... 概念,係一個熱力學系統具有嘅外延性質(外延性質係會同個系統嘅大細成比例嘅物理性質)。考慮 呢個數值:是但搵個熱力學系統,佢會有一啲宏觀...
一杯凍檸水溶化,冰當中嘅 H2O 分子變成,並且散開。

粵拼soeng1英文entropy)係統計力學熱力學等領域常用嘅一個概念,係一個熱力學系統具有嘅外延性質(外延性質係會同個系統嘅大細成比例嘅物理性質)。考慮 呢個數值:是但搵個熱力學系統,佢會有一啲宏觀性質(例如溫度壓力等),而個系統會有若干個可能嘅微狀態(microstate;「粒子 A 喺位置 X 而粒子 B 喺位置 Y...」、「粒子 A 喺位置 Y 而粒子 B 喺位置 X...」等等),能夠同個系統啲宏觀性質吻合嘅微狀態數量就係 咁多個;熵係 函數,即係話熵反映咗「已知個系統嘅宏觀性質如此,個系統有幾多個可能嘅微狀態」。假設每個微狀態都一樣咁有可能發生(概率一樣),個系統嘅熵可以用以下呢條式計出嚟[1] [2] :

當中 kB波茲曼常數(Boltzmann constant)[3] 。

喺實際應用上, 嘅數值通常都極之大:根據估計,一嚿喺室溫同大氣壓力之下、容量 20 公升氣體總共有大約 N&000000082000-80-66.0000006×1023 咁多粒氣體分子(阿伏加德羅常數;Avogadro number),而呢嚿氣體嘅 數值( 反映「已知呢嚿氣體有 N&000000082000-80-66.0000006×1023 粒分子,可能嘅微狀態數量」)會更加大[3] 。

熱力學第二定律

睇埋:熱力學第二定律

根據熱力學第二定律(The second law of thermodynamics),一個封閉系統(closed system)當中嘅熵永遠唔會跌,只有可能維持不變或者升。熱力學第二定律意味住,搵個封閉系統,隨住時間過去,個系統內部嘅粒子同能量頂櫳維持唔郁,而喺現實多數會慢慢走位(可能嘅微狀態數量上升),會漸漸趨向熱力學平衡(thermodynamic equilibrium)-熵數值最大化嘅狀態。好似生物等嘅非封閉系統(會同周圍環境傳能量)可以內部熵下降,但噉做實會引致佢周圍環境嘅熵升,而且升至少同一樣咁多。因為噉,宇宙嘅總熵依然會升[4] 。

順帶一提,如果宇宙最後真係完全變成熱力學平衡,根據物理學家計算,宇宙最後會變成溫度分佈完全平均,而且溫度接近絕對零度攝氏零下 273.15 度)嘅空間,唔會再有任何作功,更加唔會有生命-而呢個情況就係假想中嘅熱寂(heat death)[5] 。

同資訊嘅啦掕

睇埋:資訊理論

熵仲同資訊有住密切嘅啦掕:熵由帶隨機性嘅微狀態數量決定,所以熵會反映「知道咗個系統嘅宏觀性質,需要幾多資訊先可以講明個系統處於乜嘢物理狀態」;因為呢個緣故,外行人會話熵表達咗個系統有幾「亂」-一個系統嘅熵愈高,就表示觀察者對個系統知道得愈少(有愈多不確定嘅可能性),所以就愈「亂」。而對物理意義上嘅熵嘅考量的確同資訊理論(information theory)有關(不過資訊理論當中講嘅「」係一個同物理熵唔同嘅概念)[6] [7] 。

睇埋

參考

  • Adam, Gerhard; Otto Hittmair (1992). Wärmetheorie. Vieweg, Braunschweig. ISBN 978-3-528-33311-9.
  • Atkins, Peter; Julio De Paula (2006). Physical Chemistry (8th ed.). Oxford University Press. ISBN 978-0-19-870072-2.
  • Baierlein, Ralph (2003). Thermal Physics. Cambridge University Press. ISBN 978-0-521-65838-6.
  • Ben-Naim, Arieh (2007). Entropy Demystified. World Scientific. ISBN 978-981-270-055-1.
  • Callen, Herbert, B (2001). Thermodynamics and an Introduction to Thermostatistics (2nd ed.). John Wiley and Sons. ISBN 978-0-471-86256-7.
  • Chang, Raymond (1998). Chemistry (6th ed.). New York: McGraw Hill. ISBN 978-0-07-115221-1.
  • Cutnell, John, D.; Johnson, Kenneth, J. (1998). Physics (4th ed.). John Wiley and Sons, Inc. ISBN 978-0-471-19113-1.
  • Dugdale, J. S. (1996). Entropy and its Physical Meaning (2nd ed.). Taylor and Francis (UK); CRC (US). ISBN 978-0-7484-0569-5.
  • Fermi, Enrico (1937). Thermodynamics. Prentice Hall. ISBN 978-0-486-60361-2.
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  • Haddad, Wassim M.; Chellaboina, VijaySekhar; Nersesov, Sergey G. (2005). Thermodynamics – A Dynamical Systems Approach. Princeton University Press. ISBN 978-0-691-12327-1.
  • Kroemer, Herbert; Charles Kittel (1980). Thermal Physics (2nd ed.). W. H. Freeman Company. ISBN 978-0-7167-1088-2.
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  • Penrose, Roger (2005). The Road to Reality: A Complete Guide to the Laws of the Universe. New York: A. A. Knopf. ISBN 978-0-679-45443-4.
  • Reif, F. (1965). Fundamentals of statistical and thermal physics. McGraw-Hill. ISBN 978-0-07-051800-1.
  • Schroeder, Daniel V. (2000). Introduction to Thermal Physics. New York: Addison Wesley Longman. ISBN 978-0-201-38027-9.
  • Serway, Raymond, A. (1992). Physics for Scientists and Engineers. Saunders Golden Subburst Series. ISBN 978-0-03-096026-0.
  • Spirax-Sarco Limited, Entropy – A Basic Understanding A primer on entropy tables for steam engineering.
  • von Baeyer; Hans Christian (1998). Maxwell's Demon: Why Warmth Disperses and Time Passes. Random House. ISBN 978-0-679-43342-2.

  1. Ligrone, Roberto (2019). "Glossary". Biological Innovations that Built the World: A Four-billion-year Journey through Life & Earth History. Entropy. Springer. p. 478.
  2. Baierlein, Ralph (2003). Thermal Physics. Cambridge University Press.
  3. 1 2 Richard Feynman (1970). The Feynman Lectures on Physics Vol I. Addison Wesley Longman.
  4. Zohuri, Bahman (2016). Dimensional Analysis Beyond the Pi Theorem. Springer. p. 111.
  5. Adams, Fred C.; Laughlin, Gregory (1997). "A dying universe: the long-term fate and evolution of astrophysical objects". Reviews of Modern Physics. 69 (2): 337–72.
  6. Rietman, Edward A.; Tuszynski, Jack A. (2017). "Thermodynamics & Cancer Dormancy: A Perspective". In Wang, Yuzhuo; Crea, Francesco (eds.). Tumor Dormancy & Recurrence (Cancer Drug Discovery and Development). Introduction: Entropy & Information. Humana Press. p. 63.
  7. Brooks, D. R., Collier, J., Maurer, B. A., Smith, J. D., & Wiley, E. O. (1989). Entropy and information in evolving biological systems. Biology and Philosophy, 4(4), 407-432.





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