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Radio, Television and Satellites
In space, there are no solids, gases or liquids (mediums) to travel through meaning sound can't exist. Spacemen use radios to communicate with each other in space. So literally “In space no one can hear you scream”.
The first radio was created by Guglielmo Marconi in 1895. He was the first to send telegraph signals through the air without using wires. Radio waves are a form of energy that travel through the air.
John Logie Baird created the first television using lense set in revolving disc to scan a picture. It was later developed by Americans Vladimir Zworykin and Philo Farnsworth. .
Microwave radio signals must travel in straight lines in. In olden days they had to be sent from relay station to relay station. Then in 1945 a science fiction writer called Arthur C. Clarke came up with a solution to the problem. He suggested putting the relay equipment on satellites which could go around the earth every 24 hours staying fixed in one point in the sky at 36,000km above the ground. In 1964, his dream came true as the first geostationary satellite called Syncom 3 was launched successfully into orbit. Nowadays signals can go from one place to anywhere else in the world almost instantly.