Elementary particle physics is entering a spectacular new era in which experiments at the Large Hadron Collider (LHC) at CERN and at astrophysical observatories will soon start probing some of the most profound questions in physics, such as: Why is gravity so weak? What is the origin of mass? What is the Dark Matter of the Universe? Are there new dimensions of space? Can we produce black holes and strings in the lab? Are there other parallel universes, each with different laws of Nature? LHC is expected to shed light on such questions and lead to a new deeper theory of particle physics. Surprisingly, recent developments suggest that the principle of minimalism which has been driving scientific thinking for centuries, is losing ground to the old principle of plenitude, as the complexity of the extra dimensions in string theory suggests the existence of a plethora of ultra-light particles with exciting observational signatures in Cosmology, Astrophysics and at the LHC.