WASHINGTON—Observations by NASA’s James Webb Space Telescope are upending the understanding of the early universe, indicating the presence of large and mature but remarkably compact galaxies teeming with stars far sooner than scientists had considered possible.
Astronomers said data obtained by the telescope reveals what appear to be six big galaxies as mature as our Milky Way existing about 540 million to 770 million years after an explosion though to be a “Big Bang” that kicked off the universe 13.8 billion years ago.
These galaxies, one of which appears to have a mass rivaling our Milky Way but 30 times more densely packed, seem to differ in fundamental ways from those populating the universe today….