These red dots could change everything we think we know about how galaxies form

Scientists have peered billions of years into the past and discovered something that could fundamentally change what we think we know about how galaxies form.

Images from the James Webb Space Telescope (JWST) show bright six red dots, which are believed to be distant galaxies as they would have appeared more than 13 billion years ago.

But if they are indeed galaxies, then they are unlike any galaxies that scientists have previously observed. That's because they're impossibly large and dense for their relatively young age.

"The first thing I said was, 'There's no way that's right. That's insane,'" astronomer Katherine Suess told As It Happens host Nil Köksal.

Suess, a cosmology fellow at Stanford University and UC Santa Cruz, is one of the authors of a study describing the discovery, which was published last week in the journal Nature.

A galaxy is a collection of gas, dust, dark matter, stars and their solar systems, all held together by gravity. According to NASA, most are between 10 billion and 13.6 billion years old.

Because light takes time to travel from one place to another, telescope images are snapshots of the past. These mysterious red dots were photographed as they would have appeared about 500 to 700 million years after the Big Bang created the universe 13.8 billion years ago.

And yet, already, they have mass and density far beyond what scientists thought possible in that timeframe — rivalling our own Milky Way, which is believed to 13.6 billion years old, not much younger than the universe itself.

That flies in the face of how scientists believed galaxies formed in the early universe, Suess says.

"So there's the Big Bang, which is the beginning of everything — you know. It's the beginning of all of space, all of time, all of matter, all of energy. And then we think it takes some amount of time for things to grow. You know, so galaxies have to gobble up all of this gas and form it into stars before we can see them," she said.

"And we thought this process took billions of years. But instead we found this huge galaxy less than 500 million years after the Big Bang — which sounds like a lot, but it's like only three per cent of the total age of the universe. So it's really, really fast."

One of these potential galaxies has an equivalent mass as our Milky Way galaxy does today.

"I have a two-year-old nephew, so it's like if I went to go wake my nephew up from a nap, and instead of being my two-year-old nephew, he was like 40," Suess said. "It's not what you think you're going to find."

Canadian extragalactic astronomer Sarah Gallagher, who was not involved in the research, says the findings are "intriguing," but also "something that needs to be checked out."