What is the cosmological constant?

[Admin]

What we know about the history and properties of "Einstein's biggest mistake," the cosmological constant

What is the cosmological constant? : Read more

 

[Helio]

Given the label “Hubble Constant”, it’s understandable that he is, erroneously, assumed to have argued for an expanding universe, but this never happened.

IMO, he was reluctant to do so since the highly respected de Sitter had already produced a model demonstrating that redshift was not due to expansion. Also, other past astronomers had, to their regret, stepped in as theorists. He seemed set on being regarded as a, or the, great astronomer.

It was Lemaitre, father of BBT, who first produced a value for expansion in his original paper. He only had Slipher’s redshift data to work with, so he knew his calculation was only a first attempt. Slipher was the first to associate velocities with galactic redshifts.

Friedman was first to present a math solution that allowed either expansion of contraction. Lemaitre also, independently, presented similar math but also presented a physical explanation as well. He solved the conundrum of Einstein’s model that was static but could not account for redshifts, and de Sitter’s static model that accounted for redshift but without any matter in the universe.

 

[rod]

There is more discussion about the cosmological constant on the forums here too, https://forums.space.com/threads/cosmological-constant.37076/