This manuscript analyses disputable aspects of the second postulate of the special theory of relativity. To verify them, the electric circuit theory is used. The respective theoretical and experimental research has proved that the statement of the special theory of relativity which denies that imaginary and complex numbers have physical meaning is incorrect. It is demonstrated that this misstatement of the special theory of relativity is refuted even by the fact of existence of such natural phenomena as tsunami, tolling of church bells, and others. Explanation of the physical meaning of imaginary and complex numbers is suggested. It is also proved that another statement of the special theory of relativity â€“ the principle of light speed invariance â€“ is restrictedly true; that is, it is incorrect in its current interpretation, and correct with the adjustments suggested herein. All the formulae describing relativistic effects are conditionally correct; that is, they are correct only with regard to our tardyon Universe, and incorrect with regard to all other parallel Universes that form the Multiverse. Ways of correcting these formulae are suggested.