Arno A. Penzias, whose astronomical probes yielded incontrovertible evidence of a dynamic, evolving universe with a clear point of origin, confirming what became known as the Big Bang theory, died on Monday in San Francisco. He was 90.
His death, in an assisted living facility, was caused by complications of Alzheimer’s disease, his son, David, said.
Dr. Penzias (pronounced PEN-zee-as) shared one-half of the 1978 Nobel Prize in Physics with Robert Woodrow Wilson for their discovery in 1964 of cosmic microwave background radiation, remnants of an explosion that gave birth to the universe some 14 billion years ago. That explosion, known as the Big Bang, is now the widely accepted explanation for the origin and evolution of the universe. (A third physicist, Pyotr Kapitsa of Russia, received the other half of the prize, for unrelated advances in developing liquid helium.)
Until Dr. Penzias and Dr. Wilson published their observations, the Big Bang theory competed with the steady-state theory, which envisioned a more static, timeless expanse growing into infinite space, with new matter formed to fill the gaps.
Dr. Penzias and Dr. Wilson’s discovery finally settled the debate. Yet it was the serendipitous product of a different investigation altogether.
In 1961, Dr. Penzias joined AT&T’s Bell Laboratories in Holmdel, N.J., with the intention of using a radio antenna, which was being developed for satellite communications, as a radio telescope to make cosmological measurements.