Paris Hilton out of jail

Hotel heiress Paris Hilton walked out of a Los Angeles-area jail early today with a big smile on her face after serving 23 days for violating her probation on a reckless driving conviction.

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A reflector left on the Moon as part of the Apollo 14 mission consists of many closely spaced reflecting prisms arranged in a grid (Image: NASA)

NASA is funding the development of lasers that could be placed on the Moon to check for subtle deviations from the standard theory of gravity.

Lasers have been used to make very precise measurements of the Earth-Moon distance since the Apollo era, when astronauts left reflectors at three sites on the lunar surface. A fourth reflecting device is attached to a robotic lunar lander launched by the Soviet Union.

To pin down the Moon's distance, scientist bounce light from Earth-based lasers off of these reflectors and measure how long it takes to return. Because the Moon's motion is governed by gravity, such studies can be used to test whether Einstein's general theory of relativity gives an accurate description of this motion.

IF THE universe has weird extra-spatial dimensions in parallel to the 3D world we see around us, then billion-dollar particle accelerators may not be the only place to find them.

So say Gergely Gabor Barnaföldi and colleagues at the Research Institute for Particle and Nuclear Physics in Budapest, Hungary, who propose that extra dimensions may show their face in areas of extreme gravity around dense stars. The concept could also solve a 25-year-old puzzle about the origin of mysterious particles emanating from a distant star system.

Some string theories predict that there are many more dimensions than the four we experience: the 3D world plus time. From next year, particle physicists hope to spot these dimensions at the Large Hadron Collider near Geneva, Switzerland.

Instead, Barnaföldi's team looked to outer space for evidence of extra dimensions interacting with matter. They analysed the Cygnus X-3 binary system, in which a normal star orbits a second object, generally thought to be a neutron star.