The shape of the known universe? Is the Universe closed or open?
|Is the Universe closed or open?|
According to a new study published in Nature Astronomy by researchers at the universities of Manchester, the United Kingdom, La Sapienza, Italy, and John Hopkins, the universe could be a curved one, like a huge, bloating balloon, rather than a flat sheet, as current theories claim.
Researchers have come to that conclusion after finding an "anomaly" in the cosmic microwave background (CMB), the weak echo of the Big Bang that permeates the entire universe.
If the universe were curved, as the study points out, it would mean that, just like on Earth, we could move in a straight line and end up, at some point, being back at the starting point.
This is what is known as a "closed universe." Of course, curvature occurs on such a large scale that it is difficult to perceive it locally, from the Earth, the solar system, or even at the galactic level. It would take a much broader perspective to realize.
The point is that decades ago cosmologists threw out the idea of a closed universe, because it doesn't fit at all existing theories about how the Cosmos works.
Instead, the idea of a "flat universe" has been imposed, extending without limit in all directions and never at any time replicating itself. But now, in the best measure done so far by CMB, an anomaly in that background radiation seems to indicate that, after all, we might be living in a closed universe.
What does the closed universe theory say?According to the current inflation model, the universe should be open. In the first billionth of a second after the Big Bang, the model says, there was a moment of exponential expansion during which the universe went from a single point to a specific physical space.
And the physics of that super-fast expansion points to a flat universe. That is precisely why most physicists are now engaged in this choice.
But if the universe turns out not to be flat, you have to "adjust" all physics to that new reality, and perform a huge number of other calculations. Something that, according to the authors of the work, might be needed very soon.
An abnormality in CMBWhat is the abnormality detected in the cosmic microwave background? CMB is the oldest element we can see in the whole universe.
|What does the cosmic microwave background radiation prove?|
It consists of a subdued "environmental" microwave radiation that floods the entire space and is one of the most important sources of data on the history and behaviour of the universe as a whole.
Well, according to the latest measurement data, the most accurate to date, there's a much larger number of CMB "gravitational lenses" than one would expect, and that means gravity might be "bending" CMB microwaves much more than current physics can explain.
The researchers themselves, however, suggest that, even though the evidence is strong, their results are not entirely conclusive.
Closed universe theory evidenceAccording to the team's calculations, the data point to a closed universe with a standard deviation of 3.5 sigma (a statistical measurement that means that there is a 99.8% chance that the result will not be due to a statistical error).
And that's still far below the 5 sigma that physicists need before they confirm an idea. The debate is therefore well served. The study has found a major discrepancy, an anomaly that needs an explanation. And the closed universe might be the most valid. However, new research could provide other ideas that would help to solve the problem.
For now, suffice it to say that it's possible that the idea that we live in a closed universe has been scrapped too quickly.