THE HERO OF ALEXANDRIA

The multi-talented Hero was a mechanic ,mathematician and scientist whose inventions inspired everyone from the Arabs to Leonardo da Vinci.Nineteenth century scientists were astonished to find he had even built a working steam engine !!

For centuries it was unclear if he actually lived.But now the historians are certain that he was active during the 1st century AD.

He is said to have invented the screw lathe - a machine for cutting screws ,water clock and fire extinguisher pump..

Hero wrote extensively, on several branches of geometry, land surveying, mechanics and optics. His works include: "Geometry", "Definitions", "Stereometry", "Engines of War", "Winches", "Ballistics", "Reflections". Many of his works have been lost, while others survive in fragments in Greek or Latin.

Five complete works survive: "Pneumatics" and "Automata" in Greek and "Mechanics", "Metrics" and "Dioptra" in Arabic.Hero is best known today for his famous mechanical "Fountain", and for his formula for finding the area of a triangle from the length of the sides. His most important invention, however, was the aeolipile, a steam-powered engine.

INSPIRATION FOR MANY

Hero wrote down his works and ideas and large part of his writings survived.

The Byzantines , Aramaeans, Persians and especially the Arabs copied his work.His work is said to have provided inspiration for Leonardo da Vinci as well.

His steam engine was reconstructed by John Landels, the english classicist.

Hero was known for his amazing mechanical ingenuity in the ancient world, to include his contributions in military technology and theater.By the standards of modern technology, even though his steam engine is inadeqaute, he deserves all our admiration!

THE RIDDLE OF BLACK HOLES

The most mysterious objects in the universe must certainly be the invisible and inconceivably dense objects known as black holes.Nothing can escape its grip.But how can we be certain of their existence if we cannot see them??




To imagine a black hole, think of an abyss- small in size yet unimaginably dense- swallowing everything that comes within its reach.

Einstein's theory of general relativity, developed in 1916, explains BLACK HOLE as when large enough amount of mass is present within a small enough volume, all paths through space are
warped inwards towards the center of the volume. When an object is compressed enough for this to occur, collapse is unavoidable . When an object passes within the event horizon at the boundary of the black hole, it is lost forever .

• INDICATIONS FOR EXISTENCE : INDIRECT TRACES

According to astrophysicists' calculations , the mass of all the matter in space is not sufficient to hold the distant stars. This has given rise to the idea that there is some invisible mass of matter that is capable of exerting sufficient force on all existing stars. It is possible that this force could be exerted by one or two gigantic black holes at the centre of the universe.

• SIZES OF BLACK HOLES

Black holes can be of almost any mass. Super massive black holes containing millions to billions of times the mass of the sun, Intermediate-mass black holes, whose size is measured in thousands of
solar masses,Stellar-mass black holes have masses ranging from about 1.5-3.0 solar masses to 15 solar masses , or Micro black holes, which have masses much less than that of stars.

• WHY IS BLACK HOLE INESCAPABLE ???

General relativity describes mass as changing the shape of space time, and the shape of space time as describing how matter moves through space. For objects much less dense than black holes,
this results in something similar to Newton's laws of gravity: objects with mass attract each other, but it's possible to define an escape velocity which allows a test object to leave the gravitational
field of any large object. For objects as dense as black holes, this stops being the case. The effort required to leave the hole becomes infinite, with no escape velocity defined.

• BLACK HOLES AND EARTH

Black holes are possibly the most serious potential threats to Earth and humanity,as a naturally-produced black hole could pass through our Solar System , and a large particle accelerator might
produce a micro black hole, and if this escaped it could gradually eat the whole of the Earth.

THE GREAT FIRE OF ROME

Could a ruler, even one as eccentric as the Roman emperor Nero, set fire to his own capital? The disastrous blaze that devastated the city of Rome in 64 BC has never been satisfactorily explained....

Though the infamous emperor Nero ruled Rome for less than two decades, his reign witnessed tremendous changes to the empire's capital city. Lucius Domitius Ahenobarbus -- more often known as Nero -- was a great-grandson of Caesar Augustus.

The Great Fire of Rome erupted on the night of July 18 to July 19, 64. The fire started at the southeastern end of the Circus Maximus,Rome's mammoth chariot stadium. in shops selling flammable goods.

In a city of two million, there was nothing unusual about such a fire -- the sweltering summer heat kindled conflagrations around Rome on a regular basis, particularly in the slums that covered much of the city. Yet this was no ordinary fire. The flames raged for six days before coming under control; then the fire reignited and burned for another three.

When the smoke cleared, 10 of Rome's 14 districts were in ruin. The 800-year-old Temple of Jupiter Stator and the Atrium Vestae, the hearth of the Vestal Virgins, were gone. Two thirds of Rome had been destroyed.

According to Tacitus { aristocrat and historian } , upon hearing news of the fire, Nero rushed back to Rome to organize a relief effort, which he paid for from his own funds.

After the fire, Nero opened his palaces to provide shelter for the homeless, and arranged for food supplies to be delivered in order to prevent starvation among the survivors.In the wake of the fire, he made a new urban development plan. Houses after the fire were spaced out, built in brick, and faced by porticos on wide roads.

Nero also built a new palace complex known as the Domus Aurea in an area cleared by the fire. This was a 300 acre palatial complex that featured the Colossus Neronis, a 37-meter-high bronze statue of Nero placed just outside of the entrance. To find the necessary funds for the reconstruction, tributes were imposed on the provinces of the empire.

HISTORICAL VIEWS

The varying historical accounts of the fire come from three secondary sources- Cassius Dio, Suetonius and Tacitus. The primary accounts, which possibly included histories written by Fabius Rusticus, Cluvius Rufus and Pliny the Elder, did not survive.

These primary accounts are described as contradictory and gross exaggerations.At least four separate stories circulated regarding Nero and fire:

Cassius Dio:

Motivated by a desire to destroy the city, Nero secretly sent out men pretending to be drunk to set fire to the city. Nero watched from his palace on the Palatine Hill singing and playing the lyre.

Suetonius:

Motivated by an insane whim, Nero quite openly sent out men to set fire to the city. Nero watched from the Tower of Maecenas on the Esquiline Hill singing and playing the lyre.

Tacitus 1:

Nero sent out men to set fire to the city. Nero sang and played his lyre from a private stage.

Tacitus 2:

The fire was an accident. Nero was in Antium.

Tacitus was a member of this Roman elite, and whether there is a bias in his writing is difficult to know. Indeed, Tacitus was still a boy of 9 at the time of the fire, and he would have been a young teenager in 68 A.D., when Nero died.

WAS NERO THE ARSONIST ??

NERO has always been labelled as a tyrant and an eccentric, and the long list of his evil deeds , as the murder of his wife and mother, certainly gave grounds for suspicion.

Rumours are that one of the grandest plans of Nero was to tear down a third of Rome so that he could build an elaborate series of palaces that would be known as Neropolis. The senate, however, objected ardently to this proposal.

The emperor's passion for theatre fed rumours that he wanted an opportunity to sing a poem of about the burning of Troy.

IDEAL SUSPECTS

It was an easy matter to blame the CHRISTIANS for the blaze.Small in number and poor, they were considered as foreigners by the citizens of Rome. The fire gave Nero the perfect opportunity to begin a systemic persecution of the christians in the hope that he could placate the anger of the people and turn opinion in his favour.

Countless arrests were made and many met gruesome deaths- fed to lions during gladiator matches, crucified and used as human torches...

Yet there is evidence that, in 64 A.D., many Roman Christians believed in prophecies predicting that Rome would soon be destroyed by fire. Perhaps the fire was set off by someone hoping to make the prediction come true.

Today, 20 centuries later, the mystery remains!