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12 | NewScientist | 16 January 2010 DIMINUTIVE they may be, but the smallest galaxies seem most able to muscle out visible matter, and so are darker than their larger cousins. This deepens a mystery about where all of the universe’s visible matter has gone. Ordinary matter – the zoo of protons, electrons and other particles we see around us – is thought to make up just 4 per cent of the universe, with the rest being dark matter and dark energy. But inventories of the stars and gas in the nearby universe have revealed only about half the matter that is predicted by cosmological models. Now there’s another twist in the mystery: it seems pint-sized galaxies hold even less matter than expected. The smaller a galaxy, the smaller its proportion of normal matter to dark matter, Why Antarctica isn’t melting much ANTARCTICA is warming, but not melting anything like as much as expected. In fact, during the continent’s summer this time last year, there was less melting than at any time in the 30 years that we have had reliable satellite measurements of the region. That’s because of the seasonal pattern of warming, say Andrew Monaghan of the National Center for Atmospheric Research in Boulder, Colorado, and Marco Tedesco of the City College of New York. The continent’s winters and springs have warmed most, but it is still too cold in these seasons for anything to melt. Melting in Antarctica happens almost entirely in the summers, which have warmed very little, Tedesco warns that as the Antarctic ozone hole heals in the coming decades, the winds that seal the continent from warm air will weaken and it will become much warmer in summer. Exotic form of symmetry makes real-world debut A COMPLEX and beautiful form of mathematical symmetry has been spotted in the lab for the first time. In the 1800s, mathematicians found a 248-dimensional structure called E8. In the 1970s, the form turned up in calculations relating to string theory. E8 is also the basis for another “theory of everything” proposed by physicist Garrett Lisi, who called E8 “perhaps the most beautiful structure in mathematics”. Now physicists have detected its signature in a very different realm – super-chilled crystals. Radu Coldea of the University of Oxford and colleagues applied a CLAUDIO ROCCHINI IN BRIEF Missing matter mystery in small galaxies says Stacy McGaugh of the University of Maryland in College Park, who presented a census of galaxies at a meeting of the American Astronomical Society in Washington DC last week. Why so? One possibility is that exploding stars blast normal matter out of galaxies. Smaller galaxies would have a weaker gravitational hold on this material, so they could end up dominated by dark matter, which would be unaffected by the explosions. powerful magnetic field to a crystal of cobalt and niobium at 0.04 kelvin. Its atoms are arranged in parallel chains. Because of a quantum property called spin, electrons attached to those chains act like tiny bar magnets. When the field was applied, patterns appeared in the electron spins. Each pattern had a different energy associated with it – and the ratio of these energy levels showed that the electron spins were ordering themselves according to mathematical relationships in E8 symmetry ( Science, DOI: 10.1126/science.1180085). It is “remarkable” to see this exotic piece of mathematics appear in the real world, says Robert Konik of Brookhaven National Laboratory in Upton, New York. But he adds that the discovery does not provide evidence for string theory or Lisi’s proposal. PATCHES of synthetic skin could deliver gene therapies to patients without the need for injections. Jon Vogel’s team at the National Institutes of Health in Bethesda, Maryland, cultured fibroblasts and keratinocytes – the principal cells of the skin – and introduced into their genomes the gene for atrial natriuretic peptide, which is released naturally by cells in the heart. It reduces blood pressure by dilating blood vessels and lowering blood volume. They mixed the cells into a jelly-like matrix and applied the grafts to mice. This caused the animals’ blood pressure to drop, and it even stayed low on a high-salt diet (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0908882). Skin cells get extra gene to help heart
