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Lonely, spun-out proton reveals magnetic secret
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‘Gravity lines’ trace warped space-time David Shiga
WANT to see how black holes warp the fabric of space-time around them? There’s a new technique to help show us. Just as magnetic field lines show how magnetic forces vary in space, a new study suggests that “tendex” and “vortex” lines show how gravity warps space. The work sheds light on why some black holes get a kick after undergoing a merger. Einstein’s general theory of relativity predicts that space-time deforms around massive objects, such as black holes. But this
warping is notoriously difficult to visualise, since the theory states that each point in space-time is associated with 10 numbers. Now a team of physicists led by Robert Owen of Cornell University in Ithaca, New York, says relatively simple patterns of lines can capture its essence. “We’ve found ways to visualise warped spacetime like never before,” says team member Kip Thorne of the California Institute of Technology in Pasadena. The numbers associated with each point in space-time can be represented by sets of little
Look at it this way Vortex and tendex lines can each or both appear around a variety of black holes. The top image shows tendex lines around a non-spinning black hole and the bottom image shows vortex lines around a spinning black hole TENDEX lines show the stretching (green) and compressing (blue) forces that can rip apart and crush objects that lie along those lines near black holes
VORTEX lines represent the twisting effects of warped space-time that would wring, like a towel, an object lying along those lines
14 | NewScientist | 23 April 2011
Lonely, spun-out proton spills magnetic secret
arrows, like tiny compass needles that fill space. In the new method, these arrows are linked together to make long lines, similar to the magnetic field lines that emanate from the poles of a AN ISOLATED proton has been trapped magnet (see diagram). Tendex and coaxed into revealing the strength lines – named for the Latin word of its magnetism, a feat that could help tendere, meaning “to stretch” – investigate an enduring question show how objects along those lines get stretched or compressed. about antimatter. Many subatomic particles act like Vortex lines represent how tiny magnets, with their strength warped space-time can wring dubbed their “g-factor”. Prior objects as you would a towel. attempts to measure the proton’s The lines can help explain a g-factor were not precise as they puzzling phenomenon seen in were restricted to probing protons simulations of merging pairs of in atoms, where orbiting electrons black holes. In the simulations, disguise the proton’s properties. some of the final, merged black Now physicists led by Jochen Walz holes end up being hurled fast at the University of Mainz in Germany enough to escape their host galaxies, leaving them to journey have managed to isolate a single proton and measure its g-factor. through space alone. Such blackThey start by shooting electrons hole “superkicks” are thought at a substance: the impact releases to result from the black hole protons, which can be trapped using a emitting gravitational waves magnet. Next, the researchers slowly asymmetrically, but why this let the protons escape until just one asymmetry happens in the is left. The magnet causes the lone first place is unclear. proton to “precess” like a spinning Owen and his colleagues top, at a frequency that depends on suggest it is due to the interplay its g-factor. The researchers deduced of the vortex and tendex lines. In this frequency using radio waves that the team’s simulation of a black flipped the orientation of the proton’s hole merger, they found the two magnet only when their frequency types of lines cancelled each other’s effects on one side of the “The technique could be black hole but reinforced each other on the other side, spawning used to probe whether antimatter really is a copious gravitational waves mirror image of matter” that produce the kick (Physical Review Letters, DOI: 10.1103/ matched the precession frequency PhysRevLett.106.151101). (arxiv.org/abs/1104.1206v1). “This is very exciting because This in itself did not yield a more the generation of the superkicks precise value for the g-factor than has not been well understood,” previously, but it will if the proof-ofsays Yosef Zlochower at the Rochester Institute of Technology principle experiment is repeated in New York, who was not involved using a higher-precision trap, says Wolfgang Quint, a team member from in the study. the Helmholtz Centre for Heavy Ion The new technique could also Research in Darmstadt, Germany. help physicists better predict the The technique could also be used to properties of gravitational waves measure the g-factor of antiprotons. emitted by black holes as they merge, the team says, which in turn It is thought that antimatter is a mirror image of matter – exactly the could help them pick out signs of same but with an opposite charge. these waves in the deluge of data If this is true, then the g-factors of collected at detectors such as the Laser Interferometer Gravitational the proton and antiproton should be identical. Mark Buchanan n Wave Observatory in the US. n
‘Gravity lines’ trace warped space-time David Shiga
WANT to see how black holes warp the fabric of space-time around them? There’s a new technique to help show us. Just as magnetic field lines show how magnetic forces vary in space, a new study suggests that “tendex” and “vortex” lines show how gravity warps space. The work sheds light on why some black holes get a kick after undergoing a merger. Einstein’s general theory of relativity predicts that space-time deforms around massive objects, such as black holes. But this
warping is notoriously difficult to visualise, since the theory states that each point in space-time is associated with 10 numbers. Now a team of physicists led by Robert Owen of Cornell University in Ithaca, New York, says relatively simple patterns of lines can capture its essence. “We’ve found ways to visualise warped spacetime like never before,” says team member Kip Thorne of the California Institute of Technology in Pasadena. The numbers associated with each point in space-time can be represented by sets of little
Look at it this way Vortex and tendex lines can each or both appear around a variety of black holes. The top image shows tendex lines around a non-spinning black hole and the bottom image shows vortex lines around a spinning black hole TENDEX lines show the stretching (green) and compressing (blue) forces that can rip apart and crush objects that lie along those lines near black holes
VORTEX lines represent the twisting effects of warped space-time that would wring, like a towel, an object lying along those lines
14 | NewScientist | 23 April 2011
Lonely, spun-out proton spills magnetic secret
arrows, like tiny compass needles that fill space. In the new method, these arrows are linked together to make long lines, similar to the magnetic field lines that emanate from the poles of a AN ISOLATED proton has been trapped magnet (see diagram). Tendex and coaxed into revealing the strength lines – named for the Latin word of its magnetism, a feat that could help tendere, meaning “to stretch” – investigate an enduring question show how objects along those lines get stretched or compressed. about antimatter. Many subatomic particles act like Vortex lines represent how tiny magnets, with their strength warped space-time can wring dubbed their “g-factor”. Prior objects as you would a towel. attempts to measure the proton’s The lines can help explain a g-factor were not precise as they puzzling phenomenon seen in were restricted to probing protons simulations of merging pairs of in atoms, where orbiting electrons black holes. In the simulations, disguise the proton’s properties. some of the final, merged black Now physicists led by Jochen Walz holes end up being hurled fast at the University of Mainz in Germany enough to escape their host galaxies, leaving them to journey have managed to isolate a single proton and measure its g-factor. through space alone. Such blackThey start by shooting electrons hole “superkicks” are thought at a substance: the impact releases to result from the black hole protons, which can be trapped using a emitting gravitational waves magnet. Next, the researchers slowly asymmetrically, but why this let the protons escape until just one asymmetry happens in the is left. The magnet causes the lone first place is unclear. proton to “precess” like a spinning Owen and his colleagues top, at a frequency that depends on suggest it is due to the interplay its g-factor. The researchers deduced of the vortex and tendex lines. In this frequency using radio waves that the team’s simulation of a black flipped the orientation of the proton’s hole merger, they found the two magnet only when their frequency types of lines cancelled each other’s effects on one side of the “The technique could be black hole but reinforced each other on the other side, spawning used to probe whether antimatter really is a copious gravitational waves mirror image of matter” that produce the kick (Physical Review Letters, DOI: 10.1103/ matched the precession frequency PhysRevLett.106.151101). (arxiv.org/abs/1104.1206v1). “This is very exciting because This in itself did not yield a more the generation of the superkicks precise value for the g-factor than has not been well understood,” previously, but it will if the proof-ofsays Yosef Zlochower at the Rochester Institute of Technology principle experiment is repeated in New York, who was not involved using a higher-precision trap, says Wolfgang Quint, a team member from in the study. the Helmholtz Centre for Heavy Ion The new technique could also Research in Darmstadt, Germany. help physicists better predict the The technique could also be used to properties of gravitational waves measure the g-factor of antiprotons. emitted by black holes as they merge, the team says, which in turn It is thought that antimatter is a mirror image of matter – exactly the could help them pick out signs of same but with an opposite charge. these waves in the deluge of data If this is true, then the g-factors of collected at detectors such as the Laser Interferometer Gravitational the proton and antiproton should be identical. Mark Buchanan n Wave Observatory in the US. n