“Nature shows us only the tail of the lion. But I do not doubt that the lion belongs to it even though he cannot at once reveal himself because of his enormous size.”
Albert Einstein, in a letter, March 1914
(from Subtle is the Lord, Abraham Pais).

Bearing in mind that only a few months ago, detectors on Earth measured gravitational waves produced some 1.3 billion light-years from us, Einstein’s quote sounds prophetic. He made this observation in correspondence concerning his belief in the principles of the theory of general relativity he was working on. Following an intense effort to solve the difficulties he encountered trying to formulate the field equations of general relativity, Einstein published his theory in November 1915.
The first exact solution to Einstein’s field equations predicted the existence of black holes.
In June 1916, Einstein published a paper predicting the existence of gravitational waves which propagate with the velocity of light.
On September 14, 2015, a transient gravitational-wave signal was observed by two LIGO (Laser Interferometer Gravitational-wave Observatory) detectors. Analyzing the features of the signal (“the tail of the lion”) scientists deduced that it was caused by collision of two orbiting black holes!!!

Image from: The Centennial of Einstein’s General Theory of Relativity

Albert Einstein was born on March 14, 1879, in Ulm, Germany. He studied at Institute of Technology in Zurich, graduated with an undistinguished record, tired and failed to get a university job. A recommendation from a father of a friend helped Einstein to get a position at the Swiss Patent Office in Bern. 1905 was Einstein’s magic year. In that year (while working at the patent office), Einstein produced six papers:

• A paper on the light-quantum and the photoelectric effect.
• A paper with a new determination of molecular dimensions.
• Two papers on Brownin motion.
• Two papers on special relativity. The second paper contained the relation: E=mc^2

Late in 1906, Einstein became the founder of the quantum theory of the solid state by giving the essentially correct explanation of the anomalous behavior of hard solids (such as diamonds) at low temperatures.
Excerpt from my post Albert Einstein’s birthday.