AdS is an unphysical Space time hence not to be taken for real. The only hope of the Protagonists of the correspondence is that by introducing the cosmological constant to find a crossover from AdS to dS. But the cosmological constant itself is a very doubtful concrpt hence the whole correspondence seems to be built on Sand. Please comment.
[email protected]. I am totally incompetent on this topic. from the experimental viewpoint,the cosmological constant is a parameter reqired to describe various data sets (Supernovae,CMB,BAO), and there are still large uncertainties bearing on its determination and redshift dependence, except that it has a non zero value.
As far as I know, the AdS/CFT duality is a strong support for the holographic principle, i.e, that gravity is essentially two dimensional, despite appearances. Anyway, the AdS/CFT duality is only a conjecture.