Vacuum Birefringence: Weird Quantum Effect Observed For The First Time In Empty Space Around Neutron Star
For the first time in 80 years since scientists predicted it, vacuum birefringence actually exists. Scientists from Italy and Poland observed a weird quantum effect in the polarized light of empty space around a neutron star.
In 1930, physicists Werner Heisenberg and Hans Heinrich Euler predicted that an extremely strong magnetic fields could change the polarity of light waves in a vacuum. This effect, dubbed as vacuum birefringence, was never observed, not until now.
Observed For The First Time in 80 Years
The scientists, who used the European Southern Observatory's (ESO) Very Large Telescope (VLT), said they may have witnessed this effect in the light coming from a neutron star, RX J1856.5-3754, a cosmo with a very strong magnetic field, Space reports.
Despite being one of the closest neutron stars, RX J1856.5-3754, which is about 400 lightyears away from Earth, its extreme dimness made astronomers observe it with visible light using the FORS2 instrument on the VLT.
Quantum Electrodynamics (QED)
Neutron stars are very dense remnant cores of massive stars that have exploded. They have extreme magnetic fields, which are billions of times stronger to those of the Earth's Sun.
With magnetic fields so strong, they could affect the properties of the empty space around the star. Normally, a vacuum was previously thought to be empty and light could travel through it without being changed.
However, quantum electrodynamics (QED), a theory, states that photons and charged particles jump around and vanish, rather than remaining constant. Extremely strong magnetic fields, just like what the neutron star generates, can affect light polarization.
"This effect can be detected only in the presence of enormously strong magnetic fields, such as those around neutron stars. This shows, once more, that neutron stars are invaluable laboratories in which to study the fundamental laws of nature." Roberto Turolla, a study author, said in a press release by the European Southern Observatory (ESO).
After analysis of the data from VLT, the team observed linear polarization, at a significant degree of about 16 percent. This could be likely due to the boosting effect of vacuum birefringence happening in the empty area around the neutron star.
The researchers believe the findings of the study, which are available online via the ESO, could open the door not only for future discoveries of vacuum birefringence but also highlight the power of the VLT to potentially measure X-ray wavelengths.