Part 8/10:
Despite advances in cosmic understanding, the enigmatic aspect of whether the universe is expanding into anything remains unresolved. Theoretical explorations dive into higher-dimensional spacetimes, leading to the Braneworld theories—where our observable universe is a 'brane' embedded in a multi-dimensional cosmos.
String theory supports this framework, proposing particles as vibrating strings. Crucially, this theory includes the conjecture of a graviton—the elusive particle theorized to carry gravitational force—potentially penetrating dimensions beyond our perceived reality. If gravity operates not solely within our universe but spills into a larger framework, it fundamentally alters our grasp of cosmic dynamics.