To answer some of the most pressing questions about the universe, scientists have revealed the largest 3D map of the universe ever created. The map, published on June 19, is a result of an analysis of more than two million galaxies and quasars (luminous galactic nuclei which have supermassive blackholes) covering over 11 billion years of cosmic time. It fills in the most significant gaps in our knowledge of the universe.
Announced by Sloan Digital Sky Survey (SDSS), the results come from the extended Baryon Oscillation Spectroscopic Survey (eBOSS), an international collaboration of more than 100 astrophysicists and one of the SDSS’s main surveys. Within the eBOSS team, groups of scientists from different universities around the world focused on different aspects of the analysis. The map today represents their combined effort of mapping the universe for over two decades.
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“We know both the ancient history of the Universe and its recent expansion history fairly well, but there is a troublesome gap in the middle 11 billion years,” said cosmologist Kyle Dawson, who leads the team, in a statement. “For five years, we have worked to fill in that gap, and we are using that information to provide some of the most substantial advances in cosmology in the last decade.”
The map depicts the Universe from when it was only about 300,000 years old. A close look at it reveals all the filaments and voids that define the structure in the Universe. The history that has been revealed in this map shows that about six billion years ago, the expansion of the Universe began to accelerate. Since then, it has only continued to get faster. Scientists say this accelerated expansion seems to be due to a mysterious invisible component called “dark energy”, something that they haven’t yet understood with their current grasp of particle physics.
The map even reveals cracks in the picture of the universe we have right now. In particular, the team’s measurement of the current rate of expansion of the Universe—what is commonly known as the “Hubble Constant”—is about 10 percent lower than the value we know. The scientists say that the high precision of the eBOSS data means that it is highly unlikely that this mismatch is due to chance.
There is no broadly accepted explanation for this discrepancy yet, but one exciting possibility is that a previously-unknown form of matter or energy might have left a trace on our history. The scientists leave these questions as a legacy to future projects. The statement said, “In the next decade, future surveys may resolve the conundrum, or perhaps, will reveal more surprises.”
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