Scientists have explained mathematically why the famous "silly walks" of Monty Python's John Cleese have never caught on in the long history of Homo sapiens.

The giant, leg-twirling strides of silly walks may enable an individual to leap around swiftly but are simply too expensive in metabolic energy compared to conventional locomotion, according to a paper published on Wednesday by Britain's Royal Society.

Manoj Srinavasan and Andy Ruina, researchers in applied mechanics at New York's Cornell University, drew up a geometrical model of human walking and running.

They found that, in essence, each leg is a "telescoping actuator" that can change its length.

In walking, the body vaults forwards in circular arcs, driven forward by the pendular swing of the legs, with the toe and heel providing the push-off and landing point for each movement. In running, though, the body travels from one parabolic arc to the next, with a bounce in between.

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Srinavasan and Ruina then factored in the metabolic cost of three drains on energy on both movements.

These are the energy expenditure required to keep the body's basic functions ticking over; the cost of swinging the legs; and the cost incurred when a leg is in contact with the ground.

A baby mammoth unearthed in the permafrost of north-west Siberia could be the best preserved specimen of its type, scientists have said.

The frozen carcass is to be sent to Japan for detailed study.

The six-month-old female calf was discovered on the Yamal peninsula of Russia and is thought to have died 10,000 years ago.

The animal's trunk and eyes are still intact and some of its fur remains on the body.

EDWARDS AFB - If your house shakes and you hear a mysterious boom during the next nine days, look up.

NASA's Dryden Flight Research Center will be experimenting with sonic booms today through July 20 to assess the impact on modern housing construction.

Called the Housing Structural Response to Sonic Booms Test, the experiment consists of an F-18 research aircraft flying at supersonic speeds to subject an Edwards base house to sonic booms.

WASHINGTON - The National Science Foundation on Tuesday chose South Dakota's closed Homestake Gold Mine as the site for a new underground physics lab to study the history and makeup of the universe.

Forget science fiction. If you want to hear some really crazy ideas about the universe, just listen to our leading theoretical physicists. Wish you could travel back in time? You can, according to some interpretations of quantum mechanics. Could there be an infinite number of parallel worlds? Nobel Prize-winning physicist Steven Weinberg considers this a real possibility. Even the big bang, which for decades has been the standard explanation for how the universe started, is getting a second look. Now, many cosmologists speculate that we live in a "multiverse," with big bangs exploding all over the cosmos, each creating its own bubble universe with its own laws of physics. And lucky for us, our bubble turned out to be life-friendly.

The National Aeronautics and Space Administration has discovered evidence of hydrocarbons on Saturn's moon Hyperion, scientists said Monday.

NASA said the Cassini spacecraft revealed, for the first time, surface details of Saturn's moon Hyperion that include cup-like craters filled with hydrocarbons. That discovery suggests a more widespread presence in our solar system of basic chemicals necessary for life, NASA scientists said.

For the third time in two days, NASA postponed the launch of its asteroid-bound Dawn probe Saturday, with liftoff now slated for no earlier than September.

Its rock-hard surface can take a full-on assault from a baseball bat, yet remains flexible enough to allow you to kick, leap and roll with perfect ease. Crafted from cutting-edge science, its unique molecular structure means that while providing armoured protection against crude concrete and even barbed wire, it remains light enough to allow you to run at high speed.

It sounds like the stuff of Batman comics - but the superhero suit is here.

The search for life elsewhere in the solar system and beyond should include efforts to detect what scientists sometimes refer to as "weird" life -- that is, life with an alternative biochemistry to that of life on Earth -- says a new report from the National Research Council. The committee that wrote the report found that the fundamental requirements for life as we generally know it -- a liquid water biosolvent, carbon-based metabolism, molecular system capable of evolution, and the ability to exchange energy with the environment -- are not the only ways to support phenomena recognized as life. "Our investigation made clear that life is possible in forms different than those on Earth," said committee chair John Baross, professor of oceanography at the University of Washington, Seattle.

The report emphasizes that "no discovery that we can make in our exploration of the solar system would have greater impact on our view of our position in the cosmos, or be more inspiring, than the discovery of an alien life form, even a primitive one. At the same time, it is clear that nothing would be more tragic in the American exploration of space than to encounter alien life without recognizing it."

The tacit assumption that alien life would utilize the same biochemical architecture as life on Earth does means that scientists have artificially limited the scope of their thinking as to where extraterrestrial life might be found, the report says. The assumption that life requires water, for example, has limited thinking about likely habitats on Mars to those places where liquid water is thought to be present or have once flowed, such as the deep subsurface. However, according to the committee, liquids such as ammonia or formamide could also work as biosolvents -- liquids that dissolve substances within an organism -- albeit through a different biochemistry. The recent evidence that liquid water-ammonia mixtures may exist in the interior of Saturn's moon Titan suggests that increased priority be given to a follow-on mission to probe Titan, a locale the committee considers the solar system's most likely home for weird life.

After pondering the weighty question of the mass of the Milky Way galaxy, astronomers have come up with an answer: 42.

That is, our galaxy weighs three times 10 to the power of 42kg - a number written as 3 followed by 42 zeroes, which has echoes of author Douglas Adams's fictional answer to the question of life, the universe and everything in his series Hitchhiker's Guide to the Galaxy.