A donut shaped universe
For decades, astronomers have debated whether our universe is “flat” (that is, imagined parallel lines would remain parallel forever), “closed” (that parallel lines would eventually cross), or “open” (that is, parallel lines they would eventually overlap). This is an important matter because the geometry of the universe will determine its destiny. If it is flat and open it would continue to grow indefinitely but …
If we lived in a donut or donut shaped universe, we would already know that the cosmos is finite and also that it is much smaller than we thought (only three to four times bigger than what we can currently see). This is significant, since it also would imply that the universe will eventually collapse in on itself, instead of expanding outward forever.
Can we give credence to this hypothesis? The truth is that there is a great deal of scientific evidence. This is the procedure followed by scientists at the University of Lyon: to map the topology of the universe, astrophysicists measured disruptions in the cosmic microwave background (CMB), the ambient background noise from the beginning of the universe, at the Big Bang. . By examining the light from the early universe, the researchers deduced that our cosmos could be closed in on itself in three dimensions like a three-dimensional donut, with the limits of the observable universe some 45 billion light-years away.
We couldn’t get to the starting point
However, even if the universe is finite and donut shaped, a spacecraft could not “circle” back to its initial position after traveling across the surface of the cosmos. This is because the universe is expanding faster than the speed of light, which means that unless a faster-than-light means of space travel is discovered, no one could ever get so far as to get to where they started from.
Be that as it may, scientists emphasize that it is a preliminary result and that more research is needed.