Following up on the questions raised here:
If you take all the matter and energy out of a significantly large volume of spacetime, what you'll be left with is a small chunk of spacetime that - in the assumptions of $\lambda CDM$ - will be Lorentzian. By Lorentzian, we mean that two particles with no mass and at rest with respect to each other and separated by a distance, $\zeta$, will stay separated by $\zeta$ for all time.
I can't reconcile this with the equations of GR. GR has this λ constant which exists on all scales. Whatever λ is - and we really don't know - this property is intrinsic to all spacetime. That is, it can't be removed. The net effect of this intrinsic property is that space grows exponentially with time.
Now put two test particles with no mass in this completely empty, 'local' space. Won't they accelerate away from each other? Reduce the scale and repeat the experiment. The acceleration is the same. How is this spacetime, even on the smallest scale, Lorentzian if test particles act like it's curved?