Are we living in a ringing universe?
- June 29, 2015
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The universe may be ringing like a crystal glass, with its expansion repeatedly speeding up and slowing back down, cosmologists claim.
The “ringing,” however, would seem to be dying down after having undergone seven rounds of oscillation.
“Space itself… has been speeding up its expansion followed by slowing down seven times since creation,” explained Harry Ringermacher of the University of Southern Mississippi, who co-authored a new paper on the research.
Ringermacher and co-author Lawrence Mead, also of the university, stressed that further research is necessary to confirm the findings.
Scientists believe the universe began with the “big bang” and expanded to the size it is today. Yet, the gravity of all of this matter, stars, gas, galaxies, and mysterious dark matter, tries to pull the universe back together, slowing down the expansion.
In 1978 Arno Allan Penzias and Robert Woodrow Wilson won a Nobel Prize for their 1964 discovery of the the leftover radiation from the Big Bang, known as the “cosmic microwave background.”
Then in 1998 came “the finding that the universe was not only expanding, but was speeding up, or accelerating in its expansion,” said Mead-a shock discovery from two teams of researchers working separately.
“A new form of matter, dark energy, repulsive in nature, was responsible for the speed-up. The teams led by Saul Perlmutter, Adam Riess, and Brian Schmidt won the 2011 Nobel Prize in physics for that discovery.”
According to Ringermacher and Mead, the overall change from slowing down to speeding up took place around 6 to 7 billion years ago, as a slew of high-tech data has verified.
But “the new finding suggests that the universe has slowed down and speeded up, not just once, but seven times in the last 13.8 billion years, on average emulating dark matter in the process,” said Mead. “The ringing has been decaying and is now very small – much like striking a crystal glass and hearing it ring down.”
The research is published in the April issue of the Astronomical Journal.
Ringermacher said they made the finding accidentally when, through a related study, they found a new way of plotting a classic textbook graph describing the scale of the universe against its age. The new method didn't depend on one's prior choice of models of the universe, as had been traditional.
As astronomers had before, however, the pair used stellar explosions called Type 1a supernovae as “standard candles” for measuring cosmic distances. The reason is that calculations show all such explosions have similar inherent brightness.
“Analyzing this new plot to locate the transition time of the universe,” from slowing to speeding up, Ringermacher said, “we found there was more than one such time – in fact multiple oscillations.”
source : http://www.world-science.net
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