For the most part, scientists are of two minds about the still-shocking ten-year-old discovery that the universe's expansion is actually accelerating over time.
Many believe there is some mysterious, as-yet-undetected energy permeating the universe leading to this effect, now called dark energy (not to be confused with the also-speculative dark matter). However, it's also possible that our current theory of gravity and gravitation have gaping holes, and that other features – such as new space dimensions – need to be added.
To date, it's been impossible to prove whether one or the other of these options best fit the observations made. But a team of astronomers using the ESO’s Very Large Telescope (VLT) now say they have a way.
The researchers are using data collected by the VLT to make a vast, three-dimensional map of the distribution of galaxies over portions of the observable universe. By looking at the motion of these galaxies over the last 30 years (a tiny segment of time in intergalactic terms), they have been able to tease out in part what component of observed motion is due to the overall universe's expansion, and what due to local gravitational forces.
This information, if replicated on a larger scale (about ten times the volume of space currently observed) should be able to help answer some questions about the source of the universe's odd accelerated expansion, they say.
The surveys of the distant universe that are continuing, using the
VLT's Visible Multi-Object Spectrograph device (VIMOS), will help on the way to that goal. A paper on the issue was published in the current issue of Nature.
New light on dark energy [ESO]
(Image: Raw spectra data from the VLT Visible Multi-Object Spectrograph tool. Source: ESO/VIRMOS)
