An international team of astrophysicists has come closer to solving one of the key mysteries of quantum physics, a puzzle that has existed for nearly a century. While studying an extreme cosmic object, they detected signs of an effect predicted by Werner Heisenberg in the 1930s: that a vacuum is not truly empty and can influence the way light travels.

Quantum Properties of the Vacuum

According to the laws of quantum electrodynamics, even in absolute emptiness, pairs of virtual matter and antimatter particles constantly appear and disappear. Modern technology does not allow us to observe this process directly. However, when a vacuum is placed in an extremely strong magnetic field, these virtual particles align in a certain direction, causing space itself to bend light, much like a transparent crystal. This phenomenon is called vacuum birefringence: light waves with different polarizations pass through the vacuum at different speeds.

Experimental Observations

To test Heisenberg's hypothesis, astrophysicists needed a magnetic field 100 million times stronger than what can be created in Earth-based laboratories. For this, they used magnetars—a rare type of neutron star with the most powerful magnetic fields in the universe. NASA’s space telescopes (IXPE and NICER), along with the Parkes radio telescope in Australia, were directed at the magnetar 1E 1547.0−5408, whose magnetic field is a trillion times stronger than Earth's.

At MEPhI, a complete analytical description of the experiment to observe vacuum polarization was created for the first time. Researchers from the Department of Theoretical Nuclear Physics at the Laplace Institute of MEPhI developed a theoretical model to analyze such observations.

Results and Significance of the Discovery

The magnetar was found to be oriented toward Earth almost directly with its magnetic pole, providing optimal conditions for observation. Measurements of the polarization of X-ray and radio emissions showed that the light from the star changes its properties in exactly the way expected when passing through a vacuum filled with ordered virtual particles. The results of the study were published in the journal Nature.

This research could become the first direct experimental confirmation of vacuum birefringence. To fully verify the theory, additional observations and computer modeling are required. If the conclusions are confirmed, Heisenberg’s hypothesis, which has existed for 90 years, will be proven, and a new tool for studying the structure of the universe will emerge.