Mar 29, 2014

Sources of Energy – until 1859 when the first oil well in the United States was drilled in Pennsylvania

When the steam engine was invented at the beginning of the 18th century, most sources of fuel worldwide were the same as they had been for centuries: wood for cooking, oil for lighting, coal for heating and industry. The advent of commercially successful steam power in 1712 allowed for machinery and engines that were larger and more capable than any machines had ever been, catalyzing the dramatic changes of the Industrial Revolution. During the 19th century, continuous improvements to steam engine design transformed factories and built railroads across Europe and the Americas. Both inventors and engineers knew, however, that steam power had significant limitations. Steam must be generated by burning fuel, usually coal: and steam engines were large and bulky to allow for a furnace. The first steam-powered locomotive, invented in 1804 by the English engineer Richard Trevethick, was so heavy it broke the rails it rode on. From the earliest days of the Industrial Revolution, engineers looked for alternatives to steam that would allow for lighter, more powerful engines.

Internal combustion provided one such alternative. For centuries, inventors had imagined and tinkered with internal combustion engines; the medieval Arab scholar Al-Jazari described twin-cylinder reciprocating pistons in 1206, and Leonardo da Vinci sketched compressionless engines in 1509. The modem combustion engine was the British inventor Robert Street's 1794 model, which used exploding gas to drive the pistons.

Mar 22, 2014

Mar 15, 2014

A black hole is born …

The sun is of only average mass, starwise, and after burning through the last of its hydrogen fuel in about five billion years, its outer layers will drift away, and the core will eventually compact to become what's known as a white dwarf, an Earth-size ember of the cosmos.

For a star ten times as big as the sun, death is far more dramatic. The outer layers are blasted into space in a supernova explosion that, for a couple of weeks, is one of the brightest objects in the universe. The core, meanwhile, is squeezed by gravity into a neutron star, a spinning ball bearing a dozen miles in diameter. A sugar-cube-size fragment of a neutron star would weigh a billion tons on Earth; a neutron star's gravitational pull is so severe that if you were to drop a marshmallow on it, the impact would generate as much energy as an atom bomb.

But this is nothing compared with the death throes of a star some 20 times the mass of the sun. Detonate a Hiroshima-like bomb every millisecond for the entire life of the universe, and you would still fall short of the energy released in the final moments of a giant-star collapse. The star's core plunges inward. Temperatures reach 100 billion degrees. The crushing force of gravity is unstoppable. Hunks of iron bigger than Mount Everest are compacted almost instantly into grains of sand. Atoms are shattered into electrons, protons, neutrons. Those minute pieces are pulped into quarks and leptons and gluons. And so on, tinier and tinier, denser and denser, until. ..

Until no one knows. When trying to explain such a momentous phenomenon, the two major theories governing the workings of the universe – general relativity and quantum mechanics – both go haywire, like dials on an airplane wildly rotating during a tailspin.

The star has become a black hole. (Michael Finkel, National Geographic)

Mar 2, 2014

Water bears – micro-animals theoretically capable of surviving a space journey without protection

Tardigrades (also known as water bears or moss piglets) are water-dwelling, segmented micro-animals, with eight legs. They were first described by the German pastor J.A.E. Goeze in 1773. The name Tardigrada (meaning "slow stepper") was given three years later by the Italian biologist Lazzaro Spallanzani.

Usually, tardigrades are about 0.5 mm (0.020 in) long when they are fully grown. They are short and plump with four pairs of legs, each with four to eight claws also known as "disks". The animals are prevalent in mosses and lichens and feed on plant cells, algae, and small invertebrates. When collected, they may be viewed under a very-low-power microscope, making them accessible to students and amateur scientists. Their mouths have sharp pointy objects, called stylets. They use their stylets to cut into moss leaves or algae, their main foods. Then they suck the juices from the plant. Tardigrades live worldwide in moist land habitats, along rocky shorelines, and on the bottoms of streams, lakes, and oceans.