Images of a supernova 10 billion light-years from Earth give new weight to the
theory of negative pressure (Einstein’s cosmological constant). The observations of the
exploding star, made using the Hubble Space Telescope, appear brighter than they should if the
universe had been expanding at a constant rate.
The bright supernova, the most distant ever
detected, supports a picture of the universe where gravity dominated in the early years, slowing
down expansion and holding galaxies relatively close together so that they appeared brighter.
Later, a repulsive force – a kind of “negative pressure” – started to counteract the attraction of
gravity and the rate of expansion of the universe began to accelerate, stretching the expanse
between galaxies and making objects within them appear to be dimmer.
This view is
supported by microwave observations, and calculations of dark matter using gravitational lensing
techniques (see Watch this space for
cosmophysics ;June 2000; and Astrowatch;October 2000). At such a
great distance, the observation of this new supernova is an important step forward. It is 50%
farther away than the next farthest supernova observed by other survey groups.
