Abstract

Already the beginning of the 20th century was marked by the greatest achievements of the human mind. May 7, 1895 at a meeting of the Russian Physico-Chemical Society AS Popov demonstrated the device he invented without wires, and a year later a similar device was proposed by the Italian technician and businessman G. Marconi. So the radio was born. At the end of the outgoing century, a car with a gasoline engine was created, which replaced the invention invented back in the 18th century. The steam car. By the beginning of the 20th century metro lines were already operating in London, New York, Budapest, Vienna. December 17, 1903, the American engineer’s brothers Orville and Wilbor Wright flew 260m on the world's first airplane created by them, and 12 years later the Russian engineer II Sikorsky designed and built the world's first multimotor aircraft, giving him the name "Ilya Muromets." Equally striking were the achievements in physics. Only in one decade at the turn of the two centuries, five discoveries were made. In the year 1895, the German physicist V. Roentgen discovered a new type of radiation, later named after him; for this discovery he received in 1901. Nobel Prize, thus becoming the first Nobel laureate in history. In the year 1896, French physicist Antoine Henri Becquerel discovered the phenomenon of radioactivity - the Nobel Prize in 1903. In 1897, the English physicist JJ Thomson discovered the electron and in the following year measured its charge - the Nobel Prize of 1906. December 14, 1900 at a meeting of the German Physical Society Max Planck gave a derivation of the formula for the emissivity of a black body; this conclusion was based on completely new ideas, which became the foundation of quantum theory - one of the basic physical theories of the twentieth century. In 1905 the young Albert Einstein - he was then only 26 years old - published a special theory of relativity. All these discoveries produced a staggering impression and plunged many into confusion - they did not fit into the framework of the existing physics, they demanded a revision of its basic ideas. As soon as it began, the 20th century ushered in the birth of a new physics, marked the invisible frontier behind which the former physics, called the "classical", remained. And today the man has at his disposal an almighty laser beam. What will he use this new conquest of the mind? What will become a laser: a universal tool, a reliable helper or, on the contrary, a formidable space weapon, another destroyer?.

Key words: Basic physical theories, Laser, Physicochemical, Therapy.