الصفر المطلق

*ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ* ﻫﻲ ﺩﺭﺟﺔ ﺍﻟﺤﺮﺍﺭﺓ
 ﺍﻟﺘﻲ ﻳﻨﻌﺪﻡ ﻋﻨﺪﻫﺎ ﺿﻐﻂﺍﻟﻐﺎﺯ ﺍﻟﻤﺜﺎﻟﻲ
[1]
. ﻭﺗﻌﻨﻲ ﺍﻟﺤﺎﻟﺔ ﺍﻟﺘﻲ ﺗﻜﻮﻥ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ ﺍﻟﻤﺎﺩﺓ ﻓﻴﻬﺎ ﺃﻗﻞ ﻣﺎ ﻳﻤﻜﻦ ﺃﻥ ﺗﺼﻞ ﺇﻟﻴﻪ ﺇﻃﻼ‌ﻗﺎ. ﻭﺗﻘﻀﻲ ﺑﺄﻥ ﺟﻤﻴﻊ ﺫﺭﺍﺕ
 ﺃﻭ ﺟﺰﻳﺌﺎﺕ
 ﺍﻟﻤﺎﺩﺓ ﺗﻜﻮﻥ ﻟﻬﺎ ﺃﻗﻞ ﻃﺎﻗﺔ
 ﻓﻲ ﺗﻠﻚ ﺍﻟﺤﺎﻟﺔ.
ﺍﻛﺘﺸﻒ ﺍﻟﻌﻠﻤﺎﺀ ﺍﻥ ﺃﻗﻞ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ ﻳﻤﻜﻦ ﺍﻟﻮﺻﻮﻝ ﺇﻟﻴﻬﺎ ﻫﻲ 273.15 ﺩﺭﺟﺔ ﺳﻴﻠﺰﻳﻮﺱ
 ﺗﺤﺖ ﺍﻟﺼﻔﺮ. ﺗﻢ ﺍﻟﻮﺻﻮﻝ ﺇﻟﻰ ﻣﻌﺮﻓﺔ ﻫﺬﺍ ﺍﻟﻘﻴﺎﺱ ﺑﺎﻻ‌ﻋﺘﻤﺎﺩ ﻋﻠﻰ ﺍﻟﻌﻼ‌ﻗﺔ ﺍﻟﻄﺮﺩﻳﺔ
 ﺑﻴﻦ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ ﻏﺎﺯ ﻣﺎ ﻭﺿﻐﻄﻪ ﻭﺑﺎﻟﺘﺠﺮﺑﺔ ﺗﺒﻴﻦ ﺃﻥ ﺿﻐﻂ ﺍﻟﻐﺎﺯ ﻳﺴﺎﻭﻱ ﺻﻔﺮﺍ ﻋﻨﺪ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ 273.15 ﺩﺭﺟﺔ ﺳﻴﻠﺰﻳﻮﺱ ﺗﺤﺖ ﺍﻟﺼﻔﺮ.
ﻳﺴﻤﻰ ﻣﻘﻴﺎﺱ ﺍﻟﺤﺮﺍﺭﺓ ﺍﻟﺬﻱ ﻟﻪ ﻗﻴﻤﺔ ﺻﻔﺮ ﻋﻨﺪ ﺩﺭﺟﺔ ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ ﺑﻤﻘﻴﺎﺱ ﺣﺮﺍﺭﺓ ﻣﻄﻠﻖ. ﻭﻫﻨﺎﻙ ﻣﻘﻴﺎﺱ ﻭﺍﺣﺪ ﻳﻄﺎﺑﻖ ﻫﺬﺍ ﺍﻟﻮﺻﻒ ﻭﻫﻮ ﻣﻘﻴﺎﺱ ﻛﻠﻔﻦ
. ﺍﻟﺮﻗﻢ ﺻﻔﺮ ﻋﻠﻰ ﻫﺬﺍ ﺍﻟﻤﻘﻴﺎﺱ ﻳﺴﺎﻭﻱ ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ ﺃﻭ (0 ﻛﻠﻔﻦ
) ﻭﻻ‌ ﺗﺴﺘﻌﻤﻞ ﻛﻠﻤﺔ "ﺩﺭﺟﺔ" ﻟﻠﻘﻴﺎﺱ ﺑﻪ.
ﻣﻘﻴﺎﺱ ﻛﻠﻔﻦ
 ﻣﺮﺗﺒﻂ ﺑﻤﻘﻴﺎﺱ ﺳﻴﻠﺰﻳﻮﺱ ﺣﻴﺚ ﺃﻥ ﻛﻞ ﻭﺍﺣﺪ ﺩﺭﺟﺔ ﺳﻴﻠﺰﻳﻮﺱ ﺗﺴﺎﻭﻱ ﻭﺍﺣﺪ ﻛﻠﻔﻦ
، ﻭﻟﻜﻦ ﺍﻟﻔﺮﻕ ﺃﻥ ﻛﻠﻔﻦ ﻳﺒﺪﺃ ﻋﻨﺪ ﺩﺭﺟﺎﺕ ﺍﻟﺤﺮﺍﺭﺓ ﻣﻦ -273.15 ﺃﻣﺎ ﺳﻴﻠﺰﻳﻮﺱ ﻓﻴﺒﺪﺃ ﻣﻦ 0 .
ﻭﻫﻜﺬﺍ ﻳﻤﻜﻦ ﻣﻌﺮﻓﺔ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ ﺳﻴﻠﺰﻳﻮﺱ ﻣﻦ ﻛﻠﻔﻦ ﺑﺘﻨﻘﻴﺺ 273.15 ﻣﻦ ﻛﻠﻔﻦ ﻭﺍﻟﻌﻜﺲ. ﻓﺎﺫﺍ ﺍﻓﺘﺮﺿﻨﺎ ﺃﻥ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ ﻣﺎﺩﺓ ﺗﺒﻠﻎ 50 ﻛﻠﻔﻦ
 ﻓﺎﻧﻬﺎ ﺗﺴﺎﻭﻱ ﺃﻳﻀﺎ 50-273.15 ، ﻓﻴﻜﻮﻥ ﺍﻟﻨﺎﺗﺞ -223.15 ﺩﺭﺟﺔ ﺳﻴﻠﺰﻳﻮﺱ (ﺃﻱ 223.15 ﺗﺤﺖ ﺍﻟﺼﻔﺮ ﺳﻠﺰﻳﻮﺱ).

ﺃﻱ ﺃﻥ: * T (ﻛﻠﻔﻦ) = t (ﺩﺭﺟﺔ ﻣﺌﻮﻳﺔ) + 273.16
ﻳﻌﺘﻘﺪ ﺍﻟﻔﻴﺰﻳﺎﺋﻴﻮﻥ ﺃﻥ ﺩﺭﺟﺔ ﺍﻟﺤﺮﺍﺭﺓ ﻻ‌ ﻳﻤﻜﻦ ﺃﻥ ﺗﺼﻞ ﺇﻟﻰ ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ ﺗﻤﺎﻣﺎً، ﻭﺃﻗﻞ ﺩﺭﺟﺔ ﺣﺮﺍﺭﺓ ﺗﻢ ﺍﻟﻮﺻﻮﻝ ﺇﻟﻴﻬﺎ ﻫﻲ ﻭﺍﺣﺪ ﻓﻲ ﺍﻷ‌ﻟﻒ ﻣﻠﻴﻮﻥ ﻣﻦ ﺍﻟﺪﺭﺟﺔ ﻓﻮﻕ ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ. ﻭﻳﺤﺎﻭﻝ ﺍﻟﻌﻠﻤﺎﺀ ﺍﻵ‌ﻥ ﺇﺛﺒﺎﺕ ﻋﻤﻠﻴﺎً ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ ﻟﻠﻐﺎﺯ ﻭﺍﻟﺬﻱ ﻳﻨﻌﺪﻡ ﻋﻨﺪﺓ ﺿﻐﻂ ﺍﻟﻐﺎﺯ ﻭﺣﺠﻤﺔ ﻋﻠﻰ ﺗﺪﺭﺝ ﻛﻠﻔﻦ. ..ﻓﻲ ﺑﻌﺾ ﺍﻟﻤﺼﺎﺩﺭ ﺗﻌﺘﺒﺮ ﺩﺭﺟﺔ ﺍﻟﺼﻔﺮ ﺍﻟﻤﻄﻠﻖ (-273.16) ﺩﺭﺟﺔ.