Black Holes

Black holes collide Nothing in the universe is more violent than the colli­sion of two black holes. At that instant, the impact releases more energy than every star in the universe combined. It also creates ripples in spacetime that travel at the speed of light, known as gravitational waves. Though invisible, they appear as blue lines in this image created by a NASA supercomputer.

Black holes are notoriously difficult to observe. They can’t be seen directly by a telescope because they absorb all light. We’re only able to tell they’re out there by the way they bend and heat the gasses around them. But we can, however, think up analogues which approximate some of the mechanics, which is what a team at the University of St. Andrews in Scotland has done, using just a length of fiber optics.

The event horizon of a black hole is the line at which nothing can escape. Cross that line, and you will never come back. Since black holes were first described by general relativity in the early twentieth century, the thinking has maintained that all matter entering the event horizon added to the mass of the hole. Nothing went in the other direction. In the early 1970s, however, physicist Stephen Hawking used quantum mechanics to postulate the existence of a radiation emitting mass from the edge of these holes.

This so-called Hawking radiation has held up theoretically in the years since, but is impossible to observe in the physical universe. What the researchers at St. Andrews
are attempting to do is to observe the behavior of particles in their experiment with the hope that they behave as Hawking radiation would. In order to recreate the properties of an event horizon, the scientists are shooting two beams of light down a fiber optic cable. The second pulse has a wavelength longer than the first. As it mashes itself up behind the trailing edge of the first beam, the hope is to see particles shooting off as if that space were the event horizon of a black hole.

The researchers acknowledge the experiment is in its early stages and that the technique needs refinement in order to achieve the right effects, but the thinking at present is to use this experiment as a step closer to understanding one of the biggest mysteries in space.