Description: A rising circular wave on the coin's obverse depicts an Einstein ring—a multiplied image of the light source at left. A central galaxy cluster, simplified, gravitationally deflects the light between source and observer. The German term for 'gravitational lens' and the light deflection formula Δ∅=4GM/bc² complete the design.
Inscription: REPUBLIK ÖSTERREICH 2025 •
Δ∅ Δ∅= 4GM/bc²
LICHT-QUELLE
GRAVITATIONS-LINSE
20 EURO
Translation: REPUBLIC OF AUSTRIA 2025 •
Δ∅ Δ∅= 4GM/bc²
LIGHT SOURCE
GRAVITATIONAL LENS
20 EURO