One of Stephen Hawking’s weirder theoretical discoveries about black holes has been observationally proven. Three years ago, Hawking died at age 76, which is an age many of us can only hope to attain. Had he lived just a bit longer, however, this discovery might finally have allowed him to get the Nobel Prize so many of us hoped his theoretical work would one day earn him. Nobel Prizes are only given to people who make discoveries of provable attributes of our universe, mathematics, medicine, chemistry, and the other fields Nobel Prizes are given for. Theory alone doesn’t get you one, and Hawking’s theories exceeded our observational abilities until recently.

This particular theory stated that while black holes can grow in area as they consume matter, effects like increasing spin can’t shrink a black hole. This is sort of the inverse of the ice skater who spins faster when their arms are drawn in. Instead, you’d expect a black hole to get smaller as it spins faster, but it turns out that while you can form a smaller black hole by having it spin while forming, you cannot shrink it by spinning it faster later. 

The physics of black holes is just weird, kind of uncomfortable to think about, and now testable thanks to gravitational wave science. By looking at pre- and post-merger data for a black hole-black hole merger, researchers were able to see that the area of the final black hole exceeded the combined area of the two original black holes. That Hawking figured this out without data to hint that this could be true shows how creative his mind was. This work is published in Physical Review Letters and was led by Maximilliano Isi.

More Information

Gravitational waves confirm a black hole law predicted by Stephen Hawking (Science News)

“Testing the black-hole area law with GW150914,” Maximiliano Isi et al., to be published in Physical Review Letters (preprint on arxiv.org)