Two points,

 

i) Einstein died in 1955 well before observational cosmology developed in to the science it is today.

 

ii) Einstein always was unhappy with quantum mechanics and did not actively work on quantum field theory. Having a zero value parameter in quantum field theory is awkward and "unnatural".

 

The cosmological constant is NOT in quantum mechanics. It's in Einstein's theories of Relativity.

 

Please read my previous post about the history.

the journal called General Relativity and Gravitation has a special issue devoted to Dark Energy coming out.

 

So far, I have read only the article contributed by Martin Bojowald.

 

He explains the acceleration in distance-expansion as a quantum correction to the gravitational field---generic in Loop Quantum Cosmology (and possibly also in a broader class of quantum cosmologies).

 

Bojowald is proposing a hypothesis to explain the positive cosmological constant. There are other hypotheses out there.

 

Not surprisingly, Bojowald (the inventor and chief advocate of Loop Quantum Cosmology) thinks LQC provides such a hypothesis.

 

Martin, I've notice a tendency of you to cheerlead Bojowald before. I caution against it. LQC is ONE of the hypotheses being proposed. Sit back, relax, and exercise a bit of patience. Wait to see what the results of the tests are.

 

If you wanted to put this out as FYI, then you should have waited until you read the remaining articles and then put a list of the proposed hypotheses.