NASA’s James Webb Space Telescope is raising big questions about the early universe.
In its first images, JWST captured what appeared to be huge galaxies in the ancient universe. In fact, those galaxies looked much too big to fit scientists’ current theory of how the universe grew up. This has raised some concerns that the history of the early universe needs to be rewritten.
But a new look at old data from the Hubble Space Telescope tells another story. Perhaps JWST hasn’t upended cosmology as much as some scientists feared. Instead, the huge-looking galaxies JWST saw may have simpler explanations.
Researchers shared these findings in the February 9 Physical Review Letters.
JWST is giving us a new language to understand the early universe, says Julian Muñoz. He’s a cosmologist at the University of Texas at Austin. “Before we say, ‘Hey, we need to throw away everything we knew in cosmology,’ we should understand this language.”
‘Universe breakers’
The trouble began almost as soon as JWST first peered into the distant universe.
When this telescope looks at distant objects, it sees those objects as they appeared far back in time. Why? Because the light from such far-off objects has taken so long to travel to Earth. So when JWST peers at the most distant cosmos, it sees things as they were shortly after the Big Bang.
JWST’s first views of such distant, ancient regions of space were confusing in two ways.
First, some of its images contained huge numbers of galaxies. Far more, in fact, than astronomers thought possible so far back in time.
Second, a handful of those galaxies appeared to be monstrously massive. These all dated back to the first 700 million years of the universe. And they were up to 100 times as heavy as scientists thought possible back then. For that reason, these galaxies were dubbed “universe breakers.”
Our current understanding of how the universe grew up goes…
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