what do this statement mean light plus light=no light
http://www.exo.net/~pauld/summer_institute/summer_day8interference/Interference_laser.html
The statement "light plus light = no light" refers to a phenomenon called destructive interference in the context of waves, particularly light waves. To understand this statement, we need to explore the concept of interference.
Interference occurs when two or more waves overlap, resulting in the addition or subtraction of their amplitudes (the strength of the wave). Light waves can interfere, and depending on the phase relationship between them, we observe different outcomes.
When two light waves interfere destructively, their amplitudes subtract from each other, resulting in a decrease or cancellation of intensity. In other words, the crests of one wave align with the troughs of the other wave, leading to a net loss of energy. This causes the regions where the two waves superpose to appear dim or dark.
The link you provided leads to a page explaining the interference of laser light waves. In the specific example mentioned in the statement, two laser beams are combined at an angle on a screen. Due to the properties of the lasers, the waves interfere destructively in this configuration. Hence, where the beams overlap, we observe a decrease in intensity, resulting in no light or darkness.
It is important to note that destructive interference does not mean that the energy is destroyed but rather redistributed in a way that results in regions of canceled or reduced amplitude.