A researcher from Oxford University may have found the answer to one of the biggest mysteries of the Universe, what is dark energy and matter? In a unifying theory, the scientist has reunited the two concepts under one and the same entity, a kind of hypothetical fluid with a negative mass, which could correspond to the ‘missing 95% of the Universe.’Attraction and repulsionIt is a fundamental law of physics, mass causes objects to be attracted to each other. The Earth attracts your body towards it with the force of gravity, and, in a tiny measure, your body attracts the Earth to it in return. But an object with negative mass, and therefore negative gravitational force, would repel the objects that surround it. ‘Although this material seems exotic, it suggests that the cosmos would be symmetrical in its positive and negative characteristics,’ says Jamie Farnes, author of the study published in the Astronomy and Astrophysics journal.Such a theory would make it possible to explain the expansion of the Universe. At present, the matter that constitutes it is always moving away from us and away from each point of the cosmos. The ‘negative matter’ could be at the origin of this force pushing the normal matter outwards. However, its existence had already been considered improbable, because as the Universe continues to expand, the ‘negative matter’ should theoretically become less and less dense and its expansion should slow down, which is not the case.Creation of negative matterDr. Farnes nonetheless suggests that new negative matter (a negative fluid) could be continuously created, to guarantee the acceleration of expansion. His calculations are consistent with our current description of dark energy as well as predictions of the behaviour of dark matter halos. Scientists believe that galaxies are surrounded by a dark matter boundary that prevents them from tearing under the effect of their own rotational speed.‘Previous approaches combining dark matter and energy have attempted to alter Einstein's theory of general relativity, which turns out to be incredibly complicated. This new approach takes two proven ideas that are compatible with Einstein's theory, the negative masses and the creation of matter, and combines them.’‘The result is quite beautiful, matter and dark energy can be unified into a single substance that has both their effects, explicable as the manifestation of a mass of positive matter floating on a sea of negative masses.’ Dr. Farnes' predictions could be put to the test in the future thanks to the use of the huge SKA radio telescope.