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.
How long can humans live for?
The maximum human lifespan is around 125 years. However, some experts believe that this limit could be extended by somewhere between 10 and 15 years.
So far, the oldest person whose age could be proved was a Frenchwoman who died in 1997 at 122 years of age. In 1933, The New York Times reported the death of a Chinese man who was allegedly 253 years old, but this and similar reports of people living to such great ages are now considered unreliable.
Over the course of history, there has been no change in the maximum age, which is the same for all ethnic groups. What has increased since the end of the 19th century is the average life expectancy in industrialised countries. Thanks to the improvement in living conditions, this is now between about 79 and 82 years for both sexes (at birth).
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.
What is fire made of?
Fire is a combination of chemical and physical changes in which substances interact to release heat, light, smoke and ash. Whether it is a fire in electrical insulation, an oil fire or a simple domestic fire, they all require three ingredients – combustible material, oxygen and a thermal trigger.
If one of these is absent, the fire goes out. This principle is the basis of fire-fighting, which aims to cool the flames by smothering them, removing oxygen, or depriving them of fuel.
Combustible material often consists mainly of carbon and hydrogen and can be almost anything solid, liquid or gaseous, from hydrogen to wax, oil, wood and plastic. Even metal will burn provided the temperature is high enough.
Sufficient quantities of oxygen are usually supplied by the air, and the energy to light a fire is produced by friction or sparks.
Why will a piece of flint produce sparks?
Flint produces sparks because it is so hard. However, pieces of flint are only striking tools, and the sparks themselves come from a sparking material such as pyrite – a compound of iron and sulfur – steel, or a composite metal with iron content.
In the Stone Age, a firelighter was often a lump of pyrite, a firestone to strike it on and some dried moss or the tinder fungus sometimes known as touchwood. In medieval pistols, the flint created the spark by striking iron, while in today’s disposable cigarette lighters a friction wheel creates tiny sparks from a composite metal which ignites the flow of gas.
Expensive lighters use piezoelectric quartz crystals to produce sparks.
Why are candle flames yellow?
The colour of a flame is the result of several factors – the temperature of the flame, the chemical composition of the fuel that sustains it and the eye’s ability to perceive it.
The predominant yellow colour comes from burning carbon molecules. After the heat has stripped the wax from the wick, the carbon initially clumps together into soot particles, which then burn further up with a bright light fed by oxygen in the air.
The presence of some metal atoms in a flame can give rise to a rich range of colours. However, what an observer sees depends partly on the structure of the human eye, which is less sensitive to some colours than others.
Reds appear less intense than yellows or greens, and so the flame may appear to be mostly yellow.
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 ‘email@example.com’, 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.