Physics

We are all familiar with raindrops on our wind screens. The small ones stay in place while the big ones roll down the window. This is because surface tension holds the small drops onto the screen until they get to a size where the force of gravity is greater than the surface tension. We are all familiar with raindrops on our wind screens. The small ones stay in place while the big ones roll down the window. This is because surface tension holds the small drops onto the screen until they get to a size where the force of gravity is greater than the surface tension. But mathematicians at the…

Einstein's Theory Of General Relativity has been under assault for the better part of a century. No one can really prove it wrong but it's commonly assumed to be wrong. Sergei Kopeikin, associate professor of physics and astronomy at University of Missouri-Columbia, has spent the last five years defending Einstein's prediction that gravity moves at the speed of light - they want to prove Einstein right and they say they can measure the speed of propagation of tiny ripples of space-time known as gravitational waves. He says his paper, "Gravimagnetism, causality, and aberration of gravity…

With atoms and molecules in a gas moving at thousands of kilometres per hour, physicists have long sought a way to slow them down to a few kilometres per hour to trap them. A group of physicists from The University of Texas at Austin have found a way to slow down, stop and explore a much wider range of atoms than ever before. Inspired by the coilgun that was developed by the University’s Center for Electromechanics, the group has developed an "atomic coilgun" that slows and gradually stops atoms with a sequence of pulsed magnetic fields. Dr. Mark Raizen and his colleagues in Texas ultimately…

Dark matter is believed to exist in the form of tiny particles that do not interact with light. Because they don’t emit or reflect electromagnetic radiation the way atomic, or baryonic, matter does, these dark matter particles haven’t been directly observed. However, scientists have long theorized their existence based on their gravitational effects on visible matter throughout the universe. “The evidence for dark matter is now overwhelming, and the required amount of dark matter is becoming precisely known," says Howard Baer, Professor of Physics at Florida State University. “For example,…

The amount of dark matter left over from the early universe may be less than previously believed. Research published in the open access journal PMC Physics A shows that the "relic abundance" of stable dark matter particles such as the neutralino may be reduced as compared to standard cosmology theories due to the effects of the "dilaton"', a particle with zero spin in the gravitational sector of strings. Nikolaos Mavromatos of King's College London and colleagues in Athens and Texas obtained their result by studying a special "off-shell" time-dependent term (due to the dilaton) in the…

Quantum gravity can be understood by considering the logical consqquences of a single unifying postulate or principle of nature. I call it the postulate of quantized space time. First some observations. The Gravitational force seems to pervade the entire universe. However gravity is the weakest of all the forces in the entire universe. To get a easily measurable force of gravity there needs to be a planetary or larger mass nearby. So any theory of quantum gravity must require a large amount of mass to create a small effect in space time. Gravity also seems to be an exclusively…

Materials researchers at the National Institute of Standards and Technology (NIST), together with colleagues from IBM and the Massachusetts Institute of Technology, have pushed the measurement of thin films to the edge—literally—to produce the first data on how the edges of metallic thin films contribute to their magnetic properties. Their results may impact the design of future nanoscale electronics. Ferromagnetic thin films of metallic materials—ranging in thickness from fractions of a nanometer to several micrometers—are layered in patterns on a substrate (such as silicon) during the…

For as many people as seem to like the metric system, few realize that both the motive for its creation ( competing with England, much like the calendar the French created, though that did not last ) and its inherent accuracy were flawed. The French took a provisional measurement ( conveniently in Paris ) between the North Pole and the Equator for the meter, for example, and got it wrong. Likewise, the 'official' kilogram has been losing weight for a while and some people think it's time to fix the metric measure of mass so that it will still be accurate 10 or 10,000 years from now, using…

"We've never seen anything quite like it," says solar physicist Lika Guhathakurta from NASA headquarters. Last week she sat in an audience of nearly two hundred colleagues at the "Living with a Star" workshop in Boulder, Colorado, and watched in amazement as Saku Tsuneta of Japan played a movie of sunspot 10926 breaking through the turbulent surface of the sun. Before their very eyes an object as big as a planet materialized, and no one was prepared for the form it took. "It looks like a prehistoric trilobite," said Marc De Rosa, a scientist from Lockheed Martin's Solar and Astrophysics…

The tunic believed to have been worn by Saint Francis of Assisi preserved in the Church of Saint Francis in Cortona (Province of Arezzo) dates back to the period in which the saint lived, whereas the tunic preserved in the Church of Santa Croce in Florence was made after his death. Carbon 14 measurements, which allow a relic to be dated, show that the tunic in Santa Croce dates back to some time between the late 13th century and late 14th century and thus could not have belonged to the “Poor Man of Assisi”, who died in 1226. These and other discovers were made possible through the analysis…