Dr. A. P. J. Abdul Kalam
Sunday 23 September 2012
Friday 20 July 2012
The Bermuda Triangle
The Bermuda Triangle
The "Bermuda Triangle" or "Devil's
Triangle" is an imaginary area located off the southeastern Atlantic coast
of the United States of America, which is noted for a supposedly high incidence
of unexplained disappearances of ships and aircraft. The apexes of the triangle
are generally believed to be Bermuda; Miami, Florida; and San Juan, Puerto
Rico. The US Board of Geographic Names does not recognize the Bermuda Triangle
as an official name. The US Navy does not believe the Bermuda Triangle exists.
It is reported that Lloyd's of London, the world's leading market for
specialist insurance, does not charge higher premiums for vessels transiting
this heavily traveled area.
The most famous US Navy losses which have occurred in the
area popularly known as the Bermuda Triangle are USS CYCLOPS in
March 1918 and the aircraft of Flight 19 in December 1945. The
ship probably sank in an unexpected storm, and the aircraft ran out of fuel and
crashed into the ocean -- no physical traces of them have ever been found.
Another well known disappearance is the civilian tanker SS Marine
Sulphur Queen carrying bulk molten sulfur which sank in
February 1963. Although the wreck of Marine Sulphur
Queen has not been located, a life preserver and
other floating artifacts were recovered. These disappearances have been used to
provide credence to the popular belief in the mystery and purported
supernatural qualities of the "Bermuda Triangle."
Since the days of early civilization many thousands of ships
have sunk and/or disappeared in waters around the world due to navigational and
other human errors, storms, piracy, fires, and structural/mechanical failures.
Aircraft are subject to the same problems, and many of them have crashed at sea
around the globe. Often, there were no living witnesses to the sinking or
crash, and hence the exact cause of the loss and the location of the lost ship
or aircraft are unknown. A large number of pleasure boats travel the waters
between Florida and the Bahamas. All too often, crossings are attempted with
too small a boat, insufficient knowledge of the area's hazards, and a lack of
good seamanship.
To see how common accidents are at sea, you can examine some
of the recent accident reports of the National Transportation Safety Board for ships and aircraft.
One of the aircraft accident reports concerns an in-flight engine failure and
subsequent ditching of a Cessna aircraft near Great Abaco Island in the Bahamas
on 13 July 2003. This is the type of accident that would likely have been
attributed to mysterious causes in the Bermuda Triangle if there had been no
survivors or other eyewitnesses of the crash.
A significant factor with regard to missing vessels in the
Bermuda Triangle is a strong ocean current called the Gulf Stream. It is
extremely swift and turbulent and can quickly erase evidence of a disaster. The
weather also plays its role. Prior to the development of telegraph, radio and
radar, sailors did not know a storm or hurricane was nearby until it
appeared on the horizon. For example, the Continental Navy sloop Saratoga was
lost off the Bahamas in such a storm with all her crew on 18 March 1781. Many other US Navy ships have been lost at sea in storms around the
world. Sudden local thunder storms and water spouts can sometimes
spell disaster for mariners and air crews. Finally, the topography of the ocean
floor varies from extensive shoals around the islands to some of the deepest
marine trenches in the world. With the interaction of the strong currents over
the many reefs the topography of the ocean bottom is in a state of flux and the
development of new navigational hazards can sometimes be swift.
It has been inaccurately claimed that the Bermuda Triangle is
one of the two places on earth at which a magnetic compass points towards true
north. Normally a compass will point toward magnetic north. The difference
between the two is known as compass variation. The amount of variation changes
by as much as 60 degrees at various locations around the World. If this compass
variation or error is not compensated for, navigators can find themselves far
off course and in deep trouble. Although in the past this compass variation did
affect the "Bermuda Triangle" region, due to fluctuations in the
Earth's magnetic field this has apparently not been the case since the
nineteenth century.
We know of no US Government-issued maps that delineate the
boundaries of the Bermuda Triangle. However, general maps as well as nautical
and aviation charts of the general area are widely available in libraries and
from commercial map dealers.
Thursday 19 July 2012
BLACK HOLE
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| BLACK HOLE |
What Is a Black Hole?
A black hole is a place in space where
gravity pulls so much that even light can not get out. The gravity is so strong
because matter has been squeezed into a tiny space. This can happen when a star
is dying.
Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
Could a Black Hole Destroy Earth?
Black holes do not go around in space
eating stars, moons and planets. Earth will not fall into a black hole because
no black hole is close enough to the solar system for Earth to do that.
Even if a black hole the same mass as
the sun were to take the place of the sun, Earth still would not fall in. The
black hole would have the same gravity as the sun. Earth and the other planets
would orbit the black hole as they orbit the sun now. The sun will never turn into a black
hole. The sun is not a big enough star to make a black hole.
Black holes are the cold remnants of former
stars, so dense that no matter—not even light—is able to escape their powerful
gravitational pull.
While most stars end up as white dwarfs or neutron stars, black holes are the last evolutionary stage in the lifetimes
of enormous stars that had been at least 10 or 15 times as massive as our own
sun.
When giant stars reach the final stages of their lives they often
detonate in cataclysms known as supernovae. Such an explosion scatters most of a star into the void
of space but leaves behind a large "cold" remnant on which fusion no
longer takes place.
In younger stars, nuclear fusion creates energy and a constant outward
pressure that exists in balance with the inward pull of gravity caused by the
star's own mass. But in the dead remnants of a massive supernova, no force
opposes gravity—so the star begins to collapse in upon itself.
With no force to check gravity, a budding black hole shrinks to zero
volume—at which point it is infinitely dense. Even the light from such a star
is unable to escape its immense gravitational pull. The star's own light
becomes trapped in orbit, and the dark star becomes known as a black hole.
Black holes pull matter and even energy into themselves—but no more so
than other stars or cosmic objects of similar mass. That means that a black
hole with the mass of our own sun would not "suck" objects into it
any more than our own sun does with its own gravitational pull.
Planets, light, and other matter must pass close to a black hole in
order to be pulled into its grasp. When they reach a point of no return they
are said to have entered the event horizon—the point from which any escape is impossible because it
requires moving faster than the speed of light.
Small But Powerful
Black holes are small in size. A million-solar-mass hole, like that
believed to be at the center of some galaxies, would have a radius of just
about two million miles (three million kilometers)—only about four times the
size of the sun. A black hole with a mass equal to that of the sun would have a
two-mile (three-kilometer) radius.
Because they are so small, distant,
and dark, black holes cannot be directly observed. Yet scientists have
confirmed their long-held suspicions that they exist. This is typically done by
measuring mass in a region of the sky and looking for areas of large, dark
mass.
Many black holes exist in binary star systems. These holes may continually pull mass from
their neighboring star, growing the black hole and shrinking the other star,
until the black hole is large and the companion star has completely vanished.
Extremely large black
holes may exist at the center of some galaxies—including our own Milky Way.
These massive features may have the mass of 10 to 100 billion suns. They are
similar to smaller black holes but grow to enormous size because there is so
much matter in the center of the galaxy for them to add. Black holes can accrue
limitless amounts of matter; they simply become even denser as their mass
increases.
Black holes capture the
public's imagination and feature prominently in extremely theoretical concepts
like wormholes. These "tunnels" could allow
rapid travel through space and time—but there is no evidence that they exist.
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