Do some physicists believe that the universe is a three-dimensional space wrapped on a four-dimension doughnut?
The astrophysicists believe if this is true, the universe would be finite. The entire cosmos may be only three or four times larger than the limits of the observable universe, which is about 45 billion light-years away. If true, a doughnut-shaped universe also has the possibility of allowing a spaceship that goes in one direction to eventually return to where it started without turning around.
The shape of the universe is something that astronomers have been debating for decades. Some believe the universe is flat where parallel lines stay parallel forever. Others believe the universe is closed, being the parallel lines eventually intersect. Astronomers say the geometry of the universe dictates its fate.
While open universes continue to expand forever, a closed universe eventually collapses in on itself. Observations focusing on cosmic microwave background, which is the flash of light released when the universe is only 380,000 years old, have established that our universe is flat and parallel lines will stay parallel forever with an ever-evolving universe. 764
However, there’s more to shape than geometry, and topology has to be considered. Topology allows shapes to change while maintaining the same geometric rules.
An example is a sheet of flat paper that has parallel lines that stay parallel. If you roll the paper into a cylinder, the parallel lines are still parallel. If you take that sheet of paper and connect the opposite ends while it’s rolled like a cylinder, you get the shape of a doughnut, which is still geometrically flat. The team believes the warping occurs beyond observational limits and will be very difficult to detect. The team was looking at perturbations, which describe bumps and wiggles in the cosmic microwave background radiation temperature. They believe there could be a maximum size to the perturbations that could reveal the universe’s topology. <PERSON> and his team emphasize their results are preliminary and note that instrument effects could explain some of their results.
https://www.slashgear.com/astrophysicists-believe-the-universe-may-be-shaped-like-a-giant-3d-doughnut-20683133/
Do some physicists believe that the universe is a three-dimensional space wrapped on a four-dimension doughnut? I was reading this article and was confused about the geometry being discussed, they say the universe is flat, not in the sense that it's two-dimensional, but in the sense that parallel lines remain parallel indefinitely, then they mention that it's wrapped on a doughnut, which is impossible unless they mean a four-dimensional doughnut which would allow parallel lines to join, is this what is being said here? A topological three-dimensional plane wrapped on a fourth-dimensional doughnut would retain its geometrical feature like a two-dimensional plane wrapped on a three-dimensional doughnut would. 484