How will Europe's Euclid space telescope see into the dark universe?

The new European space telescope Euclid will look for evidence of dark matter and dark energy in the cosmos.

There is a problem with our understanding of the universe: It doesn't make sense if we account only for the matter and energy that we can see, measure or detect.

Albert Einstein's famous general theory of relativity, which describes the physical 'rules' of the universe in a series of equations only adds up on cosmic scales if there is five times as much matter dispersed throughout the cosmos than what we can see and detect.