This is the clearest image yet of the faint afterglow of the Big Bang, known as the cosmic microwave background radiation (half-sky image on the left, close-up on the right). The orange and blue colours reflect the different levels of radiation intensity, revealing new gas clouds in the Universe. The Milky Way is shown as a red band in the half-sky image. Studying this high-resolution cosmic microwave background has enabled scientists to confirm a simple model of the Universe and disprove many alternative theories. (Image credit: ACT Collaboration; ESA/Planck Collaboration)
Astronomers have produced the clearest images yet of the young universe – and they confirm that the dominant theory of the universe's evolution accurately describes its early stages.
New images capture light that has traveled more than 13 billion years to reach the Atacama Cosmology Telescope (ACT) in Chile. They show the cosmos at just 380,000 years old – like baby pictures of our now-mature universe.
At that time, our universe was emitting the cosmic microwave background, emerging from its extremely hot, opaque state after the Big Bang, making space transparent. This faint afterglow represents the first available snapshot of our universe's childhood.
But the new images show not only the transition from darkness to light, but also, in high resolution, the formation and movement of gas clouds of primordial hydrogen and helium that, over millions and billions of years, coalesced into the stars and galaxies we see today.
“We can look back into cosmic history – from our Milky Way, beyond distant galaxies that host huge black holes and giant galaxy clusters, all the way back to that infancy,” said Jo Dunkley, a professor of physics and astrophysical sciences at Princeton University in New Jersey, who led the ACT analysis.
“By looking back to a time when things were much simpler, we can piece together the story of how our Universe transformed into the rich and complex place we are today,” she added in another statement.
The results of the study were published in the Journal of Cosmology and Astrophysics and presented at a meeting of the American Physical Society in California on Wednesday (March 19).
About 1900 “zetta suns”
Analysis of these new images revealed that the observable universe extends nearly 50 billion light-years in all directions from Earth. Although the cosmos is 13.8 billion years old, it has also expanded in that time, giving light and matter more room to spread out.
The results also indicate that the universe contains a mass equal to 1,900 “zetta suns,” equivalent to nearly 2 trillion trillion suns. Of these, only 100 zetta suns are ordinary matter — the stuff we can observe and measure, which is dominated by hydrogen, followed by helium.
Of the remaining 1,800 zetta suns of matter, 500 zetta suns are dark matter – an invisible substance permeating the cosmos that has yet to be directly detected, while a whopping 1,300 zetta suns are due to the density of dark energy – an equally mysterious phenomenon that is causing the universe to expand at an accelerating rate.
The high-resolution observations have given scientists a chance to test how well the simple, prevailing model of how the universe evolves — known as Lambda cold dark matter (Lambda CDM) — describes the early universe. The data show no sign of new particles or unusual physics in the early universe, the scientists said.
“Our standard braid model
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