## Tuesday, January 27, 2009

### E = m*(c^2) ---> A boon or a bane

Well.... here comes an off-beat blog from me.. especially centered upon one of the most important equations of modern physics which has shaped the current world of discoveries. This equation was derived by the renowned Albert Einstien in 1905 in the paper "Does the inertia of a body depend upon its energy content?", one of his ANNUS MIRABILIS papers. Though Einstien was not the first to propose an energy-mass relationship, he was the first to propose(and in fact prove) that the equivalence of mass and energy is a general principle, a consequences of symmetries of space and time. This paper is based primarily on James Clerk Maxwell's and Heinrich Rudolf Hertz's investigations in addition with the axioms of relativity. Einstien thus proved that the energy(E) emitted or radiated by a body/molecule is equal to the body's mass(m) times the square of speed of light(c). Einstien in fact was clearly confident that this could not be achieved practically and it was next to impossible. He even went on record quoting "It is equivalent to shooting a bird in the dark in a place where there are few number of birds".
Now we go on to see two fine examples of the equation.
Example 1
Way back in August 2, 1939 a letter signed by Einstien was delivered to the White House. But due to the American president Roosevelt's preoccupation with Aldof Hitler's invasion of Poland (Remember history?? - this was the beginning of World War II), it was delivered to him on October 11th. The letter was originally framed by another scientist Leo Szilard (A Budapest born Hungarian-German-American Physicist) with the help of fellow Hungarian Physicists Edward Teller(Father of the Hydrogen bomb) and Eugene Winger. The letter was about the threat of Germany going forward with a research to develop an atomic bomb using nuclear fission.
Actually Szilard 1933-34 had concluded that nuclear chain reaction was possible (he conceived the idea while waiting for traffic lights to change when walking to work!!!!) and also managed to make him prove that after all Einstien was true in his mass-energy relationship. When he learnt about the achievement of nuclear fission by Otto Hahn of Germany in December 1939, he along with Noble Laureate Enrico Fermi (who along with szilard was instrumental in building the first nuclear reactor) concluded that Uranium was the material which could sustain a chain reaction and with further experiment they discovered significant neutron multiplication in uranium thus proving that chain reaction was possible and nuclear weapons were on the way. SzilĂˇrd later described the event: "We turned the switch, saw the flashes, watched for ten minutes, then switched everything off and went home. That night I knew the world was headed for sorrow". Later Szilard heard that his former colleagues in Germany had gone further ahead and were experimenting with the control of chain reaction using graphite and were unsuccessful. This instilled fear in his minds and he rushed to Einstien to seek help in rushing a letter to the President warning of Germany's advances. He managed to convince Einstien in this regard and Einstien accepted to sign that letter as the base of all these findings was his energy-mass relation principle.
The letter states that Germany's action in blocking export of Uranium from former Czechoslovakia (taken over by Germany) proves that they are well on the way to develop an atomic bomb which could lead to large scale destruction. It also was advised in that letter that America speed up its nuclear research and also look into the possibility of building a bomb. It was also stated that the bomb would be heavy and difficult to transport due to its size and volume. This letter made Roosevelt to call upon his Chief of Army and later saw the establishment of the Manhattan Project in 1939. This project was an extensive project and employed nearly 130,000 people and nearly US\$ 2 billion (in 1939!!!!! - translates to USD 24 billion) and was located at various sites across America. Thus was born the nuclear bomb which was dropped in Nagasaki and Hiroshima. Szilard, Fermi, Teller, Oppenheimer among a host of other eminent Physicists worked on it. Einstien later expressed about his regret in signing the letter and also was sorrowed by his grave mistake of finding the mass-energy relationship.
Example 2
Another amazing finding based on Einstien's equation is the Big Bang Theory. This theory establishes the fact that universe came into existence at a definite moment in time, some 13 billion years ago, in the form of a superhot, superdense fireball of energetic radiation. Until the arrival of the Big Bang theory the universe was believed to be essentially eternal and unchanging, represented by the Steady State model. The first clear hint that the universe might change as time passes came in 1917 when Albert Einstein developed his General Theory of Relativity. Einstein realised that his equations said that the universe must be either expanding or contracting, but it could not be standing still, because if it were then gravity would attract all the galaxies towards one another. This was, at the time, a revolutionary concept, so revolutionary that Einstein refused to believe it and introduced his infamous 'cosmological constant' into the equations so that the sums agreed that the universe could be static. He later claimed it was the biggest blunder of his career. It was in 1920 that Edwin Hubble discovered that the universe was expanding by measuring the light from distant galaxies. This discovery was followed in 1927 by Georges Lemaitre, a Belgian astronomer, who was the first person to produce a version of what is now known as the Big Bang model. To this day there are numerous theories either supporting or opposing this theory by various astrophysicists. But the theory remains and will continue to remain.
This Big Bang theory was in fact established clearly with Einstien's theory of relativity which in fact was based upon Einstien's Annus Mirabilis. Upon seeing two fine examples of Einstien's work, I really feel that a simple equation has in fact ruled the 20th century and still continues to do so.... Is this equation a boon or a bane.. wat else is in store for being discovered...