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Why do air travelers experience jet lag after a long-haul flight? And how to prevent or remedy it?

Jet lag affects travelers flying east-west or west-east journey, crossing the time zone and finding themselves in a place where the local time differs from the home time. The rising and setting of the Sun is out of sync with their body clock, which is still on time due to 24-hour biological rhythms. So jet lag is the failure of the body to adjust its own routine to a clock that may, for instance, bring darkness (and bedtime) ten hours earlier or later than usual. In such conditions, the long-haul passengers feel like going to sleep just as darkness turns to light with the rising of the Sun, and just as everyone else is waking up ready to start the new day. Eating and exercising are also uncomfortably affected and mental reactions may slow down considerably. The result could be headaches, poor sleep, constipation, poor mental performance, giddiness and even slight depression.

The effects of jet lag seem to be greater on eastbound flights than on westbound. This is because traveling westwards you are traveling with the Sun, and the hours of daylight you experience will be longer than normal. The day will appear to be longer than 24 hours. This goes well with the biological clock, because many of the body rhythms have a period of 25 hours and they show a natural tendency to move towards the new time zone at the rate of about one hour a day. Conversely, when traveling eastwards, the day is shortened. So, body rhythms have to be pulled back to less than 24 hours, against their natural tendency to lengthen.

There is no way one can prevent jet lag and it is not possible to bring all the body rhythms back in sync immediately. Experience shows that one full day of natural recovery is needed for each five-hour time change. However, travelers should try to go to bed as near as possible to their usual bedtime on the first night after arriving. This helps, though not much.

Additional reading:
Jet lag (Wikipedia)

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Is our Milky Way a static object or rotates like planets and stars?

There is no object in the Universe that does not rotate on its axis and our Milky Way is no exception. This vast system of stars, shaped like a flattened disc, is a spiral, with stars, dust and gas clouds visibly concentrated along enormous spiral arms which curve away from the galactic center to its edge.

The whole system is rotating, but not like a solid body. Gravity makes its inner regions swirl around far more rapidly than those parts as far out as the Sun, so that a star in an inner orbit will do a lap in only a few thousand years -- a trip which takes our Sun 250 million years to complete, even though it is travelling at almost 1 million kilometers per hour! The net result of this differential rotation should be to wind up the spiral pattern after just a few revolutions, but this clearly hasn't happened. Nor do any of the million of other spiral galaxies how any signs of being wound up. One of the biggest puzzles facing astronomers today is to explain how spiral galaxies keep their shape.

Additional reading:
Milky Way (Wikipedia)

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Why is diamond so hard even though it is basically graphite?

The hardness of minerals is measured on a scale of 1-10 which was devised in 1822 by an Austrian named Friedrich Mohs. Number 1 on Mohs' scale is talc, an extremely soft mineral. Number 10 is diamond, the hardest natural substance. When cut and polished, diamond is prized in jewellery, but the only thing that can be used to cut and polish a diamond is diamond itself.

Diamond, which is 40 times as hard as talc, is made of pure carbon. Chemically, it is exactly the same as graphite, the substance used to make pencil lead. Graphite has hardness of between 1 and 2 on Mohs' scale. The difference between hard carbon and soft graphite is caused by the arrangement of carbon atoms. In graphite, the atoms are linked in flat planes which readily slide over each other. In diamond, which is formed in great heat and under intense pressure, the atoms are bound in a rigid structure.

Additional reading:
Diamond (Wikipedia)
Mohs scale of mineral hardness (Wikipedia)

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Who designed Analytical Engine, the first programmable computer?

Charles Babbage

The idea of the computer first occurred to the British inventor Charles Babbage (picture, left) in about 1833. Others had made calculating machines before him. But Babbage was the first person to conceive of a machine that could be programmed to carry out different calculating operations, as a computer can. Babbage designed a machine called the Analytical Engine that had the basic feature of a modern computer. It was to be a mechanical computer, containing complex systems of shafts and gear wheels. However, only some parts of the Analytical Engine (see photo below) could be built. The engineering required to complete it was far beyond the techniques of the age, and Babbage died in 1871 without knowing whether his computer would work or not.

Analytical Engine

In fact, Babbage was far ahead of his time. The first computer -- a British wartime decoder called Colossus -- was not built until 1943. Like modern computers, it used electronics, as mechanical operations were too slow. Colossus and all other computers since are really the descendants of Babbage's Analytical Engine.

Additional reading:
Charles Babbage (Wikipedia)
Analytical Engine (Wikipedia)

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Which is the most valuable object relative to its weight and size?

Treskilling Yellow

How about a postage stamp? In terms of size and weight, no other natural or man-made object is more valuable than the rarest of the rare stamps.

The world's most expansive stamp was printed in Sweden in 1855 and was the result of a painting error. Instead of printing the Treskilling stamp on green stock, it was printed on yellow / orange stock paper. Only one copy of Treskilling Yellow postage stamp is known to exist. It first achieved a million dollar price tag when it was sold in 1990. Six years later, it was sold for 2.5 million Swiss Francs, around 2.3 million US dollars. In 2010, the stamp made headlines again with a record-breaking sale. While the exact figure is unknown, the auctioneer revealed that it at least maintained the $2.3 million price achieved in 1996.

Additional reading:
Treskilling Yellow (Wikipedia)

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What is horsepower? Why is it calculated on the basis of horse's physical strength?

In the late 18th century, huge quantities of coal were required to keep up with the increasing demand generated by Industrial Revolution. Proprietors of coal mines in England used strong dray horses for hauling coal out of the underground seams. Some horses, strapped into a harness, were lowered into the shaft to work at the bottom of the pit. One of the serious problems was that few of the mines, especially located far below surface, were flooded with large quantities of water, which had to be pumped out constantly. Dray horses were used for this task also. In fact, horses were the major power source for mines as well as farms.

The Scottish inventor of steam engine, which was to replace horses, had to associate the power output of his engine with that of a horse's power. Watt did all his calculation on this basis and therefore, horsepower became a standard unit of power. The electrical equivalent of one horsepower is 746 watts in the international or SI system of units and heat equivalent is 2,545 BTU/British Thermal Units. James Watt himself defined one horsepower as 550 foot-pounds of work per second. If an engine lifts a 550-pound object to a height of 2 feet in 1 second, it is working at the rate of 1,100 foot-pounds per second and is delivering 2 horsepower.

Additional reading:
Horsepower (Wikipedia)

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How does Strangler Fig squeeze its host tree to death?

Before the European explorers set their feet on Africa, this giant landmass was known as the Dark Continent by the people of Europe. Actually, Africa wasn't a dark continent at all. Instead, the Europeans were in the dark since they had no knowledge about Africa. In the 15th century, some Portuguese explorers reached the shores of Africa for the first time. During their exploration, they came across a variety of birds, animals, insects and plants species which they had never seen before. They jotted down about strange creatures in their diary, and shared their experiences when they came back to their respective homelands. The narration, course was spiced up with a bit of exaggeration In order to make it sensational. Among many fairytale like stories they narrated, one was that of a tree which devours humans!

Strangler Fig

Today, we know that no such trees exist in Africa -- or any part of the world. What the 15th and 16th century explorers said about the so-called man-eating trees was more of a fiction than a fact! Nevertheless, their narration cannot be completely ignored. As a matter of fact, certain species of plants and trees do exist in the world which though do not devour human beings, yet feast on other species of plants and trees. These trees creep around the trunk of other trees and alter reaching a particular height, they actually strangulate them. Once the tree is 'victimized' it is reduced to nothing.

It is hard to digest the fact that one tree actually kills another, but it is true. A species of tree, aptly called strangler fig, exists in Africa and all tropical rain forests of the world. It belongs to the category of Ficus and is similar to the banyan and peepal trees. The only difference is that the strangler fig initially grows in the form of a creeper and grows into an actual tree with the help of another tree next to it. Once Stranger fig grows in full, it destroys the very tree around which it had crept and grown. After the strangler fig 'strangulates' its victim, it blooms to its fullest and bears fruits. The fruits are consumed by birds, squirrels, monkeys and other creatures along with the seeds. They cannot digest the hard seeds, but the outer shell of the seed is dissolved in their stomach during digestion. The 'uncovered'seeds are then excreted by them.

The seeds germinate in new grounds in a few days. A shoot erupts from the seed and it starts growing by climbing around the nearest tree. Gradually it starts sucking the sap from the victim and gains extra strength along with the nourishment it receives from the ground through the roots. This double whammy situation of the strangler fig tree creates double trouble for the victim and leads to its faster death. Firstly, due to the presence of the strangler fig, it is deprived of proper nutrition from the soil. Secondly, whatever food it photosynthesizes for itself is also sucked away by the strangler fig. To further add to its crisis, the strangler fig tightly strangulates the tree which further prevents the water and other important minerals from reaching every part of the tree. As a result,the leaves dry and wither away and finally the entire tree dries up. The place where it once grew in full bloom reduces to nothing but a hollow space.

The strangler fig grows in this place and bears fruits which are then eaten by birds, squirrels and monkeys. They spread the seeds in another area, and so, more trees fall victim to strangler fig. There is little sunlight and water on the tropical rainforest ground, so the strangler fig has found a way to avoid being deprived of solar energy and water by growing on other trees -- and then killing them too!

Additional reading:
Strangler fig (Wikipedia)

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