Physics

"Designed materials are probably best illustrated by composites, which allow us to reinforce materials at the right places and in the right amounts to minimize weight and produce the desired mechanical properties. The graphite tennis racquet, golf club shaft, and fishing rod are all products of this designed materials revolution, as are the wings of new high-performance aircraft such as the Harrier."

"Among the most fascinating remains of many ancient civilizations are their elaborate time-watching devices. Great stone structures like Stonehenge, in Southern England, and the 4000-year-old passage grave of Newgrange, near Dublin, Ireland, that have challenged anthropologists and archaeologists for centuries, have proved to be observatories for watching the movement of heavenly bodies. Antedating writing within the culture, often by centuries, these crude clocks and calendars were developed by people on all parts of our globe."

"You will definitely feel microgravity conditions at the amusement park, because your apparent weight may feel less than your actual weight at times. The sudden changes in motion create this effect. We can now define microgravity more precisely than we did previously to be “an environment where your apparent weight is less than your actual weight.” At the park the key to this condition is free fall. Think of a steep roller coaster hill. Gravity pulls the coaster car down towards the center of Earth. When not in the state of free fall, between the coaster and the ground is a rail that pushes up on the car to keep the coaster from falling to the ground."

"Along with breaking the Japanese diplomatic cryptosystem, usually referred to as PURPLE, probably the greatest example of Allied cryptanalytic success in World War II was the breaking of the German Enigma machine. This cryptodevice was used by all of the German armed forces as the primary cryptosystem for all units below Army level or the equivalent. As D-Day approached, other German cryptodevices, the SZ-42 and the various T-52 machines, assumed great importance since they were used by the higher commands of the German armed forces. Many references to these German machines in the histories fail to provide information on what they looked like or how they worked."

"The Enigma cipher machine is one of the best known cipher machines in the world. Initially broken by Polish cryptanalysts, Enigma decrypts from British and later American efforts were given the covername ULTRA to reflect the value of the information. Today the Enigma stands as a silent sentinel to the folIy of those who placed their absolute confidence in its security. But it also stands in renowned tribute to the cryptanalysts who pitted their minds against a problem of seemingly invincible odds and who scaled its lofty heights."

"Black holes cannot suck matter into them except under certain conditions. If the sun turned into a black hole, Earth and even Mercury would continue to orbit the new sun and not fall in. There are two common cases in the universe in which matter can be dragged into a black hole. Case 1: If a body orbits close to the event horizon in an elliptical orbit, it emits gravitational radiation, and its orbit will eventually decay in millions of years. Case 2: A disk of gas can form around a black hole, and through friction, matter will slowly slide into the black hole over time."

"Heat is efficiently transferred across a narrow air gap from a stationary base to a rotating structure that combines the functionality of cooling fins with a centrifugal impeller. Because low-thermal-resistance CPU coolers are particularly susceptible to performance degradation due to cooling-fin fouling (a thin layer of dust can easily increase thermal resistance by a factor of two), the added benefit of immunity to fouling is also a crucial performance specification."

"Aerogels Insulate Against Extreme Temperatures. In 1992, NASA started to pursue the development of aerogel for cryogenic insulation. Kennedy Space Center awarded Small Business Innovation Research (SBIR) contracts to Aspen Systems Inc., of Marlborough, Massachusetts, that resulted in a new manufacturing process and a new flexible, durable, easy-to-use form of aerogel. Aspen Systems formed Aspen Aerogels Inc., in Northborough, Massachusetts, to market the product, and by 2009, the company had become the leading provider of aerogel in the United States, producing nearly 20 million square feet per year. With an array of commercial applications, the NASA-derived aerogel has most recently been applied to protect and insulate people’s hands and feet."