The vibration is influenced by the force of gravity

Researchers see large-scale vibrations of space-time as the cause of the mysterious dark energy

Gravitational waves

Cardiff (Great Britain) - According to a British researcher, gravitational waves produced during the Big Bang with wavelengths as large as the entire universe are the cause of two previously puzzling cosmological phenomena. The vibrations of space-time could both simulate the acceleration of the expansion of the universe and cause the asymmetry in the cosmic background radiation, writes the astrophysicist. His technical article is published online on the scientific document server "arXiv" and was therefore not examined in a peer-review process.

The universe has been expanding since it was formed 13.7 billion years ago. Gravity should slow down cosmic expansion. But in the 1990s, observations of distant exploding stars - so-called supernovae - showed that, on the contrary, the expansion was actually accelerating. The cosmologists postulated a mysterious dark energy as the cause of this acceleration. What it is really about has so far remained completely unclear - a kind of tension in space, perhaps, or an exotic, previously unknown form of matter.

"Strong, large-scale gravitational waves can explain cosmic acceleration in the context of general relativity without having to resort to exotic concepts," explains Edmund Schluessel from Cardiff University. Astronomers have long assumed that the Big Bang, the explosive formation of the cosmos, also produced gravitational waves. So far, however, they have only considered spacetime oscillations whose wavelengths are significantly smaller than the diameter of the visible universe.

Schluessel now shows the effects of gravitational waves whose wavelengths are more than ten billion light years and are of the same size as the visible cosmos. The vibrations of space-time can influence the radiation of distant supernovae in such a way that an increase in expansion is simulated. Even more: The gravitational waves can also lead to the cosmic background radiation, a kind of radiation echo of the Big Bang, not being distributed symmetrically over the sky.

Schluessel's thesis not only explains two cosmological phenomena within the framework of standard physics, it also makes an observable prediction: The apparent acceleration of cosmic expansion should be direction-dependent, i.e. greater on one half of the sky than on the other. In fact, two Chinese researchers recently found evidence of such an asymmetrical acceleration in the data from 557 distant supernovae. These observations have yet to be independently confirmed by other astronomers.