Posts tagged light

ALPHA observes light spectrum of antimatter for first time

antimatter, ALPHA, physics, light, spectral, antihydrogen

Today’s ALPHA result is the first observation of a spectral line in an antihydrogen atom, allowing the light spectrum of matter and antimatter to be compared for the first time. Within experimental limits, the result shows no difference compared to the equivalent spectral line in hydrogen. This is consistent with the Standard Model of particle physics, the theory that best describes particles and the forces at work between them, which predicts that hydrogen and antihydrogen should have identical spectroscopic characteristics. ALPHA is a unique experiment at CERN’s Antiproton Decelerator facility, able to produce antihydrogen atoms and hold them in a specially-designed magnetic trap, manipulating antiatoms a few at a time. Trapping antihydrogen atoms allows them to be studied using lasers or other radiation sources.

via http://phys.org/news/2016–12-alpha-spectrum-antimatter.html

There are three constituents of a shadow: umbra, penumbra, antumbra. I hold my hand between the lamp and the desk’s surface. The…

shadow, light, absence

“There are three constituents of a shadow: umbra, penumbra, antumbra. I hold my hand between the lamp and the desk’s surface. The darkest place, where my hand blocks the direct rays of electric light, is the umbra – latin for shadow. The penumbra (almost, nearly, shadow) is the partial occlusion of light, where the darkness is less severe, seen in this case, emanating briefly from the edges of the umbra, from my dark finger tips. The antumbra is something that cannot be described.”

Hugh Fulham-McQuillan