Dec 2020
A recent stellar flash may have signaled the birth of a highly magnetic, spinning stellar corpse
Astronomers spotted colliding neutron stars that may have formed a magnetar
Aug 2021
In a demonstration of Einstein’s E=mc2, collisions of light yielded electrons and positrons
Colliding photons were spotted making matter. But are the photons ‘real’?
Apr 2024
The Purkinje effect may play tricks on your color vision as light dims
During a total solar eclipse, some colors really pop. Here's why
Aug 2023
Twilight conditions may let the frogs' skin emit colors that can be easily seen by other frogs
Many frogs glow in blue light, and it may be a secret, eerie language
May 2022
Their magnetic environs are perfect for boosting particles to ultrahigh energies
Pulsars may power cosmic rays with the highest-known energies in the universe
Sep 2021
Fluorescent homes may help wayward insects find their way in the dim twilight
Some wasps’ nests glow green under ultraviolet light
Nov 2019
Light waves can transport information more efficiently than electric current
A tiny switch could redirect light between computer chips in mere nanoseconds
Oct 2018
In the journal Science (September 2018), researchers reported a method for making a coating that reflects sunlight and radiates heat. The coating can be used to cool buildings and reduce air-conditioning use, keeping surfaces painted with the material about 6 degrees Celsius cooler than the surrounding air temperature. The paint can be easily applied to most surfaces, including the exterior walls and roofs of existing buildings. The cooling effect is based on a phenomenon known as passive daytime radiative cooling, whereby a surface cools without any energy input by reflecting ultraviolet to near-infrared solar radiation (278- to 4600-nanometer wavelengths) and radiating long-wave radiation (8000- to 13,000-nanometer wavelengths) through the atmosphere to outer space. Cool roofs designed using metals (such as aluminum) or white-pigmented paints help keep building temperatures lower by reflecting sunlight but are less effective at emitting the heat they absorb because heat is reflected inside these materials. See also: Buildings; Emissivity; Heat transfer; Infrared radiation; Paint and coatings; Radiation; Reflection of electromagnetic radiation; Solar radiation
Cooling paint
Jan 2013
Until recent years, the research focus on the high-energy photons known as gamma rays has been on nuclear and cosmic sources for them. Now it has moved to the cloud—the thundercloud, that is—where short bursts of gamma rays, known as terrestrial gamma ray flashes (TGFs) or dark lightning, have been observed. In a thunderstorm, a gamma-ray burst occurs when electrons accelerated by a strong electric field to almost the speed of light collide with air molecules. See also: Electric field; Gamma-ray burst; Gamma rays; Photon; Thunderstorm
Dark lightning linked to visible lightning
Oct 2020
For the first time, researchers have measured a process that occurs in mere zeptoseconds, or trillionths of a billionth of a second (10-21 seconds). The process is the transit of a light particle, or photon, across the two atoms that compose a hydrogen molecule. The travel time of the photon was revealed through the fundamental light-matter interaction known as photoionization, which occurs when a light particle adds energy to an atom and causes the ejection of one or more electrons. In the new research, the measured time interval between the ejection of an electron from the first atom and the second atom in the molecule was 247 zeptoseconds on average. The study's approach could be used to learn more about photoionization and other ultrafast reactions. See also: Atom; Atomic structure and spectra; Electron; Energy; Hydrogen; Molecule; Photon
A new realm of ultrafast physics at the zeptosecond scale