The reason for the Brownian motion is the thermal motion of the molecules. Molecules in motion hit small particles, causing them to change direction and speed. As a result, we see chaotic movement of small particles, which is called Brownian. It should be noted that the particles are small only for the observer, the sizes of the particles are much larger than the sizes of the molecules themselves.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.