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    The mystery of time travel as it is portrayed in science fiction is not as simple as building a time machine. In fact, these fictional ideas require overturning Albert Einstein's special theory of relativity and somehow traveling close to the speed of light.      Physicists continue to ponder the possibilities of faster-than-light travel (FLT) and what it means for space exploration and our universe. The first example of faster-than-light speeds in popular culture occurred in the television series Star Trek, when "warp drive" sent spaceships traveling billions of light-years away in a matter of seconds. If this were possible, those space travelers might return to their original location and find that time had progressed at its usual speed, meaning 50 years may have passed during the short time the ship was absent, simulating time travel.     While most people view time as a constant, Einstein proved that time is relative to how fast an objec...

       Italian inventor Andrea Rossi really wants us to believe in cold fusion. He claims that his Energy Catalyzer, or E-Cat, a liter-sized device he designed, can output three times as much energy as it draws via low energy nuclear reactions, or LENRs As hydrogen passes over an electrified nickel-based catalyst, hydrogen nuclei supposedly fuse to the nickel, transmuting the metal into copper and releasing heat in the process. If we could harness that heat, the process could furnish cheap electricity banishing greenhouse simultaneously production gases-all creating any harmful waste.      There's only one problem: Cold fusion is almost certainly a myth. Backers aside, has yet to perform a truly independent test of his E-Cat; in most tests by third parties, Rossi handled the materials or was involved in some way. Critics argue that Rossi's device doesn't produce nearly as much energy as he claims and that his suggestion of building factories for large...

       Despite what you may have heard, diamonds are not forever. Given enough time, your sparkling rock will degrade into common graphite. The carbon atoms that constitute that diamond, however, are forever, or close enough. Stable isotopes of carbon are thought to enjoy lifetimes that extend far longer than the estimated age of the universe But not every atom of carbon lives forever.     Radioisotopes are forms of chemical elements with unstable nuclei and emit radiation during their decaying process to a stable state. Carbon-14, a radioisotope, is unstable, with a half-life of less than 6,000 years; after 5,730 years, there is a 50 percent chance that a carbon-14 atom will lose an electron and become nitrogen-14 (which is itself stable and the most common form of nitrogen on Earth).     Carbon-14 is the key element in carbon dating: Since radioactive carbon is only absorbed through respiration by living creatures, the date of their death can b...

       For more than 2,000 years, scientists have observed the unique phenomenon that, in some conditions, hot water freezes faster than cold water. In the fourth century B.C.E., Greek scientist Aristotle noted, “The fact that the water has previously been warmed contributes to its freezing quickly: for so it cools Sooner.      Seventeenth-century English scientist Francis Bacon noted, "slightly tepid water freezes more easily than that which is utterly cold.” Several years later, French mathematician René Descartes echoed his predecessors' observations, writing, "One can see by experience that water that has been kept on a fire for a long time freezes faster than other."      Given the centuries old knowledge that hot water does indeed freeze faster than cold in certain circumstances, it should have come as no surprise when Tanzanian schoolboy Erasto Mpemba claimed in his science class in 1963 that ice cream would freeze faster if it w...

     I t's easy to understand the theoretical minimum temperature: absolute zero.     The absolute maximum, on the other hand, is squirrely. "We just don't know whether we can take energy all the way up to infinity," says Stephon Alexander, a physicist at Dartmouth University. "But it's theoretically plausible.”    The most straightforward candidate for an upper limit is the Planck temperature, or 142 nonillion (1.42 x 1032) kelvins (K)— the highest temperature allowable under the Standard Model of particle physics. But temperature comes about only when particles interact and achieve thermal equilibrium, Alexander explains. "To have a notion of temperature, you need to have a notion of interaction."        Many cosmologists believe the hottest actual temperature in the history of the universe was several orders of magnitude cooler than the Planck temperature. In the first moments after the Big Bang, expansion occurred so rapidly tha...

    A nthropologists theorize that the first boomerangs were heavy projectile objects thrown by hunters to bludgeon a target with speed and accuracy. They were most likely made out of flattened sticks or animal tusks, and they weren't intended to return to their thrower—that is, until someone unknowingly carved the weapon into just the right shape needed for it to spin. A happy accident, huh?      Proper wing design produces the lift needed for a boomerang's flight, says John "Ernie” Esser, a boomerang hobbyist who works as a postdoctoral researcher at the University of California at Irvine's Math Department. “The wings of a boomerang are designed to generate lift as they spin through the air,” Esser says. “This is due to the wings' airfoil shape, their angle of attack, and the possible addition of beveling on the underside of the wings.” But a phenomenon known as gyroscopic precession is the key to making a returning boomerang come back to its thrower.   ...

       F or centuries, scientists debated the nature of light. Some claimed that light was a wave, behaving like a ripple in a pool. The opposing view was that light was a particle, like the droplets of water that flow from a kitchen faucet. Just when a prevailing view gained momentum, evidence for the other caused confusion. Finally, in the early 20th Einstein called a tie: Light is both wave and particle.     Those who believed in the particle theory of light followed Sir Isaac Newton. He described light as a series of particles, using a prism to prove his theory. To Newton, the clarity and sharpness of the  prism shadows meant that light traveled as a shower of particles, each following a straight line until disturbed. Those who opposed Newton’s theory followed scientist Christiaan Huygens, who cited light’s diffraction and interference as proof that it is a wave. Diffraction, the bending of light as it passes around an object, and interference, whe...