What about brake fluid which is said to be incompressible. When I push down the brake pedal, the master cylindre pushes the brake liquid inside the hoses which tightens the brakes immediately? So what is the speed of propagation in this scenario if it cannot be faster than c even though brake fluid seems incompressible?
By Siv Schwink
September 9, 2012
The 2012 Engineering at Illinois Hall of Fame Ceremony will be held Friday, September 14, 2012, at 5:15 p.m. in Beckman Auditorium, at The Beckman Institute for Science and Technology in Urbana. The induction ceremony is open to friends, family, and supporters, and Physics students and faculty are encouraged to attend.
Henry is among eight distinguished alumni of the College who will be honored for their significant achievements in leadership, entrepreneurship, and innovation of great impact to society.
After graduating from Physics Illinois, Henry spent his entire professional career working in the Physics Research Division at Bell Laboratories in Murray Hill, New Jersey. Over the course of his 32 years as a leading researcher, his many discoveries, observations, and theories truly revolutionized the field of optoelectronics.
Henry is a condensed matter physicist best known for his invention of the quantum well laser, the device that made possible modern optical communications. It was near the end of 1972 when his “greatest idea as a physicist” first occurred to him:
“In the early 70s when I had the sudden realization that the quantum well could be a greatly improved semiconductor laser, I sensed that it was an important fundamental advance in semiconductor laser technology,” said Henry. “I am proud that this potential has been realized in the development of lasers and devices used in many fields today that have transformed our lives.”
The 1976 patent for the quantum well laser is one of 28 patents Henry holds. Throughout his career, Henry worked at the forefront of semiconductor-based optical technologies and science—LEDs, semiconductor lasers, and integrated optical circuits. He was a great inventor as well as a great experimentalist.
In addition to his seminal work on quantum wells and the quantum well laser, Henry established the “alpha parameter” to explain the behavior of semiconductor lasers, and initiated a new optical integrated circuit technology that enabled optical routers and multiplexing.
Henry is a recipient of the 1999 IEEE Jack A. Morton Award, the 1999 Charles Hard Townes Award of the Optical Society of America, and the 2001/2002 Prize for Industrial Applications of Physics of the American Institute of Physics. In 2001, he received an Alumni Award for Distinguished Service from Engineering at Illinois.
“The news that I will be inducted into the College of Engineering Hall of Fame 2012 came as a very pleasant surprise and I am deeply honored that my work will be remembered in this way,” said Henry.
Dr. Henry and his wife, Helene Henry, plan to attend the induction ceremony Friday.
Dr. Henry’s doctoral advisor, Professor Emeritus Charles P. Slichter, writes of his extraordinary graduate student:
In his PhD thesis research in the 1960s, Chuck Henry displayed the deep understanding of experimental physics and the powerful, inventive talent at theoretical physics that he later displayed in the invention of the quantum well laser and other work for which the College of Engineering will honor him. I knew at the time he was a graduate student that he was someone very special, one of the most talented graduate students I had ever known, and was excited to see what would unfold in his career over the years. He was a joy to have as a student. I counted him and his wife Helene as close friends.
The exciting development in his thesis was his invention of a new theoretical method to understand the effect of application of externally applied electric fields, magnetic fields, or stresses on the optical properties of certain materials.
Optical properties of materials was not a field that my students or I were studying, but several of my colleagues, especially Professors Fred Brown and Dale Compton and their students and postdocs whose labs were just down the hall from the labs of my group, were performing innovative experiments to explore these effects. To explain their results, they employed a simple theoretical model that enabled them to analyze their data. Chuck and I became interested in their work, but because of our background in magnetic resonance soon realized that there were severe problems with their theoretical interpretation.
Building on his magnetic resonance background, Chuck found a powerful new method to make a rigorously correct analysis of their experimental data. He applied it to the data of Brown’s group and also, in collaboration with Compton’s student Steve Schnatterly, to Steve’s data as well.[Effect of Applied Fields on the Optical Properties of Color Centers. Charles H. Henry, Stephen E. Schnatterly, and Charles P. Slichter, Physical Review Letters 13, 130 (1964)]
The importance of Chuck’s discovery and the excitement it produced are demonstrated by the fact that while still a graduate student, he was invited to give a Colloquium on this work in our Physics Department, something that very rarely happens.
His PhD thesis also involved experimental work (electron spin resonance of color centers in the alkali halides). He thinks of himself, I believe, as an experimental physicist who likes to apply theory to develop a deep understanding of experimental observations and to invent devices to solve technical problems. He thinks about technical problems at the level of both the individual device as well as the systems.
He went directly to Bell Labs from graduate school, where he began experimental work. At Bell labs, he became strongly interested in creation of practical devices, adding an important dimension of engineering invention to his technical repertoire. His mastery of theoretical physics as well as his interest in practical applications made it possible for him to be the inventor of the quantum well laser.
The citation for his award mentions his most important scientific/ technical contributions, in my opinion, but his career involved a rich succession of important contributions to science and technology that are only hinted at in the award. —Charles Slichter
If you have questions about the Department of Physics or ideas for other stories, contact Siv Schwink, 217.300.2201
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