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Dwarf planet Eris may reveal quantum gravity
NASA/SCIENCE PHOTO LIBRARY
THIS WEEK Is Earth bashing through walls of dark matter?
time itself is imbued with a small charge that could be causing objects in the universe to speed away from each other. To test whether quantum-scale gravity is at work, Hajdukovic plans THE knives are out for dark matter to borrow a trick from Einstein (see diagram). Due to gravitational (see left), but our search for the effects in the solar system, such as cryptic stuff that may make up about the tug of other planets, Mercury’s 86 per cent of all matter could be set for a breakthrough – literally. Earth oval-shaped path around the sun may be smashing through huge walls slowly turns, or precesses. In the of dark matter that we could detect. 1800s astronomers noticed that According to a leading theory, dark this happens at a different rate matter is made of weakly interacting than predicted by Newtonian massive particles, but the hunt for physics. Einstein showed that the WIMPs keeps coming up empty. sun’s mass creates a curvature in “I feel like it’s time to broaden the –Eris eyes up its next victim– space-time that affects Mercury enough to explain the difference, scope of our search,” says Maxim Pospelov of the University of Victoria lending credence to his theory of in Vancouver, Canada. He is focusing general relativity. on the idea that some dark matter Hajdukovic’s quantum gravity might create a similar discrepancy may be tied up in domain walls – with more distant orbiting bodies, structures separating areas of the universe where an exotic force field he says – which is where Eris and its moon Dysnomia come in. In the presence of a gravitational Best known for depriving Pluto “If magnetometers around the world saw an unusual field, the particles would generate of planethood by showing that signal, Earth may have a secondary field, which, in the there are many similar bodies in pierced a dark matter wall” case of galaxies, could explain the orbit beyond Neptune, Eris’s great mass discrepancy. distance from the sun means in the early cosmos settled down Hajdukovic’s theory could also the effects of general relativity with different values. explain dark energy, the baffling become negligible. Newtonian To maintain these distinct values, force thought to be driving the physics should dominate, putting the domain walls must be rich in universe apart at an accelerated Dysnomia’s precession rate energy. As the theory of relativity pace. If virtual particles have around Eris at 13 arc seconds per says that mass and energy are gravitational charges, then space- century. But if quantum gravity interchangeable, on a large scale the exists, the rate should be -190 arc domain walls look like concentrations seconds per century, Hajdukovic Einstein’s trick Einstein’s trick calculates (Astrophysics and Space of mass – that is, like dark matter. Mercury’s orbit around the sun rotates Mercury’s orbit around the sun rotates Earth may pass through a domain faster than Newtonian physics predicts, Science, doi.org/j6r). faster than Newtonian physics predicts, wall every few years as it drifts He thinks the required a sign of Einstein’s general relativity a sign of Einstein’s general relativity through space. We wouldn’t feel it, measurements could be made says Pospelov, but if a worldwide from Earth using existing MERCURY observatories. “Einstein was lucky network of magnetometers MERCURY simultaneously saw an unusual that there is a planet so close to signal, it could signify that Earth has the sun as Mercury,” he says. “My pierced a dark matter wall (Physical theory might be lucky that there Review Letters, doi.org/j9h). are trans-Neptunian objects Douglas Finkbeiner of the Harvardallowing astronomical tests.” Smithsonian Center for Astrophysics Gary Page of Longwood is not convinced that dark matter University in Farmville, Virginia, SUN SUN walls exist. But he is glad that is sceptical that Earth-based tests physicists are keeping an open mind would be sensitive enough to Newtonian prediction: about alternatives to WIMPs. “We’ve pick up the effect. Still, he praises Newtonian prediction: 5557 arc seconds per century looked for WIMP dark matter in so Hajdukovic for going beyond the 5557 arc seconds per century Observation: Observation: many ways,” he says. “At some point party line. “It’s always good when 5600 arc seconds per century 5600 arc seconds per century (one arc second = 1/3600 degrees) people are willing to go a little bit you have to ask, are we totally on the (one arc second = 1/3600 degrees) wrong track?” Lisa Grossman n out on a limb.” n
Dwarf planet feels quantum gravity Ker Than
KILLING Pluto was only the beginning. The dwarf planet Eris, named for the Greek goddess of strife, could also bring down the most popular explanations for dark matter and dark energy. Many galaxies appear to have stronger gravity – and thus more mass – than can be explained by their visible matter alone. Overly massive galaxies are most often attributed to dark matter, an invisible substance that interacts with matter through gravity. To date, though, no one has directly detected dark matter particles. But a well-established notion in physics could hold another explanation for their size. This says that empty space is really a frothy, turbulent sea full of virtual particles – matter and antimatter that spring in and out of existence so fast that we can’t see them. Though they are tiny, quantum objects, Dragan Hajdukovic, a physicist at CERN near Geneva, Switzerland, thinks these bubbling particles may have opposing gravitational charges, similar to electrical charges. 12 | NewScientist | 26 January 2013
THIS WEEK Is Earth bashing through walls of dark matter?
time itself is imbued with a small charge that could be causing objects in the universe to speed away from each other. To test whether quantum-scale gravity is at work, Hajdukovic plans THE knives are out for dark matter to borrow a trick from Einstein (see diagram). Due to gravitational (see left), but our search for the effects in the solar system, such as cryptic stuff that may make up about the tug of other planets, Mercury’s 86 per cent of all matter could be set for a breakthrough – literally. Earth oval-shaped path around the sun may be smashing through huge walls slowly turns, or precesses. In the of dark matter that we could detect. 1800s astronomers noticed that According to a leading theory, dark this happens at a different rate matter is made of weakly interacting than predicted by Newtonian massive particles, but the hunt for physics. Einstein showed that the WIMPs keeps coming up empty. sun’s mass creates a curvature in “I feel like it’s time to broaden the –Eris eyes up its next victim– space-time that affects Mercury enough to explain the difference, scope of our search,” says Maxim Pospelov of the University of Victoria lending credence to his theory of in Vancouver, Canada. He is focusing general relativity. on the idea that some dark matter Hajdukovic’s quantum gravity might create a similar discrepancy may be tied up in domain walls – with more distant orbiting bodies, structures separating areas of the universe where an exotic force field he says – which is where Eris and its moon Dysnomia come in. In the presence of a gravitational Best known for depriving Pluto “If magnetometers around the world saw an unusual field, the particles would generate of planethood by showing that signal, Earth may have a secondary field, which, in the there are many similar bodies in pierced a dark matter wall” case of galaxies, could explain the orbit beyond Neptune, Eris’s great mass discrepancy. distance from the sun means in the early cosmos settled down Hajdukovic’s theory could also the effects of general relativity with different values. explain dark energy, the baffling become negligible. Newtonian To maintain these distinct values, force thought to be driving the physics should dominate, putting the domain walls must be rich in universe apart at an accelerated Dysnomia’s precession rate energy. As the theory of relativity pace. If virtual particles have around Eris at 13 arc seconds per says that mass and energy are gravitational charges, then space- century. But if quantum gravity interchangeable, on a large scale the exists, the rate should be -190 arc domain walls look like concentrations seconds per century, Hajdukovic Einstein’s trick Einstein’s trick calculates (Astrophysics and Space of mass – that is, like dark matter. Mercury’s orbit around the sun rotates Mercury’s orbit around the sun rotates Earth may pass through a domain faster than Newtonian physics predicts, Science, doi.org/j6r). faster than Newtonian physics predicts, wall every few years as it drifts He thinks the required a sign of Einstein’s general relativity a sign of Einstein’s general relativity through space. We wouldn’t feel it, measurements could be made says Pospelov, but if a worldwide from Earth using existing MERCURY observatories. “Einstein was lucky network of magnetometers MERCURY simultaneously saw an unusual that there is a planet so close to signal, it could signify that Earth has the sun as Mercury,” he says. “My pierced a dark matter wall (Physical theory might be lucky that there Review Letters, doi.org/j9h). are trans-Neptunian objects Douglas Finkbeiner of the Harvardallowing astronomical tests.” Smithsonian Center for Astrophysics Gary Page of Longwood is not convinced that dark matter University in Farmville, Virginia, SUN SUN walls exist. But he is glad that is sceptical that Earth-based tests physicists are keeping an open mind would be sensitive enough to Newtonian prediction: about alternatives to WIMPs. “We’ve pick up the effect. Still, he praises Newtonian prediction: 5557 arc seconds per century looked for WIMP dark matter in so Hajdukovic for going beyond the 5557 arc seconds per century Observation: Observation: many ways,” he says. “At some point party line. “It’s always good when 5600 arc seconds per century 5600 arc seconds per century (one arc second = 1/3600 degrees) people are willing to go a little bit you have to ask, are we totally on the (one arc second = 1/3600 degrees) wrong track?” Lisa Grossman n out on a limb.” n
Dwarf planet feels quantum gravity Ker Than
KILLING Pluto was only the beginning. The dwarf planet Eris, named for the Greek goddess of strife, could also bring down the most popular explanations for dark matter and dark energy. Many galaxies appear to have stronger gravity – and thus more mass – than can be explained by their visible matter alone. Overly massive galaxies are most often attributed to dark matter, an invisible substance that interacts with matter through gravity. To date, though, no one has directly detected dark matter particles. But a well-established notion in physics could hold another explanation for their size. This says that empty space is really a frothy, turbulent sea full of virtual particles – matter and antimatter that spring in and out of existence so fast that we can’t see them. Though they are tiny, quantum objects, Dragan Hajdukovic, a physicist at CERN near Geneva, Switzerland, thinks these bubbling particles may have opposing gravitational charges, similar to electrical charges. 12 | NewScientist | 26 January 2013