Black Holes move
through the Cosmos and destroy everything in their paths .
Black Holes: What Are They?
Black holes are the
evolutionary endpoints of stars at least 10 to 15 times as massive
as the Sun. If a star that massive or larger undergoes a supernova
explosion, it may leave behind a fairly massive burned out stellar
remnant. With no outward forces to oppose gravitational forces,
the remnant will collapse in on itself. The star eventually
collapses to the point of zero volume and infinite density,
creating what is known as a " singularity ". As the
density increases, the path of light rays emitted from the star
are bent and eventually wrapped irrevocably around the star. Any
emitted photons are trapped into an orbit by the intense
gravitational field; they will never leave it. Because no light
escapes after the star reaches this infinite density, it is called
a black hole.
But contrary to popular myth, a
black hole is not a cosmic vacuum cleaner. If our Sun was suddenly
replaced with a black hole of the same mass, the earth's orbit
around the Sun would be unchanged. (Of course the Earth's
temperature would change, and there would be no solar wind or
solar magnetic storms affecting us.) To be "sucked" into
a black hole, one has to cross inside the Schwarzschild radius. At
this radius, the escape speed is equal to the speed of light, and
once light passes through, even it cannot escape.
Karl
Schwarzschild
Schwarzschild Radius is
the distance from the center of a black hole to its event horizon.
Before Russian physicist Karl Schwarzschild calculated this
distance, the boundaries of black holes were a mystery. His
calculations were spurred by Einstein's theory of general
relativity, which induced the ability to calculate gravity at high
speeds and large masses. The equation for calculating the
Schwarzschild radius is:
Where M is the mass of
the black hole, G is the universal gravitational constant,
and c is the speed of light. The "radius" is
essentially the distance from the center of the black hole,
singularity, to the edge of the black hole, the event horizon.
Event Horizon is the
area surrounding a black hole where the escape velocity is equal
to the speed of light.
Singularity is
a located at the direct center of a black hole. It is also a place
of infinite space time curvature. This point exists due to the
star's entire density being crushed to a single point having, then
infinite density.
Escape Velocity:
The escape velocity is the speed at which one must travel to
escape the gravitational pull of a given field. With black holes,
the escape velocity is always greater than the speed of light.
Because nothing can travel faster than the speed of light, and no
signals can leave the black hole, the only indication of its
presence is gravity 3. Though nothing can escape a black hole, we
can calculate the rate that it would need to have.
Where m equals the mass
of the black hole, G equals the universal constant, and r
is the Schwarzschild radius. The following table lists the
Schwartzschild radii and escape velocities of several objects 3
Three properties of Black
Holes:
1. Mass
2. Spin
3. Electrical Charge
A black hole must have at least
3 stellar masses, otherwise it could not form on its own.
How a Black Hole can be
detected: Since no light escapes from them, black holes
obviously cannot be seen. However, they do emit X-rays because all
matter that is being pulled into them by their gravitational
forces will be charged by heating and compression, which causes
the emission of X-rays.
Where to find them: many
are thought to be at the center of galaxies, such as our own
Mini Black holes: These
are black holes that did not have the mass to form on their own
power, but Steven Hawking theorized that these types of black
holes may exist by virtue of the fact that when the universe was
formed, gravitational forces and pressures may have forced a mass
to collapse on itself, thus forming a black hole that is smaller
than normal.
Super Massive Black Holes: These
are black holes that have masses a few million times that of the
sun or more and are speculated to be the power behind the nuclear
activities that form galaxies.
White Holes: This is
another theory that hasn't been proven, but can be correctly
solved by the Schwarzschild equation: A black hole might actually
emit light or particles from its event horizon, perhaps into
another universe.
Wormholes: This is the
linkage of a white hole and a black hole, such that what falls
into a black hole would be emitted by a white hole, thus allowing
"travel" between the two.
The Evaporation of Black
Holes:
Stephen Hawking has postulated a theory that states that Black
Holes actually evaporate over time. This is because energy is used
from the radiation and mass is slowly decreased. As mass decreases
however, the radiation emitted increases, and the hole eventually
vanishes. No one is really sure what happens after that. Some
scientists believe that a small bit of the hole remains as a
stable remnant.
Data
compiled from The British Antarctic Study, NASA, Environment Canada,
UNEP, EPA and other sources as stated and credited Researched
by Charles Welch-Updated dailyThis Website is a project of the The
Ozone Hole Inc. a 501(c)(3) Nonprofit Organization
