Tag Archives | Dark Energy

The Largest Galaxy Clusters in the Universe Hint That Something is Behaving Strangely

Galaxy Cluster LCDCS-0829Via the Daily Galaxy:

The large-scale structure of the Universe appears to be dominated by vast “hyperclusters” of galaxies, according to the new the Sloan Digital Sky Survey, compiled with a telescope at Apache Point, New Mexico. The survey plots the 2D positions of galaxies across a quarter of the sky. The science team has concluded that it could mean that gravity or dark energy — or something completely unknown — is behaving very strangely.

We know that the universe was smooth just after its birth. Measurements of the cosmic microwave background radiation (CMB), the light emitted 370,000 light years after the big bang, reveal only very slight variations in density from place to place. Gravity then took hold and amplified these variations into today’s galaxies and galaxy clusters, which in turn are arranged into big strings and knots called superclusters, with relatively empty voids in between.

On even larger scales, though, cosmological models say that the expansion of the universe should trump the clumping effect of gravity.

Read the rest

Continue Reading

Dark Energy: The Biggest Mystery in the Universe

Far from light and plunged into months-long darkness, Antarctica's South Pole Telescope is one of the best places on Earth for observing the universe. Photo: Keith Vanderlinde / National Science Foundation

Far from light and plunged into months-long darkness, Antarctica's South Pole Telescope is one of the best places on Earth for observing the universe. Photo: Keith Vanderlinde / National Science Foundation

At the South Pole, astronomers try to unravel a force greater than gravity that will determine the fate of the cosmos. Richard Panek reports for Smithsonian Magazine:

Twice a day, seven days a week, from February to November for the past four years, two researchers have layered themselves with thermal underwear and outerwear, with fleece, flannel, double gloves, double socks, padded overalls and puffy red parkas, mummifying themselves until they look like twin Michelin Men. Then they step outside, trading the warmth and modern conveniences of a science station (foosball, fitness center, 24-hour cafeteria) for a minus-100-degree Fahrenheit featureless landscape, flatter than Kansas and one of the coldest places on the planet. They trudge in darkness nearly a mile, across a plateau of snow and ice, until they discern, against the backdrop of more stars than any hands-in-pocket backyard observer has ever seen, the silhouette of the giant disk of the South Pole Telescope, where they join a global effort to solve possibly the greatest riddle in the universe: what most of it is made of.

Read the rest

Continue Reading