It is human nature to try to explain the laws in accordance with which the world around us lives. At the dawn of Consciousness, all observed natural phenomena were attributed to a host of different gods: rain, thunder, lightning, wind - all of them owe their origin to the deities. Then mysticism gave way to science. Although she was still in its infancy, nevertheless, it already allowed inquiring minds to explain some of the natural phenomena, without resorting to the gods. Of particular interest was visible light. In attempts to somehow explain it, an assumption was put forward that he was a continuous stream of some tiny particles-corpuscles. I. Newton adhered to this model and actively defended it. And since there is a particle, then it must be characterized in some way.
Everyone knows that if you put your hand in the sun, then you feel warm. It is known that this is possible due to radiation. But how exactly does radiation transfer heat? So the photon energy was discovered - first by an indirect method. And the particle itself was called the "quantum of light." Photon energy is widely used in modern technology: for example, it is it that launches the mechanism of automatic door opening in large retail outlets.
The possibility of the impossible
So, a photon is a particle of light, a quantum of energy. However, further studies have cast doubt on the accuracy of the corpuscular model. First, Huygens pointed out some unusual properties, and then Jung, through his experience with several gaps, discovered the phenomenon of interference and, on its basis, brilliantly proved ... the wave nature of light. It would seem that you can put an end to it, but everything turned out to be much more complicated. It is hard to believe, but a photon exhibits the properties of both a particle and a wave, and at the same time. The result of any experiment depends on the expectations of the researcher himself. Thought and intention somehow transform the particle into a wave and vice versa. The photon energy remains unchanged and can be calculated in the framework of the classical electromagnetic theory.
The term "speed of light" is directly related to photons. Actually, 300 thousand km / s is the speed with which these particles without mass are moving. Their existence is inseparable from movement: already at their occurrence, photons move, forming a beam.
Photon energy
Energy, speed and mass are interconnected by Einstein’s famous formula E = mc2. Supplementing it with Planck’s constant, we obtain:
E = h * v,
where v is the wavelength of light radiation (photon frequency); h is the Planck constant.
By composing both equations, we can calculate the mass:
m = (h * v) / c2
We repeat that since this particle exists only in motion, the obtained value is applicable precisely for such a state.
Obviously, with increasing wavelength (increasing frequency), energy also becomes larger. However, the human eye is capable of capturing photons with relatively low inherent energies. This is due to the value of the Planck constant, which is represented by a -34 degree number, which gives extremely low energy. For example, the most intense color is green. But even his energy is 4 * 10 to the degree of -19 Joules.
Afterword
The transition from classical mechanics to modern quantum mechanics, in which almost all microworld processes can be explained in terms of the corresponding models, continued until the 1900s. One part of the physicists adhered to the corpuscular theory expressed by Einstein, while the other adhered to the wave model of light proposed by Maxwell. Finally, the modern idea of a photon was established after an experiment with its scattering by an electron (since the latter is outside the atom, the concept of energy shells does not apply to it).