Dr Obinna Umeh is a postdoctoral researcher at the University of the Western Cape in Cape Town, supported by the Square Kilometre Array project in South Africa

The accurate determination of cosmological distances is the most important probe in cosmology. Observations of type Ia supernovae imply dark energy exists because we know the relation between the distance of an object and its redshift – this changes with the relative amount of matter to dark energy, for example. But intervening matter between the supernovae and us cause fluctuations in this relationship. To a first approximation this is just normal gravitational lensing, an integrated contribution from the wobbly path the light takes to us.

Is this an accurate enough picture? Maybe at the moment, but not Continue reading →