Cosmic Speed Limitation

The special theory of relativity excludes moving faster than the speed of light. If this "superluminal" speed were to be allowed, the order of cause and effect would be reversed, leading to paradoxical situations in which the effect arises before the event that caused it. This universal speed limitation is revealed by the fact that it is becoming increasingly difficult for objects to accelerate further when approaching the speed of light. The faster you go, the more energy it takes to accelerate further, until the energy required at the speed of light becomes infinite.

E=mc²

The equation E=mc² is probably the most famous of all physics. It follows directly from the mathematics of the special theory and indicates the relationship between energy (E), mass (m) and the speed of light (c). In essence, this means that mass and energy are identical. If you measure the mass of a piece of coal and after the coal has burned that of the ash and smoke, you will find that the mass after combustion is less than that of before. The difference in mass multiplied by c gives the total amount of energy released during combustion. Einstein considered E=mc² so important that he devoted a complete publication to it. And he was right: later, this would become a key to nuclear energy theory.

Quantum Spin

Subatomic particles exhibit a property that physicists call "quantum spin". This spider does not resemble the everyday spin, which like movement and acceleration is a movement property. Quantum spin is a fundamental particle property, such as mass and electric charge. In 1924, the Austrian physicist Wolfgang Pauli presented a mathematical description of quantum spin. It seemed to be correct, even though he had no idea what exactly the physical basis for his theory was. It was presented three years later by the British theoretical physicist Paul Dirac. He deduced the equations of Pauli's quantum spin by applying the special theory of relativity to the laws of quantum theory, the physics that govern the behavior of the subatomic world. Einstein's theory became visible in the most unexpected areas.