From the properties of dark matter to how the universe took shape shortly after the Big Bang, some of the universe’s oldest and best-kept secrets could soon be exposed as construction moves forward on three “extremely large telescopes,” each with an expanse of mirrors bigger than a basketball court.
Scientists hope the competing telescopes — all expected to be running within a decade — will enable them to observe the early universe as it transitioned from a uniformly hot and opaque beginning to a cool, structured state, in which matter became concentrated inside objects, setting light free to roam the cosmos.
“We’re basically talking about the gap between 100 million and 500 million years after the universe began; that’s the time when the first stars and chemical elements and black holes and other exotica came into existence for the first time,” said Gerry Gilmore, an astronomer at Cambridge University.
The huge telescopes will look back in time at some of the earliest light ever emitted by objects. The universe inflated like the surface of a balloon shortly after the Big Bang, and some places stretched so far from here that their first bursts of light are only now arriving. Resolving this light would reveal the structure and chemical makeup of the universe’s first objects, which, as faint images from the Hubble Space Telescope suggest, developed much earlier than current theories would predict. Better observations are likely to lead to new theories of the birth and evolution of space and time, Gilmore said.
At projected costs ranging from $900 million to $1.6 billion each, the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope — which will have segmented mirrors measuring 24.5 meters, 30 meters and 39.3 meters across, respectively — will dwarf existing optical telescopes (the current largest is 10.4 meters). They will be between 5 and 200 times more powerful, depending on the telescope and the task.