Quantum physics tells us that reality is far beyond human perception and intuition. In other words, our rational mind and common sense are just not capable of understanding the true nature of reality.
Einstein's theory of relativity introduced a new way of looking at the physical properties of the universe. The Newtonian constraints of absolute time and space were abandoned. Time and space were unified and made relative, it formed a continuum that curved and enfolded about itself. Gravity was a distortion of this continuum caused by the presence of mass. From this, the famous formula e=mc~ was derived. (e=energy, m=mass, c=the speed of light, the magical constant in the system, the absolute maximum speed that anything can travel.)
So Einstein's famous theory has one absolute (speed of light) in a relative universe, and it forms a kind of boundary around all we can know. Even though this theory has been borne out by many experiments, its consequences appear very bizarre. Objects shrink when they are in motion, space time curves, light is bent by gravity etc.