Black holes can form if stars collapse under gravity.

Evidence

In some cases they may explode or manage to throw off enough matter to reduce their mass below the limit and so avoid catastrophic gravitational collapse, but it was difficult to believe that this always happened, no matter how big the star. — Hawking, Stephen, A Brief History of Time, 153

Categorization

• corroborated: 2 independent passages support this claim — Hawking, Stephen, A Brief History of Time, 153
• XREF: connects to: Saturated social systems collapse into absorbing black holes — Jean Baudrillard, Simulacra and Simulation, 249