(+)The typewriter keyboard that we use today was modified to make typing a little slower. On the first invented keyboard, all the common letters were placed close to each other and were not jumbled, so that it was possible to type quickly. But the speed often made the typewriter keys jam. 

In 1872, Christopher Sholes designed a keyboard on which the common letters were jumbled up so that typing was relatively slower and the keys no longer jammed. Even after the development of the computer, the layout of the keyboard has remained. 

Another explanation to this question is : The keys are arranged in a special manner so that the most common keys appear at the centre of the keyboard, whereby a typist can use his/her middle and index fingers most conveniently and faster. 
ps. If the reader knows of a specific answer to this question, other  than the ones mentioned above (obviously!); please mail it to us. Thank You 
 

(+)Greenwich is a city near London where the famous UK Old Royal Observatory is located. 

Both GMT (Greenwich Mean Time) and 'Prime Meridian Greenwich' (0 degree meridian) 
proposed by the UK were adopted as an international reference by the international community (of that time) in 1884. 

GMT is the time associated to the 0 degree meridian time zone. Roughly speaking, GMT is defined by 12:00:00 noon, being the time when the Sun crosses the vertical (zenital position) at 0 degree meridian. 

In 1986, GMT was replaced  by the UTC (United Time Coordinated), which takes into account periodical corrections related to the earth's motion. 

A second of time is defined as 1/60th of a minute, one minute - 1/60th of an hour and an hour - 1/24th of a day (Egyptians, about 5000 years ago set up a day as 2 x 12 hours). As one day is the duration of one rotation, one second is deducted to be 1/86400 of one earth rotation. 

Due to irregularities in the Earth's rotation, the precise duration of one second was later linked to a nuclear physicist's reference, as "9,192,631,770 cycles of period of transition of 2 hyperfine levels of the ground state of Cesium 133 isotope." 
 

(+) Triskaidekaphobia is the fear of the number thirteen. 
 

(+) Nike is the Greek Goddess if Victory.