When stars at the edges of galaxies rotate faster than calculations based on visible mass predict, standard cosmology invokes the hypothesis of hidden dark matter — invisible substance that reveals itself only through gravity. A new study offers an alternative that requires no new particles. To bypass singularities, points in spacetime where the equations of general relativity break down due to infinite values, the researchers used a mathematical trick: they 'cut' spacetime and glued its fragments back together in a new way, altering the boundary conditions. At these artificial boundaries, boundary oscillations of the gravitational field spontaneously arise, so-called boundary effects. These create the extra attraction that accelerates stars to the observed speeds, mimicking the influence of dark matter.
A surprising twist: a mathematical technique originally developed to eliminate singularities in black holes unexpectedly explains the dynamics of entire galaxies. This suggests that dark matter might not be a substance but a fundamental feature of gravity that manifests at boundaries introduced in a particular mathematical description of spacetime.
Astronomers used to think the strange rotation of galaxies was just a measurement error, until Vera Rubin proved the effect was real.
In science fiction, universes are glued together with wormholes; here, sheets of space are glued to bypass 'glitches' in the equations, and this unexpectedly explains the motion of stars.