How to Tell a Black Hole from Its Doppelgänger express
Black holes are famous for their dark silhouette against a bright glow.
Yet the cosmos also hosts impostors — ultra-dense bodies without an event horizon that warp light in their own distinct way. These distortions can reveal the ruse.
Scientists modeled two such 'fakes' (JMN-1 and JNW). They found that one only creates a light trap when its central singularity is squeezed into a zero-type configuration. The other always captures rays, just like a true black hole. Most surprising: infalling matter doesn't vanish: it bounces back, as if on a spring. These rebounds leave a telltale light signature. Telescopes like the Event Horizon Telescope can now discern these differences and distinguish a genuine black hole from its cosmic counterfeit.
At the heart of some 'fake' black holes lies not a point but a dip in space. Infalling matter freezes for an instant, then shoots back, like a cosmic-scale trampoline.
In science fiction, such objects evoke wormholes — tunnels through spacetime. Although the objects described here are impassable, the lack of an event horizon links them to these fantastical bridges.