He developed both the Keller-Segel model of chemotaxis, in cell biology, and the Newell-Whitehead-Segel equation, in fluid dynamics.

[1] Segel was active in the Santa Fe Institute, the first of the over 50 research centers which focus, today, on complex physical, computational, biological, and social systems.

Louis Segel was something of an intellectual as could be seen in his house from, e.g., the Kollwitz and Beckman prints and the Shakespeare and Co. edition of 'Ulysses', all purchased in Europe in the 1930s.

Thinking he might want to go into the brand-new field of computers, he started graduate studies in MIT, where he concentrated on applied mathematics instead.

In 1959 he married Ruth Galinski, a lawyer and a distant cousin, in her native London, where they spent the first two years of their wedded life.

At Los Alamos National Laboratory he was a summer consultant to the theoretical biology group from 1984 to 1999, and he was named Ulam Visiting Scholar for 1992–93.

[7] Chemotaxis plays important roles in axon guidance, wound healing, tissue morphogenesis and other physiological events.

[13] Hillen and Painter say of it: "its success ... a consequence of its intuitive simplicity, analytical tractability and capacity to replicate key behaviour of chemotactic populations.

[22] The Faculty of Mathematics and Computer Science at the Weizmann Institute awards a yearly Lee A. Segel Prize in Theoretical Biology.