Our Universe behaves like a stretched elastic sheet: massive bodies dent it, creating spacetime curvature — gravity. In brane-world theory, a hidden dimension is added, and this sheet becomes just a surface in a higher-dimensional space. The brane tension determines how much the sheet dents: the weaker the tension, the weaker the gravity.
Scientists have studied how this affects black holes of the Schwarzschild type, surrounded by a dense cloud of particles. For light holes (less than a star's mass), the weakened gravity might not form a horizon — the boundary from which nothing can escape. Constraints on brane tension come from observations of neutron stars.
An unexpected effect: the black hole's shadow grows while the Einstein ring — the luminous halo around it — shrinks. Measuring these two parameters could reveal the presence of extra dimensions.
If brane tension disappeared, our Universe would become completely flat and devoid of gravity.
In the film *Interstellar*, highly advanced beings live in five dimensions — much like the brane idea from scientific theories.