Is the universe finite? Which shape has?
If we made a trip from anywhere on the Earth’s surface and traveled a long enough distance in a straight line, at some point we would arrive at the same point where we started at the beginning. We would have made a complete tour of the surface of our planet after traveling some 40,000 kilometers, crossing mountains, oceans, deserts … but the final destination is unmistakable: it would be the same as your starting position.
Will the universe work the same way?
Astrophysicist Thomas Buchert from the University of Lyon has a very interesting theory about this. Buchert and a team of researchers have been working to learn more about the universe and have been examining the light from the early universe. Experts, according to Live Science , believe that the universe can be connected in a multiple way, which means that space is closed in on itself in three dimensions like a huge three-dimensional donut.
This idea has yet to be tested, but it would provide strange new clues about the behavior, structure, and ultimate fate of the universe.
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 larger than what we can see today). This is significant, as it would also imply that the universe will eventually collapse in on itself , rather than 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 “spin” 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 go so far as to get to the point starting from where it started.
Be that as it may, the scientists emphasize that this is a preliminary result and that more research is needed.
Referencia: The variance of the CMB temperature gradient: a new signature of a multiply connected Universe Ralf Aurich, Thomas Buchert, Martin J. France, Frank Steiner arXiv:2106.13205v1 2021
