Superconductor World Record Surpasses 250K

Superconductors.ORG herein reports the observation of record high superconductivity near 254 Kelvin (-19C, -2F). This temperature critical (Tc) is believed accurate +/- 2 degrees, making this the first material to enter a superconductive state at temperatures commonly found in household freezers.

As a point of reference, dry ice sublimates at about 195 K

Update: Probably a case of “nothing to see here, move along.” I missed some lack-of-credibility signs.

Photonic Thermos

Hot soup in a thermos is surrounded by a vacuum between the inner and outer walls, which prevents heat from conducting directly through the sides, as it would if the walls were a one-piece solid. But the soup still loses heat by “glowing” in infrared light because the light radiated through the walls takes energy away with it.

Shanhui Fan of Stanford University in California and his colleagues wondered if photonic crystals–periodic structures famous for blocking narrow frequency ranges of light–could block the broad range of infrared frequencies radiated by a warm body.

Cosmic Variance: A New Challenge to Einstein?

There is a straightforward way, in principle, to measure these two types of curvature. A slowly-moving object (like a planet moving around the Sun) is influenced by the curvature of time, but not by the curvature of space. (That sounds backwards, but keep in mind that “slowly-moving” is equivalent to “moves more through time than through space,” so the curvature of time is more important.) But light, which moves as fast as you can, is pushed around equally by the two types of curvature. So all you have to do is, for example, compare the gravitational field felt by slowly-moving objects to that felt by a passing light ray. GR predicts that they should, in a well-defined sense, be the same.

We’ve done this in the Solar System, of course, and everything is fine. But it’s always possible that some deviation from Einstein shows up at much larger distance and weaker gravitational fields than we have access to in our local neighborhood. That’s basically what Rachel’s paper does, considering different measures of the statistical properties of large-scale structure and comparing them to the predictions of a phenomenological model of the gravitational field. A crucial role is played by gravitational lensing, since that’s where the deflection of light comes in.

Built on Facts: Longfellow, Wellington, and Coriolis.

In the early days of physics the question of refining the predictions of projectile motion was not merely one of academic or poetic interest. If you’re commander Wellington of the noble British army wishing to lob cannon shells at the nefarious French (or vice versa), these other more delicate physics corrections to the projectile equations can mean the difference between life and death – or at least which side experiences which.