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CQI Distinguished Speaker Lecture: Wolfgang Ketterle

For 130 years, a cylinder made of a platinum-iridium alloy stored near Paris was the official definition of a kilogram, the basic unit of mass. This all changed on May 20, 2019. A kilogram is now defined by a fundamental constant of nature known as the Planck constant (h), which relates the energy of a photon to its frequency: h= 6.62607015 10-34 kilograms times square meters per second.

The definition of the kilogram is now connected to the definition of time, realized by atom clocks, and the speed of light.  Sounds complicated? In this talk, Ketterle will provide the reasons for changing the definition of the kilogram, give simple explanations of what the new kilogram is conceptually, and explain how objects with exactly known masses can be realized using precision measurements and advanced quantum technology.


Speaker Biography:

Wolfgang Ketterle has been the John D. MacArthur professor of physics at MIT since 1998.  He received a diploma (equivalent to a master’s degree) from the Technical University of Munich (1982), and a Ph.D. in physics from the University of Munich (1986).  He did postdoctoral work at the Max-Planck Institute for Quantum Optics in Garching and at the University of Heidelberg in molecular spectroscopy and combustion diagnostics.

In 1990, he came to MIT as a postdoc and joined the physics faculty in 1993.  Since 2006, he has been the Director of the Center of Ultracold Atoms, an NSF-funded research center, and Associate Director of the Research Laboratory of Electronics.  His research group studies the properties of ultracold quantum matter.

For his observation of Bose-Einstein condensation in a gas in 1995, he received the Nobel Prize in Physics in 2001.  Other honors include the Gustav-Hertz Prize of the German Physical Society (1997), the Rabi Prize of the American Physical Society (1997), the Fritz London Prize in Low Temperature Physics (1999), the Benjamin Franklin Medal in Physics (2000), and a Humboldt research award (2009).

This is an in-person event that is open to the public with RSVP. Walk-ins may be accommodated if space allows the day of the event. 

Event Contact Information:
Columbia Quantum Initiative


May 01 2023


12:00 pm - 1:00 pm


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Formats (virtual, in person, hybrid)



Schapiro Center for Engineering and Physical Science Research, Davis Auditorium
530 West 120th Street New York, NY 10027


Columbia University
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