After five years of looking into the deepest reaches of space, researchers have released what they call the “largest three-dimensional map of the universe.” No, you can’t see your house.
The mind-blowing map is the result of an ongoing project called the Sloan Digital Sky Survey (SDSS), an ambitious international search to map the expansion of the observable universe and hopefully solve some cosmic puzzles in the process. With this most recent update, the project has mapped and measured over 2 million galaxies, from our Milky Way galaxy to ancient objects more than 11 billion light-years away.
Related: 11 fascinating facts about our Milky Way
The new detailed map will help astronomers reconstruct a murky period of the universe’s expansion known as “the gap.”
“We know the ancient history of the universe and its recent history of expansion quite well, but there is a problematic gap in the middle of 11 billion years,” Kyle Dawson, cosmologist at the University of Utah and principal investigator on the project, he said in a statement. “For five years, we have worked to fill that gap.”
The gap begins a few billion years after the big Bang. Scientists can measure the rate of expansion of the universe before this thanks to the cosmic microwave background – old radiation left over from the childhood of the universe that researchers can still detect; and they can calculate recent expansion by measuring how the distance from Earth to nearby galaxies increases over time. But expansion in the middle period has been little studied because the light from galaxies more than a few hundred million light-years away can be incredibly weak. To fill the void, a team of more than 100 scientists from around the world observed not only distant galaxies, but also fiery quasars (extremely luminous objects powered by the most hungry black holes in the cosmos).
The key to this study is a phenomenon called redshift, a process by which light from the oldest and most distant galaxies is literally stretched by the expansion of the universe, increasing its wavelength and shifting it toward the redder end of the spectrum. . As a result of this cosmic color change, distant light sources appear redder, while those closest to Earth appear bluer (you can see this phenomenon illustrated on the team maps above).
To calculate the rate of cosmic expansion 11 billion years ago, the team measured the redshift of millions of distant objects along with their speeds, a measurement that shows how much it pulls on a galaxy. gravity of other matter around him. The team’s results, which are described in 23 new studies Published on July 20, it shows that the universe began to expand at an accelerated rate about 6 billion years ago, after a period of slowdown.
Scientists attribute the expansion of the universe to a mysterious force called dark energyAlthough nobody is completely sure what it is or where it exists. Surveys like this help scientists better restrict the properties of dark energy, the researchers said, although it is still far from being understood. The solution to this enigma will have to wait another day … hopefully billions of years are not missing.
Originally published in Live Science.
