others.

    The second laws vas violated! They claimed

    But it was not, either implicit or explicit :biggrin:

    Moreover, you also appears to confound closed and isolated systems. Also the definition of isolated system is implicit in above "closed"?
     
  18. Aug 22, 2005 #17
    Part of the energy absorbed by trees and other plants is converted into complex organic molecules which may in turn be consumed by animals which use the molecules to grow and move around. In other words biological organisms tend to increase order.
     
  19. Aug 22, 2005 #18
    Biological life, however it came to exist, reduces the potential entrophy of a planet. Energy reflected or radiated back into space is essentially lost because it cannot do anything. By using energy for constructive purposes biological life reduces the amount of entrophy that would otherwise occur if there were no biological life.
     
  20. Aug 22, 2005 #19

    Bystander

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    This is a bold assertion. You have written the partition function for an abiotic earth and compared it to that for a biotic earth? And, found the second case to yield a smaller entropy than the first?

    I KNOW you haven't. Life ain't an "ordered" process. Mother nature is an entropic, wasteful sloven. Roget's Thesaurus is not a suitable source for establishing the equivalence of order, organization, complexity, structure, and other ID words with a state of low entropy.

    Write the partition functions or keep your peace. Hand waving is not suffered gladly on this forum.
     
  21. Aug 22, 2005 #20

    russ_watters

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    There's a trick there, Bystander, that I think you missed:
    That statement doesn't say that life decreases the entropy of a system, it says that a system with life involves less of an increase in entropy than one without. I would tend to agree, but its a pretty uselsess thing to discuss.
     
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