Inside the interferometer, a particle is in two places at once. Its mass, like a brush, paints two gravitational pictures on the quantum vacuum. While the pictures are almost identical, there is one reality. But as the mass grows, they split apart irreversibly — the Universe fractures into two independent layers. This isn't fantasy; it's a precise calculation of the contrast of gravitational shadows. Thus we approach testing the quantum nature of gravity and, perhaps, unraveling why the classical cosmos emerges from quantum fog.
🎯 The idea that gravity "peeks" at a quantum system and destroys its superposition has been wandering through physics since the mid-20th century. But the precise calculation of the contrast C turns it into an elegant tool: we know at what mass and distance Schrödinger's cat will split into two forever separated worlds. A thought-provoking detail: the entanglement entropy reaches ln 2 — the maximum information capacity of a single qubit. Gravity seems to pack reality into two classical bits, between which no quantum whisper will ever leak again.