A stream from one source is divided into two streams, which follow different paths, and then join in a certain region of space, called the region of interference. The waves that form the interference pattern in this case are coherent, since the phase difference of the oscillations they excite depends only on the difference in their paths and does not depend on time.
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.