The expansion of the Universe is getting faster and we don't know why. To solve this mystery we are using an effect called gravitational lensing to answer three questions:
- How fast is the Universe currently expanding?
- How does gravity work over astronomical distance scales?
- What is the dominant component of the Universe's energy budget?
Gravitational lensing occurs when two galaxies are aligned on the sky to about 1/3600 of a degree. The mass of the foreground galaxy warps spacetime and deflects the light from the background galaxy as it passes. Despite being a powerful cosmological probe for matter distribution, strong gravitational lensing is hamstrung by the small number of lensing systems: only a few hundred systems are known. The EU-funded LensEra project plans to combine machine learning, citizen science and automated lens modelling to build an engine to find 30 000 new lensing systems in the Large Synoptic Survey Telescope data in Chile. Analysis of subsets of lens populations will enable us to explore the most profound questions of our Universe, including the nature of dark matter and the measurement of dark energy's equation of state.