Top 10 Scientific Discoveries

1. The Pythagorean Theorem. It's a staple of high school geometry: in every right triangle, a² + b² = c² , where a and b stand for the two short sides and c for the long. The first to prove this was (probably) the Greek philosopher Pythagoras in the 6th century bc. But it's not the theorem per se that matters; it's the bigger idea it reflected. Pythagoras taught that numbers were the real reality, that the core of the physical world was mathematical. That's why he went around telling everyone, 'Here's a pure idea that is true of every actual object of a certain shape.' Coupling physics to mathematics proved to be one of the most fruitful marriages of all time. Even now we regard a scientific theory as really reliable if it can be proven mathematically.

2. The existence of microorganisms. In the late 1600s, when microscopes were new, Dutch lens maker Antoni van Leeuwenhoek scraped some plaque off his own teeth and looked at it through a microscope. Gasp! It was crawling with "animalcules." In fact, tiny creatures invisible to the naked eye abounded everywhere, he found. Less than two centuries later, knowledge of this invisible universe enabled Louis Pasteur to construct his "germ theory of disease,"which in turn enabled doctors to conquer a whole host of diseases: typhoid, typhus, polio, diphtheria, tetanus, smallpox tuberculosis, anthrax--the list goes on. The leading cause of death changed after that from infectious disease to heart disease, cancer, and "old age." See Bacteria.

3. The three laws of motion. Pythagoras would have been so proud of Isaac Newton! More than any scientist in history, this 18th-century Englishman succeeded in reducing physics to mathematics. Newton came up with three laws to explain the motion of all objects in the universe, from runaway trains to orbiting planets. (He also invented differential calculus, explained gravity, and discovered the spectrum*--not bad for one lifetime.)

4. The structure of matter. In 1789, five years before he was beheaded by a guillotine, French chemist Antoine Lavoisier published a list of "elements"--substances that he said could not be broken down further by any chemical process. His list was incomplete and contained mistakes, but he was onto something. Building on his work, chemists developed our modern view that all matter can be broken down into just 109 elements, that all elements are made of atoms, and that all atoms are made of just three types of particles--protons, neutrons, and electrons.

5. The circulation of blood. Each person has a fixed amount of blood circulating throughout his or her system in one fixed direction. This fact, first discovered in the 12th century by an Arab doctor named Ibn al-Nafīs*, was rediscovered--for good, this time--by the 17th-century English doctor William Harvey. Harvey's work opened the floodgates to research a full understanding of the physiology of living bodies, human and animal. See Circulatory System.

6. Electrical currents. Ancient people knew about static electricity--rub something and it gives off a spark. They knew about lightning bolts--get struck by one and you're dead meat. But not till 19th-century scientists (such as Alessandro Volta*) got electricity to flow did people become aware of this as a distinct force. Today, electricity powers everything from light bulbs to computers, of course. But the discovery of electricity is bigger than its practical applications. Once scientists knew about this force, they couldn't stop wondering what it was. That's when they discovered that electricity, magnetism, radio waves, and light are all different versions of one underlying force, a glue that holds the universe together.

7. The Evolution of Species. People used to think that every life form now on Earth was here from the start--that no new species had been born and none had ever changed. Charles Darwin's theory of evolution, developed in the 19th century, revealed the dynamic nature of life on Earth. The word "theory" leads some to think that evolution itself remains controversial among scientists, but actually, no mainstream scientist doubts that old species die out and new ones come into being. It's only the exact mechanism of evolution that remains in play, and modified versions of Darwin's idea of evolution by random natural selection still dominate biological thought.

8. Genes. Gregor Mendel never described a gene, saw one, or used the word, yet this shy Austrian monk uncovered the principals of heredity simply by breeding snow peas, charting his results, and drawing brilliant conclusions. Mendel found that parents pass distinct traits to their offspring in combinations governed by predictable laws. Scientists soon decided some actual thing must carry these traits and coined the word "gene." Only in 1953, did Francis Crick and James Watson really figure out what genes are. That year, they discovered the structure of DNA, a molecule shaped like a twisted ladder and contained in every cell. Genes, it turns out, are the combinations of chemicals that form the "rungs" of this ladder. See Genetics.

9. The four laws of thermodynamics. In the 18th century, a series of scientists from Nicolas Carnot* to Baron Kelvin, Rudolf Clausius*, and others found four laws, just four, that governed the transformation of energy into work in any system--a locomotive, a body, a bonfire, a solar system, the universe--you name it. Engineering and inventions, especially of heat-engines, could not have moved forward without knowledge of these laws, for anything that runs on fuel is bound by them. But the laws of thermodynamics* have vast implications for the universe has a whole, not the least of which is this: The total amount of disorder is always increasing.

10. The dual nature of light. Newton learned that light behaves like a wave. Later, other scientists learned that light behaves like a stream of particles. So which is it--wave or particle? It can't be both--or can it? Early in the 20th century, Neils Bohr, Max Planck, Albert Einstein, and others discovered that yes, light is both wave and particle.This paradox gave rise to quantum mechanics, the dominant achievement of 20th-century physics and our deepest current description of "what the universe is really made of." But the quantum picture of reality can't be "pictured." It goes against intuition and laughs at all our senses. The only way to understand the sub-subatomic world of quantum mechanics is mathematically--which brings us right back to Pythagoras.

Source : Encarta

The Physics of Slapshots and Mid-ice Collisions

When two NHL hockey players collide, their pads and body tissues can absorb enough energy to power a 100-watt light bulb for a minute and a half. During the 60 minutes of a hockey game, players can burn 6,000 calories and lose up to 15 pounds.

These are the calculations of Alain Hache, a physicist at the University of Moncton in New Brunswick, Canada. An amateur goalie, Hache has combined two of his passions in his book The Physics of Hockey.

Hache begins his look at one of the north’s favorite sports by examining the physical properties of ice, one of Alaska’s most abundant natural resources. Friction at the contact points between surfaces is what slows most sports down, but the low friction coefficient of ice makes hockey players faster on their feet than the athletes of any other team sport. Many NHL players can skate faster than 25 miles per hour, and Hall of Famer Bobby Hull was once clocked at 29.3 miles per hour. Scientists once tracked Hull during a game and calculated that he had skated more than eight miles during his 29 minutes on the ice.

While everyone agrees that ice is slippery, scientists have long debated the reasons why. Hache wrote about a study in the year 2000 by researchers at the University of California at Berkeley that revealed one of ice’s slicker secrets. The California scientists used an atomic microscope to find a thin, wet layer of quasi-fluid water on the surface of an ice crystal. That layer provides a lubricant, even when ice is very cold. Without it, the friction of ice would be comparable to concrete, Hache wrote. This microscopic wet layer and other physical properties of ice make a sharpened skate on ice one of the fastest non-motorized ways of propelling the human body. Though downhill skis move fast, the friction between a waxed downhill ski and snow is 10 times greater than that between a steel skate blade and ice.

Using the magical surface of ice to combat friction, hockey players are able to generate incredible amounts of energy. Hache calculated that 180-pound Colorado Avalanche forward Paul Kariya has more kinetic energy while skating at full speed than does a charging National Football League lineman of 300 pounds. He also calculated that a hockey player’s pads and flesh will compress as much as four inches during a collision with another player.

A goaltender on a series of teams since his youth, Hache devotes a chapter of his book to facts about that position. A goalie’s huge leg pads and other equipment cover 60 percent of a shooter’s target, the 4-by-6 foot goal made of red pipe and netting. Those leg pads, which cover 20 percent of the net space all by themselves, are made of leather and light synthetic padding because a hard plastic shell would allow the puck to bounce too far.

Hockey players have blasted slapshots faster than 100 miles per hour using a three-stage process, Hache wrote. First, a player rotates his torso and stick in an accelerated motion toward the puck. Next, his stick blade touches the ice and the puck as the stick bends for a fraction of a second, storing energy like a loaded spring. The puck accelerates off and the stick returns to its original shape as the player completes his swing. The puck rockets toward the goal as the player converts angular momentum (stick and torso swing) to linear momentum (the puck traveling a straight course for the goal).

Players mastering this technique include Al MacInnis of the St. Louis Blues, who won the 2003 NHL hard shot competition with a speed of 98.9 miles per hour, and the retired Al Iafrate, whose slapshot registered 105.2 miles per hour in 1993.

Source : University of Alaska Fairbanks