© Slovak post, 2005 In December 2000, the World Congress of Physical Societies was held in Berlin. The more than 40 physical societies from around the world that were present approved the proposal to declare 2005 as the World Year of Physics. UNESCO expressed its support for and approved of this proposal in 2003, followed by the United Nations in 2004. The background of this proposal was the centennial of the publishing of Albert Einstein’s legendary scientific papers (the so-called “Annus Mirabilis” in 1905). These papers set the fundamentals for three fields of physics: the principle of relativity, the quantum theory, and the theory of Brownian motion. In so doing, the papers completely changed the then prevailing perception of the world. Einstein’s revolutionary ideas concerned the fundamental aspects of physics, namely the existence of atoms, the nature of light and the perception of space, energy and substance. The aim of the World Year of Physics is to increase public awareness of and interest in physics through remembering Albert Einstein, the recipient of the Nobel Prize in Physics, the world-acclaimed celebrity, and the most famous physicist and mastermind of the 20th century. Physics has played a key role in the development of science and technology, and beyond theory it also influences living standards in society. The stamp portrays a bolt of lightning – a natural phenomenon in accordance with physical laws. Lightning is a strong electrical discharge that occurs among clouds or between clouds and land. In addition, the First Day Cover depicts Dionýz Ilkovič (1907 – 1980) – a notable Slovak physician who became famous for his equation for polarographic diffusion current. Marián Reiffers