A circular wave curves upwards on the obverse of the coin. Representing an Einstein ring, this is the pictorial multiplication of the light source on the left. Between the light source and the observer, a cluster of galaxies is simplified in the centre, which deflects the light many times due to its gravity. The German for ‘gravitational lens’ refers to its function in this context. The formula Δ∅=4GM/bcÇ, which can be used to calculate the deflection of light, completes the design.
Obverse script
Latin
Obverse lettering
REPUBLIK ÖSTERREICH 2025
Δ∅ Δ∅= 4GM/bc²
LICHT-QUELLE
GRAVITATIONS-LINSE
20 EURO
Reverse description
The coin’s reverse has the same basic shape as the obverse but features a colour-printed interpretation of an Einstein ring.
