引用:
lovelegend寫到:
我應該修正我的說話, 光並不是 wave 也不是粒子, 而是量子...
論點出處是愛因斯坦在 1905 年 Annalen der Physik (一本科學雜誌)上發表的三大論文之一 "On a heuristic viewpoint concerning the production and transformation of light" (愛因斯坦亦是憑這篇論文而得到 1921 年的諾貝爾物理獎的)...
當然我沒有看過那篇論文
, 我看的是一本介紹 Quantum Physics 的書, John Gribbin 的 In Search of Schrödinger's Cat - Quantum Physics and Reality:
而書中說到愛因斯坦這篇論文的部份是在第 47 頁:
In effect, all Einstein did was to apply the equation E=hv to the electromagnetic radiation, instead of to the little oscillators inside the atom. He said that light is not a continuous wave, as scientists had thought for a hundred years, but instead comes in definite packets, or quanta. All the light of a particular frequency v, which means of a particular color, comes in packets that have the same energy E. Every time one of these light quanta hits an electron, it gives it the same amount of energy and therefore the same velocity. More intense light simply means that there are more light quanta (now we call them photons) that all have the same energy, but changing the color of the light changes its frequency, and so changes the amount of energy that is carried by each photon.
這篇論文的重要實驗就是著名的 "光電效應"啦！ 也因為這個實驗讓世人看見了 波和粒子是可以如此的接近!
我們都知道波是能量在介質中向某方向傳遞，而質能是可以轉換的... 光電效應中, 特定頻率(能量)的光才能從靶材中轉換出(我故意不說"打擊")電子... 其實這只意味了光不是單純的連續波，但並沒有完全推翻光的波動性(光波的偏極化現象(就是偏光啦)便是粒子性解釋不來的)。 它只顯現了能量從光量子(即光子)的形式轉換成具動量型態的電子時, 是非連續的。實際上要描述光的性質時是無法以單一理論來完整它的.
Grant R. Fowels 所着光學入門聖典: Introduction to Modern Optics 中就說到:
If one were to ask the question "What is light, really?" there can be no simple answer. There is no familiar object or macroscopic modle to employ as an analogy. But understanding need not be based on analogy. A consistent and unambiguous theoretcial explanation of all optical phenomena is furnished jointly by Maxwell's electromagnetic theory and the quantum theory.
麥斯威爾...(好啦! 馬克斯威... 
) 方程加上連續方程式可將光的傳播、極化...等, 描述的很好；而要描述光和物質間的交互作用或說是吸收和放射就得用到量子理論。兩相結合後就是著名的 量子電動力學 ，之後的統一場論便是奠基於此，屆時所有物質現象都能用電磁理論描述。
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(題外話一下, 這本書亦提到了愛因斯坦和 Erwin Schrödinger 在量子物理學上的爭拗 (所以書名也用到了 Schrödinger's cat 假說), Schrödinger 說 "Nothing is real unless it is observed", 但愛因斯坦很不以為然, 並說 "God does not play dice"... 這個爭拗一直不能解決, 直到 1982 年 University of Paris-South 進行了一些實驗, 最終證實 Schrödinger 是對的...
P.S. 其實 Schrödinger 也很不太能接受自己的理論, 所以他說過一句話: "I don't like it, and I'm sorry I ever had anything to do with it"
)
這個就是在說物質波啦... 所謂物質波即是一種機率波, 是單一粒子於某一瞬間在空間中出現的機率分布情況(這一句實在很難描述完整... 
)，也就是說，在某時間 t 該粒子視機率會出現在空間中任一位置(好像也沒清楚多少... 
)。
這是在極小尺度的世界中所展現的性質, 你會發現 粒子性和波動性在此的界線已非常模糊...
但對追求真理(凡事都有確定的解釋)的物理學家們來說, 用機率來描述實在是再奇怪不過的事情啊！
也難怪老愛無法接受...
引用:
在網上找了一下亦在 Wikipedia 找到光子的解釋:
http://en.wikipedia.org/wiki/Light_quanta
In some respects a photon acts as a particle, for instance when registered by the light sensitive device in a camera. In other respects, a photon acts like a wave, as when passing through the optics in a camera. According to the so-called wave-particle duality in quantum physics, it is natural for the photon to display either aspect of its nature, according to the circumstances
最後一句才是重點喔! "光子"視情況表現出 波-粒二相性 中之其一...
[frankliu 在 2005-10-23 04:07 PM 作了最後編輯]
