**Hermann Bondi** was an Austrian-born scientist who made contributions to a wide variety of areas in mathematics and physics and was associated with the "Steady-state" theory of the universe.

- Encouraged by Eddington to study at Trinity College, Cambridge, this seemed such a superb opportunity for Bondi, who was unhappy with the ever increasing anti-Semitism to which he was subjected.
- Very happy to be free from the problems back in Austria, Bondi began to become increasingly worried about the situation that his parents were in.
- The moves made by Hitler in February 1938 to force Austria to comply with his wishes under threat of force made Bondi act.
- Bondi's parents eventually settled in New York.
- Bondi thrived at Cambridge, completing his undergraduate studies in 1940.
- Bondi quickly felt an affinity with Britain and never wanted, as his parents expected, to follow them to the United States.
- In May 1940, immediately after completing his degree, Bondi was interned as an "enemy alien" by the British government.
- Bondi's potential to help in the war effort had been recognised and he was appointed Temporary Experimental Officer for the Admiralty to work under Fred Hoyle.
- At Bondi's request Gold was also brought in as a member of the team that was working on radar at the Admiralty Signals Establishment.
- Bondi, among other things, led a research team with all its cumbersome equipment to the top of Snowdon (Hoyle's idea), to make systematic measurements of these effects.
- During the time that Bondi, Hoyle and Gold worked together on this wartime project they were discussing theoretical astronomy, and their collaboration which began at that time lasted for many years.
- Bondi became a research fellow at Trinity College in 1943 and was appointed as Assistant Lecturer in Mathematics at Cambridge University in 1945, then, in the following year, he became a British subject.
- In 1948 Bondi was promoted to lecturer in mathematics at Cambridge, and in 1954 he became Professor of Mathematics at King's College, London.
- Bondi is perhaps best known as a creator of the steady-state theory of the universe which goes further than the accepted theory that the universe looks essentially the same from every place, and proposes in addition that the universe essentially remains 'the same' for all time.
- As a consequence of this, in order to explain how this might be possible in an expanding universe Bondi, Gold and Hoyle proposed that matter was continually created so that the average density remains constant despite the expansion.
- Of special note is the case of the "Perfect Cosmological Principle", which would require that the world-views obtained by equivalent observers are in addition stationary (but not necessarily static); upon it are based the Bondi-Gold steady-state theory (deductive) and the Hoyle theory of continuous creation (mainly extrapolative).
- It would certainly be a mistake to think that this represents the most important part of Bondi's scientific work, however, for he was a leading expert on many topics in applied mathematics, in particular in relativity theory.
- When evidence began to accumulate showing that the steady-state theory did not hold, Bondi's reputation was not seriously affected.
- Let us look at a few examples of Bondi's other contributions.
- Let us now note some remarkable pure mathematics papers published by Bondi.
- There is one further paper by Bondi of this kind, namely The cubes (1979).
- Bondi defines when two solutions are considered equivalent, then finds 123 distinct solution.
- Popularising science and teaching were topics which interested Bondi throughout his life.
- We noted at the beginning of this article about Bondi's upbringing, in particular about the influences on his at that time.
- Bondi was an organiser, shaped by determination to be understood, by intellectual weight and by a manifest desire to be on top.

Born 1 November 1919, Vienna, Austria. Died 10 September 2005, Cambridge, England.

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Astronomy, Origin Austria

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive