The Light show of the world
The doctrine of light (optics) occupies among other branches of physics special place. If electrodynamics and atomic physics developed as part of the exact Sciences, the basic concept of light (with the help of view we get about 90% of the information about the macrocosm) man made at the dawn of “civilization. The rectilinear propagation of light in free space and the formation of shadows from opaque obstacles in ancient times gave rise to the presentation of light — flow rectilinearly moving particles. Much later, in the seventeenth century, more subtle observations also revealed the wave properties of light (interference, diffraction). In the seventies of the nineteenth century Maxwell in electrodynamics tied optics with electromagnetism, putting in to the unified nature of light and predicted electromagnetic waves.
A detailed study of the interaction of light with matter and radiation processes showed that the wave concept is insufficient for understanding these phenomena, and ultimately led to fundamental changes in our views on the nature of light and elementary particles that interact with light, appeared and quickly developed quantum mechanics, where the apparent contradiction between the wave and corpuscular properties of light (and matter) found the explanation.
However, almost all phenomena observed in the propagation of light in transparent media and in vacuum, well describes the “wave” language — it is mainly, and would apply to most of the “Optics”.
Visible radiation (frequencies from 4 • 10 14 to 7.5 x 10 14 Hz; wavelength in vacuum of 7.5•10 -7 to 4-10
7 m) occupies a very small part in the full spectrum of electromagnetic waves, but plays for man a decisive role. Therefore, in this book it appears radiation is the main focus.
As you know, low frequencies in the visible range cause a person the feeling of red, high — purple. Even more low and high frequencies do not cause visual sensations’ but have physiological effects, sometimes very harmful. But as the nature of all these radiations are the same, the term “light” is often used in physics to all radiations, i.e. wider than in everyday life.
We live in a world populated by particles. Born during nuclear transformations antiparticles (even stable) soon meet with the relevant particles together and disappear, giving rise to photons or ?-the mesons.
However, in principle it is possible the existence of the world, consisting of antiparticles as stable as our world. In this anti-world, for example, an atom of antihydrogen would consist of the antiproton th positive electron. Its chemical properties and its spectrum does not differ from chemical properties and spectrum of hydrogen. Therefore, studying the spectra of distant galaxies, we can’t say whether any of the galaxy from matter or antimatter. In any case, the latter possibility is not excluded, and, perhaps, in the development of the Universe could be cases of interaction of galaxies of matter and antimatter, resulting in tremendous explosions with very quick and powerful release of energy.
The diversity of microscopic phenomena, quite unlike the phenomena familiar to us of the macrocosm, is subject to quite specific (still poorly understood) laws and, despite its strangeness, is a brilliant confirmation of the doctrine of dialectical materialism about the inexhaustibility of the world and its cognoscibility. Literally the same can be said about the megaworld – the world of stars, pulsars and black holes discussed above. Here it is appropriate to recall the idea of V. I. Lenin that the phenomenon of nature can be quite varied as the properties of its constituent bodies. But the most important remains the property of matter to exist objectively and to be in continuous change, to describe what we create our not always perfect theory.