Widely loved and celebrated cosmologist Professor Stephen Hawking died early on March 14, 2018 and he left an impact on the world.

There is one formula he created which was so prolific, he requested that it be placed on his tombstone in 2002, during a 60^{th} birthday “party” which was really a workshop on theoretical physics and cosmology and the future of the fields.

The formula describes the entropy of a black hole. The formula is said to be the centerpiece and primary point of reference for our understanding of the mysterious black hole, and the pinnacle of Stephen Hawking’s achievement in life. He worked on it with his peer Jacob Bekenstein.

The black hole formula draws an important connection between important thermodynamical quantities necessary for an understanding of black holes, such as entropy represented by a capital S in the formula, to the physical properties of the hole, most specifically its area (A).

The other letters in the formula represent the constants of the universe. C is the speed of light, k is the Boltzmann constant, h-bar is the reduced Planck constant, and G is the universal gravitation constant.

Even regular physics textbooks in school describe entropy as a measure of disorder within a macroscopic system. The amount of information that can be stored in an object is another definition of entropy: data, that is the essential importance of this.

They say the entropy of a black hole is proportional to its surface area, and not its volume. Its event horizon is the surface of a black hole, and past that, they say nothing can escape.

Quantum mechanics was applied to these incredibly dense apparent black holes, and that’s how Hawking understood the thermodynamics of them. This led to one proposal of Hawking radiation. He claimed black holes had a temperature and entropy.

Hawking took this understanding to a whole other scale. The said the entire universe could be looked at like a black hole, having a “cosmological event horizon,” which suggests the entire universe has a certain temperature and entropy value, as difficult as that is to wrap the mind around.

This concept was the foundation of the holographic principle, which suggests that all information encoded in the entire universe can be decoded from a lower dimensional boundary’s properties.

Austrian physicist Ludwig Boltzmann was the first to propose the law of entropy, and his tombstone also bears his formula. I guess scientists like to celebrate just like the rest of us.

Rest in peace Stephen, and thank you for all the food for thought.

*(Image credit: kayfabenews, nytimes)*