While in high school, he and a friend created and sold a word processor written in pure machine code for the Swedish eight-bit computer ABC 80,[5] and a 3D Tetris-like game called Frac.

With Daniel Eisenstein and Wayne Hu, he introduced the idea of using baryon acoustic oscillations as a standard ruler.

[9][10] With Angelica de Oliveira-Costa and Andrew Hamilton, he discovered the anomalous multipole alignment in the WMAP data sometimes referred to as the "axis of evil".

"[16] Tegmark was elected Fellow of the American Physical Society in 2012 for, according to the citation, "his contributions to cosmology, including precision measurements from cosmic microwave background and galaxy clustering data, tests of inflation and gravitation theories, and the development of a new technology for low-frequency radio interferometry".

[17] He was awarded the Royal Swedish Academy of Engineering Science's Gold Medal in 2019 for, according to the citation, "his contributions to our understanding of humanity’s place in the cosmos and the opportunities and risks associated with artificial intelligence.

He has courageously tackled these existential questions in his research and, in a commendable way, succeeded in communicating the issues to a wider public.