San Marino · Galileo Galilei, Year of Physics

The International Year of Physics was observed in 2005 on the occasion of the centenary of Albert Einstein’s “Annus mirabilis”. In 1905, Einstein published several papers that shaped 20th-century physics. They dealt with the light quantum hypothesis and the photoelectric effect, Brownian motion, and the special theory of relativity. In this context, the relationship between mass and energy also emerged, later becoming known through the formula \(E=mc^2\). The commemorative year originated from an initiative of the international physics community and was supported by the United Nations. It was intended to convey publicly the role of physical research in science, education, and technology.

Galileo Galilei was born in Pisa in 1564 and died near Florence in 1642. He worked as a mathematician, natural philosopher, and astronomer. Galileo combined observations and experiments with mathematical descriptions of natural processes. His investigations into the motion of bodies contributed to the development of later classical mechanics.

For his astronomical work, Galileo used a telescope whose design he improved. With it, he observed, among other things, the uneven surface of the Moon, four moons of Jupiter, and the phases of Venus. These findings contradicted parts of the Aristotelian worldview prevailing at the time and supported the heliocentric model, according to which the Earth and the other planets orbit the Sun. Because of his public defense of this doctrine, Galileo came into conflict with the Roman Inquisition. In 1633, he was forced to recant his views and spent the rest of his life under house arrest.

Although the Year of Physics directly followed on from Einstein, Galileo was suitable as an overarching symbolic figure for the history of physics. He represents the transition from traditional natural-philosophical ideas to a science increasingly based on measurement, observation, and mathematics. The coin issue thus not only commemorated the anniversary of 1905 but also placed it in a broader context of the history of science.