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Is there a fish that can live out of water for a considerable length of time?

2014-04-07T20:35:00.001-07:00

Only a few types of fishes can survive in terrestrial environment for more than a couple of minutes. Perhaps best known is the mudskipper (photo, below), which is a (10 to 12 cm) froglike go by that lives on the mud flats along mangrove shores of the Indo-Pacific region. When the tide moves out the mudskippers stay on the flats. They have long pectoral fins with which they propel themselves, hopping about like frogs. Their big, bulging eyes also contribute to their froglike appearance. Mudskippers do not have to go back into the water as long as their gills are kept moist. They spend more time on land than in the water. Why, then, are they considered to be fish? According to ichthyologists, mudskippers have all that it takes to be a fish, they are finned, gill-breathing vertebrates. Though they prefer basking in the Sun, they need water in order to breathe and carry it on land stored in spongy sacs in their heads. They gulp air, mix it with the stored water and pass it over their gills, which, like their skin, must remain wet. During the age of fish 350 million years ago, a season-ally wet and dry climate encouraged the development of the fish that became terrestrial animals; only fish that could take oxygen directly from the atmosphere would have survived in water that was shallow, warm, stagnant and thus oxygen-poor. Still, only one small group of fish developed the other traits needed to become entirely free of the water: strong limbs to contend with gravity and a way to retain moisture without having to stay wet. This group of fish, forced to change drastically emerged from the water completely and adapted to life on land. They evolved into amphibians, reptiles and mammals—including us. The mud skipper, on the other hand, came out on land but never went anywhere. This odd fish has virtually remained unchanged for 30 million years."

What is heavy water? Why is it used in a nuclear power reactor?

2014-04-06T19:18:00.001-07:00

Unlike ordinary water, heavy water contains heavy hydrogen, or deuterium, instead of normal hydrogen. Deuterium is an isotope of hydrogen that has a greater atomic mass than normal hydrogen. It is present in water in small amount. Nuclear reactors use heavy water as moderator, i.e. to slow down fast-moving neutrons. The basic concept of a nuclear reactor is simple: assemble a critical mass of fissionable material and bombard it with neutrons in order to break Uranium-235 (U-235) atom. For complicated reasons, the U-235 nuclei seek out slow moving neutrons and capture them. Because U-235 nuclei emit fast moving neutrons when they fission, most nuclear reactors contain some-thing else besides uranium. Along with uranium, they use a material called a moderator that slows the neutrons down, so that U-235 nuclei can grab them and break up afterwards, releasing more neutrons. A fast moving neutron from a fissioning U-235 nucleus enters the moderator, rattles around for about a thousandth of a second, and emerges as a slow moving neutron, one with only thermal energy left. It then induces fission in another U-235 nucleus. To be a good moderator, a material must simply remove energy and momentum from the neutrons without absorbing them. When a fission neutron leaves a good moderator, it has only thermal energy left. The best moderators are nuclei that rarely or never absorb neutrons and don't fall apart during collisions with them. Water, heavy water and graphite are the best moderators for nuclear reactors. They slow neutrons down to thermal speeds without absorbing many of them. Of these moderators, heavy water slows the neutrons quickly yet doesn't absorb them at all. However, heavy water is expensive because only 0.015% of hydrogen atoms are deuterium and separating that deuterium from ordinary hydrogen is difficult. The core of a typical thermal fission reactor consists of small uranium oxide fuel pellets, separated them at all. However, heavy water is expensive because only 0.015% of hydrogen atoms are deuterium and separating that deuterium from ordinary hydrogen is difficult. The core of a typical thermal fission reactor consists of small uranium oxide fuel pellets, separated

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

2014-04-06T02:08:00.001-07:00

There is no object in the Universe that doesn't rotate on its axis and our milky 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 centre to its edge. The whole system is rotating, but not like a solid body. Gravity makes its inner regions swirl round 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 kilometres 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 millions of other spiral galaxies show any signs of being wound up. One of the biggest puzzles facing astronomers today is to explain how spiral galaxies keep their shape.

Why is diamond so hard even through it is basically graphite, a substance used in pencil lead?

2014-04-06T02:02:00.002-07:00

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 diamond is diamond itself. Diamond, which is about 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 a hardness of between 1 and 2 on the Mohs' scale. The difference between hard carbon and soft graphite is caused by the arrangement of the 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.

Which is the oldest living tree in the world?

2014-04-03T19:16:00.001-07:00

For many years, a pine tree code named WPN-114 (photo, below) in the state of Nevada of the USA was known to be the oldest tree in existence. This tree was 4,862 years old, (possibly even more than that), when it was cut down by the United States Forest Service in the year 1964 for botanical research. It happened to be the 114th tree which was cut for the research, hence code named WPN-114. The circum-stances leading to cutting of this tree is controversial, yet, it was a sad end to the mighty tree. This tree was known as Prometheus (mythological character, who stole fire from gods and gave it to men) by the local people. However, in the year 2008, a spruce tree was discovered in Dalama, Sweden. Its age was determined to be 9,550 years by using the carbon dating process. This is known to be the oldest living tree in the world.

What is the size of the human DNA (Deoxyri-bonucleic acid) molecule?

2014-04-02T09:28:00.002-07:00

The chromosomes in the nucleus of a cell contain all the information a cell needs to carry on its life processes. They are made up of a complex chemical (a nucleic acid) called deoxyribonucleic acid or DNA for short. DNA is the hereditary material of all cells. It is a double-stranded helical molecule consisting of nucleotide monomers (building blocks of more complex molecules, called polymers). In the chromosomes of a cell, DNA occurs as fine, spirally coiled threads that in turn coil around another, like a twisted ladder (see picture). An adult human being has approximately 1,00,000 billion cells, and each cell has a twisted string of DNA. The width of each DNA is not more than 0.0000000001 centimetres. Size of all the DNA of a human body put together would be 175 cen-timetres. If we shrink the width to the thickness of a violin string, the length would extend up to 15 kilometres. How-ever, if we join the DNA of each cell end to end in its original size, its length would be nearly 175 billion kilometres—that's almost 12 times distance between the Earth and the Sun. It is a miracle of nature that we human beings go about our daily chores throughout our life carrying this immensely long string of DNA, within which incessant biological activity goes on round the clock.

A motor vehicle's engine capacity is expressed in CC, though traditionally it is measured by horse-power. What does CC indicate?

2014-03-21T00:45:00.003-07:00

The abbreviation stands for cubic centimetres, but it's not so simple as 'the volume taken up by the engine.' Cubic centimetres, as applied to motorcycle engine or automobile engine, is a measure of the combustion space in the cylin-ders. A typical engine works in four strokes of the piston in the cylinder:

The intake stroke: The piston moves down, sucking the fuel-air mixture into the cylinder.
The com-pression stroke: The piston goes up to compress the fuel-air mixture into a small space.
The power stroke: The fuel-air mixture explodes, pushing the piston back down.
The exhaust stroke: The piston returns to the top, pushing the exhausted gases out of the cylinder.

All internal combustion engines work in this way, though some have a 2-stroke cycle instead of a 4-stroke one. The size of an engine is measured by theoretically removing the top of a cylinder, pushing the piston all the way down, and then filling the cylinder with liquid. The cubic centimetres of liquid displaced (spilled out) when the piston is returned to its high position is the measure of the com-bustion area of that cylinder. If a car has four cylinders, each displacing 200 CCs, it has an 800 CC engine. It was for this reason Maruti Udyog's first car was known as Maruti-800.

What is the temperature inside a black hole?

2014-03-20T20:25:00.001-07:00

When a star reaches the final stage of its life, it often detonates in cataclysms known as supernovae. Such an explosion scatters most of a star into the void of space but leaves behind a large 'cold' remnant on which fusion no longer takes place. The gravitational pull of a black hole is so strong that even light rays cannot escape from it. The temperature of a black hole is estimated by scientists to be extremely cold. Temperature inside a black hole of the size of our Sun is estimated by scientists to be just 0.000001 degree above absolute zero (-273.10 degrees Celsius). However, temperature just outside the centre of a black hole can be immensely hotter due to extensive friction between other materials which move at the speed of light. At the outermost proximity of a black hole there is an event horizon, which separates the outer space and the command area of a black hole. This is also known as the point of no return. Once matter crosses this boundary, nothing, not even light can escape from within. Astronomers observing black holes through powerful telescopes cannot see beyond event horizon, and therefore, much of what oes on inside this remains shrounded in mystery.

Why does our finger nails grow faster than the toe nails?

2014-03-20T11:03:00.003-07:00

It is a fact that fingernails grow 3 times faster than the toenails. However, the exact reason for this is not yet known to scientists and doctors. While it takes about 6 months for a fingernail to replace itself from the root at a rate of about 3 millimetres per month, toenails take nearly 18 months to replace at a rate of about 1 millimetre every month. It is generally believed that the faster growth rate of the fingernails is due to greater blood circulation in the hands as com-pared to feet. Due to the same reason, a wound in the feet takes longer to heal as compared to a wound in the hand. Growth of nails occurs because a newly growing nail pushes the dead old nail cells upward. Due to higher blood circulation in the hand, the pace of regeneration of cells is also faster. As a result of this, fingernails grow faster than toenails.

Eating carrot will help you see in the dark

2014-03-08T18:57:00.002-08:00

There is a slice of truth in this claim, but certainly not as much as it is made out to be. The claim has its roots in World War II propaganda. The British spread the rumor that its fighter-bomber gunners could shoot down German planes (image, below) at night because these air warriors were eating a sizable number of carrots every day. The rumor was used to prevent the Germans from discovering that Britain had developed radar, which really can see in the dark. As it turned out, the radar proved to be a game changer during the Battle of Britain which began in July, 1940 and ended in May, 1941. The German air force retreated and vacated the British sky. But what was it about carrots that made the rumor plausible? A link between eye diseases and poor diet had been known for more than two thousand years, but it was not before 1913 that vitamin A was discovered and its deficiency was proved to be cause of night blindness twenty years later. Scientists found that the human body needs vitamin A to make the chemical retinal, without which our eyes cannot absorb light. However, only tiny amounts of all vitamins are necessary and overindulging in certain ones, particularly fat-soluble like vitamin A and D, can prove harmful. An excess of vitamin A in your diet (or ingested from supplement) can accumulate in your body, leading to toxic effects such as headaches, dizziness, vomiting, liver problems and, ironically, blurred vision.

Computers operate by means of the binary number system using only two digits 0 and 1. How does the system work?

2014-03-08T18:54:00.000-08:00

Electronic digital computers handle numbers in the binary form, which means that the ordinary or decimal numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 are written in binary notation as follows: 0, 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010. It is easy to deduce the rules from this. In essence, binary system works in the same way as decimal in that once all the symbols have been used in one column, another column is added to the left. In binary system:

Zero = 0

One = 1

Having used the two binary numbers for zero and one respectively, we have to add a column to the left just as we do after using the last digit 9 in the decimal system. Thus, in binary number system:

Two = 10

Three = 11

Again another column is added, followed by yet another column to represent subsequent numbers shown below:

One = 1

Four = 100

Five = 101

Six = 110

Seven = 111

Eight = 1000

Nine = 1001

Ten = 1010... \and so on.

Whereas in the decimal system each column represents additional power of ten, in binary each column represents an additional power of two. The point is you 'carry 1, i.e. move the digit 1 a place to the left, when you reach 2. In decimal notation, you move 1 a place left when you reach 10. In other words, instead of columns for units, tens, hundreds, thousand etc. the columns are for units, twos, fours, eights etc. So, in binary notation: '1 +1 = 0 with 1 to carry'. The advantage of the binary system for use in digital computers is that only two electronic states, off and on, are required to represent all binary digits, which in turn represent specific decimal numbers.

How do migratory birds mange to fly non-stop all the way to their breeding ground thousands of kilometres away?

2014-03-08T06:17:00.000-08:00

In preparation for their arduous journeys many migrant birds accumulate generous deposits of fat shortly before embarkation—as much as 50 per cent of total body weight in case of some birds. This fatty fuel is primarily in the form of high-energy triglyceride, which is different from structural body fats. A clear evidence of the role of fat as a fuel for migration comes from studies of the weights of migratory birds before and after they cross a large and hostile environment where feeding would be impossible. One banded North American bird belonging to Turn-stone species (photo above), flew from Alaska to the Hawaii Islands in 4 days, averaging over 1,000 kilometers per day. It weighed 174 grams when banded and 154.8 grams when recaptured—a loss of 19.2 grams. This is equivalent to flying 100 kilometers on just 1/2 gram of fat. An equally impressive long-distance travel-ler is the tiny Ruby throated Hummingbird (photo, below). Weighing about 4.5 grams of which 2 grams is fat, it can fly non-stop for 26 hours, consuming the fat at the rate of barely 0.69 calories per hour. At an average speed of 40 kilometres per hour, the bird's flying range would be about 1,050 kilometers easily enough to span the Gulf of Mexico!

What is the reliably measured highest and longest jump that a kangaroo has been able to achieve?

2014-03-04T05:59:00.002-08:00

There are over 50 species of the kangaroo family, the biggest of which-the Red kangaroo of the arid plains of central Australia. Adult Red kangaroos can grow to a height of 1.5 meters (5 feet) or more. Kangaroos are the only mam-mals, with the exception of man, to move mainly or solely on two legs. The small forelimbs are generally held clear of the ground while the enlarged well-muscled hind limbs provide the propulsion force for their bounding movement. Elastic energy that gets stored in the hind legs when the kangaroos land after a long or high bound powers the next leap. The greatest measured height cleared by a hunted kangaroo is 3.20 meters (10.5 feet) over a pile of lumber. During the course of a chase in January, 1951 a female Red kangaroo made a series of bounds which included one of 12.80 meters (42 feet). During the leaps, the kangaroo's long, thick and powerful tail acts as a counterweight, providing stability on landing.

Which ingredients are used for making ink for pen? What is the function of hole in the middle of the nib of a fountain pen?

2014-03-01T21:19:00.003-08:00

Ink is made from two main constituents, viz, colour pigment and liquid which can carry colour pigment via the nib. These constituents of ink are made from various substances. In some countries manufacturers use tincture of a wood known as logwood (such logwood trees grow profusely in Central America, Mexico and the West Indies). Natural colour of logwood is deep red but after long exposure to open air this wood automatically becomes blue-black. The ii pigment of this colour for makig ink is extracted through distillation. It is essential that colour of ink remains fast on paper and does not become blurred.

In order to infuse this property in ink manufacturers besides mixint43.5 grams pigment in each litre of distilled water add 5.0 gramsAolic acid, 7.5 grams ferrous sulphate and 1.0 gram tartaric acid. The ink of ball pen has to be viscous rather than liquid and should not evaporate like liquid. Therefore, a colourless viscous substance named ethylene glycol is used in manufacture of ball pen ink instead of distilled water. The line drawn by tiny bearing of ball pen is very thin. It does not spread automatically on paper so it does not become bold. To overcome this drawback about 20 times more pigment is used in making ball pen ink as compared with the ink for pen. The reason for a hole in the nib of a fountain pen is quite elementary and can be gauged with some focused reasoning. Just as tiny ball bearing performs basic work of writing in case of ball pen, split nib performs the work of writing by the pen. (See the diagram below). As the nib is placed on paper some light pressure that comes to be applied on it slightly widens the split of nib. This phenomenon brings internally stored ink via serrated feeders on to the split of nib through capillary action—and thus writing on paper commences. It is obvious that as the ink comes out it creates vacuum inside pen. The hole on the nib is the tiny window which lets in air to fill the vacuum. How can writing proceed unless there is equilibrium between internal and external atmospheric pressures?

In case of sore throat some doctors advise frequent gargling with salt water. What is the reason behind this?

2014-03-01T21:07:00.000-08:00

Soreness of throat is generally caused due to bacterial infection. (See the enlarged form of bacteria as seen under microscope in the accompanied photograph.) Bacteria are very stubborn microbes which can easily resist an ordinary substance like salt. But it is the elementary principle of osmosis which puts their survival on stake. Stated briefly the principle is that if a porous partition separates dilute and concentrated solutions then the dilute solution permeates through the porous partition into the concentrated solution. This process does not stop till the concentration of both the solutions is equal. Salt water is more concentrated than the water in bacteria. Once such water comes in contact with the bacteria, they gradually lose their body fluid. They cannot remain active after dehydration and wither and die before long. Answer to the question as to whether salt water fish can remain alive in fresh water and fresh water fish can remain alive in salt water is contained in the above explanation. The nature has covered bodies of both kinds of fish with skin which allows only one way traffic of osmosis. Dilute body fluid of sea water fish does not ooze out to mix with the concentrated fluid, i.e. sea water. So the sea water fish do not dehydrate and wither away like bacteria. Similarly the skin of fresh water fish does not allow dilute river water to seep into its body. The skins of both fish permit only one way passage.

Why does sliced potato or apple become dark if kept in open air for sometime?

2014-03-01T10:08:00.002-08:00

Two substances known as tyrosine and tannin which are present in potato and apple are responsible for this. Oxygen in the air oxidizes tannin within 10-15 minutes transforming it into polyphynol, which is dark brown in colour. Simultaneously oxygen transforms tyrosine into a black-coloured pigment named melanin.

FYI: There is abundant melanin in the skin of Negro people so they are black. Lesser the amount of melanin in the skin whiter is the complexion. Skin of European have very little melanin.

Why some medicines are in capsule form whereas others are in tablet form?

2014-03-01T10:00:00.002-08:00

There are a number of reasons. The manufacturers take into account the properties of medicines first. Chemical properties of some medicinenhange and efficacy reduce on their being exposed to humidity or oxygen in the air. Doses of such medicines have to be packed in capsules. A capsule also becomes necessary in case of bitter dose. If tablet form is essential then that tablet has to be coated with a tasteless material. Whether digestive system has to assimilate the dose immediately or gradually in the stomach is also an important matter to be considered. A dose meant to be assimilated gradually is best administered in the form of a hard tablet because capsule ordinarily made from gelatine is quickly dissolved by the acidic gastric juices of the stomach.

It is possible to give this kind of dose in capsule also provided that the dose is in granular form and not in powder form. In such a case overriding medical reason is assimilation of the dose in small quantities spread over a long period rather than assimilation of the entire dose in a few minutes.

How do plants manage to turn towards the light?

2014-03-01T01:04:00.001-08:00

It is easy to think of plants as inert life forms that simply sit at one place, soaking up sunlight and water. Yet plants are capable of some complex behavior. For example, plant gradually turn towards light sources to maximize the amount of energy they generate by photosynthesis—the process that takes place only when a plant is exposed to light. This inexorable orientation towards light is known as phototropism, which involves necessary adjustments to be made by the plant as it grows. The plant doesnot bend over as we humans do when we touch our toes; instead, it bends by growing in aparticular direction to reach out for light.A plant's growth movements are controlled by internal chemical substances When one side of a plant is in shade, a growth hormone called auxin moves to the darker side of the plant and causes that side to grow much faster. As can be seenin the accompanying illustration, more cells are produced in that side of the stem. Asa result, the stem becomes bent towards the light. A house plant set on a windowsill soon turns towards the outside and has to be rotated to maintain its shape.

How is a pearl formed inside the seabed oyster? Which has been the highest-priced pearl?

2014-03-01T00:34:00.003-08:00

Pearls are produced when a tiny piece of grit or sand becomes trapped inside the shell of an oyster. This irritates the oyster, which then produces a layer of what is called mother-of-pearl or nacre around the particle to prevent it harming the oys-tear's internal organs. (Mother-of pearl is a hard, iridescent substance produced by the oyster normally to coat the inside of its shell). Layer upon layer of mother-of-pearl is coated around the particle until a pearl is formed as shown in the diagram below. Pearls vary considerably in size and shape and no two pearls are exactly alike. Japanese? Bahraini and Tahitian divers free dive (i.e. without an oxygen canister) to collect the pearl-bearing oysters for which their regions are well known. In the past, thousands of oysters had to be collected to reap a handful of pearls, and for this reason pearls were a very valuable commodity.

Today, however, the farming of cultured pearls has dispensed with the need for harvesting natural pearls to make cultured pearl, a tiny pellet made from nacre or mussel shell is inserted into an oyster. The oyster then works to protect itself against the pellet and coats it in successive thin layers. Pearls come in various colors, but the most valuable pearls are white and silvery-white salt-water pearls. The highest price of $ 8,64,280 was paid by the buyer of an egg-shaped pearl weighing 15.13 grams. The pearl, formerly part of the French Crown Jewels was sold at Christie's, Geneva, Switzerland on May 21, 1988. •

Why are all the planets of the solar system globular in shape?

2014-03-01T00:21:00.003-08:00

Because one principle of physics has compelled them to be globular! Put in simple terms, the principle states that in the case of gigantic spinning object, its mass tends to concentrate towards the object's core. It is for this reason the planets took ball-like globular shape in the course of their formation. Only objects having round shape can rotate with minimum effort.

Your dog understands what you tell him

2014-02-24T23:40:00.000-08:00

It is now confirmed - your dog understands what you tell them .

Placing dogs in a MRI scanner , researchers from Hungary canine brain in the same way that the human brain reacts to sounds that are found .

Such as crying or laughing emotionally charged voice , perhaps explaining why the dogs are attuned to human emotions prompted similar responses .

Researchers in most species had the feeling of a common response . Feelings of their human owners of the dogs in this study significantly better tuning may be the first step toward understanding how .

The study " dog brain , like people , are sensitive to acoustic signals that feeling ," he says.

MRI brain scanner, 11 dogs trained scientists lay motionless . Something that had never been done before - that it's possible for both dog and human participants had to run on the same neuroimaging experiment .

Whining or crying or laughing, playful barking of the dog and the human voice range of about 200 when they both dogs ' and humans ' brain gain activities .

The images of the dog and the human brain , including in the areas of sound features .

That responds more strongly to other human beings , while the sound of wonder dogs react more strongly to other dogs .

The researchers also loaded the sound of the dog and the human brain processes emotional noted the striking similarities .

Both species , in an area near the primary auditory cortex lit up with the sound of happy than unhappy .

There were some differences : dogs , 48 % of all voice -sensitive brain regions other than the voices sound more robust response . That voice -sensitive brain regions, only 3% of the vocals sound more responsive versus non- vocal displays , including humans , are the opposite .

The findings of the noise produced at least 100 million years ago suggests that the last common ancestor of humans and dogs , the researchers say .

" Dogs and humans share the same social environment " in Hungary MTA - ELTE Comparative Ethology Research Group, says Attila Andics . " Our findings also uses methods of social information processing in the brain are similar to those suggested . Vocal communication between the two species successfulness of the base , " he added

Do viruses get sick or die like all living things?

2013-09-11T05:47:00.000-07:00

Death apart, years of debate have centred around the question of whether viruses are living or non-living things in the first place. This is because viruses (shown in blue along with red blood cells in the illustration below), unlike true microorganisms, are not cells, do not replicate by binary fission nor contain any genome (DNA or RNA) surrounded by protein coat. A virus can multiply only after it enters a host cell. Ironically when it injects its genetic material into a host in order to reproduce, all that remains of the invading virus is its protein coat. Technically, you could say its dead. A virus which has not gained access to a host cell can survive outside only under favourable conditions. When conditions change, it dies. Some viruses are destroyed by the ultraviolet rays in sunlight; others succumb to lack of moisture. Since viruses are disease-causing agents, we hardly think of them as vulnerable to sickness, but in a broad sense a virus can get infected by another one. For example, Hepatitis D virus can steal Hepatitis B's protein coat, thereby making it 'sick', i.e. weaker.

How actually far away is space from the surface of our planet?

2013-09-10T13:19:00.000-07:00

If you think space is thousands of kilometers away, let's see what the renowned British astronomer Sir Fred Hoyle had to say on the subject. 'Space isn't remote at all. It's only an hour's drive away if your car could go straight upwards.' With this striking perspective, he emphasized just how near we live to the alien world of space Actually, there is no clear boundary between Earth's layer of air and empty space, because our atmosphere peters out gradually with height. Nevertheless, scientists take a height of 100 kilometers as a convenient point to say that space begins. One may draw a somewhat specific line of demarcation and state that space begins at the altitude of 32 kilometers because thereafter you need a rocket to go further up. In the bustle of their everyday life, many people travel more than 32 kilo meters to get to work each day, but we don't have freedom to move upwards as easily as we can travel horizontally. The gravity holds us to the Earth's surface.

When lightning strikes the sea, what happens to all the fish? Do they die?

2013-09-10T13:11:00.001-07:00

Lightning is basically a bolt of high-powered electricity which prefers to travel along the path of least resistance, i.e. through a good conductor. Sea water, being salty, is a pretty good conduc-tor. Hence, one might infer that lightning hitting the sea would spread right through it, killing all the fish. In reality, that's not what happens, be-cause apart from the material's conductivity, the amount of material that the lightning encounters also influences its passage. The more stuff it has to go through, the more resistance there is to the electricity moving through it. There is millions of cubic meters of water where the lightning thunderbolt strikes So even though salt water is a good conductor, the electricity would not be able to pass through it all. Instead, it spreads across the surface of the water and soon dissipates.

How much carbon dioxide is emmited by car that travel 15 kilometreson a litre of petrol?

2013-09-04T09:13:00.000-07:00

The dominant greenhouse gas in a car's exhaust is carbon dioxide/CO2' but other gases are also important with respect to global warming. For example, nitrous oxide/N20 though emitted in smaller quantities, is about 300 times more potent greenhouse gas than carbon dioxide. Hence, the convention is to express a carbon footprint in terms of carbon dioxide equivalent (CO2e). Measured in this unit, com-bustion of a litre of petrol emits greenhouse gas equivalent to 3.15 kilogram of carbon dioxide. One can say this is the footprint of the car that burns a litre of petrol to travel 15 kilometres. However, the petrol's combustion accounts for only about three-quarters of the carbon story. The other quarter is caused by supply chain of the fuel: Getting it out of the ground, shipping it, refining it and getting it to the pump. Based on these calculations, your travel by car from Ahmedabad to Mumbai will have a 'footprint' of about 1'15 kilograms of carbon dioxide equivalent.