"The trouble with most folks isn't so much their ignorance. It's know'n so many things that ain't so." - A favorite quote of Richard A. Muller, by 19th century humorist Josh Billings.

When you think big, as Richard A. Muller does, you're bound to create ideas now and then that are so compelling you just can't let go of them -- ideas so outlandish that mainstream scientists are equally eager to dismiss them.

Muller, a physicist at University of California at Berkeley, has had his share of big ideas.

If you don't count the restaurant he owned between 1976 and 1982 ("If anyone near and dear to you wants to open a restaurant, I can now be hired to talk them out of it."), Muller's ideas are generally rooted in solid science and genius extrapolation. He's got a gaggle of prestigious awards to prove it, with titles that say things like "outstanding" and "highly original."

But Muller's biggest idea is a real Nemesis. Or so he claims.

A Neolithic comet

(Appeared in an anthology: "God, the universe and men - Why do we exist?" (ed. Wabbel, T.D.), Patmos, Dusseldorf, 2003 (original in German).

Comets are jokers in the celestial pack. They irrupt, usually without forewarning, into the orderly progression of the sky. They cross the celestial sphere in weeks or months, growing one or more tails, before fading and disappearing from sight. On rare occasions a comet may be an awesome sight, and the historical literature of the past two thousand years is sprinkled with accounts of the fear induced when a great comet, its smoky red tail bisecting the heavens, appears in the night sky. In the remote past, tales of such apparitions were often conflated with stories of disaster on Earth. A comet called Typhon in Greek mythology was connected with a mythological flood, and the legend of Phaethon, in which the sun's chariot went off course and the Earth was first burned up and then flooded, may describe an exceptional meteorite impact. There is good evidence that the sky in Neolithic times was dominated by a recurrent, giant comet, and that the Earth annually ran through an associated meteor storm of huge intensity. The origin of religion dates to these times and may be tied up with this spectacular night sky. The prospect that cosmic myths, megaliths and art dating from this time may have been responses on the ground to threats in the sky has in recent years moved from Velikovskian fancy to a subject for serious scholarly discussion. In more scientific times, too, it was often suggested that a comet striking the Earth might create create worldwide havoc. For example past encounters of Halley's comet were supposed to have coincided with Noah's flood in 2342 BC.

A British computer hacker equipped with a "Dummies" guide recently tapped into the Pentagon. As hackers get smarter, computers get more powerful and national security is put at risk. The same goes for your own personal and financial information transmitted by phone, on the Internet or through bank machines.

Now a new invention developed by Dr. Jacob Scheuer of Tel Aviv University's School of Electrical Engineering promises an information security system that can beat today's hackers -- and the hackers of the future -- with existing fiber optic and computer technology. Transmitting binary lock-and-key information in the form of light pulses, his device ensures that a shared key code can be unlocked by the sender and receiver, and absolutely nobody else. He will present his new findings to peers at the next laser and electro-optics conference this May at the Conference for Lasers and Electro-Optics (CLEO) in San Jose, California.

Athens - The oldest stone wall in Greece, which has stood at the entrance of a cave in Thessaly for the last 23,000 years, has been discovered by palaeontologists, the ministry of culture said Monday.

The age of the find, determined by an optical dating test, singles it out as "probably one of the oldest in the world", according to a ministry press release.

"The dating matches the coldest period of the most recent ice age, indicating that the cavern's paleolithic inhabitants built it to protect themselves from the cold", said the ministry.

Another mosaic housed at Hama National Museum is the "Musicians" mosaic. This piece, measuring 4.25 meters by 5.37 meters, depicts six female musicians and two children, in addition to old musical instrument including an organ, cymbals, two flutes, a harp and an Indian musical instrument consisting of metal bowls placed on a table.

In a statement to Syrian press, Professor of mosaic restoration at Athens University Stephania Chlouveraki underlined the strong composition and accuracy of representation in the Musicians mosaic, noting the small details such as attire, hair, braids, gentle smiles and wide eyes.

A new member of the human evolutionary family has been proposed for the first time based on an ancient genetic sequence, not fossil bones. Even more surprising, this novel and still mysterious hominid, if confirmed, would have lived near Stone Age Neandertals and Homo sapiens.

"It was a shock to find DNA from a new type of ancestor that has not been on our radar screens," says geneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. These enigmatic hominids left Africa in a previously unsuspected migration around 1 million years ago, a team led by Pääbo and Max Planck graduate student Johannes Krause reports in a paper published online March 24 in Nature.

When NASA's Galileo probe reached Jupiter in 1995 and began sending back data about the gas giant, astronomers were in for a surprise: Jupiter was unusually poor in helium and neon, the two lightest noble gases. New simulations of the physics inside the planet reveal why.

The results, which provide a glimpse into Jupiter's turbulent innards, are reported in the current issue of Physical Review Letters and highlighted with a Viewpoint by Jonathan Fortney (University of California, Santa Cruz) in the March 22 issue of Physics.

To understand how a planet might have formed and what the inside of it might be like, astronomers compare the abundances of its constituent elements with the amounts of those elements found in the sun and meteorites. Jupiter, like the sun, is mostly hydrogen and helium. But the Galileo probe showed that, while it was richer than the sun in six elements, the planet seemed to be missing a small amount of helium and a substantial amount of neon - although neon makes up 1/600 of the mass of the solar system, it made up only 1/6000 of the mass of Jupiter's upper atmosphere, where Galileo made its observations.

Britain launched its own space agency Tuesday with the help of home-grown astronaut Major Timothy Peake, aimed at boosting the country's multi-billion-pound space technology industry.

While Peake may be its only astronaut, Britain is a world leader in areas such as robotics, satellites and telecommunications, which contribute about six billion pounds (nine billion dollars, 6.7 billion euros) a year to the economy.

The new UK Space Agency, complete with a logo depicting the Union flag morphed into a soaring arrow, will manage what is now a loose partnership of government departments and research councils dealing with space.

About 68,000 people are employed directly or indirectly in the industry and Business Secretary Peter Mandelson said it was "exactly the kind of high value-added industry we need to support".

An amateur stargazer has captured the moment a comet exploded in space - an event missed by the world's professional astronomers.

Musical instrument designer Nick Howes, 40, used the internet to access an online telescope as he sat at his desk in his office.

Mr Howes, of Cherhill near Calne, Wilts, logged on to a telescope in Hawaii and began staring into deep space. But he spotted a massive comet breaking up and was able to use the telescope to take photos.

Nick, who works for Yamaha, actually captured the moment the comet exploded, blowing a chunk the size of Mount Everest off one side.

He was the only person in the world to witness the dramatic event - with even American astronomers completely missing the opportunity.

Two decades of hard work have finally paid off for a collaboration of researchers from the University of Wisconsin-Madison, the Rice University, and the NASA Jet Propulsion Laboratory (JPL). Geophysicist Chuck DeMets (UWM), alongside colleagues Richard Gordon (Rice) and Donald Argus (JPL), has managed to produce an image of the dynamic 3D puzzle that is the crust of our planet. The investigation has covered 25 tectonic plates in continuous interaction, and 97 percent of the planet's surface, the team says.

"This model can be used to predict the movement of one plate relative to any other plate on the Earth's surface. Plate tectonics describes almost everything about how the Earth's surface moves and deforms, but it's remarkably simple in a mathematical way," the team leader says. "We live on a dynamic planet, and it's important to understand how the surface of the planet changes. The frequency and magnitude of earthquakes depend upon how the tectonic plates move. Understanding how plates move can help us understand surface processes like mountain-building and subsurface processes like mantle convection," Gordon adds.

Though it appears extremely solid, the Earth's crust is in fact moving constantly atop the ocean of magma that is the planet's upper mantle. The crust is not made of a single piece, but out of a lot more, each of different sizes. There are a few impressively large tectonic plates, such as the one under the Pacific Ocean, the Eurasian one, the African one, and so on. There are, however, a myriad of smaller plates, each of them engaged in various collision or separation processes with their neighbors. Studying the interactions between these formations could give researchers some clues as to where the next earthquakes might hit, and which volcanoes may blow their tops off.