The JWST peers into the young Universe after expansion began and finds, in the centers of the first galaxies, black holes weighing a billion suns. They couldn't have grown that big the usual way — there just wasn't enough time. Karl Schwarzschild first described such objects, and Edwin Hubble proved that the expanding Universe lets us look back into the past.

Maybe the answer lies in a multidimensional neighbor. Our Universe is like one of two sheets of paper pressed tightly together: the gap between them is thinner than a hair. A black hole pierces both sheets, and matter from the invisible side also falls into the shared funnel. We're only seeing half its 'diet', hence the illusion of supercharged growth. Light from the infalling gas produces brilliant quasars, but some mass remains hidden. This also explains the smoothness of the cosmic microwave background — the early baby picture of the sky: the holes didn't disturb it so violently.

When two such holes merge, they should produce distinctive gravitational waves — ripples in the fabric of spacetime. Observatories like Rainer Weiss's project will be able to catch them. And then we’ll hear the echo of a neighboring world without ever leaving Earth.