It’s been a few months since I’ve taken any science questions, so I feel its high time that changes. I received about a dozen, and I will certainly get around to answering them all, but one stood out this time that deserves some special attention.
Michael Wallace from Salem Oregon asks, “Explain colliding and combining black holes to me, like I was a five-year-old.” You’re in luck, Wally, since I happen to have a five year old I was able to run this one by her before writing the article.
Black holes are objects in space of incredible mass and virtually unlimited gravity, so much so that not even light, the fastest thing in the known universe, can get away from it. They are normally formed as an after-product of super-massive stars who have been locked in a billions of years battle between their energy produced by fusion of atoms and the enormous gravitational press caused by the mass of the star itself. Eventually this battle will be won by gravity, but not before energy gets one last major punch in. Just as the star begins to lose the battle to gravity a tiny black hole is formed which begins to cannibalize its mighty parent. As the black hole grows it begins eating just a little too fast and starts a kind of hiccuping out super-hot gas. Just as this process begins, in a fraction of a second the black hole collapses the star causing it to shoot out two unbelievably powerful bursts of energy, screaming through the universe at the speed of light known as “gamma ray bursts.”
Now that we have a little insight into what black holes are and where they come, from we can finally answer what would happen if/when two of them met. This is a really good question for a couple of reasons, first it is relevant because it was just in the news and second because it confirms one of Einstein’s most well-known theories, that space and time are malleable. If two black holes approached one another what would happen next would depend on a few factors such as how fast they are spinning relative to each other and at what angle they were approaching. Let’s say for the sake of time that everything is working perfectly and they are merging head on. As they neared one another all of space would begin to distort near them as the sheer force of gravity would cause mayhem to all the light going anyway near them. Next, as they began to merge they would emit a truly un-godly amount of energy, so much that I’m not sure how to accurately describe it in writing.
The best way to explain this energy output would be to compare it to what we can see, the stars themselves. The amount of energy that would come screaming out of this collision would equal the amount being produced by all the stars in in all the galaxies throughout the entire universe at that given moment! Wow! The collision would be so powerful that it would send shockwaves through the fabric of space-time itself, something we measured just about two years ago at the LIGO (Laser Interferometer Gravitational Wave Observatory) observatories. So this phenomena really happens and we have watched its terrifying/amazing/humbling effects. Finally, they would go through a process called “ring down” as the light surrounding the two merged holes would drift down into one forming one super-massive black hole.
A reader asks, ‘What happens when black holes collide, combine?’
Nathaniel Woodward