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  • Cheating your way out of the Second Law and into Perpetuum Mobile.

    From Rock Brentwood@21:1/5 to All on Tue Dec 20 12:54:52 2022
    Is there a way to radiate entropy out into interstellar space, in
    some kind of "entropy beam", in sufficient quantity as to enable
    to the Earth (or Solar System) to maintain a constant or even
    decreasing entropy?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Thomas Koenig@21:1/5 to Rock Brentwood on Wed Dec 21 12:56:53 2022
    Rock Brentwood <rockbrentwood@gmail.com> schrieb:
    Is there a way to radiate entropy out into interstellar space, in
    some kind of "entropy beam", in sufficient quantity as to enable
    to the Earth (or Solar System) to maintain a constant or even
    decreasing entropy?

    Of course (at least as far as Earth is concerned).

    Earth receives a stream of entropy from the sun via solar radiation (approximately the energy of the solar radiation impacting Earth divided
    by the black-body temperauter of the Sun) and emits entropy into space
    via radiation, approximately the same amount of energy from the sun
    divided by the temperature of Earth as a black body. Because that
    temperature is much lower than that of sunlight, Earth generates
    a lot of entropy.

    The Second Law states that the change in entropy of any system has
    to be larger than, or equal to, the sum of the entropies going
    over the boundariy of that system. So yes, the Earth's entropy
    could decrease, by quite a lot.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phillip Helbig (undress to reply@21:1/5 to Rock Brentwood on Wed Dec 21 12:56:36 2022
    In article <0a43cf3c-ac50-4191-9f16-521206f1371dn@googlegroups.com>,
    Rock Brentwood <rockbrentwood@gmail.com> writes:

    Is there a way to radiate entropy out into interstellar space, in
    some kind of "entropy beam", in sufficient quantity as to enable
    to the Earth (or Solar System) to maintain a constant or even
    decreasing entropy?

    Although I don't think it has anything to do with the title of your
    post, my guess is that that is already the case. The Earth is not a
    closed system and as such there is no reason to expect its entropy to
    increase. Most solar radiation is re-radiated in the infrared. Just
    like a refrigerator can remain cool because that is more than
    compensated by the heat produced outside of the cool space by the motor,
    the huge increase in entropy in the Sun can more than offset a
    decreasing entropy on Earth.

    My guess is that in the traditional sense, the entropy of the Earth is
    roughly constant. How that changes if one takes information content
    into account is probably a different question.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Sylvia Else@21:1/5 to Rock Brentwood on Wed Dec 21 12:57:04 2022
    On 21-Dec-22 7:54 am, Rock Brentwood wrote:
    Is there a way to radiate entropy out into interstellar space, in
    some kind of "entropy beam", in sufficient quantity as to enable
    to the Earth (or Solar System) to maintain a constant or even
    decreasing entropy?

    No. Entropy is not similar to energy. Rather it is a measure of the
    disorder in a system. It's not something that can be extracted and sent elsewhere.

    Sylvia.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Stefan Ram@21:1/5 to Sylvia Else on Wed Dec 21 23:21:48 2022
    Sylvia Else <sylvia@email.invalid> writes:

    No. Entropy is not similar to energy. Rather it is a measure of the
    disorder in a system. It's not something that can be extracted and sent >elsewhere.

    Entropy is an extensive property of a system, similar to
    momentum. As such, it /can/ be exchanged. A change dS of
    entropy S is connected with a change T dS of heat energy,
    where T is the temperature of the system. When entropy dS
    is leaving a system, it has to go somewhere (into another
    system). That's pretty much "extracted and sent elsewhere".
    Such an exchanged is caused by a difference in temperature
    at the boundary of two systems. The entropy will move from
    the system with the higher temperature to the system with
    the lower temperature.

    Unlike for momentum, there is only half a conservation law
    for entropy. While entropy cannot be reduced in a closed
    system, it /can/ be created. When entropy is exchanged,
    in the process, there might be additional entropy created.
    When the temperature difference between two systems is
    smaller, there is less entropy created in the exchange.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Thomas Koenig@21:1/5 to Sylvia Else on Thu Dec 22 10:29:02 2022
    Sylvia Else <sylvia@email.invalid> schrieb:
    On 21-Dec-22 7:54 am, Rock Brentwood wrote:
    Is there a way to radiate entropy out into interstellar space, in
    some kind of "entropy beam", in sufficient quantity as to enable
    to the Earth (or Solar System) to maintain a constant or even
    decreasing entropy?

    No. Entropy is not similar to energy. Rather it is a measure of the
    disorder in a system. It's not something that can be extracted and sent elsewhere.

    Of course you can send entropy elsewhere - any heat exchanger does so.

    Transfer a heat stream Q (in W) at temperature T (in K), and you get
    an entropy stream of Q/T.

    Related question: How do you decrease the entropy of a glass of water?
    Answer: Put it in a fridge (or empty it).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)