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22 | NewScientist | 26 March 2011 How to confuse a newborn chick PUT a newborn chick in front of a print of Escher’s impossible staircases and it just might scratch its head. The vertebrate brain appears to be hard-wired at birth to comprehend a 3D world – and is flummoxed by geometries that don’t make sense. Girogio Vallortigara of the University of Trento in Italy and his colleagues kept 66 chicks in the dark for 24 hours after hatching to ensure they lacked any visual experience, before placing them at one end of an enclosure. At the opposite end were two drawings, one showing the outline of a normal cube, the other showing an Escher-like version with the back and front corners impossibly overlapped. Two-thirds of the chicks approached the possible cube rather than the impossible one (Biology Letters, DOI: 10.1098/ rsbl.2011.0051). Four-month-old babies can also tell apart possible and impossible images, but Vallortigara points out that they have had four months to experience a 3D world and form 2D representations of it. He says his experiments suggest that the vertebrate brain can do this from birth. Single atom quantum memories are easier to access DELICATE quantum bits have been stored in single atoms, a feat that could make accessing memory in quantum computers more convenient. Unlike classical bits, which can store only a 0 or 1, qubits can be in a superposition of the two states at once. Two or more can also be “entangled” and remain linked across great distances. Both properties vastly enhance the power of quantum computers compared with normal ones. But while a qubit can be encoded in the polarisation of a photon, which can transport qubits efficiently, a good method for storing qubits and reading them out later has eluded us. Patterns created in ensembles of atoms can do the trick, but the information from one qubit is spread over many atoms so accessing the qubit is cumbersome. So Gerhard Rempe of the Max Planck Institute for Quantum Optics in Garching, Germany, used light beams to trap a single rubidium atom and then fired a photon carrying a qubit at it. A precise choice for the initial A THEORY that dark energy is just an illusion caused by our location within a giant void has met with a challenge. Measurements of supernova explosions in both nearby and distant galaxies suggest that the universe is expanding faster now than in the past. The popular explanation is that a dark energy permeates the universe, speeding up its expansion. But some have suggested another explanation: that our patch of the universe contains less matter than average. Within this “void”, the expansion would be faster because there is less gravity slowing it down. Now precise measurements of supernovae by the Hubble Space Telescope point to an expansion rate that is incompatible with the simplest void model, a team led by Adam Riess of Johns Hopkins University in Baltimore, Maryland, reports (The Astrophysical Journal, DOI: 10.1088/0004-637X/730/2/119). Void proponent Subir Sarkar of the University of Oxford says this is not fatal. Other void models don’t clash with the new measurement, he says, such as the “void within a void”, where the density of matter drops off steeply towards the void’s core. Dark energy is no illusion from the void CHANDRA X-RAY OBSERVATORY CENTER configuration of the atom’s electrons ensured that the photon transferred the qubit to the atom. At least 180 microseconds later, the team read out the qubit and created a photon with the same polarisation as the original (arxiv. org/abs/1103.1528). Storing qubits in single atoms is “a big step forward”, says Peter Zoller of the University of Innsbruck in Austria. “You can fairly easily make the atom interact with other atoms or photons carrying qubits and do interesting things,” he says. Sonar leaves whales hungry NAVAL sonar makes whales flee from prime feeding sites, leaving them hungry when they finally return. Peter Tyack of Woods Hole Oceanographic Institution, Massachusetts, and colleagues tracked the activity of Blainville’s beaked whale (Mesoplodon densirostris) during operations at a US navy centre near Andros Island, Bahamas. The area encompasses an underwater canyon that is a prime hunting ground for these deep divers. By satellite tagging one whale and listening out for the echolocation clicks of others using underwater microphones, the team found that whales stopped echolocating and moved away from the area during the tests (PLoS One, DOI: 10.1371/journal. pone.0017009). A related study found that three days after the tests ended, the whales had returned and were echolocating like crazy – possibly indicating they were ravenous (Marine Mammal Science, DOI: 10.1111/ j.1748-7692.2010.00457.x). Robin Baird of the Cascadia Research Collective, based in Olympia, Washington, believes the use of underwater microphones is “a great approach”, but points out that the whales’ behaviour may not be typical of those that live away from sonar test ranges. MICHAEL NOLAN/SPECIALIST STOCK IN BRIEF For new stories every day, visit www.NewScientist.com/news
