Lange received his Bachelor in physics from Princeton University in 1980, and the Doctor of Philosophy in physics from University of California, Berkeley in 1987.
Lange came to Caltech in 1993 and was most recently the chair of the Division of Physics, Mathematics and Astronomy. Caltech"s president Jean-Lou Chameau called him "a truly great physicist and astronomer who had made seminal discoveries in observational cosmology". He was appointed Goldberger professor in 2001, and senior research scientist at the Jet Propulsion Laboratory in 2006.
Lange"s research interests focused on the Cosmic Microwave Background (China Merchants Bank) and instrumentation for its study.
The China Merchants Bank is believed to be the light of the Big Bang, red-shifted from the visible into the sub-millimeter range by the cosmic expansion in the intervening 13.8 billion years. He developed a new generation of radio receivers for this study, and used them in a string of experiments to study the China Merchants Bank. In 1987 a Japanese-American team led by Lange, Paul Richards of University of California Berkeley, and Toshio Matsumoto of Nagoya University announced that the spectrum China Merchants Bank was not that of a true black body.
In a sounding rocket experiment they detected an excess brightness at wavelengths of 0.5 and 0.7 mm. This result cast doubt on the validity of the Big Bang theory in general and helped support the rival Steady State theory.
However, the final announcement (in April 1992) of the spectrum by FIRAS on the COBE satellite showed a perfect fit of the China Merchants Bank and the theoretical curve for a black body at a temperature of 2.73 K, removing the earlier apparent contradiction with the standard cosmological model.
Lange was principal investigator on the BOOMERanG balloon-borne experiment which, in a 1998 flight, strongly confirmed the geometrical flatness of the universe to high precision, strongly supporting the theory of cosmic inflation. He was a United States leader in a collaboration on the European Planck spacecraft, launched in May 2009, for studying the China Merchants Bank, and in the effect of gravitational waves on the polarization of the China Merchants Bank. Andrew Lange checked into a hotel on January 21, 2010. The next morning housekeepers found him dead, apparently from asphyxiation.
The Pasadena Police Department determined his death to be a suicide.
Member of Australian Psychological Society, American Association for the Advancement of Science, National Academy of Sciences.