Passion for Precision

Lecture presented by: Professor Theodor Hansch
Date: October 26, 2012
Location: Shanghai Jiao Tong University in Shanghai, China

Some of the most fundamental insights in physics, such as the relativity of space and time, have been gained by increasing the precision of experimental measurements. The Balmer spectrum of atomic hydrogen has provided the Rosetta stone for deciphering the strange laws of quantum physics during the early 20th century. More than once, seemingly tiny discrepancies between theory and experiment have led to important conceptual breakthroughs. Precise spectroscopy of the simple hydrogen atom can yield accurate values of important physical constants and it can stringently test basic physics laws. The invention of the laser frequency comb a decade ago has given us a tool for counting the ripples of a light wave with extreme precision, so that we are now able to measure resonance frequencies in hydrogen to 15 decimal digits. An optical fiber link of 920 km length across Germany permits the direct comparison of optical frequency references at the Max-Planck Institute of Quantum Optics in Garching and at the Physikalisch-Technische Bundesanstalt in Braunschweig. In the future, it may become possible to redefine the second in terms of atomic hydrogen. Comparisons of hydrogen and antihydrogen may reveal conceivable differences between matter and antimatter. Recently, it has become possible to perform laser spectroscopy of exotic muonic hydrogen, where the electron is replaced by a 200 times heavier muon. The measured 2S – 2P Lamb shift gives an accurate value of the charge radius of the proton. However, this radius is significantly smaller than the value obtained from spectroscopy of ordinary hydrogen or from electron scattering experiments. This proton size puzzle is subject of intense discussions. It may be caused by a mistake, or it may indicate a dent in the armor of quantum electrodynamic theory.

Nobel Laureate “Wows” Students in Shanghai


November 13, 2012

“Be open to discovering the unexpected,” advised Nobel Laureate Theodor Hänsch, a renowned scientist in the theoretical and applied study of optics, to the physics and engineering students of Shanghai Jiao Tong University (SJTU) last week.

Professor Hänsch, who received the Nobel Prize in Physics in 2005, was in Shanghai as part of the Honeywell Initiative for Science & Engineering (HISE), a global educational program that reaches top universities in India, China, Eastern Europe and Latin America. Through a combination of interactive forums, lectures and seminars, HISE gives students direct access to Nobel laureates in physics and chemistry as well as Honeywell’s technology leaders and engineers.

A key component of the HISE program is the Honeywell Traveling Technology Exhibit (TTE), which was brought to the SJTU campus so that students could learn about Honeywell’s products, meet its engineers, and talk to recruiters. The TTE has been effective at helping students understand how they can apply their engineering degrees at technology companies like Honeywell.

During his visit to SJTU, Prof Hänsch gave several lectures, joined two panel discussions, and shared his personal path to success, reaching more than 1,500 physics students over the course of two days. He also attended a town hall on the Honeywell campus in Shanghai, communicating face-to-face with more than 150 engineers.

“We are pleased to collaborate with SJTU to give tomorrow’s scientists and engineers the opportunity to engage face-to-face with one of the world’s master scientists,” said Stephen Shang, president of Honeywell China. “HISE not only bridges the gap between formal academic study and practical business applications, but also supports Honeywell’s drive to bring in the best talent in fast-growing regions. This activity helps ensure our continuing success as one of the world’s leading technology companies.”

“At SJTU, we inspire scientific spirit and innovative thinking, and we are pleased to partner with Honeywell on this journey,” said Mr. Zhang Wenjun, vice president of Shanghai Jiao Tong University.

SJTU is alma mater to several Honeywell China engineers. “When I was a student at SJTU, I attended an HISE event,” said Peter Zhang, Technology Solutions lab manager in Shanghai. “At the time I wasn’t sure whether to go into academia or industry after graduation. HISE helped change my mind.”

“Very impressive,” commented an optical engineering student after the professor’s lecture on laser-based precision spectroscopy. The student later visited the TTE to talk to a recruiter about a possible job after graduation.

“I am grateful to Honeywell for inviting me to speak to the students and media and share my personal story of discovery,” said Hänsch, who is no stranger to HISE, having participated in the program in 2009. Hänsch was co-winner of the 2005 Nobel Prize in Physics for his contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique.

Professor Hänsch is the Carl-Friedrich-von-Siemens Professor for Experimental Physics at the Ludwig-Maximilians-University,Munich, Germany, and Director at the Max-Planck-Institute of Quantum Optics in Garching, Germany.

HISE and Nobel Laureate Ted Hänsch visit Shanghai Jiao Tong University in October 2012.