This Clock Has Stopped

Norman Ramsey Dies at 96; Work Led to the Atomic Clock

In 1949, Dr. Ramsey invented an experimental technique to measure the frequencies of electromagnetic radiation most readily absorbed by atoms and molecules. The technique allowed scientists to investigate their structure with greater accuracy and enabled the development of a new kind of timekeeping device known as the atomic clock. Dr. Ramsey received the Nobel Prize in Physics in 1989 for both achievements.

I had the privilege of meeting him and hearing him at a few talks where he told stories of the old days (I thought perhaps he was working on a book). Here is a picture of us at a conference in Seattle in 2005, where I am showing our nascent clock’s “Ramsey fringes” results to him — an interference pattern from the spectroscopy technique he pioneered — along with the clock stability results.


(photo credit: Tom Van Baak)