Scientific discoveries this week: 11/26/12

Cambridge, Massachusetts – Astronomers have long sought an explanation as to why planets often have axes that are tilted from their orbital plane. In the case of the Earth, its axis is 23 degrees from vertical, which causes there to be seasons. For the past 17 years, most astronomers agreed that the most plausible explanation for this phenomenon was that the disk of the planet formed far from the star, then over time migrated closer. This theory has not stood the test of time, as a few years ago astronomers discovered planets on severely tilted and even backwards orbits. The only way this extreme level of tilt could be achieved is if some other celestial body had acted on the planet in some way. Just last week an astronomer from the Harvard-Smithsonian Center for Astrophysics in Cambridge postulated that the cause of these maligned orbits is not disk migration, but rather the reality that many planets are born in multi-stellar environments. This means that the planet was born amongst a group of stars, and that as the stars migrated apart, the planet’s axis tilted due to the massive gravitational pull of the multiple stars.

Princeton, New Jersey – Droughts across the globe have not increased at nearly the rate researchers predicted back in the 1970s and 80s, according to a new study by hydrologists at Princeton University. Back when the idea of climate change and global warming were first introduced, the primary method for predicting drought was the Palmer Drought Severity Index (PDSI), which compares the amount of precipitation in a region to total moisture lost. The researchers involved in the study at Princeton evaluated the PDSI method and found that it consistently overestimated the increase in drought severity across the globe from 1980 to 2008 by roughly seven times. This points to a problem in the method, which the researchers said comes from the fact that PDSI does not take into account the variability of evaporation due to sunlight, wind speed, and the wavelength of light reaching the ground. While drought has worsened over the years, it has not worsened by nearly the amount predicted.

Dallas, Texas – Artificial “smart muscles” could potentially solve numerous problems. The ability to build an artificial muscle that could replace a severely damaged or missing muscle in the human body would be of great benefit in medical applications, as well as robotics and other sectors. Last week, a team of materials scientists and engineers discovered a way to build an artificial muscle with the speed and efficiency of a human muscle, but with much greater strength. The muscle is made from graphene nanofibers and paraffin wax. The process they use involves weaving these nanofibers together and soaking them in wax, which causes the fibers to behave like a chinese finger trap; when the wax is expanded, they shorten, and vice versa. By regulating the temperature of the wax, the researchers can control the expansion and contraction of the artificial muscle. Currently, the technology only works at high temperatures, but with more study and experimentation, the team is hopeful to expand the useful range of this technology to include everyday environments.

Montreal, Canada – Why do people naturally tend to prefer musical harmonies to the sound of dissonance? This question has baffled audiologists and acousticians for as long as they have been studying the human ear and the way sound interacts with it. The prevailing wisdom in this field is that the effect known as “beating” is the culprit behind a dislike for dissonance, but recent studies have shown that beating does not play the role scientists thought it did. “Beating” is the phenomenon experienced when two musical notes that are very close in pitch are played at the same time. Because the notes are close in pitch, but not the same in pitch, they constructively and destructively interfere, leading to a warbling effect. The new study shows that this may not be why people do not like dissonance. By testing amusics, those who are “tone-deaf,” the researchers found that the beating still bothered them. If beating were the cause of a dislike of dissonance, then the amusics would not have noticed the beating at all. This means that the human preference for harmonies over dissonance is a result of the shape of the ear canal and the design of the auditory nerve. People are “programmed” to prefer the sound of harmony over the sound of dissonance, this result suggests.

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