big bang theory is one of the widely accepted theory for the begining of the universe .the universe began to shape 10 ^-6 sec later after the big bang .3 sec later the basic elements were formed .5 billion later the sun was born and 3.8 billion years later earliest life forms appeared.homo sapiens appeared 600,000 yrs before the present .here i have mentioned the technological developments that led to the development of big bang theory .