送交者: 秦州刺史 于 2005-6-20, 22:57:17:
号说那虹桥论坛号称“网上学历最高的论坛”，“网友中教授者众”，今得闲观其众网友讨论“温度本质”，却发现原来应是“草包者众”。
网友“老泉”（估计是搞生物的，亦或国内教授，未可知也） 首先发问：
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某斗胆讨教一个业余问题:温度的本质到底是啥? 送交者: 老泉 于 June 21
比如那谁说了,大爆炸留下的背景辐射,温度若干K,啥意思? 送交者: 老泉
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下面是虹桥网友的一些会答：
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1.能想象到跟压力差不多就很好了。送交者: mirror 于 June 21, 2005
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2.电子轨道的能量是否可以看作是温度? 送交者: 老泉 于 June 21, 2005
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3.温度的本质是原子分子的热运动。送交者: 离乡客 于 June 21, 2005
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不应该问温度的本质，而是应该问热的本质 送交者: 元江 于 June 21, 2005
热,体现在原子内部,是否就是电子轨道的能级? 送交者: 老泉 于 June 21
不是，热是能量“死了”的表现。送交者: 元江 于 June 21
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我的评论：
１。众人中只有元江触及到一些问题本质。
２。Mirror 的回答好象相面先生，装神弄鬼，其实还是不懂装懂。
３。离乡客，作为一位国内培养的物理博士，还在背中学物理教科书。
４。老泉，应该是一位民科，如果是搞科研的，上帝应该哭泣。
我的回答：
Temeperature is a thermodynamic property, by saying thermodynamic property, we mean this is a property associated with an ensemble of particles, not like properties of mass, charge, velocity that can be associated with an individual particle. A system's tempeture determines the distributation of particles in each available energy levels, in classic sense, that distributation is Boltzman distributation.
For example: in a simple system with two energy levels, E_0, E_1,
if E_1-E_0=k*500K，(k, boltzman constant, K, kevin)
if Temperature at 500 kevin,
then 1/(1+exp(-(E_1-E_0)/kT)=1/(1+exp(-500k/500k))=1/(1+exp(-1))=73% particles in lower energy state,
exp(-(E_1-E_0)/kT)/(1+exp(-500k/500k))=27% particles in E_1 state.
when temperature goes to infinity
if T->infinity, exp(-(E_1-E_0)/kT) ---> 1, so 50% in lower state, 50% in higher energy state.
what about negative tempeture:
if T=-500K for above system, exp(-(E_1-E_0)/kT)=exp(1), then 73% particles in higher energy level E_1, 27% particles in ground state E_0.
Then go back to the concept of heat, in thermodynamic, we usually differeniate between two kinds of energy: heat and work. What's the difference between this two? why?
short answer: heat is related to the population changes at different energy levels.
work is related to the change of energy levels themselves.
Layman and "文科傻妞” don't need to understand this.
I am not a physics major, but I am sure I got better understanding of temperature, heat etc. than those guys in 虹桥论坛.