Cosmologists are a small, elite fraternity whose work informs our knowledge of the cosmos at the highest, grandest levels.

But their close-knit universe was rocked this past weekend as word spread of the sudden death of Andrew Lange. Although not mentioned in the brief announcement posted by Caltech, where until recently he'd served as chairman of its Physics, Mathematics, and Astronomy Division, he had struggled with personal issues and apparently took his own life.

Andrew lange

Caltech cosmologist Andrew Lange was known worldwide for his work on the cosmic microwave background.


Although I never met Lange in person, I've been keenly aware of his importance to our understanding of the early universe. Most notably, he was co-leader of the Boomerang project that used a balloon-borne telescope, launched from Antarctica, to map the detailed structure of the cosmic microwave background. These whispers of microwave energy are the slowly dying echoes of the primordial fireball unleashed during the Big Bang.

Lange's observations with Boomerang measured the angular size of subtle variations within the CMB and led to the realization that the infant universe assumed a flat geometry after an initially rapid growth spurt due to inflation.

Boomerang's results followed closely on the heels of a breakthrough by two teams, led respectively by Adam Riess and Saul Perlmutter (both at University of California, Berkeley), who found that distant galaxies are moving away from us at ever-greater speeds and that the flat universe must be permeated with a type of negative gravitational pressure — often dubbed "dark energy."

After spending six years as an assistant professor at UC Berkeley, Lange arrived at Caltech to stay in 1993 and soon distinguished himself as one of its leading scientists (in a place where just about everyone is a leading scientist). In 2003 he and Perlmutter were jointly named "California Scientists of the Year" by the California ScienCenter. The following year Lange was elected to the U.S. National Academy of Sciences.

Boomerang telescope in Antarctica

With Mount Erebus in the background, the Boomerang telescope is readied for launch on its inaugural 10-day flight around Antarctica in 2000.

Boomerang Project

On Saturday, in an address emailed to the Caltech community, president Jean-Lou Chameau noted, "Among the most difficult things that people have to deal with in life are tragedies of this sort, especially when they affect people that we know and care for; and Andrew was such a well-known, well-respected, and well-liked member of our community that many of us will be deeply affected."

Click here to watch a lecture given by Lange, just last November, on how the universe began.


Image of Alex Filippenko

Alex Filippenko

January 25, 2010 at 10:56 pm

I was shocked and saddened by the death of Andrew Lange, who was not
just a superb cosmologist, but also a friend and colleague. We first
met while he was a graduate student at the University of California,
Berkeley, and I enjoyed his presence while he was a faculty member at

Dr. Lange's contributions to cosmology, especially with the Boomerang
project, were extremely important. However, Mr. Beatty incorrectly
states that the Boomerang results "set the stage" for the discovery of
the accelerating expansion of the Universe. Studies of Type Ia
supernovae demonstrating the probable accelerating expansion were
published in September 1998 by Riess et al. (Astronomical Journal,
116, 1009), and in June 1999 by Perlmutter et al. (Astrophysical
Journal, 517, 565). The subsequent discovery of the globally flat
geometry of the Universe (by Boomerang, Maxima, and other projects)
certainly supported the conclusion of Riess et al. (1998) and
Perlmutter et al. (1999), but did not "set the stage" for it.

Also, it is unfortunate that in the November 2009 Segre Lecture at UC
Berkeley, to which Mr. Beatty refers the reader, Dr. Lange failed to
highlight the work of Riess et al. (1998), which provided the first
published, well-substantiated observational evidence for the
accelerating expansion of the Universe. I'm sure he would have
regretted the omission had it been pointed out to him.

In any case, the world has lost a towering figure in cosmology and a
wonderful human being. I will miss him.

Alex Filippenko
Professor of Astronomy
University of California, Berkeley

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Alex Filippenko

January 26, 2010 at 12:38 am

In my previous post, I accidentally neglected to give the references for the first two published papers describing the seminal work in which Dr. Andrew Lange was so heavily involved, showing that the Universe is flat on large scales. Here they are:

Boomerang: de Bernardis et al. (April 2000, Nature, 404, 955)

Maxima: Hanany et al. (December 2000, Astrophysical Journal, 545, L5)

Alex Filippenko,
Professor of Astronomy,
University of California, Berkeley

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Eric F. Diaz

January 26, 2010 at 8:05 pm

The death of Dr. Andrew Lange is a great loss. Even though I never had the privilege of meeting him, I was nevertheless very familiar with his work. It is indeed a sad day for us all. Dr. Lange was truly a great scientist who contributed greatly to cosmology.

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Kelly Beatty

January 27, 2010 at 11:53 am

Alex, you are of course correct concerning the sequence of events. In fact, I was at the 2000 IAU meeting where many of the Type 1a results were presented and their importance discussed. And these came a couple of years before the Boomerang data were in hand.

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