Deborah & William Hillyard
Deborah & William Hillyard
Deborah & William Hillyard
Deborah & William Hillyard
Deborah & William Hillyard
Science - The Early Universe
(or "What Banged in the Big Bang?")
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Primordial Black Holes
These are hypothetical objects that some suggest could have formed in the very early moments of the Big Bang. Generally, they would have been so small, minimum mass is the Planck mass, that quantum physics is required to describe them. Primordial black holes of very small mass would have evaporated by now due to Hawking Radiation. To have survived until today, a primordial black hole would need to have been of the order of one billion tons, but would still have had a Schwarzschild radius of only about 1.5 x 10-14 cm!
The Schwarzschild radius of any object is proportional to its mass. Once an object is compressed within its Schwarzschild radius, it becomes a black hole. For an object that does not rotate, the surface at the Schwarzschild radius is its event horizon. As a comparison, to compress the Earth into a black hole, its Schwarzschild radius would be about one third of an inch (9mm)! To do the same for the sun, the radius would be less than two miles (3km).
In some proposed extra-dimensional theories, involving large extra dimensions, it would be possible for the Large Hadron Collider (LHC) to produce microscopic black holes of near Planck mass, with a corresponding Schwarzschild radius close to the Planck length. These would evaporate almost instantaneously under Hawking radiation. Even if the black hole were stable, it would be of such small size compared to, say, a proton, and moving so fast, that it would leave the Earth before it could accrete any appreciable extra mass. Let us say the Schwarzschild radius of the black hole is around the Planck Length - 1.6 x 10-33 cm. The avarage spacing of atoms in a solid is between 2 x 10-12 cm and 3 x 10-12 cm. Thus, around 5 x 1020 of these microscopic black holes could fit between two atomic nuclei! The chances of a collision are slim indeed. Even if the black hole grew to, say, 50 billion tons, it would still be only the size of a proton!
Remember; the total energy the LHC will reach is 14TeV. Cosmic rays reaching Earth from space can have energies in excess of 100 million times the LHC energy, and they have been hitting the Earth for billions of years.
The Schwarzschild radius of any object is proportional to its mass. Once an object is compressed within its Schwarzschild radius, it becomes a black hole. For an object that does not rotate, the surface at the Schwarzschild radius is its event horizon. As a comparison, to compress the Earth into a black hole, its Schwarzschild radius would be about one third of an inch (9mm)! To do the same for the sun, the radius would be less than two miles (3km).
In some proposed extra-dimensional theories, involving large extra dimensions, it would be possible for the Large Hadron Collider (LHC) to produce microscopic black holes of near Planck mass, with a corresponding Schwarzschild radius close to the Planck length. These would evaporate almost instantaneously under Hawking radiation. Even if the black hole were stable, it would be of such small size compared to, say, a proton, and moving so fast, that it would leave the Earth before it could accrete any appreciable extra mass. Let us say the Schwarzschild radius of the black hole is around the Planck Length - 1.6 x 10-33 cm. The avarage spacing of atoms in a solid is between 2 x 10-12 cm and 3 x 10-12 cm. Thus, around 5 x 1020 of these microscopic black holes could fit between two atomic nuclei! The chances of a collision are slim indeed. Even if the black hole grew to, say, 50 billion tons, it would still be only the size of a proton!
Remember; the total energy the LHC will reach is 14TeV. Cosmic rays reaching Earth from space can have energies in excess of 100 million times the LHC energy, and they have been hitting the Earth for billions of years.
