I wish I knew enough math and physics to fully grasp this, but even without, it's still an amazing discovery.
In the classical physics of Newton and Einstein, the vacuum of space is entirely empty, but the theory of quantum mechanics assumes something very different.
According to quantum electrodynamics (QED) - a quantum theory that describes how light and matter interact - it’s predicted that space is actually full of 'virtual particles' that pop in and out of existence and mess with the activity of light particles (photons) as they zip around the Universe.
These virtual particles aren’t like regular physical particles like electrons and photons, but are fluctuations in quantum fields that have similar properties to a regular particle - the big difference being that they can appear and vanish at any point in space and time.
In regular empty space, photons aren't affected by these virtual particles, and travel without interference.
But in the empty space near the incredibly intense magnetic field of a neutron star, these virtual particles are 'excited', and they have a dramatic effect on any photons passing through.
"According to QED, a highly magnetised vacuum behaves as a prism for the propagation of light, an effect known as vacuum birefringence," Mignani explains in a press release.
"This effect can be detected only in the presence of enormously strong magnetic fields, such as those around neutron stars," adds team member Roberto Turollafrom the University of Padua in Italy.
As Jay Bennett reports for Popular Mechanics, the researchers directed the world's most advanced ground-based telescope, the European Southern Observatory's Very Large Telescope (VLT), at their neutron star, and observed linear polarisation - the alignment of light waves influenced by electromagnetic forced - in the empty space around the star.
"This is rather odd, because conventional relativity says that light should pass freely through a vacuum, such as space, without being altered," says Bennett.
"The linear polarisation was to such a degree (16 degrees, to be precise) that the only known explanations are theories of QED and the influence of virtual particles."