Black holes revealed in death spin

Scientists have found new evidence that a pair of voracious black holes in the galaxy cluster Abell 400 are orbiting one another, probably on a path towards an eventual merger. Learning more about such collisions could help astronomers seeking to detect the gravitational waves generated.

Supermassive black holes are extremely dense, massive objects thought to have consumed millions or billions of stars from their surrounding environment. The Milky Way's own supermassive black hole, Sagittarius A*, is thought to contain the equivalent of about 4 million suns.

Radio waves from plasma-emitting jets associated with the two supermassive black holes in Abell 400 were first detected in 1984. Observations of the jets' bending and twisting behaviour indicated that the pair were interacting, but did not prove they were actually gravitationally bound.

Now, using the Chandra X-ray Observatory, scientists from the University of Bonn, Germany, the University of Virginia, US, and the US Naval Research Laboratory in Washington, DC, have shown that the jets streaming behind the two black holes bend in the same direction. This shows the black holes are traveling together through the galaxy cluster, and that suggests the two are orbiting each other.

Black holes revealed in death spin

Israeli scientist: Jesus may have walked on ice, not water

Jesus walked on water, according to the New Testament, but a professor says he may have actually walked on a hard-to-see patch of ice.

Doron Nof, a Florida State University professor of oceanography, said a rare combination of water and atmospheric conditions in the Sea of Galilee 2000 years ago may offer a scientific explanation for one of the miracles recounted in the Bible.

Nof, a native of Israel, said a patch of ice floating in the Sea of Galilee - which is actually a freshwater lake - would have been difficult to distinguish from unfrozen water surrounding it.

"I'm not trying to provide any information that has to do with theology here," Nof said in an interview Wednesday. "All we've thought is about the natural process. What theologians or anybody else does with that, it's their business, so to speak."

According to the New Testament books of Matthew, Mark and John, Jesus' disciples were out on the Galilee at night when a storm came up. Jesus walked to the terrified men, who thought he was a ghost, according to the accounts.

Darrell Bock, a professor of New Testament studies at the Dallas Theological Seminary, lightheartedly dismissed the idea that Jesus walked on ice.


Israeli scientist: Jesus may have walked on ice, not water

Banned from laughing in woods

A German has been ordered to stop laughing out loud in the woods after joggers complained he was disturbing the peace.

Accountant Joachim Bahrenfeld, 54, from Datteln said he goes to the woods after work and at weekends to have a good belly laugh.

"It's part of living for me, like eating, drinking and breathing. I feel much better when I laugh, it's freeing and healthy," he said.

But he now faces a £4,000 fine or six months jail if he laughs out loud again after a jogger successfully took him to court saying he was disturbing the peace.

German laugh expert Susanne Maier, who founded the German Laughter Academy which aims to teach serious minded Germans to lighten up, said: "Mr Bahrenfeld has been doing what we advise our students to do and that is to find a place they like to have a good old giggle.

Banned from laughing in woods

The Avenue of Dead, Teotihuacan.

The Avenue of the Dead was the main street of Teotihuacan. It ran for more than 2.5 km, beginning at the Moon Plaza to the north and extending beyond the Ciudadela and the Great Compound complexes to the south. According to Millon (Cowgill 1992a:96; Millon 1981:221), the avenue continued even further south, terminating near the edge of the mountains that can be seen in the background of this photo.

The avenue divided the city into two sections. Apartment compounds with pyramidal constructions were arranged on both sides of the avenue, often symetrically and sharing the same orientation. This highly planned city-layout suggests that the avenue may have been planned since its earliest phases of urbanization.

Dead Avenue

Better bifocals on the horizon

Wearers of unwieldy bifocal spectacles, take heart. A new kind of lens could offer a neat solution to the problem of switching between two lens types. The electrically powered design can shift from one lens power to another in the blink of an eye, or in this case, the flip of a switch.

This is good news for bifocal and trifocal users, which will include most of us at some point in our lives. Some 90% of people over the age of 45 develop presbyopia, in which the lens loses its flexibility and becomes less able to switch its focus from distant to near objects.

The most common solutions to this affliction are bifocal or trifocal lenses, which are divided into two or three different areas, respectively, each with its own focusing power. However, such glasses limit the field of view and require the user to use a specific area of the lens to see a certain object. Close objects, for example, must be viewed by peering downwards, which can lead to dizziness and headaches. Even varifocal lenses, which feature a gradation in power, require users to raise or lower their gaze to see near or far.

Better bifocals on the horizon - Electrical lenses switch modes at the flick of a switch.