Re: [問題] 光在介質中
I'm not graduated from physics department, but I feel
you and some replier misunderstand most of theoretical ideas of light.
Please ask yourself first what is the particle description and wave description of light?
Are they parallel or not? Can you mix them or not? if yes , in what situation can
you do that?
Since most of us are not good theoritist, you shouldn't challenge relativistics in some
over casual way.
I try to reply part by part in the following. Let me know if you don't agree what I reply
※ 引述《goodluckav8d (古辣克)》之銘言：
光在介質中的速率為什麼會變慢
聽過一解釋 是光在介質中 又和介質內的原子 發生吸收 放射的作用
時間差所產生
但是如果根據光電效應理論
頻率濾過低的光 能量不夠和原子發生交互作用時
解釋不通為何光能夠通過介質 應該會遭到大量散射跟反射
First, don't forget phonon and molecular motion can also react with light.
Second, if you have waves have little interaction with matter, they will
penertrate without dispersion or frequency drift. Scattering and reflecting
are all strong interaction between light and matter.
而當如果解釋是" 光子" 被介質阻擋而變慢
又違反了相對論假設之一 光速恆為定值
Don't mix wave description and particle description.
Refraction index and dispersion is macroscopic idea. In particle discription,
the delay is caused by transition life time of electron, which isusually fs range.
So the light is always travelling in vaccume light speed between particles.
或是如果光速在介質中不是定值
狹義相對論就又瓦解了
請教各位幫助 蟹蟹
補充一下
聽說有實驗室 做出世界紀錄 光在介質中的速度
在接近絕對零度的情況下通過某種介質 光速比騎腳踏車還慢
Do you know the difference between group velocity and phase velocity?
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※ 編輯: goodluckav8d 來自: 118.171.193.34 (07/15 00:28)
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you can use both
the most typical boring wellknown explanatin from textbook you can use are:
delay of dipole motion->wave description
transition relaxation->particle description
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I will partially agree if you really think it carefully. The radiation of diploe or transition
radiation can olyny propagate in self-sustained path
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even random light have local phase of each frequency component, they won't
propaget in the way that out phase
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我有想過類似概念
可是光速恆在真空中為定值 是根據馬克是威爾方程示的解
加上麥克生的實驗 <= 才會有任何關測者皆為定值假設的關鍵
(光速在真空中 不需要介質 也不因觀察者所改變 對任何觀察者也恆以等速)
而如果在介質中變慢的話 "對任何觀察者 也需恆以等速"
那麼時間延遲效應 就會出現一個系統 有無限種時間延遲效應
只因為光 在介質中 有不同速率
Hers you mixed two idea again.
※ 編輯: goodluckav8d 來自: 118.171.193.34 (07/15 00:54)
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※ 編輯: goodluckav8d 來自: 118.171.193.34 (07/15 01:00)
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they are the same
可是根據我所知道 麥克生莫雷實驗並非在真空所做@@
如果光一旦進入介質 就會展現出 一般物質的特性
那麥克生莫雷實驗 應該會有所發現
或是偵測到 波鋒消長 的現象
例如你拿一台電扇去吹 麥克生莫雷實驗的檯子
會吹出一個干涉現象來
※ 編輯: goodluckav8d 來自: 118.171.197.230 (07/15 01:20)
※ 編輯: goodluckav8d 來自: 118.171.197.230 (07/15 01:22)
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但是我疑惑的是 如果在介質中的光速會因觀察者而不同
麥克生莫雷的實驗 不會如此的沉寂
至少在空氣中 可以發現一些氣流變化 所產生的干涉條文
(這實驗似乎是在非真空下所做的)
I think they are smart enough to get rid of air fluctuation.
而我本想要問的問題是這個@@
在真空中一道光打向一介質 光速C在真空中 假設光進入介質時候只剩下 1/2 C
但是通過介質之後 又必須在真空中恆以 C 前進 (符合馬克是威爾方程式的行進速度)
而光的動能假設 在進入介質之前是 hf 的整數倍
Does photon has "dynamic energy"?
and where do you read this assumption??
"直觀上"進入介質之後動能可能因此減少
如果速度變慢的話
古典物理的直觀上 光的動能在進入介質後是減少的
I don't have this intuition. Maybe I
am too damm
動能減少原因可能還有 頻率變低(紅移) 或是光子數量在介質中遭到阻擋
why?
但是如果出了介質之後 "直覺上" 它的動能會因為 速度變回c 而增加
而光子數量 跟頻率都不會無中生有 或提高
這裡確認了如果 光速在介質中會任意改變
其光在介質中的動能 也是可以因在於介質中而任意改變
因為光在介質中的特性就跟一般物體的運動特性沒有兩樣(需要遵守古典力學)
PLease check the logic in your content agian. You assume photon follow
classical mechanics at beginning and doubt the classical mechanics property of photon in the
end.
但是就在光離開介質的那一刻
能量守恆定律崩潰了
光的動能無中生有了
※ 編輯: goodluckav8d 來自: 118.171.195.24 (07/16 02:28)
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Hey please jungs!! Don't mix two ideas again. Think more!!
這解釋不是在緣木求魚嗎一一 (而且波長變了 頻率就變了阿)
光在介質 既要符合一般物質的特性 又可以不符合古典物理的直覺
而且如果只能從波的角度來看的話
光電效應 不就永遠只會在真空中產生嗎
I don't think you will get anything if you just shoot light into vaccum!! And of course
in microscopic view, any interation between light and matter are always in vaccum!!
Maybe you have gotten some powerful lightsource that can easily cross schwinger limit and have throught
about it all the time then got all of this question. In this case I am too stupid to have any discuss
with it.
※ 編輯: goodluckav8d 來自: 118.171.195.24 (07/16 10:31)
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