Three moved back to destinations abroad (thanks for nothing Australian immigration). And whilst we’re still in touch, it’s not the same. But two others simply vanished right in front of me. What had happened to them?
The theory of general relativity, developed by Albert Einstein in the early 20th Century predicts that a sufficiently compact mass can deform space-time to form a black hole. It is a region of space having a gravitational field so intense that no matter or radiation can escape. I propose that what I have discovered is that natural forces (dare I even say the "L" word) can cause two individuals to be similarly compacted to the point that the only explanation is that they too have formed a black hole.
We had all noticed that they seemed to be spending more time together. In the last few days we had seen them there was an obvious increase in their affection for each other, and a general dreaminess to their dispositions. As I reflect on it now, their attraction for each other escalated beyond all reasonable measure until it was like a kind of gravity. You’ve all seen it before. The couple had become inseparable: A singularity. That much was understandable, but there was more to come.
Requests to catch up, invitations to brunches or parties sat unreplied to, lost in a background of self absorption. It was as though the messages had shifted to longer, unreadable parts of the electromagnetic spectrum. Maybe their field of view had become more and more compressed until it was a smaller and smaller point in the space behind them, and they were unable to see us. Meanwhile in our field of view, outside the singularity, they had become distorted into blackness. Their attraction had grown to become so intense that nothing escaped; no words, no messages, not even light. The space around them had become dark to outsiders. It had formed an event horizon. A singularity protected by an event horizon. A black hole for two.
I think the term event horizon is the most poetic term in physics. Tantalising and poignant, the event horizon is the boundary of the region from which no escape is possible. Why? It marks the point at which the escape velocity of the black hole is equal to the speed of light. On the surface of the Earth, the escape velocity is about 11.2 km/s, approximately 33 times the speed of sound. Fire up a rocket to that magical speed and you’re off into space. On the moon, with a much smaller mass the escape velocity is a tiny 2.38km/s, not much more than the speed of a bullet out of a rifle. But the distortion of space-time around a black hole is so great that the escape velocity is the universe’s absolute speed limit, the speed of light, a ruthlessly unattainable almost 300,000 kilometres per second enforced by the laws of physics.
At one magical luminous point on the very surface of the event horizon, called the photon sphere, light could reflect off the back of your head, orbit the singularity and arrive directly at your eyes nanoseconds later, allowing you to see the back of your own head in real time. This possibly explains the last incoherent fragments of contact that were had with the couple. Once they had crossed this, there was no going back. They had gone.
You know what I'm talking about. We've all lost friends to this "love" business. I suppose we shouldn’t be sad. For the couple, safely inside the event horizon, nothing else matters. Everything would seem normal to them, or so the theory goes. Well, we don’t really know what happens at the singularity. I certainly don’t. And at my ripe old age I’m certainly not expecting to find out. Sure I’ve had my fair share of gravitational lensing, but I ain’t holding my breath.
Perhaps they’re tightly held, compressed in a deep embrace. With all that light raining in on them from the photon sphere we could even call it enlightenment.