A CD-ROM is a plastic disc with a thin aluminium layer from which music, texts, and other data can be retrieved. Like everything else in the world of computers, these files are also stored in the numeric sequence of 1 and 0. In this case, there are tiny grooves for 1 or none for 0. A laser beam in the reader scans these grooves, which reflect the laser beam in different ways. From these laser reflections, the chip in the computer or in the CD player deciphers the data present on the CD, which could be music, text, photos, or complete programs.
Tubes are present inside a conventional television set. In these tubes the images are broken down into small pixels with the help of a beam of electrically charged particles. The beam sends information about the colour and brightness of each pixel to a chemically luminescent layer on the rear of the screen. The electron beams light up the pixels on this layer depending upon the speed. They become blurred to form a picture for our eyes. Along with the fat-bellied tube televisions, there are also televisions with flat screens that have been improved very rapidly.
Pictures can ‘run’ only because our eyes cannot register more than 20 pictures per second. If we see more than 20 pictures, they look very similar but differ only in minor things; our brain perceives them as moving. Flip books or cartoon films work on this principle. The movements could not be recorded with cameras for a longtime because the exposure times were too long. The first serial photography succeeded in 1872. The British photographer Eadweard Muybridge captured a running horse with 30 cameras. He mounted the finished pictures on a disc, which was rotated in a device. Through a viewing hole you could see a running horse. Later individual photos were recorded with just one camera on a single film. This was the birth of the cinema.
The film as the storage option for images was invented at the beginning of the 19th century. The researchers at that time were experimenting with toxic chemicals to store light reflected from the objects on a long-term basis. The Frenchman, Louis Daguerre, finally succeeded in 1837 to fix the images on a light-sensitive material in a salt bath. This was the first film. However, the exposure times were very long. People had to sit for a long time while the photographer captured their image on a photographic plate. The path to the film roll was paved in 1889 by the American George Eastman - a thin layer of silver salts was applied on flexible plastic celluloid. Digital cameras do not need this because they store everything on a computer chip.
In a camera obscura, which is a Latin word meaning ‘dark chamber’, light enters a dark room or a closed box through a small hole. If the hole was small enough, a very faint inverted image would be seen on the opposite wall. At the end of the 13th century, astronomers made use of this to observe the sun. In this way they could study its hot surface, without having to look directly at it. Today, we buy a special pair of goggles to look at the sun.
Simulation programs are used for training in areas where the possibility of something going wrong is very dangerous. For instance, a trainee pilot does not fly an aircraft just after training. Before that he practices at a simulator, which behaves like an aircraft, but is on the ground so it does not crash if le pilot makes a mistake. We can also simulate a fault in a power plant or a tsunami. Trainees must demonstrate that they can handle he crisis effectively.
‘Nano’ is derived from the Greek word ‘nannos’, which means ‘dwarf’. Everything that starts with the word ‘nano’ is usually diminutive. Nano-robots are not bigger than a thousandth of a millimetre and can be even smaller. For instance, 1 nano-metre is a thousandth of a thousandth of a millimetre. Nano-robots help doctors in difficult operations. The research that is being carried out on magnetic nano-robots suggests that they can be released in the blood and can attach themselves to cancerous growths. If a rotating magnetic field is applied to the body of the cancer patient, the small magnetic robots in the cancerous tissue would start rotating. As a result, the cancerous growth would heat up and die.
Sojourner, the small exploration vehicle that landed on Mars in July 1997, was controlled by the ground station of the American space authority NASA. Commands were sent to the Sojourner from there. It was asked to travel over the surface of Mars, take photographs, soil samples, and lots more. There were glitches too. On the first day, Sojourner collided with a rock because it was travelling too fast. And sometimes the computer onboard ‘rebooted’ so the robot ‘forgot’ what it was supposed to do.
We need access to the Internet to send an e-mail. We can get the access by paying money to an internet service provider. In addition, one needs the email address of the receiver. The e-mail starts its journey when ‘Send’ is pressed from the sender’s email account. The e-mail then goes to the service provider, who sends from one ‘node’ to another, before it reaches its destination. It may happen that an e-mail sent from Berlin, goes to USA, then to India, and finally reaches your neighbour.
Like all sounds, speech also consists of sound waves. The mouthpiece of the telephone has a microphone, which converts the spoken sounds into electrical current. The transmission of electric current is done through wires. In the earpiece, the electric current is converted back to sound waves. Earlier, the wires were made of copper, but today telephonic conversations are transmitted through glass fibre cables or even via satellite connections. Telephone calls over long distances were earlier possible only through telephone operators. Since 1970, however, we can make overseas calls directly. The telephone was invented by Graham Bell, who applied for its patent in 1876.
Morse code is a method of transmitting electrical signals that are combinations of long and short sounds, flashes of light or electrical pulses – like a torch that flicks on and off. To understand the messages, the code must be known: the Morse alphabet. Samuel Morse, an American, invented it in 1833. The alphabet consists of dots and dashes: A dot stands for a short signal, a dash for a long one. An S is written as …, an O as - - - . This Means the emergency signal SOS is ‘… - - - …’ – three dots, three dashes, three dots. Amateur radio operators and telegraphy use this Morse code even today.
Blind people read by moving their fingers on raised dots. These can be on metal or plastic or can be pressed out of the paper from below. Different combinations of the dots result in letters, numbers, and punctuation marks. This dotted script was invented by 16-year-old Louis Braille in 1825. He had become blind when he was a small boy. In 1845, William Moon developed another script for the blind. It consists of rounded symbols, which are based on the letters of the alphabets. People who are not born blind and become blind only later in their life find it easier to learn the Moon script as compared to the Braille alphabet.
There are many cipher scripts. Children often write with lemon juice – the writing becomes visible only on ironing the page. During wars, spies think of many complicated systems to communicate. In the Second World War, the Germans bought a special typewriter, called Enigma meaning ‘puzzle’, for typing encoded radio messages. Its keyboard was connected to lamps. If one typed ‘D’, then an ‘A’, the encoded letter, glowed. The receiving radio operator also had an Enigma, which understood these messages.
Many of the early script languages did not use any letters, but used small pictures instead. Around 3500 B.C., the Sumerians in Mesopotamia invented the cuneiform script: Notches were made in wet clay tablets with a wooden handle. The clay tablets then dried and became hard. Initially, there were about 1500 picture – like symbols, from which 800 simplified symbols developed gradually. Many of these small notches put together resulted in a word – just like a picture puzzle of today or the script of the Chinese.
Alphabets are a standardized set of letters, each of which represents a sound that is spoken out loud. The alphabets, unlike the hieroglyphs of the ancient Egyptians or the picture symbols of the Mayans, are not based on a picture system. The English alphabet has 26 letters; out of which six are vowels. The Arabic alphabet has more letters and is also read in a different way: from right to left. In the earliest alphabet that we know, there were letters only for consonants. Starting from 1000 B.C., the Greeks introduced letters for vowels. The word ‘alphabet’ is derived from the first two letters of the Greek alphabet: alpha and beta.