Inside the 15th Annual Kaczmarczik Lecture
By Timothy Jones
April 20, 2010 —
Featuring three different looks at the events surrounding the 15th Annual K-Lecture:
Nobel Laureate Discusses the Future of Physics
The crowd at the 2010 K. Lecture.
The annual Kaczmarczik Lecture, hosted by the Department of Physics, took place on March 4, 2010 and was attended by over 800 people, including 400 visiting high school students from across the Philadelphia area. Dr. David Gross, this year’s invited speaker, discussed “The Coming Revolutions in Fundamental Physics.”
Gross received his Ph.D. in physics in 1966 from the University of California, Berkeley. While there, he was active in the free speech movement and was among the hundreds of students arrested at the legendary Sproul Hall sit-in of 1964. In the early 1970s, he went on to work at Princeton University, where he conducted groundbreaking research with his graduate student, former Kaczmarczik lecturer Dr. Frank Wilczek. Gross and Wilczek eventually developed the concept of asymptotic freedom in quantum chromodynamics, which revolutionized our understanding of the behavior of quarks and breathed new life into quantum field theory. Until their breakthrough, field theory was considered somewhat doomed because it could not account for the existence of the nucleus of atoms. In 2004, Gross and Wilczek were awarded the Nobel Prize in Physics for their work with asymptotic freedom.
Gross' lecture at Drexel focused on possible future breakthroughs in physics and discussed the sort of discoveries we can expect as the world's largest and most powerful particle collider becomes fully operational. This device, the Large Hadron Collider (LHC) at CERN--the European Organization for Nuclear Research-- is one of the greatest engineering accomplishments in history. By “smashing” subatomic particles at unprecedented energies, it will soon test some of the most advanced theories about the fundamental nature of the universe.
Gross began his lecture by reflecting on the current state of theoretical physics, and the challenges facing the field. While the physics of the very large (from the microbial scale to the universe itself via general relativity) and the physics of the very small (atomic and subatomic levels via the Standard Model) are successful in their respective scales, they are incompatible with one another. The goal of theoretical physics is to build a theory that describes all scales of the universe in an entirely self-contained and self-consistent mathematical framework. String theory is considered by many physicists to be the best candidate for such a “theory of everything.” String theorists posit that particles are in fact very small vibrating strings and advanced mathematical techniques have been invented to describe their behavior. Gross considers himself a string theorist, though he emphasizes that properly stated string theory is not a theory but rather, a mathematical framework from which a unified theory may emerge.
“The most important product of knowledge is ignorance,” Gross said, in perhaps one of his most striking statements of the afternoon. By this he meant that each advance in science expands the field of “known unknowns” regarding the nature of the universe. He offered several examples in modern physics, addressing important questions such as: Why does symmetry play such an important role in the universe? Why are the values of the universal constants set as they are? Why do the 'families' of forces and particles exist in the patterns we find them? Why is space three-dimensional?
One of the significant challenges facing modern physics is that current theories require that we experimentally find and input constants of nature that match our research observations. One of the requirements of a more complete theory is that it should predict the values of universal constants, such as the cosmological and gravitational constant. Without delving into the mathematical details, Gross said that one of the strengths of string theory is that it does not require experimental inputs: “It is what it is.” And so, with proper development, we should expect that any comprehensive theory resulting from string theory must predict the constants of nature.
Gross further examined a second requirement for a complete theory: the unification of the forces of nature. A few centuries ago, the electric and magnetic forces were thought of as independent forces. Then, in the 19th century, renowned physicist James Maxwell discovered a theoretical framework that revealed them to be manifestations of one single force: electromagnetism. Today, we understand that there are four fundamental forces: electromagnetism, “weak,” and “strong” forces formulated in the Standard Model, and gravity. Gross suggested that, like electromagnetism, it might be possible that all of these forces are actually manifestations of a single unified force.
Physicists have found that the strength of these forces depends upon the energy of the particle on which they are exerted (faster particles have more energy). Gross explained that a modification to the Standard Model, called “supersymmetric theory,” results in the unification of three of these forces, (not gravity), at extremely high energies. Supersymmetry also predicts a candidate particle for the elusive “dark matter,” which is found by astronomical observations to gravitationally bind galaxies together. Supersymmetry can even be used to correctly predict the ratio of dark matter to regular matter in the universe, as observed by astronomers. Until recently, physicists have had no direct means of testing this theory. But because supersymmetry also predicts that all known elementary particles will have a corresponding “super-partner” particle, we are now on the verge of testing this.
The Large Hadron Collider will soon be smashing particles together with enough energy to create the super-partners predicted by theory. Such a finding, Gross told the crowd, would be a monumental breakthrough for physics. It would confirm the existence of radically different elementary particles, never observed in nature, but predicted by theory—a spectacular achievement in innovative technology. Another indication that string theory may be the right framework, according to Gross, is the fact that supersymmetry theory can be derived from string theory, though he also notes that string theory has thus far failed to explain why supersymmetry is broken at lower energies.
But why does supersymmetry not apply to gravity? Dr. Gross began this discussion by explaining that gravity is a relatively weak force. He demonstrated this by picking up an apple; with the exertion of a small amount of electrochemical force (muscle), his body overcame the gravitational pull of the Earth. Indeed, of all the forces, gravity is the weakest. The electromagnetic force is many times stronger than gravity, as are the “weak” and “strong” forces, though only on the subatomic scale. However, gravity's strength increases rapidly with heightened energy (that is, at the very small scale or when particles are accelerated to near light speed). Theoretical predictions suggest that at very high energies the strength of the gravitational force approaches the strength of all the other forces. Discovering whether this is merely a coincidence or truly a sign of total unification remains one of the greatest unsolved mysteries of physics.
Gross proceeded to discuss other problems in the field with a guarded but contagious optimism. He reminded the audience that physics faced a similar state of turmoil in the early 20th century. Only through two radically different theoretical breakthroughs were we able to find models that better reflected nature. Gross expects that new conceptual revolutions will be needed to move string theory from a mathematical framework to a fully comprehensive theory. He and many of his colleagues suspect that such a revolution will come at the expense of our conceptualizations of space and time: Gross quoted physicist and Fields Medal winner Edward Witten (his former graduate student) as saying that “space and time may be doomed.” String theorist Nathan Seiberg, Gross said, is “almost certain that space and time are illusions,” suggesting that physics may once again shake up our most inveterate ways of thinking about the universe. Gross concluded by promising that the best is yet to come, as we look forward to the unknown but thrilling future of physics research.
Physics Department Head Dr. Michel Vallieres, Research Coordinator Laura D'Angelo, Dr. David Gross, and Assistant Professor Dr. Jelena Maricic.
Breakfast with a String Theorist
On the morning following the Kaczmarczik Lecture, 30 undergraduate and graduate students from across the College were given the rare opportunity to share breakfast with Nobel Laureate Dr. David Gross. Gathered in the stately Paul Peck Alumni Center, students participated in a relaxed, interactive discussion, asking questions on issues ranging from politics and religion to science funding and, of course, physics.
Dr. Gross articulated his opinions against the “Anthropic Principal” which posits that the configuration of universal constants we find in our local universe is not the same throughout the entire universe. The fact that the constants can be configured in a way that allows for the evolution of life is implied by the very fact that we are here to measure them. Gross considers this principal unscientific because there is no way to test it, and useless, as it only discourages the pursuit of theoretical explanations for the constants.
Dr. Gross also detailed his observations on the dramatic upward trajectory of Chinese science, explaining that he is highly impressed by the priority the Chinese place on scientific research and development. Gross predicted that they will make increasingly important and frequent contributions to science, and even suggested that students at the breakfast consider studying Mandarin.
One of the most salient discussions of the morning focused on government funding of science, and on the role scientists play in politics. Gross believes that scientists play an important part in educating the public and increasing scientific literacy. He suggested that the government is interested in funding scientific research, not only because it satisfies our collective curiosity, but also because it is vital to our economy. After summarizing a few of the many economic benefits that have resulted from government funded scientific research, including lasers, telecommunication breakthroughs, and the Internet itself, Gross reminded the students that the U.S. is facing increased competition in scientific fields, as other nations are rapidly augmenting their research funding.
Some of the other topics discussed included questions on the ethics of atomic bombs, controversies within the physics community over the dominance of string theory, and scientific apps for the iPhone. As the morning came to a close, Dr. Vallieres, head of the Department of Physics, thanked Gross on behalf of the University, and joined with the students in an enthusiastic applause. Many were already anticipating next year’s event, and the opportunity to once again share breakfast with a Nobel Prize winner.
From Chaos to the Coldest Place on Earth: A Tour of the Physics Department
Dr. Gross with students from Conestoga High School.
The annual Kaczmarczik Lecture has been the largest recruiting event of the year for the Department of Physics since 1995, and this year was no exception. Over 400 area high-school students attended Dr. Gross’ lecture, and each took advantage of the wonderful opportunity to tour research facilities, observe experiments, and meet some of the talented faculty in both the physics and chemistry departments. Guests were divided into small groups and guided by graduate students through five of sixteen unique presentations. One group, composed entirely of seniors who have been accepted to Drexel’s physics program, was taken on a tour designed specifically to illustrate the diverse research opportunities they could expect to encounter in the department.
The group’s first stop was a visit with Dr. Frank Ferrone, whose lab conducts cutting-edge research on sickle cell anemia and its implications for other prion-related illnesses, such as Alzheimer's disease. Dr. Ferrone explained the functional differences between healthy and sick blood cells and outlined the physical mechanisms of cell destruction caused by sickle cell anemia. He handed the presentation over to graduate student Zhengui Liu, who demonstrated the utility of lasers in growing the destructive components of sick cells for experimentation. Liu was followed by Dr. Alexey Aprelev, who showed the students live, magnified images of blood cells inside artificial capillaries.
In the Astrophysics Group's 3D theater Drs. David Goldberg and Steve McMillan took the students on a tour of the universe. Stars and galaxies seemed to float within arms-reach, demonstrating the power of high-performance computational astrophysics. The presentation closed with a stunning 3D simulation of our galaxy’s fate billions of years into the future when it collides with our closest galactic neighbor, the Andromeda galaxy. Goldberg and McMillan also showed their guests a number of 3D simulations created by first-year physics majors, promising prospective students the possibility of one day competing with the likes of James Cameron.
The third presentation of the afternoon was given by three students working with Dr. Roberto Ramos. Ramos’ lab, which is known as “the coldest place in Philadelphia,” conducts research into extremely low-temperature quantum mechanics. Surrounded by a complex array of cryogenic equipment, graduate students Zechariah Thrailkill and Joseph Lambert, along with undergraduate Kenneth Mui, gave a dazzling demonstration using liquid nitrogen, a low-temperature substance that quickly freezes normal objects. After dipping a bouquet of flowers into the liquid, students were invited to crush the petals, which crumbled in their hands like potato chips. Next, Mr. Lambert gave a brief thermodynamics lesson, explaining why balloons shrink to a very small size when dipped in the nitrogen but re-inflate after warming up. Other demonstrations included Mr. Lambert’s use of a high-temperature superconductor to float a magnet in the air; Mr. Thrailkill eating a liquid nitrogen-soaked cookie as steam vented from his mouth and nose; and the pair demonstrating how to make a light bulb and battery circuit more efficient by dipping the battery into liquid nitrogen.
The fourth stop on the tour was an interactive presentation by students from Drexel's award-winning Society of Physics Students (SPS). Undergraduates Amanda White, Sajjan Mehta, David Gurmai and Othmane Rifki had created a physics playground, complete with a Van de Graaf generator for exploring the properties of electricity, a Gauss rifle for demonstrating the power of electromagnetism, and a mini optics experiment with lasers and prisms to illustrate the power of telescopes to explore the universe. In a demonstration of angular momentum, students spun a hand-held bicycle wheel while standing on a rotating platform, finding with great amusement that they could spin their entire bodies by varying the angle at which they held the wheel.
The last demonstration of the afternoon was given by Dr. Robert Gilmore, who specializes in nonlinear dynamics and the topology of chaos. Dr. Gilmore introduced the students to the concept of chaos with a series of vivid simulations. He then discussed practical uses of nonlinear dynamics, recounting the harrowing story of a Japanese space probe, which was running low on fuel and seemed doomed to fail. However, the story had a happy ending, as nonlinear dynamics was used to calculate a path that required the least amount of fuel. The probe made it to the moon and returned with valuable scientific data.
Following their tour, the group joined with Drexel students in Grand Hall, and patiently awaited Gross’ lecture. On the verge of launching their own college careers, they now sat with a sense of the diverse opportunities offered at Drexel—opportunities that could place them shoulder-to-shoulder with influential thinkers like Gross.
Timothy Jones is a graduate student in physics at Drexel University, where he specializes in nonlinear dynamics.