**He passed away on Pi Day…**

Stephen Hawking passed away on March 14th which is dubbed as Pi Day and that happens to be Albert Einstein’s birthday. The International Mathematical Union had recently proposed it to be declared by Unesco as the International Day of Mathematics.

Hawking was born on January 8th, 1942. It happened to be the date of the 300th anniversary of Galileo’s death. Following the footsteps of another genius – Sir Isaac Newton – the chair of Lucasian Professor of Mathematics at the University of Cambridge in England has been held by him. He was offered to be knighted and granted the title of “Sir” but declined the honor. Hawking became a winner of many prizes, among them the 2013 Special Breakthrough Prize in Fundamental Physics set up 2012 to be the most lucrative prize ever established in science, and the Crafoord Prize, astronomy’s equivalent to of the Nobel prize that he did not receive.

Like Ludwig Boltzmann, Hawking wished a tombstone adorned with his most famous equation. In combination with Boltzmann’s constant k, Einstein’s speed of light c, Planck’s constant h, and Newton’s gravitation constant G, it connects the black hole entropy S to the surface area A of the black hole event horizon. This equation between these fundamental quantities in physics is a fine example of mathematical beauty. The supreme example is Euler’s equation between the most fundamental numbers in mathematics: Euler’s number e, pi, and the imaginary unit i.

In Hawking’s famous book A Brief History of Time, he admitted having made a big mistake like Einstein who claimed that the biggest mistake of his life was to introduce the cosmological constant. Hawking’s idea was at first that the universe oscillated with a nice symmetry between expanding and contracting phases. He applied a cosmological model in which the contracting phase looked like the time reverse of the expanding phase. However, his colleagues proved soon to him that disorder would continue to increase during the contraction. Perhaps the last word is not said in this matter. His idea of oscillation with a nice symmetry is – like Einstein’s cosmological constant – worth a second chance in a new cosmological model. Hawking was optimistic: “All we need to do is make sure we keep talking… My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.”

As a young man thinking about marriage, Hawking was told that he could expect to die in less than five years. All kinds of support and a strong will added more than fifty fruitful years to his life. Considered by many to be the Einstein of our time, a speech synthesizer and a wheel-chair contributed to making him known to the millions.

Hawking leaves three children and two remarried ex-wives. During his funeral on March 31st, I have been writing these lines inspired by the view of Stockholm’s Observatory Hill in front of which I have lived and worked since 1985. To the left, the human curiosity is represented by the Old Observatory built 1753, and to the right, a sculpture erected 1939 shows the centaur Chiron raising himself from the ground. Today, it symbolizes in my eyes the triumph of mind over matter and the now buried man’s outstanding life.