White dwarfs are the burned-out cores of stars like our Sun. Astronomers have discovered a pair of white dwarfs spiraling into one another at breakneck speeds. Today, these white dwarfs are so near they make a complete orbit in just 13 minutes, but they are gradually slipping closer together. About 900,000 years from now - a blink of an eye in astronomical time - they will merge and possibly explode as a supernova. By watching the stars converge, scientists will test both Einstein's general theory of relativity and the origin of some peculiar supernovae.

The two white dwarfs are circling at a bracing speed of 370 miles per second (600 km/s), or 180 times faster than the fastest jet on Earth.

A custom-built, $2.5 million "split magnet" system with the potential to revolutionize scientific research in a variety of fields has made its debut at the National High Magnetic Field Laboratory at Florida State University.

The world-record magnet is operating at 25 tesla, easily besting the 17.5 tesla French record set in 1991 for this type of magnet. ("Tesla," named for early 20th-century inventor and engineer Nikola Tesla, is a measurement of the strength of a magnetic field.) In addition to being 43 percent more powerful than the previous world best, the new magnet also has 1,500 times as much space at its center, allowing room for more flexible, varied experiments.

Unusual lavas in the Caribbean apparently originated from the lost, ancient supercontinent of Gondwana, scientists have found.

This discovery reveals that continental material can get dragged along the Earth's surface for more than a thousand miles and survive for more than a billion years, serving as cores around which islands and perhaps even continents might eventually grow.

Scientists investigated lavas from the Caribbean island of Hispaniola, home to Haiti on its western half and the Dominican Republic in the east. A better understanding of the history of this island "will be important for the modern tectonics of Hispaniola, especially Haiti, as the lavas were found in the general area of the fault system that caused the devastating earthquake in Haiti in 2010," said researcher George Kamenov, a geochemist at the University of Florida in Gainesville.

The mind-bending laws of quantum mechanics say we can't observe the smallest particles without affecting them. Physicists have now caused the smallest-ever disturbance while making a quantum measurement - in fact, almost the minimum thought to be possible.

This disturbance is called back-action, and it is one of the hallmarks of quantum mechanics, which governs the actions of the very small. It arises from the supposition that before a measurement is made, particles exist in a sort of limbo state, being neither here nor there while retaining the possibility of either.

Once an observer intervenes, the particle is forced to "choose" a state, to settle on one possibility, eliminating the other options. Thus, the state of the particle is altered by the act of measuring it.

"The atom changes because you are looking," explained physicist Peter Maunz of Duke University.

Archaeologists have unearthed a single 45cm-long fossilised browhorn belonging to a group of herbivores that included the famous Triceratops, at a geological site in the south-east of Montana, US.

While this is, in itself, not an unusual find, it is the placement of the fossil in the rock that is most important.

The fossil was found just 13cm below the layer of rock known as the Cretaceous-Tertiary - the point in rock formation that marks the extinction of the dinosaurs.

Beyond the orbit of Mars, but not as far as Jupiter, lurk the many hundreds of thousands of rocky bodies collectively known as the asteroid belt.

Many solar systems are thought to contain such belts, and science fiction movies and television shows often present these bands as rock-clogged expanses that would challenge any celestial navigator. It may be so, in other systems, but in our asteroid belt, the rocky bodies are actually quite far apart from each other.

Humankind will soon be getting an inside look at this often overlooked bit of celestial real estate, courtesy of NASA's Dawn mission. On Saturday, July 16, after a four-year journey, the Dawn spacecraft will reach Vesta, the second-largest body in the belt. [Photos: Asteroid Vesta and NASA's Dawn]

Moles get two big thumbs-up for their digging skills. These tunneling mammals sport what looks like a sixth digit on each front paw, a seeming exception to the rule limiting land vertebrates to 10 fingers. Now, a new study of embryonic moles shows that this doppelganger thumb is no thumb at all, but a co-opted wrist bone that starts to elongate relatively late in development.

Although not as famous as the panda's similar extra thumb, a heavy tool for grasping bamboo, the mole's sixth digit is an evolutionary curiosity. This thumb, a solid piece of bone on the outside of the hand that can wiggle but not bend, certainly seems useful. The extra bone widens the mole's paws, presumably making them better for scooping dirt. Primitive mole species less inclined to tunnel-building tend to have stubbier second thumbs. Whether the extra digits are useful, most land vertebrates, with the exception of rare polydactyl humans, cats, and other animals, stick to a maximum of five digits per hand or paw.

To unearth whether the mole is an evolutionary rule-breaker, Marcelo Sánchez, an evolutionary biologist at the University of Zürich in Switzerland, and colleagues went back to the thumb's beginnings. The team compared the stubby and fingerless limbs of embryonic Iberian moles (Talpa occidentalis) with the limbs of closely related shrew embryos, looking for molecular clues to early digit growth. One such clue, a gene called Sox9 that often turns on before bone growth, clearly identified the would-be digit as a finger impostor. Sox9 didn't kick into gear at the site of the future second thumb until the mole embryos were 18 days old, after the gene's activity had peaked in the true fingers. "It forms like a finger forms but later," Sánchez says.

Pepsi scrambles taste-test response

Focused sound waves aren't just the domain of children fooling around with long-distance microphones. They're also important in ultrasound machines, and in biomedical laboratories, for "acoustic actuators" using sound to sort cells.

Sound focusing has its limits, however - the diffraction limit, roughly one wavelength of the sound being focused. A 20 KHz tone has a wavelength of around 1.7cm in air, which is one of the reasons that ultrasound pictures look fuzzy and indistinct to the untrained eye. To improve the focus beyond the diffraction limit, you need expensive acoustic lenses - or an array of Coca-Cola cans.

In an experiment reported at Nature News, a French researcher has built a "superlens" out of a 7x7 array of soft drink cans with the tabs removed.

Jellyfish actively swim high and low to catch food, rather than drift passively, according to a study of large barrel jellyfish off the Welsh coast. This behavior may explain some of gelatinous blobs' success.

"It is just another feature of jellyfish that is going to help them outcompete fish and take over from fish in disturbed ecosystems," said lead researcher Graeme Hays, a professor at Swansea University in Wales.

Since jellyfish and young fish both eat plankton (tiny floating plants and animals), jellyfish can quickly gain an advantage when some other disruption - such as overfishing, or a low-oxygen environment created by nutrient pollution - hurts fish populations.

In fact, in recent years, reports of swarms of jellyfish have suggested human-caused changes to ocean environments may be just what these creatures need to thrive.

A dinosaur horn is now pointing to a catastrophic end for the Age of Dinosaurs, not a gradual one as some researchers have claimed.

The leading culprit for the end of the Age of Dinosaurs is a catastrophic meteor strike about 65 million years ago. Although it is now widely accepted that a cosmic impact took place about then - a time known as the Cretaceous-Tertiary, or K-T boundary - it was unclear if the mass extinctions started gradually before the hit, perhaps due to volcanoes or other factors.

Helping drive this controversy was a zone spanning 10 feet (3 meters) wide in the earth right below the K-T boundary that purportedly lacked dinosaur fossils. A number of scientists have claimed this gap, seen in the western interior of North America, was evidence that dinosaurs might have died off well before any impact. Other researchers have contested the notion, suggesting this layer only appeared devoid of fossils because fossils can get easily destroyed over millions of years. Also, the placement of the K-T boundary can be uncertain, meaning that dinosaurs might have actually been found in this zone before but not reported as such.