It may look like a bunch of balloons or bacteria, but this cluster of dots represents the largest structure ever discovered in the observable universe. These 73 quasars—massive, extremely remote celestial objects—stretch for about 4 billion light years. To put that in perspective, The Atlantic writes, consider that our own humble Milky Way galaxy is only 100,000 light years across.
Light from each quasar had to travel billions of years to reach our telescopes, so while they may still exist, they could be long snuffed out. All 73 of the giants are situated at the center of their own galaxies.
Einstein’s Cosmological Principle predicts that, given a large enough scale, the universe should pretty much look the same wherever you look. If nothing else, these 73 quasars certainly occur at a large scale, meaning something unusual is going on in their corner of the abyss. Astronomer Roger Clowes, whose team identified the structure, says that the cluster’s hugeness “substantially exceeds” the largest expected size of what’s allowed to exist according to Einstein’s Cosmological Principle. It may need some revision.
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