Atom & Cosmos
The source of the Milky Way’s spirals, a new way to spot gravitational waves and more in this week’s news
By Science News
Galactic close encounter
The Milky Way should have ducked: Some 1.75 billion years ago a smaller galaxy swung by our neck of the cosmic woods, smearing out the Milky Way’s stars in a gravitational tug-of-war. Astronomers have simulated this galactic close encounter in the best detail yet, and suggest that it may have formed the Milky Way’s dramatic spiral arms. Small-galaxy interactions could thus play a bigger role in shaping galaxies than previously thought, write Chris Purcell, of the University of Pittsburgh and the University of California, Irvine, and his colleagues in the Sept. 15 Nature. —Alexandra Witze
Putting the squeeze on gravitational waves
Making a deal with a quantum devil could help researchers detect gravitational waves — hypothetical ripples in the fabric of spacetime caused by supernovas, black holes and other massive, accelerating objects. These ripples are so slight that they can be hidden by random quantum fluctuations in the laser beams designed to detect them. But squeezed light — an unusual state that trades certainty about light’s amplitude for certainty about its phase — can suppress this randomness. Adding squeezed light to the GEO600 detector near Hannover, Germany, reduced noise in the detector, improving its sensitivity to high-frequency gravitational waves by more than a factor of three, researchers estimate online September 11 in Nature Physics. —Devin Powell
Primitive galaxies glow blue
The universe’s first galaxies may glow with an identifiable bluish light. These galaxies should contain exemplars of the first population of stars, those made of only hydrogen and helium. Such stars produce a great deal of energy capable of ionizing hydrogen, but the resulting blue-tinged emission tends to be lost in dusty intervening material. Swedish and Japanese astronomers now suggest September 9 on arXiv.org that this emission can actually be spotted by the Hubble Space Telescope, allowing astronomers to identify the first galaxies in the early universe. Indeed, they note, objects have already been sighted that match their criteria.—Camille M. Carlisle