Some of the greatest works by Prof. Stephen William Hawking
1) The large-scale structure of Space-time:
Hawking with his colleague George Ellis worked on the foundation of ‘space’ and nature of infinite expansion of the universe, described the large scale structure of the universe in terms of spacetime using Einstein’s General Relativity. The classic book ‘The Large Scale Structure of Space-time’ contains these works.
2) Hawking-Penrose theorem:
Sir Roger Penrose and Stephen Hawking proved in a theorem that Einstein’s General Relativity must break down at a certain point in Space-time under certain generic physical conditions. This point is called ‘Singularity’. There is singularity point inside a Black Hole and also at the moment of creation of the Universe.
Penrose diagram for Hawking-Penrose singularity
3) Hawking Radiation:
The greatest work by Hawking. Almost all the physicists once thought that Black Hole is just a swallowing machine and it’s a dead thing because we can know nothing about it as nothing comes out of it. That’s the classical General Relativistic picture. Few physicists roughly speculated that Black Hole can be a little different. Hawking, for the first time, used Quantum Mechanics in the General Relativistic realm and rigorously showed that Black Holes can radiate and has temperature. This work has given rise of a lot of research activities in the field of ‘Black Hole Thermodynamics’ and ‘Quantum Mechanics in curved space-time’. It could open a path towards the final unified theory of Physics called ‘Quantum Gravity’ or more popularly ‘The Theory of Everything’.
4) Primordial fluctuations:
Hawking had some important work in explaining how galaxies and clusters of galaxies took shape from early homogeneous gaseous universe (that eventually made ‘life’ possible in the universe). The explanation is based on some tiny fluctuations or imperfections in the extremely homogeneous early universe.
Formation of galaxies due to primordial fluctuations
5) Black Hole information paradox:
Another legendary work (question actually) by Hawking. He asked, as Black Hole swallows everything and eventually gets evaporated through ‘Hawking radiation’, the ‘information’ about the object it swallowed gets lost. But the most fundamental law of Physics is: Information MUST be conserved and Can’t be lost from the universe. So it created a paradox.
6) Soft Hair theorem:
In only 2016, Hawking himself proposed an idea based on some concepts called ‘Supertranslation’ and ‘Superrotation’ that may solve the Information Paradox. This is yet an uncleared problem in Physics but Hawking and his colleagues, most notably prof. Leonard Susskind, Gerard ‘t Hooft. Juan Maldacena etc. have done remarkable works.
7) No-boundary condition:
Hawking with colleague James Hurtle developed a Quantum Mechanical model of the Universe (called ‘Hawking-Hurtle state’) that says the Universe is self-contained (like Earth surface which has no starting point) but has No Boundary (We can’t fall from the edge of Earth). So Universe is finite but boundary-less (Like Earth surface having finite area but no edge). There was no ‘before’ prior to the creation and the moment of creation is just a normal point just like North pole of Earth (hence no requirement of a ‘creator God’).
In a little more details:
8) A Brief History of Time:
Hawking’s greatest literary work. A popular science book on some of the greatest questions on the Universe and the answers by Physics to them, in a relatively easy language for common people. This is an International best-seller and only 2nd to ‘The Holy Bible’ in sale.
9) Other literally works:
Hawking has written several other pop-science book. For examle, ‘The Black Holes and Baby Universes’, ‘The universe in a nutshell’, ‘The Grand Design’ etc. and for kids, the Greoge series books on science fiction co-written with his daughter Lucy. In ‘The Grand Design’, Hawking announced that there is no Designer for the Grand Design of the Universe. Laws of Physics make it redundant.
10) Popularization of Science and warnings for the Humanity:
Hawking, through his works, books, lectures etc., has inspired millions of people like ordinary, dumb like me and even many extra-ordinary scientists to learn science, study Physics, research in Physics and contribute to science for the welfare of Humanity. Hawking always reminded mankind about biggest problems of the World like Global Warming, Misuse of Artificial Intelligence, risk of communication with Aliens, Biological warfare etc. He always said Mankind has to go to other planets to survive. Earth is not enough.
Thank you, Prof. Hawking.