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SAY HELLO THROUGH WIRE OR AIR OR......

   

     Men communicated through sign language long back.  It is still used by physically challenged people.  Men invented language.  It paved way for the oral and written communication.
     When distance increases, how to communicate?  Written message on palm leaf, cloth,paper  were sent on horses, trains and ships.  Today, we call it snail mail.  But it is still vogue.
     Telephone , telex, telegram were invented.  Messages were sent through wires with electricity. Voice was converted into electrical signal and sent through telephone cables.  In telegram, two sounds represented each alphabet in English.  The letters are converted into sounds and sounds into electrical pulses.  Then the pulses travel from one post office to another.  The postmaster had to undergo special course to decipher the message in those days.
     Radio was born.  That is, Radio waves receiver set.  Speech and songs were converted into electricity than into Radio waves(electromagnetic waves) and transmitted.  Received by radio set and converted back into songs.  It is one way wireless communication.  distance was no longer a matter.  Walkie-talkie came for two way short distance wireless communication.
    TV appeared.  Picture transmission-same principle as radio.
     The internet(international network)  revolutionized the way we communicate.  All computers in the world were initially connected through telephone lines.  Now they are connected through dedicated cables, wires,or even without wires.  The internet is ON 24X7.  No holiday.  You can pay bills on the Sundays.  Millions of emails (electronic mails) travels around the globe in seconds.
    The big revolution; the smart phone.  Any one can contact any one anywhere on the globe instantly at zero cost.  Video phone become reality.  The smart phone is also hooked on the internet.
  Today, you can down load any book, any song, any movie, any daily magazine, any speech, any video, information on your smart phone, tablet and PC. With the smart phone, the world is in your pocket.
    The communication is so improved that an expert surgeon can do surgery remotely.  Tele-medicine is a reality.  IOT-Internet of things is coming. you will be able to control your home fan, fridge, AC, doors ... from anywhere in the world.
     In those days, in the case of emergency, they sent the SOS (save our souls) message using drums, fire, smoke.  Even today, we send SOS using torchlight, whistle etc. (Listen to airplane safety precautions)

Principle of communication:
     Info (text, audio, video,...) to electrical signals to electromagnetic waves (radio waves) or light.  Sent through glass fibers (optical cable) or through air.  Received and the process  is reversed.

     In the near future, the speed of internet will increase so that we can down load a movie in seconds and watch it for hours.
     Is the communication revolution a ban or a boon?  It is open to debate.  You can either save a person with knife or kill him with it. 

Foot note:
     "It takes a fraction of a second to send a message to the other side of the globe but it takes years to send a message from outside the head to inside the head". 
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