2018 Nobel Prize in physics has historic ties to the College

by Anne George | 10/17/18 3:00am

The 2018 Nobel Prize in Physics was awarded on Oct. 2 for research in the field of laser physics. American physicist Arthur Ashkin received half of the prize for his discovery of real-life optical tweezers, while the other half was shared by Canadian physicist Donna Strickland and French physicist Gerard Mourou for their method of generating high-intensity optical pulses that can move matter.

Ashkin’s research on optical tweezers has historical ties to Dartmouth, according to physics and astronomy department chair John Thorstensen.

“The local connection here is that [Ashkin’s findings] depend on the fact that light carries momentum and can exert pressure, which was first deduced in the 19th century by James Clerk Maxwell, who figured out electromagnetism correctly,” he said. “There was no experimental confirmation of this since the pressure is so tiny until it was found in [Wilder Laboratory] in 1902 by Ernest Fox Nichols, who was later president of Dartmouth, and Gorden Ferrie Hull.”

In Wilder Laboratory, which is apart of the Sherman Fairchild physical sciences center, Thorstensen added, Nichols and Hull invented the Nichols radiometer, which measures the pressure of radiation. Using the radiometer and the Wheatstone Bridge, an electrical circuit apparatus used to measure an unknown resistance, they successfully proved Maxwell’s theory of electromagnetic radiation. Today, the building is designated as a historical site by the American Physical Society.

Thorstensen also believes that Nichols was the first president to poise Dartmouth to become a strong research institution, but discussed how this was halted by later presidents, causing decades of catch-up for the College’s research capacity.

“We started to become what we like to think of ourselves now, which is hopefully the perfect hybrid: a small college, where we pay attention to our students, and a research institution where there is a lot of activity going on, which ultimately benefits students because there is intellectual ferment and activity involved,” Thorstensen said. “Nichols would have gotten us here quicker.”

Using the Nichols-Hull experiment to invent optical tweezers, Ashkin was able to find that converging laser beams could manipulate microscopic physical objects. Physics and astronomy professor Kevin Wright, who teaches Physics 47, “Optics,” is researching the use of these optical tweezers to manipulate the gas of “ultra-cold” atoms in a similar way.

“Basically we look at all sorts of unusual phenomena that can occur when quantum mechanics become evident at large scales,” Wright said. “It is important for things like superconductors or superfluids.”

Wright added that in an effort to get students involved in hands-on research he may have his class create optical tweezers as a final project.

“One of the nice things about both of these parts of the Nobel Prize is that they are more accessible than some of the other topics that have been awarded — to understand the optical tweezer phenomenon, you only need to know a little bit about geometric optics, the way light is bent” he said. “If you have taken introductory physics, you know enough to understand almost everything about this prize. The principles are not complex. It is mostly cleverness that brought the prize about.”

Physics and astronomy professor Roberto Onofrio, who researches macroscopic quantum mechanics, said he believes that this Nobel Prize and Wright’s research are a testament to the importance of creativity in the field of physics research. He noted that physics research often builds upon itself.

“You must be the first. You don’t need money and you need very few tools,” he said.

He added that, as a professor, he believes that interacting with students in classes keeps researchers “sharp and in touch with the foundations [of physics].”

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