Snappy Science: Stretched Rubber Bands Are Loaded with Potential Energy!

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What is Quantum Gravity [Video]

The force of gravity is the lost sheep of physics, and physicists have struggled for the best part of a century to unite it with the rest of their flock of particles and forces. An unexpectedly fruitful approach has been to think of how gravity might operate if space were only two-dimensional. By simplifying the problem, they hope to get to the heart of what gravity is and then apply the lessons to our higher-dimensional space.

Quantum Gravity in Flatland (preview)

From its earliest days as a science, physics has searched for unity in nature. Isaac Newton showed that the same force responsible for the fall of an apple also holds the planets in their orbits. James Clerk Maxwell combined electricity, magnetism and light into a single theory of electromagnetism; a century later physicists added the weak nuclear force to form a unified “electroweak” theory. Albert Einstein joined space and time themselves into a single spacetime continuum.

What Thawed the Last Ice Age?

Roughly 20,000 years ago the great ice sheets that buried much of Asia, Europe and North America stopped their creeping advance. Within a few hundred years sea levels in some places had risen by as much as 10 meters--more than if the ice sheet that still covers Greenland were to melt today. This freshwater flood filled the North Atlantic and also shut down the ocean currents that conveyed warmer water from equatorial regions northward. The equatorial heat warmed the precincts of Antarctica in the Southern Hemisphere instead, shrinking the fringing sea ice and changing the circumpolar winds. As a result--and for reasons that remain unexplained--the waters of the Southern Ocean may have begun to release carbon dioxide, enough to raise concentrations in the atmosphere by more than 100 parts per million over millennia--roughly equivalent to the rise in the last 200 years. That CO2 then warmed the globe, melting back the continental ice sheets and ushering in the current climate that enabled humanity to thrive.

Flame Retardants May Create Deadlier Fires

In one of the deadliest nightclub fires in American history, 100 people died at a rock concert in Rhode Island nearly a decade ago. But the biggest killer wasn't the flames; it was lethal gases released from burning sound-insulation foam and other plastics.

Shooting for the Moon [Slide Show]

Right now, twenty-six groups of scientists, engineers and students from around the world are competing to be the first non-government team to get a rover on the moon by 2015. In this month's issue of Scientific American , Michael Belfiore explores what the Google Lunar X PRIZE competition means for the future of private spaceflight and tells the story of one of the most impressive teams - team Astrobotic. In this Web Exclusive, take a behind-the-scenes look at Astrobotic's preparations for a trip to the moon.

Is It Possible to Build an "Unsinkable" Ship?

The claim that the RMS Titanic was "practically unsinkable" may have been more a marketing tactic than a commentary on its engineering, but its prelaunch reputation of being impervious to the perils of the high seas has lingered for the past 100 years. [More]


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Bots of Burden: U.S. Army Recruiting an Array of Animal-Inspired Robots to Assist Battlefield Troops [Video]

Three of the U.S. military's newest recruits reported for duty this week at the Army Test and Evaluation Command . These troops are different from normal soldiers in several ways--for starters, each has six feet. And they are robots designed to look and move like cockroaches. Aside from those details, the Army is hoping its new Boston Robotics RHex bots will soon join grunts in Afghanistan. [More]


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Primeval Precipitation: What Fossil Imprints of Rain Reveal about Early Earth

Some 2.7 billion years ago in what is now Omdraaisvlei farm near Prieska, South Africa, a brief storm dropped mild rain on a new layer of ash laid down by a recent volcanic eruption (not unlike ash from the 2010 Eyjafjallajökull eruptio n in Iceland) forming tiny craters. Additional ash subsequently buried the craters and, over eons, hardened to become rock known as tuff. Closer to the present, other rainstorms eroded the overlying tuff, exposing a fossil record of raindrops from the Archean eon, and may now have revealed the density of early Earth's atmosphere.

New Maps of Mercury Show Icy Looking Craters on the Solar System's Innermost Planet

THE WOODLANDS, Tex.--Mercury is a world of extremes . Daytime temperature on the planet closest to the sun can soar as high as 400 degrees Celsius near the equator, hot enough to melt lead. When day turns to night, the planet’s surface temperature plunges to below –150 degrees C.

Small Reactors Make a Bid to Revive Nuclear Power

Small may be beautiful for the nuclear power industry So argue a host of would-be builders of novel nuclear reactors. While the U.S. government has not given up on investing in large units that boast conventional designs, the Department of Energy has also announced the availability of $450 million in funds to support engineering and licensing of so-called " small modular reactors ."

Pupfish, Downfish: Subterranean Tsunami Gives Vertical Shakes to the Water-Hole Home of Endangered Fishes

On March 20 a National Park Service biologist named Jeffrey Goldstein and I descended a rocky incline into the mouth of Devils Hole, a collapsed cave in the Nevada desert 40 miles south of the visitor’s center in Death Valley. Thirty feet down, an arm of water extends out from a deep pool to cover a rock shelf the size of a Ping-Pong table with up to two and a half feet of hot water. This shallow recess is home to 100 much-studied adult Devils Hole pupfish, or Cyprinodon diabolis . Living nowhere else on the planet, the pupfish receive protection from human harm by force of federal law and padlocked gates.

Controversy Surrounds Russia's Claim that Cosmic Rays Caused Mars Mission Failure

A heartbreaking, out-of-the-gate failure of Russia’s sample return mission early this year created a wide circle of disappointment. For Russia, it was supposed to be a "cavalry charge" toward a hyperambitious goal that would have redeemed a quarter-century of interplanetary impotence but instead became a cosmic humiliation when the craft died shortly after liftoff. For planetary science, it meant that the composition of the Martian moon Phobos remains speculative and its origins still undetermined. For future human space strategies, the possibility of obtaining valuable supplies of oxygen en route to Mars , as the Phobos-Grunt mission was intended to determine, remains uncertain.

Evidence for Flowing Water on Mars Grows Stronger

THE WOODLANDS, Tex.--Today's Mars is a frigid desert, a place where water--the key to life as we know it--has gone into hiding. Whatever water may have once existed on Mars in rivers, lakes or even oceans is now frozen into ice caps, locked up in hydrated minerals or buried in debris-coated glaciers .

Recommended: The Social Conquest of Earth

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Power Plants: Could a Rechargeable Battery Be Made from Paper and Pulp By-Products?

Despite decades of predictions that a fully electronic, paperless society is almost upon us, we still live in a world populated with printed documents. This insatiable demand for plant cellulose –based writing and packaging materials may end up having a silver lining: a component for a new type of low-cost, Earth-friendly rechargeable battery . [More]


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Can Fast Reactors Speedily Solve Plutonium Problems?

The U.K. has nearly 100 metric tons of plutonium--dubbed " the element from hell " by some--that it doesn't know what to do with. The island nation does not need the potent powder to construct more nuclear weapons, and spends billions of British pounds to ensure that others don't steal it for that purpose. The unstable element, which will remain radioactive for millennia, is the residue of ill-fated efforts to recycle used nuclear fuel.

How to See around Corners

From Nature magazine