My Science School

Sometimes the Moon passes between the Sun and the Earth in such a way that all three are in a straight line. The Moon is opaque and so it casts a shadow onto the surface of the Earth. The part of the Earth in the shadow is suddenly thrown into darkness in the daytime!

If you are standing in a shadowed area looking at the Sun, you may only see part of it (a ‘partial’ eclipse) or it may be obscured altogether by the Moon — a ‘total’ eclipse.

 The light of the Sun can be blinding. You must never look directly at the Sun.

An eclipse of the Sun: the Moon passes over the Sun.

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Light travels faster than anything else we know of. The Sun is about 150 million kilometres away from Earth and yet its light takes only about eight minutes to reach us! Some of the stars are so far away that their light takes many years to reach us. We do not see them as they are, but as they were hundreds, thousands or even millions of years ago!

Sometimes you can see rays of light from the Sun as they light up dust particles in the air. The rays do not bend — they seem to travel in straight lines.

Light travels in straight lines

Light from the torch travels through the holes in the first screen. But only the rays travelling through the centre hole have a straight path through all three screens. Light rays travel in straight line.

Our most important source of light is the Sun. The Sun has an enormous amount of energy which is given out in the form of heat — at its centre, the temperature of the Sun is about 13 million degrees centigrade! It is some of this energy which reaches us as light.

Since the Earth spins around once every 24 hours, we only face the Sun part of the time — the time we call ‘day’. At night, light from the Sun can no longer reach us. But even at night there is some light. The stars, like the Sun, produce light. The Moon also provides light. But the Moon has no light of its own — it simply reflects light which has reached it from the Sun.

            Electric lights enable us to see well at night. At night, we see how the Moon reflects the Sun’s light.

Our sense of sight is one of our most important links with the world. We can see thousands of colours and shapes which help us to recognize the people, places and things around us. But our eyes are limited. Not until the discovery of lenses were we able to see the things which were either too small or too far away for our eyes to focus on.

Telescopes enable us to see faraway objects such as galaxies.

Lenses in microscopes allow us to see tiny forms of life, helping us to understand how living things function. And lenses in telescopes have enabled us to understand something of the solar system, and the universe, of which we are a tiny part. You will learn how a special type of light, laser light is changing our lives.

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Ships float, even if they are made of iron, because their overall density is less than that of the water that supports them. The water displaced by the hull of the ship pushes back upwards with a force called up thrust or buoyancy. If this is equal to or greater than the force of gravity pulling the ship’s mass downwards, the vessel will float. In fact, ships need a certain amount of weight to give them stability in the water, so many of them have hulls weighted with concrete or another kind of ballast. Without it, the ship would bob around on the water like a cork.

Not such a silly question! A ship or a boat (we'll call them all boats from now on) is a vehicle that can float and move on the ocean, a river, or some other watery place, either through its own power or using power from the elements (wind, waves, or Sun). Most boats move partly through and partly above water but some (notably hovercraft and hydrofoils) lift up and speed over it while others (submarines and submersibles, which are small submarines) go entirely under it. These sound like quite pedantic distinctions, but they turn out to be very important—as we'll see in a moment.

All boats can float, but floating is more complex and confusing than it sounds and its best discussed through a scientific concept called buoyancy, which is the force that causes floating. Any object will either float or sink in water depending on its density (how much a certain volume of it weighs). If it's denser than water, it will usually sink; if it's less dense, it will float. It doesn't matter how big or small the object is: a gold ring will sink in water, while a piece of plastic as big as a football field will float. The basic rule is that an object will sink if it weighs more than exactly the same volume of water. But that doesn't really explain why an aircraft carrier (made from dense metal) can float.

A telephone works by sending and receiving electrical signals that represent sounds, including the human voice. When the required number is dialled, a signal passes to the called telephone, causing it to ring, buzz, flash a light, or even vibrate to attract the attention of the person using it. When the telephone is picked up or switched on, a connection is made, and a conversation can take place.

Messages reach the right telephone by means of a dialled number. Pressing the keys of the telephone causes different electrical pulses or varying tones to pass to electronic equipment at the telephone exchange. This “reads” the pulses or tones and routes the call to the correct area and telephone.

The Transmitter of a telephone serves as a sensitive "electric ear." It lies behind the mouthpiece of the phone. Like the human ear, the transmitter has an 14 eardrum." The eardrum of the telephone is a thin, round metal disk called a diaphragm. When a person talks into the telephone, the sound waves strike the diaphragm and make it vibrate. The diaphragm vibrates at various speeds, depending on the variations in air pressure caused by the varying tones of the speaker's voice.

Behind the diaphragm lies a small cup filled with tiny grains of carbon. The diaphragm presses against these carbon grains. Low voltage electric current travels through the grains. This current comes from batteries at the telephone company. The pressure on the carbon grains varies as sound waves make the diaphragm vibrate. A loud sound causes the sound waves to push hard on the diaphragm. In turn, the diaphragm presses the grains tightly together. This action makes it easier for the electric current to travel through, and a large amount of electricity flows through the grains. When the sound is soft, the sound waves push lightly on the diaphragm. In turn, the diaphragm puts only a light pressure on the carbon grains. The grains are pressed together loosely. This makes it harder for the electric current to pass through them, and less current flows through the grains.

Thus, the pattern of the sound waves determines the pressure on the diaphragm. This pressure, in turn, regulates the pressure on the carbon grains. The crowded or loose grains cause the electric current to become stronger or weaker. The current copies the pattern of the sound waves and travels over a telephone wire to the receiver of another telephone. For more modern phones that have a telephone answering service, the sound wave is captured on a recording device which allows for the operator of the phone to playback at a later time.

The Receiver serves as an "electric mouth." Like a human voice, it has "vocal cords." The vocal cords of the receiver are a diaphragm. Two magnets located at the edge of the diaphragm cause it to vibrate. One of the magnets is a permanent magnet that constantly holds the diaphragm close to it. The other magnet is an electromagnet. It consists of a piece of iron with a coil of wire wound around it. When an electric current passes through the coil, the iron core becomes magnetized. The diaphragm is pulled toward the iron core and away from the permanent magnet. The pull of the electromagnet varies between strong and weak, depending on the variations in the current. Thus, the electromagnet controls the vibrations of the diaphragm in the receiver.

The electric current passing through the electromagnet becomes stronger or weaker according to the loud or soft sounds. This action causes the diaphragm to vibrate according to the speaker's speech pattern. As the diaphragm moves in and out, it pulls and pushes the air in front of it. The pressure on the air sets up sound waves that are the same as the ones sent into the transmitter. The sound waves strike the ear of the listener and he hears the words of the speaker.

Semaphore is a means of signalling using pairs of flags. Different flag positions stand for different letters and numbers. Semaphore signals are useful when the signaller is within sight of the receiver of the message but too far away to call out. It was widely used between ships sailing near each other in the days before ship-to-ship radio.

In programming, especially in UNIX systems, semaphores are a technique for coordinating or synchronizing activities in which multiple processes compete for the same operating system resources. A semaphore is a value in a designated place in operating system (or Kernel) storage that each process can check and then change. Depending on the value that is found, the process can use the resource or will find that it is already in use and must wait for some period before trying again. Semaphores can be binary (0 or 1) or can have additional values. Typically, a process using semaphores checks the value and then, if it using the resource, changes the value to reflect this so that subsequent semaphore users will know to wait.

Semaphores are commonly used for two purposes: to share a common memory space and to share access to files. Semaphores are one of the techniques for interprocess communication (IPC). The C programming language provides a set of interfaces or "functions" for managing semaphores.

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The layer of the Earth’s atmosphere called the ionosphere can reflect some radio waves back to Earth. This is used for sending messages over fairly short distances, but for messages to travel further across the Earth, the radio signals can be bounced off a satellite, orbiting almost 36,000km (22,000 miles) above the Earth’s surface. Several satellites, in different orbits, are required to give coverage over the whole globe, and different satellites are used to reflect signals for different media, such as telephone messages and television pictures.

A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals through a transponder. It basically creates a communication channel between a source transmitter and a receiver at different locations on earth. Communications satellites are used for television, telephone, radio, internet, and military applications. There are currently 2,134 communications satellites in the earth’s orbit and these comprise both private and government organizations. Several are in geostationary orbit 22,236 miles (35,785 km) above the equator, so that the satellite appears stationary at the same point in the sky. The orbital period of these satellites is the same as the rotation rate of the Earth, which in turn allows the satellite dish antennas of ground stations to be aimed permanently at that spot; they do not have to move along and track it. Since the high frequency radio waves used for telecommunications links travel by line of sight, they get obstructed by the curve of the earth. What these communications satellites do is they relay the signal around the curve of the earth thus making possible communication between widely removed geographical points. Communications satellites use a wide range of radio and microwave frequencies. To avoid signal interference, international organizations have regulations stating which frequency ranges (or bands) certain organizations are permitted to use. This allocation of bands reduces the chances of signal interference.

A group of satellites working together is called a satellite constellation. Two such constellations are supposed to offer satellite phone services (mainly to remote areas), are the Iridium and Global star systems. The Iridium system has 66 satellites. It is also possible today to provide discontinuous coverage using a low-earth-orbit satellite that can store data received while passing over one part of earth and transmitting it later while passing over another part. The CASCADE system being used by Canada’s CASSIOPE communications satellite is an apt example.

A satellite in orbit has to operate continuously over its entire life span. It needs internal power to be able to operate its electronic systems and communications payload. The main source of power is sunlight, which is harnessed by the satellite’s solar panels. A satellite also has batteries on board to provide power when the Sun is blocked by Earth. The batteries are recharged by the excess current generated by the solar panels when there is sunlight.

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Modern communications have affected our lives in numerous ways. Being able to pass information down telephone wires or via satellites means that some people can work from anywhere in the world and still keep in constant touch with their offices. A surgeon in Arizona, via a satellite link, can assist a colleague in Beijing with a complicated operation. News can travel halfway around the world as quickly as it can reach the next town. Perhaps the biggest effect of communications has been to make us all feel that the world is a smaller place, and that we need to be concerned about its future and the futures of people thousands of miles away.

The Internet has turned our existence upside down. It has revolutionized communications, to the extent that it is now our preferred medium of everyday communication. In almost everything we do, we use the Internet. Ordering a pizza, buying a television, sharing a moment with friend, sending a picture over instant messaging. Before the Internet, if you wanted to keep up with the news, you had to walk down to the newsstand when it opened in the morning and buy a local edition reporting what had happened the previous day. But today a click or two is enough to read your local paper and any news source from anywhere in the world, updated up to the minute.

Technology has improved communication, especially in recent years. We’ll always have so much information readily available at our fingertips. Writing letters to relatives living hundreds of miles away is so old-school! Instead, you can talk to them through a video call or instant messaging. This change in communication has completely changed relationships all over the world.

Services like Facebook and Twitter have also become a big part of our everyday lives. These sites allow people to see a lot of information and photos at once and are enjoyable by design. When you upload a photo to the Internet, it doesn’t simply go away. It stays for a long time. This means you can use technology to store memories that are important to you, like family photos.

With modern technology, we can live much healthier lives. Those who have fitness trackers can see how active they are. Seeing that can encourage us to be even more active. Some fitness trackers like the Apple Watch even gamify health with competitions and points!

New technology can help create cures and medicines. Someone who is sick in modern times is much more likely to be cured than someone in past times. Modern technology can automate just about anything, from turning on a light to ordering a pizza. With automation, we can do so much more in such a small amount of time. For example, you can use your voice to start the coffee maker while you’re still getting dressed.

Only a few hundred years ago, the fastest way that a piece of news could travel was to be carried by a person on horseback. Messages sent overseas could only travel as fast as the fastest sailing ship and were at the mercy of the wind and weather. The development of steam locomotives and steamships made it possible for information to move around the world more quickly, but it still had to travel physically from one place to another, as a letter. The breakthrough came with the invention of the electric telegraph and messages in Morse code. The message was sent down a wire in bursts of electric current. Today, images of written documents, sound recordings or television pictures can be flashed around the globe in less than a second by means of satellites and radio communications.

It seems like advancements in technology and changes in communication always go hand in hand. When science was working to introduce new tools to let distant people contact each other, the landlines replaced telegraph and subsequently, cell phones replaced landlines. When the Internet arrived, it not only brought revolution in the sales industry but also opened new doors of personal communication. When science was looking for more convenient ways to send messages, e-mails replaced postal emails and social media replaced text messages. So it would not be wrong to say that technology has been shaping the communication industry for over a hundred years.

Previously, there were not much mediums of communication and today we are completely overwhelmed with the disparate mediums, thanks to the ever-changing technology! From Facebook to Instagram and skype to Whatsapp, we now have the limitless database of communication tools that have brought us closer to the entire world. All these communication mediums have also impacted our lives in different ways. For example, it’s true that Smartphones have brought us closer to our friends and relatives living in distant places, but at the same time, they have also made our society somewhat impersonal. Although they have helped increasing workplace engagement and productivity, they have also given rise to certain security and privacy issues.  While some of these issues are relatively minor, but some may have profound effects on the lives of users.

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Braille is a system of writing that uses raised dots, punched into paper or plastic. It enables people with little or no vision to read with their fingers. The system was invented in the first half of the nineteenth century by Louis Braille (1809-52), a Frenchman who had him been blind since the age of three.

Braille is a system of touch reading and writing for blind persons in which raised dots represent the letters of the alphabet.  It also contains equivalents for punctuation marks and provides symbols to show letter groupings.

Braille is read by moving the hand or hands from left to right along each line.  The reading process usually involves both hands, and the index fingers generally do the reading.  The average reading speed is about 125 words per minute. But, greater speeds of up to 200 words per minute are possible.

By using the braille alphabet, people who are blind can review and study the written word.  They can also become aware of different written conventions such as spelling, punctuation, paragraphing and footnotes.

Most importantly, braille gives blind individuals access to a wide range of reading materials including recreational and educational reading, financial statements and restaurant menus.  Equally important are contracts, regulations, insurance policies, directories, and cookbooks that are all part of daily adult life.  Through braille, people who are blind can also pursue hobbies and cultural enrichment with materials such as music scores, hymnals, playing cards, and board games.

Various other methods had been attempted over the years to enable reading for the blind. However, many of them were raised versions of print letters.  It is generally accepted that the braille system has succeeded because it is based on a rational sequence of signs devised for the fingertips, rather than imitating signs devised for the eyes.

At eleven years old, Braille found inspiration to modify Charles Barbier’s “night writing” code in an effort to create an efficient written communication system for fellow blind individuals. One year earlier he was enrolled at the National Institute of the Blind in Paris. He spent the better part of the next nine years developing and refining the system of raised dots that has come to be known by his name, Braille.

After all of Braille’s work, the code was now based on cells with only 6-dots instead of 12. This crucial improvement meant that a fingertip could encompass the entire cell unit with one impression and move rapidly from one cell to the next. Over time, braille gradually came to be accepted throughout the world as the fundamental form of written communication for blind individuals. Today it remains basically as he invented it.

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Languages grow and change because they need to. New words are invented when new ideas or articles require a name. Usually, new words are based on earlier ones. When the television was invented, the word chosen to describe it was a combination of an ancient Greek word, meaning “far” and a Latin word to do with “seeing”. Sometimes a writer takes delight in inventing words. Lewis Carroll wrote a poem about a creature he called the “Jabberwock”, for example.

Sometimes a “new” world simply borrowed from another language. “Chocolate” came into the English language as a version of the Aztecs used to describe a drink made from the cocoa bean. This drink was unknown in Europe until the Spaniards discovered the Aztecs in South America. Once it was known, it had to be named! Borrowing the local name for it was an easy solution.

Many of the new words added to the ever-growing lexicon of the English language are just created from scratch, and often have little or no etymological pedigree. A good example is the word dog, etymologically unrelated to any other known word, which, in the late Middle Ages, suddenly and mysteriously displaced the Old English word hound (or hund) which had served for centuries. Some of the commonest words in the language arrived in a similarly inexplicable way (e.g. jaw, askance, tantrum, conundrum, bad, big, donkey, kick, slum, log, dodge, fuss, prod, hunch, freak, bludgeon, slang, puzzle, surf, pour, slouch, bash, etc.).

Words like gadget, blimp, raunchy, scam, nifty, zit, clobber, boffin, gimmick, jazz and googol have all appeared in the last century or two with no apparent etymology, and are more recent examples of this kind of novel creation of words. Additionally, some words that have existed for centuries in regional dialects or as rarely used terms, suddenly enter into popular use for little or no apparent reason (e.g. scrounge and seep, both old but obscure English words, suddenly came into general use in the early 20th Century).

Sometimes, if infrequently, a "nonce word" (created "for the nonce", and not expected to be re-used or generalized) does become incorporated into the language. One example is James Joyce's invention quark, which was later adopted by the physicist Murray Gell-Mann to name a new class of sub-atomic particle, and another is blurb, which dates back to 1907.

This stone was found near Rosetta, in Egypt. On it was an inscription, given three times in three different languages. One of the versions was in Greek, which scholars could read. Another version was in ancient Egyptian hieroglyphs, a kind of picture-writing that no one in modern times had been able to decipher. Given the Greek “key”, it became possible to read the hieroglyphs on the stone, and later, thousands of other hieroglyphs carved on monuments and buildings.

In the 19th century, the Rosetta Stone helped scholars at long last crack the code of hieroglyphics, the ancient Egyptian writing system. French army engineers who were part of Napoleon Bonaparte’s Egypt campaign discovered the stone slab in 1799 while making repairs to a fort near the town of Rashid (Rosetta).

The artifact, which is made of granitoid, came into the possession of the British after they defeated the French in Egypt in 1801.

The stone features a decree issued in 196 B.C. by a group of Egyptian clergy and Egypt’s ruler, Ptolemy V, attesting to his generosity and devoutness. It originally was displayed in a temple, possibly near the ancient town of Sais, then centuries later moved to Rosetta and used in the construction of Fort Julien, where it was eventually uncovered by the French.

The decree on the stone is written in three ways: in hieroglyphics, which was used mainly by priests; in ancient Egyptian demotic, used for everyday purposes; and in ancient Greek. The use of hieroglyphics died out after the 4th century and the writing system became an enigma to scholars.

British scientist Thomas Young, who began studying the Rosetta Stone’s texts in 1814, made some initial progress in analyzing its hieroglyphic inscription. Young surmised that the cartouches—hieroglyphs enclosed in ovals—contained the phonetic spellings of royal names, including Ptolemy, who was referenced in the Greek inscription.

Ultimately, it was French linguist Jean-Francois Champollion who deciphered the Rosetta Stone and cracked the hieroglyphic code. Between 1822 and 1824, Champollion showed that hieroglyphics were a combination of phonetic and ideographic signs rather than just symbolic picture writing that didn’t also represent sounds of language, as earlier scholars had suspected. For his discoveries, Champollion is heralded as the founding father of Egyptology.

Today, the Rosetta Stone, which measures about 44 inches tall and 30 inches wide, is housed in the British Museum in London, where it’s been since 1802, except for a temporary re-location for safekeeping during World War 1 to an off-site, underground spot.

Not all languages are related, but they do seem to form related groups. Most languages that were originally European, some of which are now spoken all over the world, are thought to have developed from an ancient and unknown language those linguists known as “Proto Indo-European”.

Most languages belong to language families. A language family is a group of related languages that developed from a common historic ancestor, referred to as protolanguage (proto– means ‘early’ in Greek). The ancestral language is usually not known directly, but it is possible to discover many of its features by applying the comparative method that can demonstrate the family status of many languages. Sometimes a protolanguage can be identified with a historically known language. Thus, provincial dialects of Vulgar Latin are known to have given rise to the modern Romance languages, so the *Proto-Romance language is more or less identical to Latin. Similarly, Old Norse was the ancestor of Norwegian, Swedish, Danish and Icelandic. Sanskrit was the protolanguage of many of the languages of the Indian subcontinent, such as Bengali, Hindi, Marathi, and Urdu. Further back in time, all these ancestral languages descended, in turn, from one common ancestor. We call this ancestor Proto-Indo-European (PIE). Language families can be subdivided into smaller units called branches. For instance, the Indo-European family has several branches, among them, Germanic, Romance, and Slavic.

Sometimes it is relatively easy to establish relationships among languages. Let us look at the Romance languages. We know that Italian is a descendant of Latin, a language that was spoken in Italy two thousand years ago and one which left a great number of written documents. The Roman conquest helped spread Latin throughout Europe where it eventually developed into regional dialects. When the Roman Empire broke up, these regional dialects evolved into the modern Romance languages that we know today: French, Italian, Portuguese, Spanish, and others. These languages form the Romance branch of the Indo-European language family. By looking at the word for ‘water’ in three Romance languages, one can easily see the similarities among them.

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Many people have dreamed of a world in which everyone speaks the same language. Some international jobs use one language to avoid dangerous misunderstandings. However, even gestures can be misunderstood, as a shake of the head can mean “yes” in some countries and “no” in others!

There already is a universal language -- a statement that is backed with ample evidence. That language is modern American English, also referred to as proper English. There are many good scientific and historic reasons for what has already happened, and the evidence is literally within these words that I type.

Yes, there is a tendency for languages to propagate and diverge, and yes, language and culture are one. As long as there are different cultures there will be different languages. But this has to do with how they are born. We do have a tendency to want to communicate with more people and the right people in the proper way. So there is a desire for a universal language.

But universal never meant international until very recently. If all you knew were the people in your village and had no contact with the outside world, universal would be your village. With media and better transportation, countries became smaller, and universal became national. So governments chose their national language and made it official. This is all hard evidence that backs this statement:

Hence, the real question is, (1) why doesn't English diverge and (2) why doesn't English immediately retrofit to cultures?

If you look at most languages in most countries, you will indeed see that languages naturally diverge into their dialects, and often this divergence is problematic for countries that wish to act as a whole. So in Japan for example, there is Standard Japanese (Hyojungo) that is defined as the language of Japan. Yet, plenty of dialects still are used daily, and most Japanese, if they are not born and raised in Tokyo, speak fluently in their local dialect as well as in Standard Japanese.

However, if you look at American English dialects, you will find that the language has an uncanny ability to remain rigid. Most English dialects lean towards different accents and intonations, and certainly local idioms and favoritism persist, but overall, English never breaks where other languages always do. Spelling and grammar remain, and proper English reigns supreme, globally. This all happened quite naturally... No one polices English. It organically grew into the role of a global standard. So what was the secret? What special powers does the English language possess?

Something interesting happened with English when it became the language of choice for scientists. English became more scientific. This happened in the mid-19th century. The scientific community was international and tight. They needed to be able to communicate, and the language they chose was English. They didn't force their identity and wave their flags. They sought unity.