Physical nature of light

In this chapter we are concerned primarily with the physical nature of light and the mechanism of light absorption by molecules. We will discuss... 

We saw in Chapter 3 that light from the Sun was broken into a spectrum and that a new element—helium—was discovered, identified by the dark lines in that specttum. It is essential to learn at least a little about the physical nature of light in order to understand how the lines in the specUnm can tell us about energy levels in the atoms. 

As discussed for several decades by a number of authors, the nature of light and photon physics is related not only to the propagation of plane wavefronts but also to axisymmetric wavepackets, the concepts of a rest mass, a magnetic field in the direction of propagation, and an associated angular momentum (spin). 

Einstein s idea started a truly revolutionary development in physics quantum mechanics, It opened up wide new horizons and clarified many outstanding problems in our view of the structure of matter, Quantum mechanics is based on the idea of wave-particle duality. Einstein first applied this idea to the nature of light, but it was... 

In order to obtain physical ideas without adopting a physical theory we must make ourselves familiar with the existence of physical analogies. By a physical analogy I mean that partial similarity between the laws of one science and those of another which makes each of them illustrate the other. Thus all the mathematical sciences are founded on relations between physical laws and laws of numbers, so that the aim of exact science is to reduce the problems of nature to the determination of quantities by operations with numbers. Passing from the most universal analogies to a very partial one we find the same resemblance in mathematical form between two different phenomena giving rise to a physical theory of light. 

Does the particle nature of light cause its wave aspects Or vice versa All these questions may only be asked from the point of view of classical physics, they only have meaning from the classical view. Once quantum mechanical physics enters the scene, no one even attempts to answer the questions on the classical level, if my guess that brain and mind are parallel aspects of a more fundamental reality is nebulous, perhaps it will take on some relevance when a "quantum mechanics of philosophy" will be available, whether a process of mind studying mind will accomplish such a feat is still an open question. 

Low slope for natural waters (physical dispersion of light)... 

Bohr had calculated the most accurately known experimental constant in physics by a method which was, to use a mild description, simply an outrage The corpuscular nature of light had come to stay it could no longer be ignored. No evangelist ever made so many converts in so short a time as did Bohr. 

One of the w atershed events in the development of physics and chemistry was the appearance of Einstein s landmark paper explaining the photoelectric effect, establishing the corpuscular nature of light, and leading to the modern view of the wave-particle duality of the microscopic realm. 

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