You may have fantasized, at least once in your life, about time travel. Maybe to snoop around ancient Rome or to peek at dinosaurs. For some accredited scientist it would also be possible, but that's another story, and today we're talking about something else. There's a group of astronomers who came very close to time travel, using theAtacama Cosmology Telescope to look back to a time when the universe was just being born.
An undertaking that we might call crazy, if it weren't for the fact that it's real. Think about it: we are talking about 99,99% of the history of the cosmos., when everything that exists today was still a project in progress.
Atacama, an unprecedented time jump
THEAtacama he achieved something extraordinary: observing the light emitted just 380.000 years after the Big Bang. To give you an idea of the significance of this observation, we are talking about a time when the universe was still a cosmic infant, while other telescopes had stopped “only” a few million years after the initial event.
What makes this feat even more remarkable is the quality of the images obtained. No fuzzy spots or vague interpretations, but the sharpest images ever captured of the cosmic microwave background (CMB). This type of observation is possible thanks to the advanced optics of the Atacama, capable of detecting light at millimeter wavelengths with unprecedented precision.
And to think that all this is happening while we are here, on Earth, worrying about stupid and miserable things, like wars. The universe is literally showing us its first cries, and many of us are listening to the ravings of a few madmen.
The Hubble Tension and the Standard Model
Modern cosmology is a bit like a scientific soap opera: there are tensions, disagreements and a constant search for answers. At the center of this plot is the famous "Hubble tension“, a disagreement between different measurements of the expansion rate of the universe, which has puzzled astronomers for years.
With the new data from the Atacama, the research team hoped to find some clues that could resolve this controversy. Instead, they got results which support the standard cosmological model, further fueling the mystery. As he said Adriaan Duivenvoorden, researcher at the Max Planck Institute for Astrophysics:
We've taken this completely new measurement of the sky, giving us an independent check of the cosmological model, and our results show that it holds up.
Most surprisingly, however, the team expected to find at least some partial evidence of exotic physics or particles that could explain the basis of the tension. But, as he admitted Staggs, this evidence “just wasn’t in the data.” It’s like looking for a culprit for a crime and finding that all the suspects have solid alibis. Frustrating, but fascinating.
A Ticket to the Birth of the Universe
Atacama, however, did not simply look back in time: it practically bought a ticket to witness the birth of the universe. The results of the study confirm with incredible precision the age of our universe: 13,8 billion years, with a margin of error of just 0,1%. It's as if we could determine the birth date of someone who lived thousands of years ago to within a few hours.
Even more fascinating is the confirms that all the helium in the universe was formed in the first three minutes after the Big Bang. As he explained Thibaut Louis, researcher at CNRS:
Our new measurements of its abundance agree very well with theoretical models and observations in galaxies.
It seems incredible to me to think that in those first 180 cosmic seconds, much of the chemical fate of the universe was decided. It is as if the recipe for the universe had been written in a hurry, but with such precision that it would last for billions of years. Or as if it were, perhaps, the replication of a recipe already applied over and over again, but even this it's another story.
Atacama, looking to the past to understand the present
For me, who has always been attracted by (apparently) opposites, science and poetry, the greatest power of this research is metaphorical: looking back in time helps us better understand the present. As he elegantly summarized Jo Dunkley, professor of Physics and Astrophysical Sciences at Princeton:
By looking back to a time when things were much simpler, we can piece together the story of how our universe evolved to the rich and complex place we find ourselves in today.
There is something deeply poetic in this approach. It is as if the universe were a book that we are reading backwards, starting from the final chapter (the present) and trying to get to the prologue (the Big Bang). Assuming that there was only one prologue, and that is yet another story.
The results have not yet been peer-reviewed, but they were presented at the annual meeting of the American Physical Society on March 19. And we, tiny inhabitants of this vast cosmos, continue to look at the stars, trying to read our history in the ancient light that reaches us across the immensity of time.
Take us far away, Atacama.
