Our universe might be a giant three-dimensional donut Imagine a universe where you can point a spaceship in one direction and finally come back to the starting point. If our universe were a finite donut, then such movements would be possible and physicists could potentially measure their size.
“We could say: we now know the size of the universe,” astrophysicist Thomas Buchert, of the University of Lyon, France’s Astrophysics Research Center, told Live Science in an email.
Related: 10 Wild Theories About The Universe
Our universe might be a giant three-dimensional donut By examining the light of the early universe, Buchert and a team of astrophysicists deduced that our cosmos can have multiple connections, which means that space is closed on itself in three dimensions like a donut in three.
dimensions. Such a universe would be finite, and according to their results our entire cosmos could only be about three or four times the size of the observable universe, about 45 billion light years away.
Physicists use Einstein’s language of general relativity to explain the universe. This language links the content of space-time to the bending and deformation of space-time, which then tells these contents how to interact. This is how we feel the force of gravity. In a cosmological context, this language connects the contents of the entire universe – dark matter, dark energy, regular matter, radiation and everything in between – with its general geometric form. For decades, astronomers have debated nature this way: whether our universe was “flat” (meaning that imaginary parallel lines would stay parallel forever), “closed” (parallel lines would eventually intersect) or “Open” (these lines would diverge). ).
Related: 8 Ways To See Einstein’s Theory Of Relativity In Real Life
This geometry of the universe dictates its destiny. Flat, open universes would continue to expand forever, while a closed universe would eventually collapse on itself.
Multiple observations, in particular of the cosmic diffuse background (the flash of light emitted when our universe was only 380,000 years old), have firmly established that we live in a flat universe. The parallel lines remain parallel and our universe will continue to expand.
But modeling is not limited to geometry. There is also topology, which is how shapes can change while keeping the same geometric rules.
For example, take a flat sheet of paper. It is obviously flat: the parallel lines remain parallel. Now take two strands of this paper and roll it into a cylinder. These parallel lines are always parallel: the cylinders are geometrically flat. Now take the opposite ends of the cylindrical paper and connect them. This creates the shape of a donut, which is also geometrically flat.
While our measurements of the content and shape of the universe tell us about its geometry (it is flat), they do not tell us about the topology. They don’t tell us if our universe is multiconnected, which means that one or more dimensions of our cosmos are reconnecting with each other.
Look at the light
While a perfectly flat universe would extend to infinity, a flat universe with a multi-connected topology would have finite dimensions. If we could somehow determine if one or more dimensions are enveloped in themselves, then we would know that the universe is finite in that dimension. So we could use these observations to measure the total volume of the universe.
But what would a multi-connected universe look like?
A team of astrophysicists from the University of Ulm in Germany and the University of Lyon in France examined the cosmic diffuse background (CMB). When the CMB was launched our universe was a million times smaller than it is today, so if our universe is truly multi-connected then it was much more likely to end up within observable limits. of the cosmos by then. Today, due to the expansion of the universe, coiling is much more likely to occur on a scale beyond observable limits, and therefore coiling would be much more difficult to detect. The observations of the CMB give us the best chance to see the footprints of a multifaceted connected universe.
Related: 5 Reasons We Could Live In A Multiverse
The team specifically looked at perturbations, the fictitious physical term for bumps and oscillations, in the temperature of the CMB. If one or more dimensions of our universe were to reconnect with themselves, the disturbances could not be greater than the distance around these circuits.