doi.org/10.3847/1538-4357/ae0a1e
Credibility: 989
#Universe
When you open a refrigerator, you expect it to be colder than the kitchen, right? Likewise, when astronomers look back at the Universe, billions of years ago, they expect it to be hotter than it is today
A group of Japanese scientists confirmed this very precisely, providing one of the best proofs yet of how the Universe evolved.
What did scientists discover?
Led by student Tatsuya Kotani and professor Tomoharu Oka, from Keio University, in Japan, the team measured the temperature of the cosmic background radiation, which is like a “weak light” destroyed by the Big Bang, the great explosion that gave rise to the Universe.
This radiation is present throughout space.
They discovered that, 7 billion years ago, the temperature of the Universe was 5.13 degrees above absolute zero (a super low temperature, where everything is practically frozen), with a margin of error of just ±0.06 degrees.
This is almost double the current temperature of the Universe, which is about 2.7 degrees above absolute zero.
Why is this important?
This discovery confirms a central idea of the Big Bang theory: the Universe is cooling as it expands, like a balloon that will get bigger and colder over time.
The further back we go, the hotter it should be, and this measurement measured exactly that.
What makes this study special is its precision.
Scientists obtained data from the ALMA telescope in Chile and analyzed the light from a very distant quasar (a type of bright object in space).
This light, as it traveled through the Universe, interacted with the cosmic background radiation, leaving clues that allowed temperature to be measured extremely accurately.
It is the most precise measurement ever made for this time in the history of the Universe.
What does this mean?
This discovery is like getting a weather forecast right.
Imagine the meteorologist says it’s going to rain, and when you see puddles forming, you trust the forecast more.
Likewise, scientists have a model of the Universe, called the standard model, that makes a variation on how it should work.
This temperature measurement, which almost perfectly matched that of the previous model, gives more confidence that our understanding of the origin and evolution of the Universe is correct.
Although we have already measured the temperature of the Universe in its earliest moments and today, this study fills an important chapter in the middle of this history, helping to confirm that we are on the right path to understanding how the Universe got here.
Published in 11/03/2025 07h53
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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