In the second half of the nineteenth century, the study of Brownian (chaotic) motion of molecules caused a keen interest of many theoretical physicists of the time.Developed by a Scottish scientist James Maxwell kinetic theory of molecular structure of matter, and was even recognized in the European scientific community, but there was only a hypothetical form.No its practical confirmation was not there.The movement of molecules remained inaccessible to direct observation and measurement of their speed seemed insurmountable just a scientific issue.
That is why experiments that can, in practice, prove the fact of the molecular structure of the substance and determine the speed of movement of its invisible particles, initially perceived as fundamental.Crucial of such experiments for physical science was obvious, as it allows to obtain a practical study and proof of the validity of one of the most advanced theories of the time - the molecular-kinetic.
By the early twentieth century, the world science has reached a sufficient level of development for the emergence of the real possibilities of experimental verification of Maxwell's theory.German physicist Otto Stern in 1920, using the method of molecular beams, which was invented by Frenchman Louis dune in 1911, the year was able to measure the velocity of the gas molecules of silver.Experience Stern conclusively proved the validity of the law of Maxwell distribution.The results of this experiment confirmed the faithful estimate of the average velocity of the atoms, which are derived from hypothetical assumptions made Maxwell.However, the very nature of speed graduation experience Stern was able to give only very rough information.More information science had to wait another nine years.
with greater precision the distribution law Lammert was able to check in 1929, to improve the experience of some of Stern by passing the molecular beam through a pair of rotating discs, radial holes, and had shifted relative to each other at a certain angle.By varying the speed of rotation of the unit and the angle between the holes, Lammert beam could be isolated from individual molecules that have different speed characteristics.But that experience Stern initiated the experimental investigations in the field of molecular-kinetic theory.
in 1920 established the first experimental facility needed to carry out experiments of this kind.It consisted of a pair of cylinders designed personally Stern.Inside the unit was placed a thin rod with a platinum-plated silver, which evaporates when heated with electricity axis.In a vacuum, that were created inside the unit, a narrow beam of silver atoms held dumped longitudinal slot cut through the surface of the cylinder, and settled on a special external display.Of course, the machine is in motion, and while the atoms reach the surface, managed to turn a certain angle.In this way, Stern and determined the speed of their movement.
But it is not only a scientific achievement of Otto Stern.A year later, he teamed up with Walter Gerlach conducted an experiment that confirmed the existence of atoms back and prove the fact of their spatial quantization.Stern-Gerlach experiment demanded the creation of a special experimental setup with a powerful permanent magnet at its base.Under the influence of the magnetic field generated by this powerful component elementary particles were deflected according to the orientation of the magnetic spin of their own.
