With the sad news of
Professor Hawking’s death, it is only natural that we take time to appreciate
his many contributions to science and his commitment to communicating it in
simple terms so that everyone could appreciate its importance. Hawking’s name is rarely mentioned without
noting black holes and the Big Bang.

This is for good reason.
Throughout his whole career, which spanned more than five decades, the
scientist worked to understand extreme physical situations. To describe both
black holes and the Big Bang, one needs to deal with a concept known as
spacetime singularity, a point where the gravitational field of an object
becomes infinite.

He worked on singularities
in our universe in his thesis and with collaborator Roger Penrose. Together,
they published a proof showing that based on the laws we believe govern
reality, the universe must have begun in a singularity.

He then worked on trying to
formalize the math that describes the properties of black holes. His most
famous equation was produced through this work with Jacob Bekenstein, where
they connected the entropy of a black hole to its surface area.

Out of his extensive work on
black holes, people will be most familiar with the concept of Hawking radiation,
the idea that a certain amount of radiation is released by black holes due to
quantum effects near the event horizon. The effect in question is
particle-antiparticle creation around the black hole.

When matter and antimatter
touch, they annihilate and turn into energy. The opposite approach is also
possible, where energy turns into particles. The energy of the vacuum itself
can create fluctuations that are similar to particles (so-called virtual
particles).

When these fluctuations
happen near event horizons, the black hole can capture one particle of the pair
and boost the other one into existence. The particle-antiparticle pairs are
created by the gravitational energy of the black hole, so when one particle
escapes, it lowers the energy of the black hole.

Hawking radiation can lead
to the evaporation of a black hole if it has nothing to feed on. And the
smaller the black hole is, the more radiation it will emit. We are yet to
observe Hawking radiation directly, but its existence has become a key feature in
our treatment of black holes. The late professor has also strongly influenced
how we talk about the complexity of the universe.

In his books, such as A
Brief History of Time and The Universe in a Nutshell, he was able to convey
difficult aspects of cosmology with simplicity and precision. He and his
endeavors will not be forgotten.

Via IFLScience