In the craziest cosmological kids toy since the extremely short-lived "Kids First (and Last) Matter-antimatter Combining Oven", scientists from New York's Columbia University have used pairs of black holes to create Star Smashing Spirographs. An array of simulations have categorized the possible orbits two black holes can occupy before slamming into each other in a stellar event formally known as "Oh Holy Shit Wow".
When a supermassive star goes supernova (a nuclear bomb hundreds of times bigger the sun) it's on a time limit before it collapses under its own weight into an incredibly dense object. Small stars turn into white dwarfs (among other things), large rones ending up as neutron stars - the densest objects physically possible as we understand matter. Above that size limit, supermassive stars are literally big enough to beat up the laws of physics and the colossal quantities of material compress further anyway, becoming so incredibly dense that it isn't just mind-bending - it's space bending. These black holes are less objects and more regions of spacetime where things are so warped out of shape that the laws of physics as we understand them simply don't apply. They're termed "singularities", which is the theoretical physics code-word for "Here there be incredibly scary dragons".
When two of these incredible objects interact, pulling at each other and entering into a cosmic ballet that you really don't want to be anywhere near, they eventually merge. One singularity punches a hole in the universe - when two combine it's an incredibly challenge to answer the simple "What the hell is happening?" question, but you probably shouldn't rule out the spontaneous generation of unicorns. In fact you really couldn't rule out the interdimensional generation of a team of five color-coded unicorns which merge to form a giant MegaGalvaCorn, which battles space ninjas and eats dark matter.
That might be a little far fetched, but it doesn't sound any crazier than one thing we do know that happens - these events are so titanic that they send shockwaves through spacetime itself, ripples in the fabric of reality that pulse outwards through the cosmos - and through us. Gravitational wave observatories (like Caltech's LIGO system) keep incredibly sensitive ears out for evidence of these stellar shakedowns, but the problem is that you can't just change the channel on these detectors. When you start collecting wave data you're opening the door to the entire universe and everything in it, and it's your job to filter out what you're after. This is where the stellar spirographs come in - with a catalog of available orbits, it becomes possible to simulate the expected signal, and the job of picking the needles out of the haystack becomes that much easier.
Because while a pair of colliding black holes might sound like a very big needle, the universe is a much bigger haystack.
Posted by Luke McKinney.
Periodic table (hoho) of black hole orbits (along with some stellar spirographs)
LIGO http://www.ligo.caltech.edu/