2010年10月14日星期四

波和量子【by Louis de Broglie】


(按:前两天开组会时说到了de Broglie。据某流传甚广的八卦称,de Broglie以两页纸的博士论文拿到了Nobel奖。这当然是误传。事实上他的博士论文很好找到,我从网上下载到的英文翻译有73页,因此原文几乎不可能是两页。倒是他在Nature上发表的文章只有1/3页,十分简洁,在今天看来应该是很好懂了。以下是一个大致的翻译,供有兴趣的同学参考。另外,从今天的观点看,物理专业的同学应该很容易找出文中的不少“错误”。但这其实并不意味着什么。相对于当初那些盖大楼的先辈而言,修正这些错误不过是搞搞装修罢了。)





Waves and Quanta
波和量子





The quantum relation, energy=h
×

frequency, leads one to associate a periodical phenomenon with any isolated portion of matter or energy. An observer bound to the portion of matter will associate with it a frequency determined by its internal energy, namely, by its “mass at rest.” An observer for whom a portion of matter is in steady motion with velocity βc

, will see this frequency lower in consequence of the Lorentz-Einstein time transformation. I have been able to show (Comptes rendus, September 10 and 24, of the Paris Academy of Sciences) that the fixed observer will constantly see the internal periodical phenomenon in phase with a wave the frequency of which 
  is determined by the quantum relation using the whole energy of the moving body------provided that it is assumed that the wave spreads with the velocity c/β

. This wave, the velocity of which is greater than c

, cannot carry energy.
量子关系,即能量=h ×

频率,引导人们将周期现象与孤立的一份物质或能量联系起来。相对一块物体静止的观察者将赋予该物体一个频率,此频率由物体的内秉能量,即“静质量”所确定。而若该物体对观察者作速度为βc

的匀速运动,则根据洛伦兹-爱因斯坦时间变换,观察者将发现该物体的频率降低。我已能够演示(巴黎科学院九月10日与24日的报告),固定观察者将通过波动的相位持续地观察到物体的内部周期运动。该波动的频率
由运动物体的总能量经量子关系决定——条件是,假设该波动以速度c/β

传播。此波动的速度超过光速c

,因此不能携带能量。


A radiation of frequency ν

has to be considered as divided into atoms of light of very small internal mass (<
gm.) which move with a velocity very nearly equal to c

given by 
. The atom of light slides slowly upon the non-material wave the frequency of which is ν

and velocity c/β

, very little higher than c

.
我们须认为一束频率为ν

的辐射由具有很小内秉质量(<
克)的光原子组成。由
可知,这些光原子以非常接近光速c

的速度运动。光原子在非物质波上缓慢滑行,而该非物质波的频率为ν速度为c/β

,略高于光速。


The “phase wave” has a very great importance in determining the motion of any moving body, and I have been able to show that the stability conditions of the trajectories in Bohr’s atom express that the wave is tuned with the length of the closed path.
“相波”对于确定任意运动物体的运动极为重要,我已能够演示,玻尔原子轨道的稳定性条件表达了波动按照闭合轨道的长度被调制的事实。


The path of a luminous atom is no longer straight when this atom crosses a narrow opening; that is, diffraction. It is then necessary

to give up the inertia principle, and we must suppose that any moving body follows always the ray of its “phase wave”; its path will then bend by passing through a sufficiently small aperture. Dynamics must undergo the same evolution that optics has undergone when undulation took the place of purely geometrical optics. Hypotheses based upon those of the wave theory allowed us to explain interferences and diffraction fringes. By means of these new ideas, it will probably be possible to reconcile also diffusion and dispersion with the discontinuity of light, and to solve almost all the problems brought up by quanta.
当原子穿过狭缝时,它的路径就不再是直的,因为会出现衍射。从而,我们必须

放弃惯性定律,并设想任何物体都跟随其“相波”而运动;在通过足够小的缝隙时,它的路径就将被弯曲。曾经,波动光学代替了几何光学;如今,动力学也须经过同样的革命。基于波动理论的假设使我们能够解释干涉和衍射条纹。利用这些新见解,也可能调和光的散射色散与光的不连续性之间的冲突,从而解决几乎所有由量子带来的问题。



LOUIS DE BROGLIE
路易•德布罗意

Paris, September 12.
巴黎,九月12日。


 

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