What if the deepest secrets of the early universe weren’t found in space — but from telescopes here on Earth? A new study just shattered that assumption.
Key Points at a Glance
- Telescopes in Chile captured polarized microwave light from over 13 billion years ago
- This light holds clues from the universe’s “cosmic dawn” when the first stars formed
- Findings match satellite data from NASA and ESA, confirming Earth-based accuracy
- Signals help refine our understanding of dark matter, neutrinos, and cosmic structure
- Study highlights the power of long-term support for ground-based astronomy
Perched high in Chile’s Andes mountains, a network of compact Earth-based telescopes has done what many thought impossible — it looked back more than 13 billion years to capture echoes from the universe’s first light. The breakthrough provides new insight into the cosmic dawn, the epoch when the first stars burst to life and began sculpting the modern universe.
The telescopes belong to the Cosmology Large Angular Scale Surveyor (CLASS) project, a collaboration led by Johns Hopkins University and the University of Chicago. Their mission: detect polarized microwave radiation left over from the big bang — a task so delicate, it’s typically been reserved for satellites orbiting above Earth’s noisy atmosphere.
“People thought this couldn’t be done from the ground,” said Tobias Marriage, CLASS project leader and physics professor at Johns Hopkins. “But this measurement proves otherwise. It’s a major achievement in observational cosmology.”
The faint microwave light studied by CLASS is a remnant of the big bang, known as the cosmic microwave background (CMB). But it’s not just a relic — it carries fingerprints of what happened when the universe’s first stars turned on. These stars blasted high-energy light into the surrounding hydrogen fog, ripping electrons from atoms in a phase called reionization. That burst of activity created tiny polarizations in the microwave light, which CLASS has now successfully detected from Earth.
“It’s like seeing cosmic glare,” explained lead author Yunyang Li. “When you wear polarized sunglasses to block the glare off a windshield — we’re doing that, but with the light from the big bang bouncing off the universe’s first stars.”
The team compared their results with data from two earlier satellite missions — NASA’s WMAP and the ESA’s Planck — and found a shared signal. By identifying and subtracting interference, the CLASS researchers were able to isolate this common cosmic signature with unprecedented clarity.
The result? A sharper picture of the early universe, and a better roadmap to understanding dark matter and neutrinos — mysterious particles that shaped the cosmos yet remain largely undetected.
This latest study builds on previous work that mapped 75% of the night sky with the CLASS telescopes. With continued observations, the team hopes to push the precision of CMB polarization measurements even further.
“No other ground-based experiment can do what CLASS is doing,” said Nigel Sharp from the U.S. National Science Foundation. “It’s a leap forward in our understanding of the universe’s earliest moments.”
With the universe as their laboratory, and Earth as their platform, scientists are proving that the frontier of space science may be closer than we think — and pointed firmly toward the past.
Source: Johns Hopkins University
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