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Entropy: How?

  1. Jun 29, 2003 #1
    If one thinks of the Universe as a closed system -- with the conservation of energy firmly in place -- how can there EVER be in the aggregate a "decrease in the system's ability to do work" ...or "a decrease in the energy available" (from Oxford's Dictionary of Science)?

    Further, if this "Second Law of Thermodynamics" is "true" -- that "any real change to a closed system tends toward higher entropy, and therefore, higher disorder" -- how do we/you explain the evidence to the contrary: the constant formation of coherent sub-systems...like atoms, molecules, organisms, stars and galaxies (NOT a comprehensive list!)?

    If the Universe is indeed "losing heat" -- where is the heat going?

    Finally, might not the same "cooling" of the System that caused elementary particles to "condense out" of the "primal energy" just after the Big Bang ...might not this same "cooling" that is predicted as part of the current "eternal expansion" theories cause ANOTHER "phase transition" that produces "matter" out of energy, thereby INCREASING THE OVERALL GRAVITY of the System to cause It's eventual COLLAPSE?

    And if not, why not?
    Last edited: Jun 29, 2003
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  3. Jun 29, 2003 #2


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    Do you have any strong evidence of "the constant formation of coherent sub-systems...like atoms, molecules, organisms, stars and galaxies". I believe that whether atoms are being constantly formed is an open question and that the formation macro objects is a local phenomenon resulting in increased entropy in the rest of the universe.

    In any case, increased entropy does not imply "cooling". Entropy simply means the "uniformization" of energy. In it's simplest form, hot stars give of heat cooling themselves while warming space so that energy becomes uniformly distributed through the universe.

    Notice that the quotes you give do NOT say a decrease in energy but rather "available energy". It is energy differences that make energy "available".
  4. Jun 29, 2003 #3


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    Couple points: "order/disorder" is a flawed (specious, idiotic, ill-informed, unread, pick your own favorite perjorative) analogy for the concept of entropy; restriction of the second law to "closed systems," as inevitably occurs in these threads, is an indicator of an incomplete education in thermodynamics (or a mechanical engineering or physics background).

    Entropy is a thermodynamic state function; it was derived/defined/developed from the first law (conservation) statement in the first half of the 19th century --- it includes NO specifications regarding "order, organization, coherence, or any other hand-waving appeals to intuition." The second law applies to the universe (everything), and states that the entropy of the universe increases for any observed change in any system (part of the universe separate from the system surroundings), be it open, closed, or isolated.

  5. Jun 29, 2003 #4
    Look around.

    Really? And I thought that this is what going on within stars all the time.

    So what? When someone (and I ain't talkin' about "God") creates something -- a painting, for instance -- we don't ignore the painting and point to the floor and say "Look at all that mess!" If the Universe draws energy from one part of Its System to create a coherent, dynamic sub-system -- and if It's DOING IT ALL THE TIME -- then there's your evidence for the constant formation of macro objects

    Well, according to the Oxford Dictionary of Science (ODS) "thermodynamics" refers to "the conversion of energy from one form to another, the direction that heat will flow, and the availability of energy to do the work."

    The ODS further explains that thermodynamics is "based on the concept that in an isolated system anywhere in the Universe there is a measurable quantity of energy called the internal energy -- U of the system. This is the total kinetic and potential energy of the atoms and molecules of the system of all kinds that can be transferred directly as heat (therefore excluding chemical and nuclear energy). The value of U can only be changed if the system ceases to be isolated."

    My POINT is that IF the Universe IS an "closed" and "isolated" System (ignoring theories of "multiverses" for a moment), then ENTROPY cannot, in fact, take place because the Universe would have ALL OF ITS ENERGY -- in one form or another -- ALL OF THE TIME.

    And yet, from the Big Bang up to this very moment, "hot spots" of dynamic, coherent sub-systems (like stars, as an example) form, use up their energy and disperse their "ingredients" so that the same thing can take place elsewhere in the Universe.

    That's why -- I think -- we call it "dynamic".

    And if the Universe CONSERVES Its ENERGY as an ISOLATED SYSTEM...then It's energy is always available from somewhere.

    Thus -- in the aggregate -- entropy cannot be taking place.

    And I'm sure someone will tell me why I'm wrong.
  6. Jun 29, 2003 #5
    So, you are saying that the ODS (as referenced above) should be pronouncd -- and considered -- "ODIOUS" because it says:

    "In a wider sense entropy can be interpreted as a measure of disorder; the higher the entropy the greater the disorder."

    However, the ODS and I part company in the NEXT sentence, which reads: As any real change to a closed system tends toward higher entropy, and therefore higher disorder, it follows that the entropy of the Universe (my cap) (if it can be considered a closed system) is increasing and its available energy is decreasing."

    See my response to HallsofIvy for my take on this.

    The odious ODS then says "see heat death of the Universe"...which is what I will address in my next post here.

    Meanwhile, Tom, where are you?
  7. Jun 29, 2003 #6
    More from the Oxford Dictionary of Science (ODS/odious?):

    "heat death of the universe...the condition of the universe when entropy is maximized and all large-scale samples of matter are at a uniform temperature. In this condition no energy is available for doing work and the universe is finally unwound."

    My question is this: if the Universe conserves Its energy in some "form"...how could entropy occur?

    Or, where did the energy go?

    By the way, Bystander, per your last post: where did I use the word "intuition"??? The process of organization -- the accretion of systems through the forces in the physical domain (i.e., weak, strong, gravity and what have you) -- could be completely mechanistic.

    ...or not. :wink:
    Last edited: Jun 29, 2003
  8. Jun 29, 2003 #7
    the definition of enropy is a lot simpler than it looks and not half as mystical as its made out to be.

    take a glass of hot water and cold water and pour them together. you have just incresed the total entropy of the sytem because you cannot seperate the two again. there was potencial for the energy in the hot water to do work, but now there is less or none.

    entropy: a measurement of the total energy in a sysem which is not available to do work.
  9. Jun 29, 2003 #8
    Thanks, Maximus. That was useful.

    Yet, the Universe -- up until now, anyway -- continues to create "hot spots" -- stars and galaxies -- as matter accretes via the force (bending of space, if you must) of gravity. And even when these hot spots "blow!"...their material does not remain diffused within the Universe but, over time, comes together again to form new hot spots.

    In fact, the only time that the matter and energy of the Universe was "diffused" was right after the Big Bang. Since then, it has been spending all of its time coming together into sub-systems -- then falling or blowing apart again...etc.

    There does not seem to be -- as yet -- a "mixing" inseparately of the hot and not-so-hot. Instead, we seem to almost have a "cosmic weather system" going on, with systems that "burn off energy" to sustain a cosmic equilibrium.

    I look forward to anything you may have to say about this.

    Meanwhile, I don't remember saying that I -- or the Oxford Dictionary of Science -- said that entropy was "mystical".
  10. Jun 29, 2003 #9
    It's the expansion of the Universe

    which makes it not behave like a closed system. So while you may treat parts of the universe as closed in the thermodynamic sense, on the large scale it is anything but closed. So while smaller systems may tend to go to states of higher entropy they may take a long time getting there.
  11. Jun 29, 2003 #10
    Re: It's the expansion of the Universe

    Please say more about how the expansion of the Universe keeps it from behaving like a closed system.

    Also, is it true that ALL systems eventually dissipate over time? And if so, would not their energy -- and their matter -- be "absorbed" elsewhere ...rendering NOTHING a "closed system"?

    Is it thought that, in the current eternal expansion model of the Universe that, eventually, EVERYTHING will cool to the same temperature, thereby having no "energy available to do work"?

    Thanks for your help.
  12. Jun 30, 2003 #11
    Re: Re: It's the expansion of the Universe

    That is exactly what it means, at least by my understanding. It is the difference in heat content in one region compared to another that is energy available to do work. Once the energy level is the same everywhere, whether it is absolute zero or 10,000,000 degress there is no energy available to do work.

    On a cosmological scale, the universe is then completely wound down and nothing else happens forever except continued expansion due to momentum. That is unless there is enough matter/energy in the universe to have enough gravity to stop the expansion momentum of the universe and then begin contracting back toward the Big Crunch/Big Bang.
  13. Jun 30, 2003 #12
    Re: Re: Re: It's the expansion of the Universe

    That's what I'm counting on! :wink:
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