Added January 9, 2007
By Marc Kaufman
Washington Post Staff Writer
January 8, 2007
R. Rydin comments appended in bold and italics
"It wasn't all that long ago that black holes existed only in the realm of theory. Even after scientists began to accept several decades ago that these extraordinary exotic and powerful objects were not the stuff of science fiction, they still knew virtually nothing about them. Over the past 10 years, however black holes have moved to the center of the world of astrophysics, leading to a steady flow of discoveries that have began to answer, or at least better describe, some of their mysteries."
"Recent discoveries include the likelihood that black holes, some as massive as a billion suns, exist at the center of all galaxies and may have played a key role in forming them. Researchers have also found that black holes arising from burned-out and collapsed stars generally emit bursts of super-powerful gamma rays as well as enormous jets of particles moving at 175 million mph, 26 percent of the speed of light." Black Holes are indeed at the center of all galaxies, and helped form them, but it is not clear how they themselves formed or how long it might have taken to form them. Certainly, the Big Bang age of the universe of about 14 billion years doesn't seem to be nearly long enough to do this task.
" 'Black holes are extremely exotic beasts, objects where time stands still at some point, where space-time curves, where nothing inside can be seen,' said Christopher S. Reynolds, an astrophysicist and black hole researcher with the University Of Maryland. 'The fact that they actually exist remains amazing to me.' " There are experiments in cables that prove that the speed of light is slightly different in opposite directions, related to a multiplexing problem solved many years ago by Bell Labs. This falsifies one key assumption of general relativity, the constancy of the speed of light. It can thus be argued that time doesn't slow down, and space does not curve, but light still gets trapped inside.
"As understood now, black holes are objects so dense, so brimming with gravitational force, that they constantly suck matter in - and never let it out. Researchers now believe there are millions of them, some just a few miles across, some as wide as the solar system. Although black holes are to some extent defined by their death grip on all kinds of light, astronomers now detect them by the extremely bright light and other radiation that emanates from around a hole as it swallows a nearby star or galactic gases." But they don't have a death grip on gravity!
"Detectable bursts of gamma rays, the highest-energy explosions in the universe, also shoot out as a star explodes and collapses into a black hole." This is an attempt to include gamma bursts as being powered by black holes, although there is no accepted known mechanism that transfers this energy away from the black hole.
"NASA's fleet of orbiting satellites, most especially the Hubble Space Telescope, the Swift gamma ray satellite and the Chandra X-Ray Observatory, have been drivers for these discoveries, providing information and images never before available to illuminate the behavior of black holes. The Swift satellite, which was launched in 2004, provided information for the most recent discovery, one that identifies an apparently new and different variety of black hole."
"Generally, black holes form or grow larger when the core of a massive star collapses or when an existing black hole collides with a tiny but very high density neutron star, itself the unimaginably dense remains of a burned-out star. Instruments on Swift have been able to monitor the bursts of gamma rays that accompany the formation of a black hole - an event some astronomers compare to a baby's birth scream - and scientists are learning how and why a black hole was created based on how long the bursts last. They grow larger when a black hole sucks in the matter from another star." The collision between neutron stars or neutron stars and black holes is thought to produce gamma ray bursts which may be accompanied by formation and/or enlargement of black holes.
"What was believed to be a relatively neat division between long and short bursts was challenged, however, by a gamma-ray burst recorded by Swift in June from a galaxy 1.6 billion light years away. The burst was quite long, yet it had none of the characteristics of a massive star collapse generally associated with long bursts. For now, astronomers are calling it a hybrid black hole." Perhaps this was the collision of a neutron star with a large ordinary star, and took place by a different energy release mechanism that may or may not result in a black hole.
" 'This is brand new territory, we have no theories to guide us,' said Neil Gehrels, lead investigator for Swift at the NASA Goddard Space Flight Center in Greenbelt. 'It's stretching our models to the biggest extent of any burst so far.' " This begs the question as to whether or not the models have any validity at all.
"This process of identifying black holes, which Gehrels said may well number in the hundreds of millions, is one step on the path toward understanding them better. Other researchers have sought to measure the two known characteristics of a black hole - its mass and the speed at which it spins. That spinning, and the gravitational force it reflects, is so great that black holes drag surrounding space, stars and gases into them." This is an interesting aspect, because it says that a singularity can spin. A better explanation is that the black hole contains crushed neutrons in a finite sphere inside the event horizon, and this sphere is what is spinning. Light is caused to move in a circular path by gravitational attraction, so it is totally internally reflected and does not get out. But gravity does get out, which means that there is real mass inside the black hole. It also means that gravity propagates at a speed much greater than light, as noted in many experiments.
"Using data from NASA's Rossi X-Ray Timing Explorer satellite, a team from the Harvard-Smithsonian Center for Astrophysics determined last year that one particularly large black hole was spinning at more than 950 times per second."
"The fast pace of recent discoveries has set the stage for a new generation of sophisticated observatories, which together have been dubbed Beyond Einstein by NASA. While several of the proposed satellites would study black holes, the most pertinent is Constellation-X, a four-telescope X-ray observatory planned to be 100 times as powerful as any instrument now available for probing X-ray radiation and black holes."
"Some researchers say new revelations could come from a very different direction. The world's largest particle accelerator, the European Large Hadron Collider, is set to begin operations this year; and some think the extremely violent collisions it will generate can and will create tiny black holes." If extreme gravity is part of the characteristic of forming a black hole, energy alone will not do it. This might actually prove that Hawking's miniature black holes are theoretical and not real.
"In any event, research into black holes will continue. What remains unclear is whether that research will solve the mysteries in bits and pieces or whether it will, with the help of powerful new technologies, rapidly reveal the secrets hidden in the hitherto unfathomable depths." Perhaps this research will never solve the mysteries as long as it is based on Big Bang theory.