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Given below are some questions that most of us like to know the answers of:Do the stars influence our destiny?Astrologers claim that our destiny is influenced by the position of the Sun, Moon and the planets in relation to the stars. However, numerous research projects – some carried out according to criteria laid down jointly by astrologers and astronomers – have shown that such connections do not exist.When a daily horoscope in the newspaper seems unusually accurate it is because it is so cleverly composed that almost any reader can identify with it. However, it would be unfair to accuse astrologers of cheating the public. Many are simply trying to offer sensible advice about dealing with everyday problems. Nevertheless, their work is based on a false doctrine and unscientific principles.What makes up the zodiac?When we talk about the zodiac, we are referring to constellations through which the Sun moves in the course of the year. These constellations are mostly named after animals and cover an area about 14° wide running above and below the Sun’s apparent annual path across the heavens. Even though we cannot see these stars by day, they are still there, hidden by the brightness of the Sun.Originally there were 12 signs of the zodiac, but since the adoption of constellation boundaries defined by the International Astronomical Union in 1930, the Sun now passes through a 13th constellation – Ophiuchus, the serpent bearer. The Sun crosses through Ophiuchus in moving from Scorpius to Sagittarius, but Ophiuchus is not included in the traditional signs of the zodiac.Why is it that women live longer than men?On average, women live seven years longer than men, although in some parts of the developing world the gap is not as wide. Men of all ages in industrialised countries run a greater risk of dying than women. This is particularly true of young men and those over 60.At first, it was thought that this difference had biological origins and might, for example, be due to sex hormones. However, a study carried out in German monasteries and convents found that monks lived almost as long as nuns and other women. It seems clear that lifestyle and living conditions play a greater role in life expectancy than genetic differences.The average life expectancy of men is probably shorter than that of women because they run more risks and are more weighed down by stress and work – unless they happen to live in a monastery. The fact that men generally pay less attention to their health may also be significant.Is there a longevity gene?Although the maximum life span for the human species is determined by the human genotype, a person’s individual life expectancy is not only a matter of genes. Nutrition and other environmental factors have a strong influence on how long we live. Together with genes, these factors can dictate how many free radicals – which damage cells – are created as the body generates energy, and how effectively these can be rendered harmless and the damage repaired.In flies, worms and mice, various genes have been discovered which have a particularly marked effect on life span. By modifying the way such ‘Methuselah genes’ act, scientists have succeeded in considerably prolonging the lives of animals. For example, gene activation in mice resulted in metabolic changes similar to those brought on by a life-prolonging starvation diet.Corresponding genes are also found in humans. Some researchers believe that, with the help of newly developed pharmaceuticals, it will also be possible to one day extend the human life span.Why does the sky change colour?Without sunlight, we would not only be in darkness, but the world would also be completely devoid of colour. As a general rule, sunlight appears to us as a pale whitish-yellow, but it is actually made up of the whole spectrum of colours visible to the human eye – literally, all the colours of the rainbow.The coloured components of the Sun’s light becomes visible when it is broken up as a result of refraction and scattering in the atmosphere. During the day, the sky is predominantly blue because many different solid and gaseous particles in the atmosphere scatter the sunlight in a particular way.The British physicist Lord Rayleigh (1842–1919) was the first to come up with a conclusive explanation of the sky’s blue colour – which is why the phenomenon is known as Rayleigh scattering.Why are dawn and sunset skies often red?The explanation for the reddish tints seen in the sky at either end of the day also lies in Rayleigh scattering. As it passes through layers in the atmosphere, light with shorter wavelengths is scattered more than light with longer wavelengths.For this reason, blue light, with its short wavelength, is scattered more than red light. When the Sun is high in the sky, and the journey that sunlight takes through the atmosphere is relatively short, blue is predominantly scattered and the result is a blue sky.When the sun is low, the light travels much further through the atmosphere and scattering reduces the blue content to such a degree that red predominates. Blue is literally scattered away. This is why the sky is red at sunrise and sunset. Sunlit clouds and droplets of water in the air further intensify the red tint.How are the colours in a rainbow formed?The ideal conditions for a rainbow occur when a brief morning or evening shower is followed by a rapidly brightening sky. Large numbers of water droplets are still present in the air, and the Sun shines onto them from a relatively low position in the sky.This is the reason why morning rainbows only appear in the west and evening rainbows only in the east. Rainbows are only ever seen on the side of the sky opposite to the Sun.The fascinating technicolour display that is a rainbow is the result of white sunlight being broken down by refraction into its component colours. This happens on the curved surfaces of the almost spherical droplets of rain, which is also why rainbows have their characteristic arched shape.As is the case with white light broken down by a prism, blue light, with its shorter wavelength, is refracted at a greater angle than red light, which has a longer wavelength. This is why the colours appear in their familiar sequence – red, orange, yellow, green, blue, indigo and violet.Sometimes it is possible to see another, weaker, secondary rainbow. This is created by the light waves being refracted a second time in the water droplets, but, with the secondary rainbow, the colours appear in reverse order to those of the primary rainbow.How do emails arrive at their destination?Just like any ordinary letter, every e-mail has a sender address and recipient address. For e-mail, these take the form ‘firstname.lastname@example.org’, where ‘mycountry’ stands for actual countries (.au, .jp, .fr, .uk, etc.), ‘domain’ stands for a class of organisations (.org), networks (.net), individuals (.name), government bodies (.gov) or educational institutions (.edu), among others.The ‘mydomain’ part may be the name of your company. When an e-mail is sent, it is divided into several data packages, which are numbered and dispatched through the widely branching network. This ensures that the message arrives, even when lines or servers are defective.Every computer involved in the process leaves a kind of stamp on the e-mail, so it is possible to reconstruct the route. The target computer does not announce an e-mail until all its parts have arrived and been put together again.Where does the @ sign come from?The ‘at’ sign probably originated in the Middle Ages; either as an abbreviation of the Latin ‘ad’ (at, towards, by) or as a mercantile abbreviation for ‘amphora’. The symbol has endured to this day in Spain, Portugal and France, as the unit of weight ‘arroba’, which is equal to about 15 litres or 10 kg.It also occurs in old German legal texts, while in English-speaking countries it served as an assignment of price (5 eggs @ 20 cents).From these distant beginnings, the symbol made its way onto typewriter keyboards, where it waited to be chosen by the author of the world’s first e-mail when he was looking for an address component. In 1971, Ray Tomlinson needed a sign that could be found on all common keyboards but wasn’t a letter of the alphabet.With the @ sign he managed to provide an unambiguous separator between the two parts of an e-mail address.Why do tears come when we cut onions?Let’s look at it from the point of view of the onion.An onion is perfectly polite to us until we start hacking at it with a knife. Alas, the act of cutting enlivens a gas, propanethiol S-oxide, which works in tandem with the enzymes in the onion to unleash a passive sulphur compound found within the onion.The result: as you cut, the gas moves upwards and, combined with the water in your eyes, creates sulphuric acid.Your eyes aren’t happy, even if you are, and react in the only way they know how when irritated by a foreign substance - they start tearing. Rubbing your eyes with your hands is about the worst way to alleviate the problem, since your hands are likely full of the tear-inducing agent too.We’ve heard all kinds of folk remedies for onion tears, ranging from rubbing the onion with lemon to wearing gloves as you cut to donning scuba diving masks while performing surgery. But we’re of the old school: no pain, no gain. Why do we wake up with such bad breath in the morning? Most bad breath is caused by sulphur-bearing compounds in the mouth. How do they get there? And why is the problem worse in the morning?Micro-organisms in the mouth aren’t fussy about what they eat. They attack:• Food left in the mouth.• Plaque.• Saliva found in the spaces between teeth, the gum and on the tongue.• Dead tissue that is being shed by the mouth, gums and tongue.The micro-organisms convert this food into amino acids and peptides, which in turn break down into compounds with a pungent sulphur odour.Brushing the teeth helps rid the mouth of all of these food sources of the micro-organisms. But the best defence is a regular salivary flow, the type you get by talking, chewing or swallowing – things that most of us do only when awake.Eliminating cavities is not the only reason to floss. The longer food particles stay in the mouth, the more fetid the breath will be, so those hours of sleep are the perfect breeding time for bacteria and a threat to sensitive noses everywhere.Why is the sea salty?Most of the salt in the ocean is there because of the processes of dissolving and leaching from the solid earth over hundreds of millions of years, according to Dr Eugene C LaFond, President of LaFond Oceanic Consultants. Rivers take the salt out of rocks and carry them into oceans; these eroded rocks supply the largest portion of salt in the ocean.But other natural phenomena contribute to the mineral load in the oceans. Salty volcanic rock washes into them. Volcanoes also release salty ‘juvenile water’, water that has never existed before in the form of liquid. Fresh basalt flows up from a giant rift that runs through all the oceans’ basins.With all of these processes dumping salt into the oceans, one might think that the seas would get saturated with sodium chloride, for oceans, like any other body of water, keep evaporating. Yet, according to the Sea Secrets Information Services of the International Oceanographic Foundation at the University of Miami, the concentration of salts in the ocean has not changed for quite a while – about, oh, 1.5 billion years or so. So how do oceans rid themselves of some of the salt?First of all, sodium chloride is extremely soluble, so it doesn’t get concentrated in certain sections of the ocean. The surface area of the oceans is so large that the salt is relatively evenly distributed. Second, some of the ions in the salt leave with the sea spray. Third, some of the salt sticks to particulate matter that sinks below the surface of the ocean. The fourth and most dramatic way sodium chloride is removed from the ocean is by the large accumulations left in salt flats on ocean coasts, where the water is shallow enough to evaporate.Thus the level of salt in the ocean, approximately 3.5 per cent, remains constant.