Flickering is caused by rapid changes in the refractive index of light due to changes in the optical density of the atmosphere along the line of sight, which is a consequence of convective processes in the lower atmosphere. It increases with an increase in the zenith distance of the star and, together with the absence of star twinkling when observed in outer space, proves the atmospheric origin of this phenomenon.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.