
And until recently no onehas needed to understand.

Actually, it is clear to everyone what the measurable real numbers, for example, 5 kg, 30 minutes or 2 meters are, though no one understands what the imaginary 5 kg, imaginary 30 minutes, or imaginary 2 meters mean.

What is the physical and mathematical background of such a study? First of all, this is the problem of understanding the physical nature of imaginary numbers distinguished in mathematics for over 500 years.

This still unknown process of transformation of visible images into invisible, or, conversely, invisible images into visible is a new object of study of physical optics.
