Some huge space objects might not have an 'event horizon' and could actually push stuff away instead of sucking it in.
March 24, 2026
Original Paper
Causal Structure of Spacetime Singularities and Their Observable Signatures
arXiv · 2603.21187
The Takeaway
While we are taught that black holes are inescapable cosmic drains, this study shows that 'horizonless' singularities are theoretically possible. Instead of crushing everything, these objects exert an 'effective repulsive behavior' that could create unique shadows visible to our current telescopes.
From the abstract
We analyze the causal structure of horizonless compact objects via the light-cone geometry and conformal compactification of the Joshi-Malafarina-Narayan (JMN-1) and Janis-Newman-Winicour (JNW) spacetimes. Penrose diagrams reveal that JMN-1 undergoes a transition from timelike $(0<M_0<2/3)$ to null $(2/3<M_0<4/5)$ singularities, while JNW remains timelike throughout, in contrast to the spacelike singularity of the Schwarzschild spacetime. We show that photon spheres exist in Schwarzschild and JN