Milky Way’s central black hole located
Ghez and colleagues collected infrared images of the nucleus of the Milky Way over a four-year period using the 10-metre Keck telescope on Mauna Kea in Hawaii. The positions of the stars nearest Sagit...
‘Naked’ black holes seen
Black holes are usually detected by the effects of their vast gravitational field on the orbits of nearby astronomical objects such as stars. Naked black holes have no such material near them making i...
Astronomy and physics dominate Science top ten
Confirmation that the universe is flat – expanding at just the right rate not to collapse – came from measurements of ripples in the cosmic background radiation left over from the big bang...
Time unaffected by eclipse
The experiments were carried out by Thomas Udem from the Max-Planck Institute for Quantum Optics in Garching and colleagues. Udem and colleagues placed four atomic clocks – one rubidium clock, t...
Newton tops PhysicsWeb poll
Almost 400 people took part in the PhysicsWeb poll, each one naming their top-five physicists. The votes for each physicist were added up and weighted according to how they were ranked by individual v...
More evidence for the accelerating universe
The first evidence for the accelerating universe came from observations of distant supernovae. However, the data were also consistent with an open universe – a universe that would expand forever...
Dropping atoms gives precise value of g
Atomic interferometers use lasers to place atoms into superpositions of different quantum states. These states acquire different phases as they move in a gravitational field, and this phase difference...
Gravity-wave detectors target quantum gravity
Both the French-Italian gravity-wave interferometer, called VIRGO, and the LIGO interferometers in the US are designed to detect very weak gravity waves by using lasers to monitor test masses placed a...
Solar system is chaotic
Murray and Holman ran numerical simulations of the planets positions over a 200 million year period using their new technique. They discovered that although the outer planets appear in stable orbits, ...
Taking a closer look at “big G”
The gravitational constant was first measured by Lord Cavendish in 1798, who used a torsion-balance to measure the force between a pair of lead spheres. Cavendish measured G to be 6.754 x 10-11 metres...
