Wednesday, 29 August 2012

Theory of Light: It's History of Development

Light had always been a guide and a source of inspiration to humanity throughout the human history. Light is bright which gives humans life. The light coming from the stars including the sun has always amazed human beings. If there was no light there was no life. The light from stars has guided the sailors for centuries, has provided the signs of astrology, helped in forming the calendars, time and knowing the seasonal patterns.
In early Greece a scholar used light to measure the size of earth. He used a stick at two different angular positions on earth and measured the length of the shadows formed and through trigonometry determined the size of the earth. Newton showed that light is-composed of a spectrum of different colors representing different wavelengths through his prism experiment. When light falls on prism it is-dispersed into different wavelengths of light. Galileo used light from the heavens to discover different moons of Jupiter through his reflecting telescope.
There has always been debate about the nature of light. It was Newton who propounded the theory that light consists of corpuscles or particles. Light was supposed-to-be a beam of particles travelling at very high velocity. His theory faced opposition from Christian Huygens who argued that light travels in waves forming the crests and the troughs. Thereafter the behavior of light was-understood very little and there was no major breakthrough in the theory of light.
It was not until the eighteenth century that Thomas young performed his interference experiments to suggest that light is a wave. Light when made to pass through two small slits an interference pattern is-formed on the screen behind the slits. The pattern consists of alternate bands of bright and dark fringes formed by constructive and destructive interference of waves. Had light had been particle in nature the interference would not have occurred with these patterns. So the wave nature of light was finally accepted as the nature of light.
Is velocity of light constant? Velocity depends on medium in which it is travelling? It is a variable? These were some of the questions prevailing in the eighteenth century. Maxwell proved light to-be consisting of alternate waves of electric and magnetic fields. The equations Maxwell framed also proved light to-be travelling at a certain speed. At that time the space was-supposed to-be filled with ether which is a medium through which the light travels so light does not has a fixed velocity. Propagation of light through the ether determines its velocity. So whether light travels a fixed speed was a puzzle not solved till now.
The question what would be the speed of light to the observer moving at the speed of light or moving at half the speed of light was-thought by Einstein. It would take special theory of relativity that would prove that in whatever frame of note the observer travels, the speed of light will appear the same. So if whether you are in a spaceship or in a boat on still water, velocity of light will be the same for each observer. This was a remarkable observation that would change everything known about light. It was this assumption of constant velocity of light that would lead Einstein to propose his special and general theory of relativity.
However it would take a special experiment by Michelson and Morley of the United States to show that light travels at a constant speed. They would measure the light in two directions one perpendicular to the earth's rotation and the other parallel to the earth's rotation. Rotation of earth affects movement of ether, the medium through which light travels thereby affecting the speed of the light. But to their surprise they would find out that the speed of light is same in both the directions. Once this was-proved it gave credibility to Einstein's work. Hence it was finally proved that light travels at a constant speed.
Other great work was the Hubble's discovery of the expansionary universe. The light that came from the distant stars showed a characteristic pattern of spectrum showing that it is-red shifted. From Doppler Effect it was clear that the galaxies are receding away from each other. This new discovery gave stimulus to the theory of expansionary universe thereby abandoning the old static theory of the universe.
The debate whether light is a wave or particle continued till when the photoelectric effect experiment proved that light is-made of particles. The light when impact the metal sheets the fast-moving electrons in light would knock out the electrons in metal sheet. This proved the corpuscular theory of newton to-be right. But how it is possible that light has a particle as well as a wave nature? It sounds strange but this was possible that gave rise to a new physics of Quantum mechanics. Under this new field of study the electrons travels at the speed of light can show wave patterns. It was finally agreed that light can-be wave as well as particle. Hence the debate which was going on for centuries was finally settled and the discovery of particle nature certainly laid a new path for the field of physics to follow.
Light journeyed from it being a harbinger of life to its heated discussion among scientists about its nature for centuries. It would take two monumental works of interference and the photoelectric effect that would put an end to the question on the nature of light. Ultimately light neither has a particle nor a wave nature but a dual nature of wave as well as a particle.

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Window Into Arctic Life Seventy Million Years Ago

The Late Cretaceous of the Arctic - Not a Place for a Swim
A joint Canadian, Polish and United States team of scientists have braved Arctic conditions to research and report upon a 70 million year old ecosystem uncovered in the Arctic circle. Freshly excavated and mapped fossil bearing sediments in the Canadian province of Nunavut in the far north of Canada have provided a unique insight into the fauna of a Late Cretaceous sea. A number of new animals have been discovered plus a large amount of Plesiosaur material, ancient shark teeth, fossil sponges and even some prehistoric poo (coprolite).
Exploring Devon Island
First discovered by geologists surveying the northern tip of Devon island in the 1980s the sediments remained unexplored until the joint Polish, Canadian and American team set out to study this area in more detail. Their research has revealed that during the Late Cretaceous this area was much warmer than today and supported a rich ecosystem of marine life.
The paper detailing the team's research has been published in the Proceedings of the British-based Royal Society. Approximately 73 million years ago (Campanian faunal stage), this area was covered with a shallow, semi-tropical sea that supported a variety of strange and exotic creatures, including the long-necked, fish-eating Plesiosaurs. On the shore there were large conifer forests which would have thrived in the short Arctic summers, with perhaps migrating herds of duck-billed dinosaurs visiting the region to take advantage of the long daylight hours in the spring and summer months.
An Arctic Prehistoric World
The prehistoric world uncovered by the palaeontologists contrasts with the bleak conditions to be found on Devon Island today. It is uninhabited (in fact it is probably the largest area of land on Earth not to be permanently inhabited by people). A few birds are indigenous to the area, and some hardy musk ox scrape out a meagre living grazing on the lower slopes of the island's uplands.
One of the more exciting finds are the thick bones and armour-like scales of an unidentified type of fish, estimated to have grown to approximately 2 metres in length and a new species of sponge, preserved in three-dimensional perfection. The sponge, Nunavutospongia irregulara
, is named for the Canadian territory where it was found and was the subject of a separate paper published earlier in the academic Canadian Journal of Earth Sciences.
Held on Behalf of the Nunavut Government
All of the specimens are being held on behalf of the Nunavut government by the Canadian Museum of Nature in Ottawa, where palaeontologist Stephen Cumbaa, a co-author of the study along with other scientists is continuing the research.
Cumbaa said the "mystery fish
," which isn't likely to have been a major predator, does not look like anything else so far described in palaeontology. The research team are still trying to piece this puzzle together, but it probably represents a new family of armoured fish.
Plesiosaurs Dominated
The largest animals living in the area at the time seem to have been the Elasmosauridae (long-necked Plesiosaurs). These fish-eating marine reptiles reached lengths in excess of 15 metres. As a group they went extinct at the end of the Cretaceous.
Evidence of Asteroid Impact
Devon Island is also important to geologists and palaeontologists for a number of reasons. Firstly, it contains a number of important mineral resources and secondly, as it is the site of a remarkably well-preserved meteorite impact crater (called the Haughton impact crater). A large extraterrestrial body crashed into the island approximately 39 million years ago (Palaeogene Period). During this period the area was still relatively warm compared with today and there were forests covering the island. However, the cold climate of this region today has helped preserved the impact crater in pristine condition, permitting scientists to study the effect of such impacts in great detail.
The knowledge gained about meteorite impacts in the cold conditions of Devon Island have helped NASA scientists predict the likely conditions to be encountered when probes visit the planet Mars.

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Why Paint and Coating Companies Use Gloss Meters for Quality

Companies in the vehicle painting and coating industry rely on gloss meters for quality control and specific measurements that would be impossible with the naked eye. When vehicles are designed, part of that design includes how the paint will appear when the vehicle leaves the assembly line. The gloss meter allows for the creation of a specific level of gloss across all the vehicles in a given line.
Most vehicles today are coated with a gloss finish, which not only looks nice but acts as a protector against damage from heat, intense cold and other natural elements. But customers don't buy protection as much as they buy the way the vehicle looks. Instrumentation that helps manufacturers and refinishers of automobiles create beautiful, attractive finishes see these meters as high-tech sales tools.
Another use for gloss meters in the industries we're talking about is, they help inspectors detect poor quality paint. Incorrectly cured paint can result in unusual - and unacceptable - gloss levels on the body of a vehicle. This defective paint, later in the vehicle manufacturing process, can chip and flake. What does this technology mean for manufacturers? It means a way to prevent a huge re-coating effort and possibly a financially ruinous recall of vehicles.
Gloss meters perform their functions by measuring specular reflection. This type of reflection is related to the ratio of incident light and reflected light. It's the foundation determining the standards and measurement of gloss values. The meters must adhere to international standards, which cover how the instruments are to work as well as a long list of technical specifications.
Some gloss meters are small, portable devices that allow for multiple measuring angles of 20°, 60° and 85° that meet ISO, ASTM, DIN, BS and JIS norms. These meters may feature just two operational keys that let the technician access calibration, language, statistics, measurement and language settings. Additionally, the powerful memory of these instruments allow for the storage of and statistical calculations on as many as 999 measurements.
Less expensive models used in the auto painting and coating industries provide just one measuring angle - 60°. This model is an ideal gloss meter when a single function repeated over and over is all that's called for.
Most people don't realize the extent to which vehicle manufacturers and re-finishers go to create products with standard and consistent finishes. Before gloss meter technology was available, the best they could hope for was that someone in the company had a good-enough set of eyes to monitor how finishes were being turned out. Now, a simple handheld device does all the work.

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Tuesday, 28 August 2012

Triceratops Fossil Unearthed in Drumheller (Alberta, Canada)

Palaeontologists Excited by Triceratops Discovery
Scientists from the world-famous Royal Tyrrell museum based in the province of Alberta have been expressing their excitement at the discovery of a partial Triceratops fossil skeleton, found just thirty minutes drive from the museum's doors.
Triceratops is perhaps one of the most famous of all the dinosaurs. The name means "three-horned face" as this enormous, Late Cretaceous herbivore had two large horns, one over each eye and a third, smaller horn located above the naris. Although there have been a number of Triceratops fossils found in North America, particularly in the American state of Montana (the famous Hell Creek Formation) and in the Canadian province of Saskatchewan, fossils of this particular genus of Ceratopsian are extremely rare in Alberta.
Rare in Strata from Alberta
Most of the exposed Cretaceous strata in Alberta relate to sediments laid down between 76 million and 70 million years ago (including material from the Campanian faunal stage). Triceratops fossils are found in strata laid down at the very end of the Cretaceous period (Maastrichtian faunal stage). The fossilised bones of this herbivore were first spotted by a former Royal Tyrrell Museum employee whilst exploring a part of the Drumheller Badlands not known for its vertebrate fossils. A team of field workers under the supervision of the Museum's curator of dinosaur palaeontology Dr. Francois Therrien was dispatched and after about a fortnights excavation about 30% of the entire fossil skeleton was recovered.
A Muddle of Fossilised Bones
The bones of this dinosaur were jumbled up, a result of the remains of this animal being washed into a river and deposited in a slack part of water. When buried, the strata preserved what has been described by scientists as a "log jam of Triceratops bones". Some of the dorsal vertebrae are an impressive sixty centimetres tall with rib bones although cracked and broken in places, approaching two metres in length. Much of the specimen has already been transported back to the Royal Tyrrell Museum's preparation laboratories, the fossil bones protected by field jackets made up of burlap and plaster. The largest piece to transport was a single jacket measuring 2.5 metres by 1.3 metres and weighing more than two metric tonnes.
Palaeontologists Keen to Transport Fossils Back to the Museum
Although the fossil specimen is yet to be formally declared as Triceratops material, Dr. Therrien believes that based on the shape and size of the bones and the geological layer in which the fossils were found, it is very likely that what they have discovered relates to this famous genus of horned dinosaur. The Royal Tyrrell Museum may be world-famous for its vast collection of Cretaceous vertebrate fossils, but surprisingly it only has fragmentary Triceratops remains in its collection. With the newly discovered fossil material, the Royal Tyrrell Museum now has the opportunity to study associated bones from a single individual.
Museum staff are keen to start work preparing the fossils in readiness for display. Some of this work can be viewed by visitors to the museum as part of the preparation area of the museum is behind a huge glass fronted viewing area, which allows observers to see the care and dedication required to prepare fossil material for use in exhibits.

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