Okay, we're getting into a weird place here.
From PhysOrg, May 19:
New research suggests an unseen "mirror world" of particles that interacts with our world only via gravity that might be the key to solving a major puzzle in cosmology today—the Hubble constant problem.
The Hubble constant is the rate of expansion of the universe today. Predictions for this rate—from cosmology's standard model—are significantly slower than the rate found by our most precise local measurements. This discrepancy is one that many cosmologists have been trying to solve by changing our current cosmological model. The challenge is to do so without ruining the agreement between standard model predictions and many other cosmological phenomena, such as the cosmic microwave background. Determining whether such a cosmological scenario exists is the question that researchers, including Francis-Yan Cyr-Racine, assistant professor in the Department of Physics and Astronomy at The University of New Mexico, Fei Ge and Lloyd Knox at the University of California, Davis have been trying to answer....
....MUCH MORE
Or, as SciTech put it:
Our Reality May Only Be Half of a Pair of Interacting Worlds
We won't even get into the cosmological constant problem (okay, just a little: theory may be off by 120 orders of magnitude)
