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Pendulum love, science class gender gaps, musical mind mirrors, and unparticle physics

News from the American Physical Society

American Physical Society

Pendulum Finds Virtual Soulmate
Vadas Gintautas and Alfred W. Hübler
Physical Review E 75,

What's nerdier than creating an online avatar that fights dragons and raids strongholds? Creating a virtual pendulum that you can sync up to your real-life pendulum. Leave it to physicists to do just that, resulting in a mixed reality state in which the two pendulums swing as one.

Vadas Gintautas and Alfred Hübler of the Center for Complex Systems Research at the University of Illinios are the first to create a linked virtual/real system. They achieved the feat by connecting a real world pendulum with a virtual version that moved under time-tested equations of motion. To get the two pendulums to communicate, the physicists fed data about the real pendulum to the virtual one, and transferred information from the virtual pendulum to a motor that influenced the motion of the real pendulum.

The real and virtual pendulums swung at different rates when they were first introduced. After a brief encounter in a dual reality state, they simply couldn't connect. Friction quickly brought them to a halt. Recognizing that these two pendulums needed to have more in common, the physicists adjusted their swing frequencies until they were more or less on the same wavelength. Upon the next meeting, two pendulums could not help but move in mixed reality unison indefinitely, defying the friction forces that had ended their previous interreality relationship.

Believe it or not, their findings may prove useful. Mixed reality can occur only when the two systems are sufficiently similar. A system with unknown parameters may be synced up to a virtual system whose parameters are set by the physicists. The unknown factors in the real system can be determined by changing the virtual system until they shift from dual reality to mixed reality. Then, the physicists will have good estimates for the values of the unknown parameters.

What's more, it may help explore existing intersections between virtual realities and the material world. Popular online games such as World of Warcraft incorporate virtual economies in which players can buy, sell, and own property within the game. In the Warcraft economy, avatars deal in virtual gold, but the real players can buy it with real US dollars. Gintautas and Hübler are curious about the possibility of mixed realities emerging from these coupled economies. - KM

Science Student Gender Gap - A Continuing Challenge
Steven J. Pollock, Noah D. Finkelstein, and Lauren E. Kost
Physical Review Special Topics - Physics Education Research, June 2007

Interactive classes don't necessarily solve the performance imbalance between the genders in physics classes, according to a new study that stands in stark contrast to previous physics education research. In fact, while students as a rule benefit from interactive classrooms, the teaching technique may even increase the imbalance in some cases.

The conclusion comes from research at the University of Colorado at Boulder where physics professors attempted to duplicate an earlier Harvard study. The researchers in both studies looked at interactive teaching methods, which can include online homework systems, help-room sessions, student discussions, and other methods that have not typically been part of science classes in the US.

Unlike the Harvard study, which showed significant narrowing in the performance gap between male and female students, the CU Boulder study indicated that the gap stayed roughly the same in both partially and fully interactive classrooms. There were some instances where the gender gap got worse, particularly in the partially interactive classrooms.

On the bright side, both male and female students performed better in the interactive classes than students laboring in traditional lecture-based classes. Overall, however, male students benefited as much or more than females, which doesn't help to narrow gender-based performance gaps.

The physicists at CU Boulder point out that there were a number of differences between their study and the Harvard experiments, including classes with three times as many students, and male to female ratios that were twice as high. In addition, the Harvard students came into the study with higher overall preparation levels in physics, as determined by various standardized tests.

The Boulder researchers don't claim that their results negate the Harvard study, but that it instead highlights the complexity and challenges of reducing gender-based disparities in science education for different populations and circumstances. - JR

Music: Mirror of the Mind
Simone Bianco and Paolo Grigolini
Physical Review E (forthcoming), on at

The long supposed connection between mind and music has been further demonstrated by an international collaboration of physicists led by Simone Bianco and Paolo Grigolini at the Center for Nonlinear Science at the University of North Texas. A statistical analysis reveals a remarkable similarity between the distributions produced by music compositions and brain activity.

Brain activity was monitored through an electroencephalograph (EEG), which records electrical signals on the surface of the brain. The musical compositions were analyzed based on the melody, harmony, rhythm, pitch, and timber among other factors.

Researchers mapped brain activity and the compositions by regions of similarity punctuated by jumps where a significant change occurred. The data illustrated the similarity between patterns of electrical signals in the brain and of musical compositions.

In addition, the team determined a complexity index for the compositions and brain function, a number to describe the intricacy of either the musical patterns or electrical signals. The complexity indices for both patterns were less than two. This suggests that both the brain and the composition are self-organized, but in the case of the composition, it probably reflects the self-organized mind of the composer. The interpretation of the complexity index remains a question for further research.

In future experiments, researchers will monitor the brain activity of participants who are listening to music. This study will assess whether the complexity of a participant¿s brain activity is affected by the complexity of the composition. In addition, they will seek "fits" where the complexity of the music resembles the brain activity of the listener. If the physcists' hypothesis is correct, the fit between a composition and your brain activity helps determine your musical preferences. - KM

Weird Physics Theory of the Month - Unparticle Stuff
Howard Georgi
Physical Review Letters

At some level, all types of matter that we usually deal with have at least one thing in common - they're made of particles. The solids, liquids, gases and plasmas that surround us are built of atoms, which are made of electrons, protons and neutrons. Protons and neutrons in turn are made of quarks.

According to Harvard University's Howard Georgi, however, there's at least the theoretical possibility that some matter in the universe is not made of particles at all. Georgi has dubbed the mind-bending matter "unparticle stuff," and hopes that we may see signs of it at the Large Hadron Collider (LHC), a super high energy proton collider due to come online in Europe later this year.

The odds of any unparticle stuff turning up at the LHC are extraordinarily slim, but if it does, we'll know it by an unusual signature. It will appear as though some of the energy from the collider's high energy experiments is carried away by a fractional number of otherwise invisible particles. So if LHC experimentalists happen to see signs of 3.34 ghostly particles, for example, they could be on the track of unparticle matter.

Unparticle stuff may go the way of countless other defunct predictions of exotic phenomena. Unlike the Higgs boson, which many physicists believe will be one of the LHC's great discoveries, there's no compelling reason to expect unparticle stuff to exist at all. But at some level that's the lot of a good theoretical physicist. After all, a theorist who restricts their imagination to merely the likely possibilities probably isn't trying hard enough.

Just what unparticle stuff would be like is hard to say, even for Georgi. "This stuff is so weird and I so far have such a tiny little theoretical window into its properties," says Georgi, "that I really don't know what a teacup full of it would look like or whether it would be good for anything. I hope eventually to understand it well enough to give a better answer." - JR


Katherine McAlpine and James Riordon contributed to this Tip Sheet.

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