The European Space Agency’s (ESA) Euclid space mission aims to reveal the nature of dark energy, the mysterious cause of the observed accelerated expansion of the universe. Identifying dark energy is arguably the most profound question facing fundamental Physics today, because of its connection between the quantum world and gravity. Euclid will measure the dark energy equation-of-state (EoS), which is to say that it will determine if dark energy is constant or varies with time, a key distinction for theoretical understanding.
