|SCIENCE TRIBUNE||Thursday, December 13, 2001, Chandigarh, India|
Peering into the dark ages
Death traps of nature
The firepower of our nuclear weapons may seem impressive but natural disasters put them to shame — instantly.
Floods, tornadoes, forestfires, hurricanes, lightening strikes, drought, torrential rains etc are among the many type of natural disasters known to occur but volcanoes and earthquakes are the quickest means of mass destruction known to layman.
Fortunately, both volcanoes and earthquakes spend most of their energy harmlessly, except in a few cases when they cause huge devastations in a matter of seconds.
More than 500 volcanoes are known to have erupted in the last 500 years and the Krakatova volcano in 1883 was measurable in hundreds of megatons explosion of TNT.
The magnitude of violence of earthquakes ranges from zero (barely perceptible tremor) to nine (catastrophic) and usually the scale of measurement is multiplicative or logarithmic: increase in one unit means a tenfold increase in energy released.
We don’t have such desperately instruments which could issue a genuine and confirmed "early warning" for earthquakes and volcanoes but we know some hints as how such an instruments would work. If everything goes well with the research being carried out in various laboratories — based on phenomenon discovered in laboratory experiments two decades ago — so called ‘Dilatency effect’ or dilatency theory which says: when a rock is squeezed, it deforms and eventually fractures but just before the fracture the rock swells due to opening and extension/widening of cracks. This increase in size or volume is the phenomenon of dilatency, which occurs when applied stress reaches about half of the breaking strength of rock.
At the dilatent conditions of rock, other measurable attributes change e.g. propagation of seismic waves through them, their electrical resistance and reduction in number of small tremors etc.
These and many more other factors would have to be considered by the scientists to devise a method which could help us predict such disasters as easily as tomorrow’s weather that we see on our TV daily.
But beware... the list of natural disasters does not ends at earthquakes. Unfortunately we do not have an earthquakes early warning machine: If we had one we would not let a single person fall victim to it. Unfortunately we could not save any one from more stranger kinds of natural disasters which we today are in a position to predict very accurately.
The danger of falling meteors, asteroids or comets is less easily dismissed. Our solar system contains uncounted billions and billions of rocks, from dust-motes to planetoids, the orbit of each is continuously influenced by combined gravity of everything else in the solar system, especially Sun and Jupiter! And thousands of tons of material from space fall toward earth each year but virtually all of it burns up before reaching the ground.
Some very large objects do come alarmingly close and occasionally something arrives which is big enough to lose only its outer skin on the way burning though our atmosphere.
Ignoring the atmosphere friction and orbital speed of earth around the Sun, a rough estimate of impact energy of a falling object towards earth at a speed of 40,000 kmph (the final velocity and object attains which falls to earth from infinity or a few million kilometres distance) has been calculated by the scientist and astronomers. Icarus, an asteroid which came within 6.5 million km of earth in 1968, is about 1 km wide and if it were to hit the earth, it would hit with 75,000 megaton explosion-dwarfing the power of all nuclear weapons of the world put together. Hermes, about 2 km in dia, will blast in with 220,000 megatons explosive power and Eros, another asteroid, would deliver 75 million magatons of explosive energy all in a matter of few minutes!!
The atmosphere is small protection against such monsters; they will flash through it in seconds producing a hot, scorching explosive shockwave. But 71% of earth’s surface is water and therefore there is 71 % chance that any falling body would hit the sea. But this does not make the difference as we have all witnessed the demo-version of a meteorite fall of 21 pieces of Comet Schumaker-levy on Jupiter on July 16, 1994. The Siberian meteorite that stuck near Tunguska on June 30, 1908, was only 30 to 60 m across and was estimated at 30 megatons impact energy — but its devastations remain clearly visible today. There are about 200,000 near earth asteroids of size about 100 in dia and population of those of dia 1000 m or more is thought to be 1,600. It was too a meteorite impact which eventually brought an end to the dinosaur kingdom.
Another possibility in the list of natural disasters is the falling of earth into the Sun! But only a collision with a very large asteroid like Ceres — which is estimated at delivering 12,000 billion megatons impact energy — could significantly shift the earth’s orbit and the collision itself would sterilise the earth (and destroy our moon too)!!
Another possibility is that of a supernova explosion — which if any star ( within 15 light years range) would undergo — the effects are hard to predict.
Still more rare chance is that a large planet with very low reflectivity or a mini-blackhole could indeed approach our solar system without our knowledge as only bright objects (in visible, UV or IR spectrum) can be seen with our telescopes.
And at last, science-fiction warns us with rarest of all (but not negligible) possibilities... if our universe contains some big chunks of antimatter floating in space... one of them might land on earth as an antimatter meteorite. If this antimatter meteor weighs a modest 10 tons it would react with equal amount of ordinary matter-soil-with an explosion of 400,000 megatons!
Peering into the dark ages
Astronomers have finally seen the shadows of the first atoms that formed after the big bang, a finding that should allow them to pinpoint when the "cosmic dark ages" ended and the first stars and galaxies began to light up the space.
The cosmic dark ages stretched roughly from 300,000 to 900,000 years after the big bang. They began when the fledging universe cooled to 3000 kelvin, cold enough to allow electrons and protons to stick together to make light-absorbing hydrogen atoms.
They ended when galaxies of stars formed from the hydrogen shone brightly enough to ionise the remaining hydrogen gas, turning it back into a thin, translucent plasma of electrons and protons, a report in New Scientist said.
No one has peered into the dark ages to see the first stars lighting up. But now the astronomers have found the shadow of the primordial hydrogen in light from the most distant quasar known, which lies around 14 billion light years from earth.
This quasar appears to have burnt towards the end of the dark ages, says Robert Becker, an astrophysicist at the University of California, Davis.
The quasar’s light that reaches earth lacks wavelengths in a telltale range, Becker’s team says in a report submitted to the Astronomical Journal. The observation implies that 14 billion years ago, space contained hydrogen gas that soaked up this part of the quasar’s radiation.
Astronomers had hunted for a quasar with this hallmark gap in its spectrum since it was predicted 35 years ago. But finding one is difficult because these distant objects are extremely faint. "It’s really been a question of getting telescopes and databases big enough to see far enough back," Becker says.
Indeed, to find the quasar, Becker and his colleagues had to use three different telescopes. They first spotted the quasar using the Sloan Digital Sky Survey’s 2.5 metre telescope at the Apache Point Observatory in New Mexico. They then studies its spectrum with a second 3.5 metre telescope at Apache Point and with the 10-metre Keck II telescope at Mauna Kea in Hawaii.
The researchers would like to confirm their result by spotting other similar quasars. But ground-based observatories may struggle to see any further into the dark ages.
Because of the expansion of the universe, light from more distant objects is stretched to near-infrared wavelengths and beyond. Optical telescopes do not detect such radiation and ground-based infrared telescopes can not see very faint objects through the warm glow of the earth’s atmosphere. PTI
NEW PRODUCTS & DISCOVERIES
Next big step in walking
It is not a hovercraft, a helicopter backpack or a teleportation pod.
The mystery transportation device developed by the award-winning inventor Dean Kamen - the subject of continuous fevered speculation since provocative clues and predictions surfaced in media reports last January - is not hydrogen- powered, a favored theory in Internet discussions. Nor does it run on a superefficient Stirling engine (yet).
But if the public’s collective yearning for Jetsonian travel technology must remain unrequited, at least the speculators have their curiosity satisfied.
Mr Kamen has demonstrated a two-wheeled battery-powered device designed for a single standing rider. Its chief novelty lies in the uncanny effect, produced by a finely tuned gyroscopic balancing mechanism, of intuiting where its rider wants to go - and going there.
The device, the Segway Human Transporter, better known by its former code-name, Ginger, can go up to 12 miles an hour and has no brakes. Its speed and direction are controlled solely by the rider’s shifting weight and a manual turning mechanism on one of the handlebars.
"You might ask, `How does it work?’ " said Mr Kamen, mounting one of the devices recently on a test track at his company’s headquarters in Manchester, N.H. "Think forward," he said, inclining his head ever so slightly and zooming toward a reporter. "Think back," he continued, effortlessly reversing course.
Tilt sensors monitor the rider’s centre of gravity more than 100 times a second, signalling to the electric motor and wheels which way to turn and how fast.
Mr Kamen says the much anticipated unveiling comes now because he has had time to file for crucial patents on the technology and is ready to test it publicly.
The United States Postal Service, the National Park Service and the City of Atlanta plan to begin limited field tests of the devices early next year. Amazon.com and several companies that make parts for the Segway, including GE Plastics and Michelin North America, plan to use the devices to try to save money by reducing the time it takes employees to move around corporate campuses and large warehouses.
At an average speed of 8 miles an hour, or three times walking pace, Mr Kamen says the Segway can go 15 miles on a six- hour charge, for less than a dime’s worth of electricity from a standard wall socket.
It has been billed as "doing for the car what the car did for the horse and cart". Mr Kamen claimed that it would fill a niche for those who need something faster than walking but slower than driving: "Nothing has happened at the level of the pedestrian to improve transportation since we invented the sneaker," he said.
Ethnicity specific Bio-weapons
Biological weapons that would attak one ethnic group but leave untouched are possible, according to scientists who warn of the attractiveness of such weapons to terrorists.
They refer to the 1999 study by British Medical Association indicating that genetic weapons could be available within ten years.
Two major genetic research developments were singled out in the study. The Human Genome Project and the Human Genetic Diversity Project (HGDP) are allowing the identification of human genetic coding and differences in genetic material between different ethnic groups.
The BMA points out that "if there are distinguishing DNA sequences between groups and if these can be targeted in a way what is known to produce a harmful outcome, a genetic weapons is possible.
International concerns about the potential application of genetics research to weapons production were underscored in October 1996 when the World Medical Association (WMA) spoke about the possible abuse of genetic knowledge, according to a January 1999 report published by Monash Bioethics Review from Britain.
At its eighth general assembly meeting in South Africa, the WMA adopted a statement saying, "the potential for scientific and medical knowledge to contribute to the development of new weapons systems targetted against specific individuals, specific populations, or against body systems is considerable."
The opinion was, however, contradicted by HGDP, which stated that "genocidal use of genetics is not possible with any currently known technology." PTI
Tiny organic Transistors
American scientists at Bell Lab have created organic transistors with a single-molecule channel length, setting the stage for a new class of inexpensive and easily assembled molecular electronics based on compounds of carbon.
The scientific breakthrough has been reported in October 18 issue of the journal Nature.
A transistor is a three-electrod, semiconductor device, conventionally made of an inorganic semiconductor like silicon. It amplifies electrical signals and acts as an electronic switch. The transistor’s channel is the space between two of its electrodes that influences the transistor’s current output and switching speed.
Bell Labs scientists Hendrik Schon, Zhenan Bao and Hong Meng have now fabricated molecular-scale organic transistors made out of compounds of carbon, which can rival silicon transistors in performance.
"When we tested them, they behaved extremely well as both amplifiers and switches", the researchers said in their report.
Though still a prototype, the demonstration of a simple circuit indicated that molecular-scale transistors could one day be used in computer microprocessors and memory chips, which could squeeze thousands of times as many transistors as are found in circuits into the same amount of space, the report said. PTI
Cleaning sewage after flooding
Researchers have designed a low-cost mechanical device capable of screening storm sewage thereby preventing a possible risk of a wider spread of an epidemic to the health of nearby and distant people.
Torrential rainfall, storms and hurricanes and their attendant environmental disasters have become frequent occurrences worldwide.
To combat this, there is a growing industry of technological development designed to minimise the impact of natural disasters and help restore life to normality.
This is increasingly being manifested in the water industry where contamination of sources such as streams and rivers after floods can result in an epidemic, a report in British Commercial News said.
Consequently, Hydrok UK, an engineering company based in south-west England, has introduced the Airmex, a low-cost mechanical screen device for cleaning up storm overflows.
During storm and flooding, the Airmex screens the storms sewage through stainless-steel wedge wire, with an aperture of six millimetres by six millimetres, thus providing a high protection for the receiving waters.
The screen is physically cleaned by a mechanical brush inside and outside of the wedge wire. The brush mechanism is activated and deactivated by a non-fouling level float opening and closing an air-feed cylinder. PTI
1. This Persian scientist who was born in 1050 and died in 1123 is known more for his poetry, especially his classic poem titled "Rubaiyat", than for his scientific work. Can you name this astronomer and mathematician?
2. This "dog", found in South Dakota, has a face like that of a common dog and its body structure resembles that of a mouse/squirrel. It makes burrows in the ground and lives in them. What is this dog called that feeds on green grass only?
3. What is the property of metals called due to which these can be drawn into thin wires beyond their elastic limit without being ruptured or borden?
4. We know human life exists till the heart beats. For how long does the human heart remain still in one’s lifetime?
5. ATP and NADP molecules transfer energy in living systems. Plants also use these compounds to harness the sun’s energy to convert atmospheric carbon dioxide and water into sugar and oxygen. What are the full forms of ATP and NADP?
6. This fruit is rich in enzymes pepsin and papain, B-carotene, pectin, iron, potassium, vitamin C, etc. It is useful for all types of stomach ailments, can cure piles, help maintain proper blood pressure and protect against cancer. Its seeds are also useful in liver ailments. Which is this fruit that is low on calories and fat?
7. In Internet technology, what is a network called that interconnects several other networks together?
8. When suitable ultrasounds fall on water, bubbles are formed in water which collapse in a very short time. During this process pressure and temperature inside the bubble become so high that the pollutants present in water get destroyed. What is this process called which can be used for cleaning water?
9. Light therapy can be used to treat winter depression. This therapeutic light stimulates the production of a substance called ROS in body’s tissues which play a role in a number of biological and brain functions. What is the full form of ROS?
10. Which important astronomical object will appear in the skies in 2061?
1. Omar Khayyam