Following the Bolshevik Revolution, when Lew was 12 years old, his family fled west under adventurous circumstances and settled in Vilnius (then in Poland).

During his youth, Lew was a talented musician and considered a music career; however, his fingers grew too large for the keyboard.

They continued their research at the Cavendish Laboratory in Cambridge for the MAUD Committee, part of the wartime Tube Alloys project.

Just before the invasions, the records and papers of Frédéric Joliot, Hans von Halban and Lew Kowarski were smuggled out of France, and eventually to England.

A staff member of CERN (Geneva) since participating in its formation in 1953,[4][5] he was a Decorated Officer Legion of Honor, Fellow of the American Nuclear Society, and a recipient of citation and prize from the U.S. Atomic Energy Commission.