Scientists have taken the clearest-ever images of the universe when it was just 380,000 years old—essentially a baby picture of the cosmos.
This incredible discovery comes from the Atacama Cosmology Telescope (ACT), which captured light that has traveled for over 13 billion years.
These images help scientists understand how the first stars and galaxies began to form.
“We are seeing the first steps toward making the earliest stars and galaxies,” said Suzanne Staggs, director of ACT and professor at Princeton University.
Unlike previous studies, these new images not only show light and dark areas but also capture the way light is polarized, adding new details about the early universe.
ACT provides five times the resolution of previous telescopes, such as Planck, making faint signals more visible.
This background radiation, known as the cosmic microwave background (CMB), comes from a time when the universe was filled with hot plasma, making it impossible for light to travel freely.
The CMB marks the first moment when the universe became transparent, offering a glimpse into its infancy.
What scientists discovered
- Movement in the Early Universe: These images reveal how hydrogen and helium gases moved in the early universe. Just like tides help us understand the moon’s effect on Earth, these gas movements provide clues about the pull of gravity in different parts of space.
- Confirming the Age of the Universe: By studying how sound waves spread in the early universe, scientists refined their estimate of the universe’s age—13.8 billion years, with only a 0.1% uncertainty.
- Measuring the Universe’s Mass: The new data also confirm that the observable universe stretches nearly 50 billion light-years in every direction. Scientists estimate its mass to be equivalent to 1,900 trillion trillion suns. However, only a small fraction of that mass is normal matter (hydrogen and helium). The rest consists of mysterious dark matter and dark energy, which shape the universe in ways we still don’t fully understand.
One of the biggest debates in modern cosmology is the Hubble tension—a disagreement over how fast the universe is expanding.
Measurements from the CMB suggest a slower expansion rate (67-68 km/s per Megaparsec), while observations of nearby galaxies suggest a faster rate (73-74 km/s/Mpc). The new ACT data match previous CMB estimates, supporting the slower expansion rate.
Scientists explored various alternative models, including new types of dark matter, changes in fundamental physics, or an early period of rapid expansion. However, the data didn’t show evidence for any of these ideas.
“The standard model of cosmology has passed an extraordinarily precise test,” said researcher Colin Hill of Columbia University.
Capturing these images was no easy task. “We needed a five-year exposure with a highly sensitive telescope,” said Mark Devlin, deputy director of ACT. The National Science Foundation funded ACT for over two decades, making this breakthrough possible.
Although ACT completed its observations in 2022, new research will continue with the more advanced Simons Observatory, which is being built at the same location in Chile. These discoveries will help scientists piece together how our universe evolved into the complex and fascinating place we see today.
