Penn collaboration with Atacama Cosmology Telescope releases images of universe's early years

The Atacama Cosmology Telescope — a National Science Foundation-funded observatory that works in collaboration with Penn — released unprecedentedly precise images of the universe’s early years. 

The project was led mainly by researchers Penn and Princeton University. While ACT operated in the Chilean Andes from 2007 to 2022, light that had travelled 13 billion years reached the telescope on the Chilean mountaintop. The images received from this telescope are known as the cosmic microwave background (CMB), and they provide an exceptionally clear picture of the universe at about 380,000 years old. 

Filled with overheated plasma after the Big Bang, the universe was opaque at this age, making it extremely difficult to acquire a detailed picture of that time. The CMB is the first instance in which the universe’s infancy can be seen with clarity. 

Additionally, the images allowed the team to more accurately identify the universe’s age at 13.8 billion years and contribute more precise data on how fast the universe is currently growing. 

“A younger universe would have had to expand more quickly to reach its current size, and the images we measure would appear to be reaching us from closer by,” Penn astronomy professor Mark Devlin — who also serves as the deputy director at ACT — told Penn Today. 

Mathew Madhavacheril, an assistant professor in the Department of Physics & Astronomy at Penn, explained the impact of the recent discovery. 

“To me, these new findings underscore just how rich the cosmic microwave background dataset can be,” Madhavacheril told Penn Today. “It lets us explore an incredible range of physics — from mere fractions of a second after the Big Bang to the more recent universe we see today. Our data’s high precision means we can deeply probe these new models and test them more thoroughly than ever before.” 

The evidence has allowed scientists at the ACT to validate the standard of cosmology which describes how the universe has formed and evolved over time. Although the ACT has made great progress in contributing to more precise measurements of the universe, the team believes there is more to explore. 

“It’s not like we just packed up and stopped after ACT," Devlin said. "We followed it up with the Simons Observatory, a much, much bigger and more capable instrument … Here's out with the old — let’s celebrate what we did and the new stuff we achieved — and then let’s look forward to what we have coming in the future, which is the Simons Observatory."