A Diamond Universe
Abstract
Cosmology is currently facing some major challenges. In addition to dark matter and dark energy, the issue of impossible galaxies has been brought to the fore by the James Webb Telescope. Something simple eludes us, and the various problems mentioned are interrelated. Our proposition is that, on the cosmological scale, it is appropriate to take a value of the speed of light c lower than its standard value c0 in vacuum. This defines an optical index n=c0/c. We account for this refringence by a Shapiro effect extended to the scale of the universe (use of Schwarzschild metric), described by its average density ρ and its equivalent gravitational radius R. Remarkably, universes with indices greater than two are entirely conceivable, and their characteristics are close to those we determine for our own. The velocities v of celestial objects are estimated from redshifts in ratios of the type v/c, where the speed c of light is usually taken to be equal to c0. With an equal v/c ratio (all things considered, only the v/c ratio has any meaning), dividing c0 by a certain factor α lowers the velocities v without postulating the existence of dark matter nor dark energy. Taking into account the problems cited earlier suggests a value of α close to 2.4. We are led to a lengthening of the age of the universe: it could reach 33 billion years. This would allow it to host in its relatively young phases objects that are already old and structured.