Wave function is a complex number , why do we have to consider it as a complex number? Quote:– but there is nothing in the wave equation that restricts them to being real numbers. If we temporarily suspend disbelief that physical quantities may be associated with complex amplitudes, then we may explore what happens when these constants take complex or imaginary values. from http://phyweb.phys.soton.ac.uk/quantum/lectures/waves4.pdf [Broken] is that mean no necessary to have wave function as a complex number? I can understand why do we use complex number in the reactance of a capacitance because the impedance of a capacitance varies with the frequency. Can you please teach me what is the meaning of the complex number in wave function ? anything change that make the intensity change?? Thank you.