Astronomers may have found some of the strongest evidence yet for one of quantum mechanics' strangest predictions: even apparently empty space can influence the way light travels. Known as 'vacuum birefringence', the phenomenon was predicted nearly 90 years ago by Werner Heisenberg, one of the pioneers of quantum mechanics. His work suggested that a perfect vacuum is not truly empty.
Instead, it should contain 'virtual particles' that briefly appear and disappear. Researchers, including Dr. Marcus Lower from Swinburne University of Technology, investigated this long-standing quantum mystery by studying a magnetar, a rare type of neutron star that possesses the strongest magnetic fields known in the universe.
Their observations may represent the first detection of vacuum birefringence occurring within a magnetar's extraordinarily powerful magnetic field. If confirmed, the result could give scientists a new way to investigate the quantum universe. The findings were published recently in Nature.
How Extreme Magnetic Fields Can Change Light According to the theory, an exceptionally strong magnetic field can affect the sea of virtual particles associated with the vacuum. Under these conditions, the particles are expected to influence how light travels, refracting it in a specific way and producing vacuum birefringence. Magnetars provide a rare opportunity to search for this effect because their magnetic fields are powerful enough to make the predicted quantum behavior potentially observable.
Lower was part of an international research team that studied the magnetar 1E 1547.0-5408 (or 1E1547 for short) with NASA's Imaging X-ray Polarimetry Explorer (IXPE). The observations were supported by the NICER X-ray telescope aboard the International Space Station and Murriyang, CSIRO's Parkes radio telescope, which is owned and operated by Australia's national science agency. Radio observations collected by Dr.
Lower using Murriyang, followed by analysis on Swinburne's Ngarrgu Tindebeek supercomputer, helped the researchers investigate what could be the first direct detection of this previously theoretical quantum phenomenon. Although vacuum birefringence was predicted in the 1930s, Dr. Lower said scientists have yet to obtain a definitive detection.
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