Back in the 1920s and 1930s, the great astronomer Edwin Hubble–for whom the Hubble Space Telescope is named–discovered that the Universe Biaya Uhamka is expanding, with all of the galaxies rushing away from one another as Space itself expands. However, determining the precise rate of this universal expansion has long been problematic for astronomers. In April 2014, astronomers from the Sloan Digital Sky Survey (SDSS) announced that they had used 140, 000 remote quasars to measure the expansion rate of the Universe when it was only about 25% of its current age–primarily by making use of the Baryon Oscillation Spectroscopic Survey (BOSS), the largest component of the third SDSS survey (SDSS-III). Thanks to the unprecedented precision of the new measurement, astronomers can more confidently cite the speed of the universal expansion that was occurring almost 11 billion years ago, when our mysterious Universe was less than 3 billion years of age.

BOSS pioneered the new technique of measuring the structure of the early Universe by using the ferocious light emanating from remote and ancient quasars to map the distribution of intergalactic hydrogen gas. The BOSS findings were presented on April 7, 2014 at a meeting of the American Physical Society (APS) that was held in Savannah, Georgia. Quasars are extremely brilliant, massive objects dancing around in the very young Universe. They send forth exceptionally large amounts of energy, and usually sport a starlike appearance when viewed from a telescope. It has been suggested that quasars harbor massive black holes and may represent a stage in the evolution of some galaxies–and that they are furiously lit up by the searing-hot and extremely bright gas that is swirling around–and then down, down, down–eventually plummeting into the hungry maw of the greedy supermassive black hole lurking in the dark heart of its host galaxy.

The new results combine two differing techniques for using intergalactic gas and quasars to measure the rate of the expansion of the Universe. The first analysis, conducted by Dr. Andreu Font-Ribera of Lawrence Berkeley National Laboratory in California and collaborators, compares the distribution of hydrogen gas to the distribution of quasars in order to measure distances in the Cosmos. The second analysis was conducted by a team led by Dr. Timothee Delubac of the Ecole Polytechnique Federale de Lausanne in Switzerland, that studied the patterns lurking within the hydrogen gas itself to measure the distribution of mass in the early Universe. Taken together, this enlightening duo of BOSS analyses suggest that 10. 8 billion years ago, the Universe was expanding by one percent every 44 million years. In 1929, Edwin Hubble discovered that the Universe is not static–as the astronomers of his day believed–but is instead expanding as if some primordial, ancient burst is driving its contents apart. Until the late 1990s, the most popular belief among cosmologists was that the Cosmos was slowing down in its expansion, as a result of the relentless pull of gravity, and that it might ultimately reverse itself in a so-called Big Crunch–thus returning to its original extremely small and dense pre-Big Bang state. However, in 1998, light emanating from a form of remote stellar relic showed that the edges of Space are rushing away from one another at an ever-faster rate. The scientists at that time were baffled. The larger the Universe grew, the faster it grew. Some strange, mysterious, bizarre, and pervasive force–eventually dubbed the dark energy–seemed to be literally tearing at the boundaries of Space, forcing everything to rush away from everything else!

Not all Sun-like stars live alone–like our own solitary Sun. Many of these stars live in a binary system, where they are in close contact with a sister star. When the Sun-like star eventually moves off the hydrogen-burning main-sequence, it is no longer a bouncy young star. In fact, it is reaching the end of the stellar road, and its looks have started to change. First it evolves into a swollen red giant star, that ultimately blows off its outer gaseous layers, only to leave behind a dense little relic stellar corpse, its former core, termed a white dwarf. The white dwarf then may begin to sip up gas from its sister star. The vampire-like behavior backfires on the white dwarf. The dwarf eventually sips up enough gas from its sister to cause it to “go critical” and self-destruct in a brilliantly fatal thermonuclear explosion. This blast completely destroys the white dwarf in what is termed a type Ia supernova event. Alternatively, two sister white dwarfs may collide and set off the type Ia blast. In either case, all Type Ia supernovae are thought to have identical luminosities. This makes them very useful as standard candles. Cosmologists use standard candles to determine distances, thus enabling them to measure the Universe’s expansion history. In 1998, two separate groups studying the expansion history of the Universe–by observing Type Ia supernovae–made the surprising discovery that the Universe is accelerating in its expansion under the influence of the mysterious dark energy. The expansion is not decelerating–as previously expected.

The idea here is that supposedly “empty” Space is not really empty. Instead, it harbors residual energy and, perhaps, this residual energy–when considered on cosmic scales–results in a force that accelerates the expansion of the Universe. The physics of the extremely small–the weird world of quantum mechanics–causes energy and matter to pop into existence out of what only appears to be nothingness, albeit only for the briefest speck of time. The constant extremely brief appearance and disappearance of matter (virtual particles), in the seeming nothingness of Space, actually injects energy into what appears to be an empty, barren expanse. According to this currrently most-widely favored concept, the dark energy is the energy of the vacuum–and it is a property of Space itself.

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