His namesake ring is also called a Chwolson Ring and is observed around celestial bodies as a result of gravitational lensing.  
The constant kappa is sometimes known as this man's namesake constant, and that constant multiplied by the stress-energy tensor equals the Ricci tensor minus one-half the scalar curvature times the metric tensor, according to this man's namesake field equations.  This man's eponymous unit is equal to a mole of photons, and his namesake effect is also known as gravitational redshift. His namesake ring is also called a Chwolson Ring and is observed around celestial bodies as a result of gravitational lensing.  For 10 points, name this physicist who lends his name to a state of matter along with Satyendra Nath Bose.
The constant kappa is sometimes known as this man's namesake constant, and that constant multiplied by the stress-energy tensor equals the Ricci tensor minus one-half the scalar curvature times the metric tensor, according to this man's namesake field equations.  
Albert {Einstein}