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How one JMU professor combines the beauty of arts with the rules of science

By Melissa Boss, '05


As one sits quietly in an audience at a dance concert and watches, transfixed by dancers' seamless movements, notions of how science, more specifically physics, plays a role in such an inherently free and beautiful scene are far off. Except if you're Dr. Christopher Hughes. This is the story of one JMU professor who is dedicated to teaching students that the physics of dance is free yet bound by laws


Physics of Dance: The Inception


The physics of dance section of a general education science class, GSCI 121, began with Dr. Christopher Hughes who wanted to bring something special to his classroom.  When he began, GSCI 121 was taught mainly by Professor Jon Staib (Ioana Niculescu also now teaches the course) who lectures on different aspects of energy, such as sound and light waves, which eventually leads to learning the fundamental laws of physics."  This section was marketed toward Theater and School of Media Arts and Design students because both fields of studies involve light and sound. However, before Hughes could add this section to his class curriculum, he needed to do a significant amount of research on the subject, and he was not certain any existed. This search led him to the pioneer of physics of dance ideas, Kenneth Laws.


The Pioneer


According to the Department of Physics faculty homepage, Kenneth Laws is a professor of Physics at Dickinson College in Carlisle, Pennsylvania. Laws is not just a professor, he has also worked with Central Pennsylvania Youth Ballet for 22 years. It is easy to see how a professor of physics, who is also a dancer, is responsible for creating three books and more than 300 presentations about how one can link the mechanics of science to the performing art of dance. Given Law's extensive background in dance and science, his presentations easily reach the young, giggling dancers who gather in one of Dickinson College's auditoriums. Most of the dancers are completely unaware of the application of physics and dance until they listen curiously to his lecture. These kinds of presentations usually involve the discussion and demonstration of several core ideas, such as moment of inertia, gravitational force, and center of gravity.




Hughes explains how the instrument on the table, a scanning tunneling microscope (STM), scans surfaces at the atomic level.


The Core Ideas


Balance in the world of dance is that magical ability to assume any position and hold the body rigid and tight as if one were a statue on the stage. In the world of physics, balance is really about how a dancer maintains his or her center of gravity in order to acquire the desired position.


  Dr. Cynthia Thompson of the JMU Dance department listens as Hughes explains the effect of friction on skin. Thompson was Hughes' main collaborator in creating his physics of dance curriculum.


  According to one of Laws' books, The Physics of Dance, published in 1984, the two forces present on a dancer are from gravity, which pulls all of us to the earth, and support from the floor, which pushes dancers up. As long as the dancer's torque is zero, then the position can be maintained. The dancer's center of gravity must be placed over the area of contact with the floor. Therefore, when a dancer is standing "on flat," then the center of mass is between the toes and heels.

If a dancer should rise to demi-pointe, then the center of gravity shifts forward to the balls of the feet. This concept is what makes pointe work incredibly difficult because it requires the dancer to master his or her own sense of being centered. As a dancer moves from demi pointe to en pointe, the contact area with the floor becomes impossibly small; sometimes as small as a quarter.



Another topic discussed frequently in physics of dance publications is the moment of inertia. This law is based on the fact that the larger an object is, the slower that object will spin. Therefore, dancers who perform pirouettes, or turns, in large positions, such as attitudes and arabesques will turn at a slower, steadier pace. Smaller positions such as coupe and passe, which place the working leg close to the supporting leg, will allow the dancer to turn more quickly. A non-dance related example of this concept is recognized in ice skaters. Ice skaters frequently perform spins during their routines and pull their arms in tight across their chests or over their heads. As they do this, their spins become very fast and results in an impressive sight. The act of bringing the arms in closer to the body affects the person's moment of inertia and allows him or her to spin faster.


Gravitational force can help explain how dancers can perform grand allegros, or large jumps, in the air and maintain "ballon." Ballon is a French term used to describe the bouncy quality dancers spend years to achieve. The physics of this quality states that the time a dancer spends in the air depends on the dancer's vertical velocity, and surprisingly, not on the mass of the dancer. First, one must be reminded of two laws: all objects when dropped will speed up at the same rate, 32 feet per second; and all objects thrown up in the air will slow down at the same rate, regardless of mass.


Therefore, as a dancer pushes off the floor, he or she will rise in the air at a set rate, pause for a moment and then fall. It is during this pause that dancers must extend the legs or raise their arms at the very peak of the jump. This stretching to hit the desired position while their mass is changing directions is what gives the illusion of dancers floating through the air.

Results and Reactions


After Hughes added the section to his curriculum, he found that his students were interested in the ideas presented, despite the lack of dance knowledge. For Hughes, physics had been a strict, scientific field that was previously thought not to be applicable to any fine arts subject. However, he discovered a niche where arts and science can coexist. Hughes hopes to one day teach this unique cross-section as its own course.


Hughes in front of the computer used to analyze data from the STM (the screen shows a mapping of atoms on the surface of a piece of graphite).




The Terms of Dance

Flat:  Position of the feet where the foot is flat on the floor with the weight evenly distributed among the toes, balls and heel.


Demi-pointe:  Position of feet where dancers have raised their heels off the ground so that their weight is on the balls of the feet.


En Pointe:  Position of feet where dancers have raised their heels off the ground so that their weight is on their toes. Performed only while wearing pointe shows.


Working leg:  The leg that the dancer is is free to move about in the air.


Supporting leg:  The leg that the dancer is standing on


Plie:  A bending of the knees and ankles that help push the dancer off the ground.


Pirouette:  Turns or spins on one foot. The working leg can be close or far away from the body.


Arabesque:  Extension of the working leg to the back of the dancer.


Attitude:  Similar to the arabesque, only the knee is slightly bent. Can also be performed to the side and front.