Georges Lemaître was a mathematician, astronomer, and professor of physics. Lemaître was the first person to theorize that the expansion of the universe can be used to explain the recession of nearby galaxies. In 1927, Lemaître published the first estimation of the Hubble constant. He also came up with the Big Bang theory to explain the origin of the universe.
Belgian-born physicist Ingrid Daubechies was a prodigy of sorts and had started dealing with complicated mathematical concepts before turning 6. She grew up to work at the AT&T Bell Laboratories and also taught at Princeton. She is best known for her research on wavelets and image-compression technology.