Edwin Hubble confirmed unambiguously: The definitive results were published in Hubble 1929b.

“That term is necessary only”: Einstein 1917, p. 188 in the English translation.

he modified his equations in such: For the mathematically inclined, the original equations were: Gμν = 8πG Tμν, where G is the gravitational constant, Tμν is the stress-energy tensor, and Gμν is Einstein’s curvature tensor representing the geometry of space-time. The modified equations were: Gμν – 8πG ρΛ gμν = 8πG Tμν, where ρΛ could be taken as an energy density associated with the cosmological constant, and gμν is the space-time tensor that defines distances.

Eddington was the first to point out: Eddington 1930.

Einstein insisted that the distribution of matter: Einstein relied here on what is known as Mach’s principle, after Austrian physicist and philosopher Ernst Mach, who suggested that motion and acceleration cannot be felt at all in an empty universe. An excellent discussion on the modern interpretation of Mach’s principle can be found in Greene 2004.