Steven Hawking passed away.
I never met him nor did I ever have the privilege of listening to him lecture in person. However, the power of the Internet means his words will live on for generations to come.
Most people know Hawking as the physicist confined to a wheelchair by ALS. His computer generated voice is distinctive.
A popular movie was made about his life. And while his research might be heady stuff, his book A Brief History of Time was a coffee table best seller.
His most important research was on black holes. He started studying their implications long before they were mainstream and discussed in shows such as Star Trek: The Next Generation.
If you are a fan of the Star Trek franchise, you know black holes were not mentioned in the original 1960s series.
In the early 1970s, he began to speculate on what quantum mechanics might have to say about the nature of black holes. He was interested in the intersection between quantum mechanics and gravity. He published seminal papers on the quantum mechanical consequences of the event horizon - the point of no return.
His research argued for the emission of particles from the surface. Specifically, he argued quantum mechanics dictated the creation of two particles by space at the surface with one propagating outwards and the other inwards. The result shocked the physics community because it essentially said black holes are not, in fact, black.
The radiation soon became known as Hawking radiation and led to an even more shocking conclusion - black holes should eventually evaporate.
The idea of a black hole forming, growing, and then slowly evaporating as the gravitational mass interacts with the rest of space was revolutionary.
In 1976, Hawking went on to argue a black hole would result in the erasure of information from the universe, in contradiction to some of the basic tenets of quantum theory. Information, in this case, isn't things like the contents of a book or images on the Internet. Rather, it is the ordering of sub-atomic particles and quantum coupling.
No one has yet been able to observe Hawking radiation but there have been some hints it is not just theoretical. Experimental results by Jeff Steinhauer on extremely cold single atoms were announced as proof but are generally considered inconclusive. The recent announcement of the detection of gravity waves might allow scientists to test some of Hawking's theories.
The lack of experimental evidence for his theories, though, is likely the reason Hawking was never awarded a Nobel Prize.
Of course Nobel Prize or not, he was still an acclaimed physicist working in cosmology right until the end.
In 2006, Thomas Hertog collaborated with Hawking on a paper trying to answer the question "How did the universe begin?"
This is one of the most profound questions of all and has been asked by human beings for all of recorded history. Scientists have been particularly perplexed since the discovery of the big bang in the 1930s.
Hawking came closer than perhaps anyone else to answering the question if such an answer exists.
Much of his research career was spent trying to reconcile gravity with quantum mechanics.
Gravity is the force of the very large, holding stars, solar systems, clusters, galaxies and galactic clusters together. As far as we can tell, gravity is the force holding the universe together.
Quantum mechanics, on the other hand, is an explanation of the very small. It allows us to understand electrons, quarks, photons, and other sub-atomic particles.
It tells us how they will behave and shows us their behaviour is vastly different from the world we know. For example, in the world of the small, an electron can disappear from one spot and reappear in another.
A theory blending gravity with the other forces of the universe (the strong force, the weak force, and electromagnetic interactions) has been dubbed The Theory of Everything.
Hawking perhaps came closer to answering this question than any other cosmologist.
His argument in 2006 boils down to saying that instead of having only single beginning, the universe had all possible beginnings.
The universe we know is just the most probable leading from the big bang to here.
This mirrors the many path approach used by Richard Feynman in the 1950s to explain quantum electrodynamics.
For all of his intellectual explorations of great cosmological questions, Stephen Hawking is perhaps best known outside of scientific circles for his tireless efforts at communicating science.
In addition to A Brief History of Time and its sequel, he wrote dozens of books, including one with the title The Theory of Everything.
He also appeared on numerous television shows, including The Big Bang Theory, the Simpsons, and Star Trek: The Next Generation.
For his intellect and his tireless communication about the wonders of science, he will be missed.
