Category Science

How are you get a cross line by dialling?

When you lift the receiver and complete the circuit to the exchange, dialling the number sends a series of electrical pulses down the line. Older telephone exchanges have automatic electromechanical switch gear, named after the American, Almon Strowger, conceived it in 1888. This has banks of fixed contacts, each in a half circle round of mobile selector arm.

The number is selected step by step. The first dialled digit sends the arm up to a bank corresponding to the digit. The arm then rotates to find a free contact – one that will connect it to the next bank ready for the next digit dialled. If no contact is free, the engaged tone is sounded. If contact is made, the next selector arm searches for that second digit, and so on. The final selector makes contact with the line of the number being called.

If the selector accidentally touches and sticks on an incorrect contact for the digit dialled, you get crossed line.

The latest telephone exchanges work electronically. Dialling sets up audible tones, and connections are made by circuits incorporating microchips that interpret the tones. Because there are no moving parts, electronic switching is silent and more reliable than electromechanical gear and crossed lines are rare.

 

Picture Credit : Google

How people can talk together across the world by telephone?

Over 500 million telephones are now in used throughout the world. In just over hundred years since the Scottish born inventor Alexander Graham Bell patented the first telephone in 1876 – telephones have revolutionized world communications.

Today, telephone networks relay not only voices but pictures and written information as well, by land and sea cables and through the air on microwaves, which are super-high-frequency radio waves. Calls can be made across half the world with less than a second delay in connection, and no difficulty in hearing. Multinational companies can even hold cross world video conferences, with executives speaking to each other from one screen to another.

Satellites, microchips and lasers

The modern inventions that have made this revolution possible include space satellites, microchips and laser beams. Early bird, the world’s first commercial satellite, was launched in 1965 by the International Telecommunication Satellite Organisation (INTELSAT).

Now there are about 130 satellites orbiting in space, relaying messages on microwaves from Earth Station to Earth Station. The orbit the earth at heights of about 22,500 miles (36,000 km) above the equator once every 24 hours, so appear to remain in the same place.

From the earth stations, microwaves carrying messages are beamed up to the satellites from huge dish aerials, some of which are 98ft (30 m) across. They are computer controlled so that they will always point directly at the satellite. Microwaves are not only used for satellite links – dish Aerials beam messages across land too, in straight lines from tower is located to ensure a clear path.

Microchips on the satellites amplify the relayed signals. Microchips have also brought about clearer, speedier communication by providing the fastest switching needed for sending telephone messages by digital transmission. And lasers have enabled the use of fibre optic cables – glass thread that carry digital messages at the speed of light, so fast that they could go seven times round the earth in a second.

Telecommunications services now available include fax, radiopaging, cordless telephones, car telephones and even aircraft telephones, allowing passengers to make calls while flying.

 

Picture Credit : Google

How Kanzi communicate loneliness?

Kanzi’s trainers do not claim that he can create grammatical sentences, but he does produce two words and three words statements that appear spontaneous, he communicate on his actions and describes to his trainers those he intends to carry out. He uses the keyboard to communicate with other pygmy chimpanzees undergoing the same training, so as telling one to tickle the other. His sentences also represent his own response to a situation. For example, when deprived of the company of another chimpanzee called Austin, Kanzi apparently felt lonely without the normal bedtime visit from his friend. After several nights, he punches the symbols for Austin and TV on his keyboard, and was shown a videotape of Austin, after which he went happily to sleep.

There is no evidence yet that animals are capable of abstract ideas or of active conversations. Even if we do improve our understanding of how they communicate, they may not have anything of enormous interest to say to us.

 

Picture Credit : Google

What are the sign languages for Chimps?

Similar experiments have done the chimpanzees, orang-utans and other apes. Because they do not have the same vocal cords as humans, apes cannot be expected to speak. So the pioneers of this research, Allen and Beatrice Gardner of the University of Nevada, had the idea of teaching one of them sign language. In 1967 they obtained a one year old female chimpanzee named Washoe, and by 1971 had taught her to use American sign language, the method used by the deaf in the United States. She was repeatedly shown the signs and then was rewarded with a tickle or with food when she responded correctly. Washoe learned fast and soon knew a large number of words. She was eventually able to use 150 hand gestures.

Walking by a Lake one day, her trainer pointed at a dog. ‘What’s that?’, He asked in sign language. ‘Water bird’, said Washoe, apparently inventing her own word for ducks. Encouraged by this, other American scientists started training their own chimpanzees, using a range of different methods of communication. Some involved the identification of plastic shapes which symbolised, among other things, objects such as apples, or the trainers name. Others meant pressing different keys on a computer to communicate words or phrases. The result seemed to show that the chimps could indeed master language: they could respond to simple commands and use the language to ask for things.

Later, cold water was poured on the whole idea by another American psychologist, professor Herbert Terrace of Columbia University, New York. When Terrace analysed all Washoe two word phrases, he found that the word order was in fact a random. Washoe might just as easily have said bird water. Terrace also found that unlike human babies learning language, the chimps did not gradually increase the complexity of their sentences.

More recently, a pygmy chimpanzee called Kanzi has rekindled interest. Kanzi lives at the language research Centre near Atlanta, Georgia. His success in picking up the elements of language appears to show that pygmy chimpanzees have greater intellectual potential than gorillas, orang-utans and common chimpanzees.

Kanzi has been provided with a keyboard, linked to a computer. Each key is marked with the geometrical symbol which represents a word. As a baby, Kanzi played in the laboratory while his mother was taught to use the keyboard, and apparently picked up the skill by watching her. To the surprise of the scientists, Kanzi began using the symbols correctly at the age of two and a half, and by the age of three had acquired skills which common chimpanzees could not manage at the age of seven.

 

Picture Credit : Google

How animals are taught to communicate with humans?

The understanding that can develop between people and animals is often almost uncanny. Dogs are good at interpreting their owner’s wishes so that at times they appear to possess a sixth sense. Horses, too, can respond to the subtlest of cues, as the complex movements of Dressage demonstrate. But will it ever be possible for people to communicate with animals using ordinary language?

Some years ago intensive efforts were made to communicate with dolphins. These mammals have brains which are similar in size to that of a human being, and they seem to be very intelligent. Dolphins are also capable of making a wide range of sounds, including squeaks, groans, clicks, barks and whistles, to indicate alarm, threat and a recognition.

Attempts to interrupt this language have not been successful. But scientists have proved that these creatures, and sea lions, can recognise hand gestures – a form of language – and can respond correctly.

Rocky, a 13 year old sea lion at the Long Marine laboratory in Santa Cruz, California, has been trained to identify objects, by being rewarded when he gets it right, and he can now collect from his pool only the toy that he is asked for. His trainer, Ron Schusterman of the university of California, scatters up to a dozen different toys in the pool- balls, discs, bottles and so on. An assistant who sits on the edge of the pool makes signs to the sea lion asking him to collect a particular toy, and Rocky picks up the right item 95% of the time.

More significantly, he has also been taught the meaning of much more complex commands such as ‘take the ball to the disc’, or ‘take the small Black disc to the bottle’. The success rate of his responses on such a task is only 40%. However it would be impossible for him to do even that well by chance. To some extent at least, he appears to understand simple sentences.

 

Picture Credit : Google

How are they calculate the age of earth?

The creation, according to Archbishop James Ussher, took place at 8 PM on October 22 in 4004 BC. The Irish cleric made his calculation in the mid-17th century after study of the ages of the old Testament of patriarchs, long genealogies and other Biblical details.

His view was challenged in 1785 in the Scottish naturalist, James Harden, declared that the formation of mountains and the erosion of river beds must have taken millions, not thousands, of years.

But it was not until the discovery of radioactivity by the French physicist Antony Henri Becquerel in 1896 that an accurate idea of the Earth’s age was made possible.

Scientists now accept that the earth’s crust solidified around 4700 million years ago. This calculation has been made possible by a study of the decay of various radioactive minerals.

When rocks are formed by the cooling and solidification of volcanic lava, radioactive elements are trapped inside. These elements decay at a precise rate, defined as half-life – the time it takes for half the radioactivity to decay.

Careful study has determined the half-lives of individual elements. By measuring the amount of any radioactive element in the sample of rock, the process of decay can be used as if it were a clock which started ticking when the rock was formed.

It is not the precise quantity of the radioactive element left that matters, because that depends on how much there was originally. What is important is the ratio between the quantity of radioactive material and the substance into which it changes. The older the rock, the lower the radioactive material it will contain and the greater will be the proportion of its decay products.

In examining rock samples, several different dating systems can be used. A common one is the decay of the radioactive element potassium 14, a process with the half-life of 11,900 million years. The decay of uranium into lead (half-life 4500 million years) is also used. In the case of the earth, about half its original uranium has decayed into lead. So the age of the earth is about the half-life of uranium.

 

Picture Credit : Google