Tiny Black Holes May Pervade Space
Most people think of black holes as supermassive objects, the remnants of collapsed stars whose powerful gravity devours all nearby matter. But some theories suggest that these strange objects may be much more common—and much closer to home—than had been thought. The solar system, for example, may contain 3,000 to 300,000 of these objects at a given time, some of them floating inside the orbit of Mars. New work suggests that such objects would produce interference fringes in the energy spectra of gamma-ray bursts, a prediction that soon should be able to be tested.
richnfg said:Hmmm...
So, if 'large' black holes are remnants of collapsed stars, where do these Tiny black holes come from? They seem to have left a lot unanswered here!
:)
Researchers have proposed a bizarre new theory that our solar system might be the home of thousands of very small black holes -- that is, pint-size versions of the weirdest objects in the universe.
If verified by a NASA satellite scheduled for launch next year, their claim might overturn orthodox ideas about nature and the universe. In particular, it could dramatically reinforce physicists' growing suspicion that the cosmos is pervaded by invisible alternate dimensions, never-never lands that cannot be detected with existing instruments.
Black holes are collapsed stars whose gravity is so intense that nothing can escape them, not even light -- hence the adjective "black." So far, there is strong evidence for only one type of black hole: the huge kind that inhabits deep space, millions of light-years from Earth. One example is a titanic black hole that is sucking up nearby stars at the core of the Milky Way. Scientists know the black hole is there because the galactic core is emitting intense radiation -- the death cry of devoured stars.
But black holes, like shoes, might come in different sizes. Physicists have speculated that very small black holes might have formed after the Big Bang that spawned our cosmos more than 13 billion years ago, then vaporized like dew drops after sunrise.
Now, researchers Charles Keeton at Rutgers University and Arlie Petters at Duke University have proposed that throughout the cosmos, very small black holes might have survived to the present day. Thousands of them could be drifting around our solar system like dust motes in an old house.
They base their claim on their interpretation of one of the hottest ideas in theoretical physics: "braneworld" theory, a distant cousin of string theory.
"Brane" is short for membrane. To greatly oversimplify: According to string theory, matter ultimately consists of infinitesimally tiny, vibrating strings of energy. A harp or guitar produces different sounds when its wires vibrate at different frequencies; likewise, a string of energy turns into different subatomic particles according to its vibrational rate. In brane theory, string theory is broadened to include multidimensional, vibrating membranes that are believed to pervade the cosmos.
High school physics students learn there are four dimensions in the universe: length, width, depth and time. But braneworld theorists say there are additional, unseen dimensions that can be described only with mathematical equations. Physicists hope that by computer-modeling hypothetical interactions of known and unknown dimensions, they can explain phenomena ranging from the force of gravity to the birth of the cosmos.
At the moment, one of the most publicized versions of braneworld theory is proposed by physicists Lisa Randall of Harvard and Raman Sundrum of Johns Hopkins University.
In an article in the May 24 issue of the journal Physical Review D, Keeton and Petters explain how, inspired by the Randall-Sundrum braneworld hypothesis, they concluded that the Big Bang generated zillions of small black holes -- many of which may have survived to the present day. The black holes might be very small -- perhaps as small as atoms -- yet hyperdense, hypermassive objects that weigh from a few pounds to the equivalent of the celestial flying mountains known as asteroids.
If Keeton and Petters are right, then our solar system should have its own share of little black holes, perhaps as few as 3,000 and as many as 300,000 at any given time.
What would happen if one of these black holes came to Earth and passed through a room? Could they suck a person up like the black holes depicted in science fiction?
Keeton, a member of Rutgers' department of physics and astronomy, said it couldn't happen. He told The Chronicle that a tiny black hole probably could suck up only a few atoms at a time.
Yet it might not go unnoticed. If a black hole as massive as an asteroid -- thousands of tons -- passes through a room, there would be a subtle gravitational tug.
Keeton and Petters propose a way to test their hypothesis: by using NASA's GLAST satellite (Gamma Ray Large Area Space Telescope), which is scheduled for launch next year. In theory, the black holes should distort gamma radiation from extremely distant, explosive objects called gamma-ray bursters, which are scattered all over the universe. If so, then GLAST might detect the distortions and thus, indirectly, the black holes.
Still, the search might take a lot of patience. Space is big; even if our solar system contains thousands of black holes, finding just one could be like looking for a raft in the Pacific Ocean. Keeton calculated that if the high-end estimate of 300,000 is correct, then about 15 black holes might exist between the sun and Mars -- the fourth planet from the sun -- at any given time.
Neither Randall nor Sundrum was involved with the writing of Keeton and Petters' paper. Sundrum told The Chronicle he was intrigued by their proposal.
"If their proposed test yields a positive result (finding small black holes), that would be fantastic," he said. "If it finds something, a new world opens up."
One of the nation's top string theorists, physicist Ed Witten of the Institute for Advanced Study in Princeton, N.J., called Keeton and Petters' proposal "extremely clever. ... I hope it pans out."
Irresistible pull
What are black holes? Collapsed stars whose gravity is so immense that nothing can escape their pull, not even light.
How big are they? The largest black holes are assumed to be so big that they can suck up entire planets or stars.
Are any known to be nearby? At the core of our galaxy, the Milky Way, is a titanic black hole that is sucking up nearby stars. Scientists know it's there because the galactic core is emitting intense radiation -- the death cry of devoured stars.
Black holes
A 2001 image from Hubble Space Telescope shows what resembles a whirling cloud of gas in the center of the galaxy M87, which is 50 million light-years from Earth. The gas is presumably being sucked into a black hole at the center of the galaxy.
The black hole could be as massive as 3 billion suns.
Whirlpool of hot gas
If viewed close up, the black hole and its immediate environment would probably resemble a pancake-shaped cloud, about 500 light-years wide, rotating at more than 1 million mph. The gas is spiraling into black hole, which itself is invisible.
Inside the black hole
As the gas plunges into the black hole, the gas heats and spews gushers of radiation and debris in two directions. This kind of black hole is called “supermassive” because of its bulk, but physicists also speculate that there might be much smaller, even atom-size black holes across the universe. In a new study, two scientists propose that our solar system might have thousands of such tiny black holes.
Braneworld gravity is a model that endows physical space with an extra dimension. In the type II Randall-Sundrum braneworld gravity model, the extra dimension modifies the spacetime geometry around black holes, and changes predictions for the formation and survival of primordial black holes. We develop a comprehensive analytical formalism for far-field black hole lensing in this model, using invariant quantities to compute all the geometric optics lensing observables: bending angle, image position, magnification, centroid, and time delay. We then make the first analysis of wave optics in braneworld lensing, working in the semiclassical limit. Through quantitative examples we show that wave optics offers the only realistic way to observe braneworld effects in black hole lensing. We point out that if primordial braneworld black holes exist, have mass M[bullet], and contribute a fraction fbh of the dark matter, then roughly ~3×105×fbh(M[bullet]/10-18M[sun])-1 of them lie within our Solar System. These objects, which we call "attolenses," would produce interference fringes in the energy spectra of gamma-ray bursts at energies E~100(M[bullet]/10-18M[sun])-1 MeV (which will soon be accessible with the GLAST satellite). Primordial braneworld black holes spread throughout the Universe could produce similar interference effects. If they contribute a fraction Omega[bullet] of the total energy density, the probability that gamma-ray bursts are "attolensed" is at least ~0.1Omega[bullet]. If observed, attolensing interference fringes would yield a simple upper limit on M[bullet]. Detection of a primordial black hole with M[bullet]<~10-19M[sun] would challenge general relativity and favor the braneworld model. Further work on lensing tests of braneworld gravity must proceed into the physical optics regime, which awaits a description of the full spacetime geometry around braneworld black holes.
how relevant, that black holes are not just one size fits allBut black holes, like shoes, might come in different sizes.
Tiny black holes are theoretical objects that are much smaller than typical black holes found in outer space. They are thought to be formed by the collapse of extremely dense and tiny objects, such as particles or strings, and have a mass similar to that of an asteroid.
Tiny black holes differ from regular black holes in terms of their size and mass. While regular black holes have a mass equivalent to several Suns, tiny black holes are thought to have a mass similar to that of an asteroid. They also have much smaller event horizons, making them harder to detect.
There is currently no evidence to suggest that tiny black holes pose a threat to Earth. They are too small and too far away to have any significant impact on our planet. Additionally, they are thought to evaporate quickly due to Hawking radiation, making them even less of a concern.
Scientists study tiny black holes through various methods, including theoretical calculations and simulations. They also look for indirect evidence of their existence, such as gravitational lensing or gravitational waves. However, due to their small size, direct detection of tiny black holes is still a challenge.
There is currently no evidence to suggest that tiny black holes could be the solution to the mystery of dark matter. While they may contribute to a small portion of dark matter, they are not thought to be the main source. Other theories, such as the existence of exotic particles, are still more widely accepted explanations for dark matter.