Three quantum-inspired cores leave opposite fingerprints on the ringing of black holes

What happened

Three quantum-inspired cores leave opposite fingerprints on the ringing of black holes, according to Phys.org. Every black hole hides a question at its center. Einstein's theory predicts that whatever falls in is crushed into a singularity, a point of infinite density where the theory itself breaks down.

Most physicists expect quantum gravity to replace that point with something finite. But the center lies hidden behind the horizon.