Black Hole Disks Are Like Cake: Watch This Cosmic Simulation to See Why They're So Fluffy

Black holes are always fascinating, and a new simulation adds to their mystery. You likely did not previously associate them with fluffy angel-food cake, but researchers at Caltech recently put together a simulation to better understand how black holes work and made the cake connection.

It's not as flashy as NASA's simulation where you can dive into a black hole, but Caltech's does call into question theories that have existed for 50 years.

The new information involves black hole disks, also called accretion disks, which are a collection of stellar debris and gas that encapsulates black holes. For decades, the theory was that thermal pressure caused by the changing of the gas in the black hole disks keeps the disks stable around the black hole. The problem is that black holes don't look like they're supposed to look according to the theory. In theory, the accretion disks should be flat, but astronomical observation shows that disks are instead fluffy. 

In the simulation, Caltech researchers attempt to recreate a black hole and then perform what they call a "super zoom-in" to observe how it acts. The simulation works by solving the same sets of fundamental equations trillions of times to see how black holes evolve. 

"Our theories told us the disks should be flat like crepes," said theoretical physics professor Phil Hopkins, who led the Caltech research team. "But we knew this wasn't right because astronomical observations reveal that the disks are actually fluffy -- more like an angel (food) cake. Our simulation helped us understand that magnetic fields are propping up the disk material, making it fluffier."

Magnetic fields -- no, not the band

As the simulation zooms in, the researchers can see the dance of radiation, gravity, magnetic fields and heat as they "interact nonlinearly in this chaotic messy system," says Hopkins. In the video, the red is energy from magnetic fields while the blue is energy from heat. The researchers expected heat to be the dominant type of energy that controls the system. Instead, the simulation showed that magnetic fields were controlling the system instead of heat. 

"Magnetic fields being so strong makes qualitatively different predictions from the theories we've had for decades," said Hopkins in the video. "So, for example, the magnetic fields can actually hold up material and prevent it from collapsing under gravity. So it's this thick ring of material around the black hole instead of being this flat disk."

Scientists have been studying black holes since Albert Einstein first predicted their existence over 100 years ago. Because black holes are notoriously difficult to find, very far away and don't act like any other celestial body out there, scientists have mostly turned to simulations to try and figure out how black holes work. Sometimes, those simulations can help scientists figure out what's really going on with one of space's biggest mysteries.