James Webb Space Telescope

This month marks three years since the James Webb Space Telescope was first launched, which still feels something like a miracle given how many years of delays it took to finally get it orbiting our planet. The advanced technology onboard the spacecraft hasn't just sent back some pretty pictures, it's also challenged some of the basic tenets of cosmology, the study of some pretty big questions, including how the universe formed and how we got here.

For decades, the cosmological field was working under the assumption that, after the universe began in a hot dense soup of energy that expanded in the Big Bang, it continued to expand, forming the galaxies and stars that make up the universe. But in recent years, this understanding of how the universe expands has been put into question as two independent measurements to calculate this rate, which is called the Hubble constant, mysteriously diverged. In other words, we're trying to find out the speed limit of the expanding universe, but some measurements have given us different answers.

“The question arose: Is this a real discrepancy?” said Wendy Freedman, the leader of the Chicago Carnegie Hubble Program (CCHP). “Is this indicating new physics and demanding that we change our understanding of what we know as the standard model of cosmology — or were there still systematic uncertainties that made it seem like there was a tension?”

Over the past decade, scientists have been retracing their steps to try and understand whether a mathematical error was behind the conflicting numbers or whether this disparity meant the way cosmologists were imagining the model of the universe was in some way flawed. But time and again when researchers crunch the numbers, the tension persists.

Because the Hubble constant factors into what we know about the age of the universe, its size, and what it's made of, this divergence, known as the “Hubble tension,” has begun to unravel our fundamental and previously held assumptions about reality.

“There is nothing more exciting than having something not work out because it is pointing to the fact that you don’t understand something,” said Adam Frank, an astrophysics professor at the University of Rochester. “There is nothing more exciting than not understanding something.”..........

https://www.salon.com/2024/12/09/cr...-challenging-what-we-know-about-the-universe/