50 Years of the Cosmic Microwave Background Radiation: What We Have Learned, What Questions Remain

August 19, 2015

Fifty years ago, in the spring of 1965, Prof. Robert Dicke at Princeton University recognized that the unexplained noise in an experimental Bell Telephone Laboratories communications receiver might be caused by radiation left from a hot early stage of our expanding universe. Months earlier Dicke had set Jim Peebles to the task of seeking the theoretical implications of such an interpretation.

At the same time, he proposed that two other young members of his research group, experimentalists Peter Roll and David Wilkinson, build a specially designed, microwave radiometer to look for remnant radiation that might be observable, thereby indicating the existence of a hot Big Bang.

The serendipitous discovery by the Bell scientists, Arno Penzias and Robert Wilson, put the Princeton group’s project into high gear. That passionate effort continued, and the early 21st century launch of the Wilkinson Microwave Anisotropy Probe (the WMAP Satellite) by NASA ushered in the new age of precision cosmology, along with the twin conundrums of dark energy and dark matter.

Throughout this extraordinarily productive, transformative quest for knowledge of the early universe, Prof. Peebles has been a leader in contributing to our theoretical understanding of the hot Big Bang, and is generally considered by his colleagues to be the father of what we now call “modern cosmology.”

In this lecture, Prof. Peebles describes examples of how this modest start grew into big science that has made the case for a relativistic hot Big Bang as compelling as it gets in natural science.

P.J.E Peebles, Albert Einstein Professor of Science, Princeton University