Frank Hsia-San Shu (Chinese: 徐遐生; Jyutping: Ceoi4 Haa4 Sang1; June 2, 1943 – April 22, 2023) was a Chinese-American astrophysicist, astronomer, and author.

[2][3] His father, Shu Shien-Siu,[5] was a mathematician and an instructor at the National Tsing Hua University, which, at that time due to World War II, was temporarily relocated to Kunming from Beijing.

[7] While at MIT, he worked one summer for Chia-Chiao Lin on the structure of spiral galaxies, and the experience made him interested in astrophysics.

[7] Over his PhD study, he built on his undergraduate work and, together with Lin, proposed the density wave theory and published several articles explaining the structure of spiral galaxies.

[7] Shu officially retired in 2009, becoming a University Professor Emeritus of the UC system,[3] and a Distinguished Research Fellow at the Academia Sinica Institute of Astronomy and Astrophysics (until 2015).

He, together with his PhD supervisor Chia-Chiao Lin, proposed the density wave theory to explain the structure of spiral galaxies.