NASA telescope finds evidence for 90-year-old quantum theory

An international team of astronomers has reported what may be the first direct astrophysical evidence of vacuum birefringence — a nearly 90-year-old quantum physics prediction that extreme magnetic fields can alter how light travels through seemingly empty space. The results, published Wednesday in Nature, draw on more than 140 hours of observations of a rare ultra-magnetic neutron star known as a magnetar.nature+1

A Cosmic Laboratory

The magnetar 1E 1547-5408, located more than 13,000 light-years from Earth and spinning once every two seconds, served as the team's natural laboratory. Scientists coordinated NASA's IXPE (Imaging X-ray Polarimetry Explorer) satellite with NASA's NICER telescope and Murriyang, CSIRO's Parkes radio telescope in rural New South Wales — owned and operated by Australia's national science agency. It marked the first-ever coordinated radio and X-ray polarization measurement of a magnetar.lsu+1

The observations revealed X-ray polarization nearly three times greater than seen in similar sources — far exceeding what standard surface emission models could explain. Given the geometry of the magnetar's magnetic fields, the polarization signal should have been close to zero at certain points in the star's rotation.science.nasa

Testing a 90-Year-Old Theory

Vacuum birefringence, first proposed in 1936 within the framework of quantum electrodynamics, predicts that the quantum vacuum — filled with constantly flickering particle-antiparticle pairs — becomes distorted by extreme magnetic fields, causing empty space to act like a polarized filter. Magnetars, with fields around a trillion times stronger than the most powerful permanent magnets on Earth, offer the only known environment where this effect could manifest.lsu+1

Simulations performed by the team support vacuum birefringence as the cause of the unexpectedly strong signal. "Our model suggests that reproducing the observed X-ray polarization signatures, while also satisfying the constraints set by radio observations, requires the presence of vacuum birefringence in the neutron star's environment," said Hoa Dinh Thi, a postdoctoral associate at Rice University and co-lead author.science.nasa

"The Fabric of Reality"

Lead author Rachael Stewart, a Ph.D. candidate at George Washington University, said the finding illustrates how astrophysics can probe fundamental physics. "The information we obtained from looking at this distant star core also gives us clues about the nature of the fabric of reality as we know it, and I find that to be incredible," Stewart said.science.nasa

LSU astrophysicist Michela Negro, another member of the team, described the approach: "We're not just studying astronomical objects anymore; we're using them to test the laws of nature."lsu

Further IXPE observations of this and other magnetars are planned to confirm the signal and potentially reveal additional exotic quantum effects.science.nasa