The year 2016 is, of course, a Leap Year. And just two weeks ago, I wrote a blog in the National Geographic series for the occasion, see February 29, 2016. A Leap Year!”.

Waking up early this morning to check my schedule for the day, I noticed on the menu bar of my computer’s calendar that it was “π-day.” In the United States, where the traditional notation for the date has the month followed by the year, today is March 14, or 3.14. Over the past few years the date has also become familiar to young students in the United States as Einstein’s birthday.

Unrivaled as the 20th century’s greatest scientist, Albert Einstein, was born 137 years ago, on March 14, 1879, in the city of Ulm, Württemberg, Germany. One hundred and eleven years ago, in 1905, at 26 years of age, experienced his “Annus Mirabilis,” his (“Miracle Year”). He wrote four papers each of monumental importance, the Photoelectric Effect, Brownian Motion, a statistical mechanical paper on the size of atoms, and “the Electrodynamics of Moving Bodies.” The last of the papers, some might say a bit kinky in its title, is otherwise known as the Special Theory of Relativity, and is by far the most important of the quartet.

Incidentally, for Einstein, the musical allusion of a “quartet,” is entirely appropriate. He was a devoted violinist, and frequently played in the chamber group of Princeton’s Institute for Advanced Study. Urban legend has it that on one occasion he might have even accompanied Jascha Heifetz (1901-1987), unrivaled as the 20th century’s greatest violinist. It can be no more than a convenient kitschy joke that the young Heifetz berated the older man, “Please, Professor Einstein, try to count!” [See one-man’s ranking of Ten Greatest Violinists of All Time.]

But there is little doubt that Einstein’s preoccupation with waves of all manner — sound, light, water and fields — helped him to intuit the underlying postulates of the Special Theory of Relativity, and in formulating the Photoelectric Effect. In explaining the latter, he introduced the wave-particle duality to explain the nature of light, so important to quantum theory. Two decades later the young French physicist/philosopher, Louis de Broglie, a Ph.D. student at the Sorbonne, extended the wave-particle duality to particles — i.e. “corporeal particles as we know them.” de Broglie’s 1924 hypothesis provided a basis for three other mathematical physicists, Schrödinger, Heisenberg and Dirac, to give us modern quantum mechanics. Schrödinger formulated wave mechanics; Heisenberg matrix mechanics; and Dirac showed their equivalence, producing a self-consistent axiomatic quantum mechanics.

Although Einstein would receive the 1921 Nobel Prize in Physics, he would not get it for Relativity — still considered somewhat “wild” — but for the “safer” theory of the Photoelectric Effect. As for his paper on the size of atoms, also a first rate work in physics, was even safer bet. He had submitted it as his Ph.D. thesis in 1905.

Then 101 years ago, in 1915, Einstein experienced a scientific rebirth, publishing his masterpiece, the General Theory of Relativity. The theory explains gravitation at a level that is more accurate than his personal hero Newton’s version. It is built on the promise (postulate) that the presence of mass curves the fabric of space-time. Here we must reiterate, Einstein’s efforts actually buttresses Newton’s formulation and does not upend it, or destroy it. Newton’s laws and his calculus still get us to the moon, but for a gentle landing, it is useful to accommodate Einstein’s version.

Last year (in 2015) the date would have been 3.1415, the value of pi to two additional significant figures.