ABSTRACT
This chapter explains the Albert Einstein's special theory of relativity (STR). The Relativity Postulate is a strong formulation of our old friend the principle of Galilean equivalence. In the 1860s James Clerk Maxwell published a work on electrical and magnetic phenomena that synthesized the sizeable quantity of experimental work. Newtonian spacetime has an affine structure: there is a distinction between curved and straight paths through the spacetime, which is invariant. By Pythagoras theorem, the square of the hypoteneuse of a right-angled triangle is equal to the sum of squares of the other two sides. The most notable of which was the compensatory theory proposed by Fitzgerald and developed in detail by Lorentz. The speed of light is not the only invariant quantity in Minkowski spacetime; the so-called 'interval' between points and events is the same in all inertial frames. Moreover, it would also be a mistake to suppose that the frame-relativity of shape is nothing more than an optical effect.
