The universe's size and shape are still unknown, but there are several theories. The observable universe, which is the part of the universe that we can see, is estimated to be around 45 billion light-years in radius and contains around 200 billion galaxies. However, the universe may be much larger and could be infinite.
There are two main options for the universe's size: it could be finite but unbounded, like the surface of a sphere, or it could be truly infinite. If the universe is finite, it could be shaped like a hypersphere or a hyper-donut, which would mean that if you travel in a straight line, you would eventually return to your starting point.
On the other hand, if the universe is truly infinite, it would mean that it has no edges or boundaries and that it goes on forever in all directions. This would lead to some strange consequences, such as the possibility of repetition and the idea that every possible combination of particles could exist an infinite number of times.
Ultimately, the size and shape of the universe are still unknown and may remain a mystery forever.
Here are the key facts extracted from the text:
1. The universe had a beginning 14 billion years ago.
2. The universe has been expanding since its beginning.
3. Information can't travel faster than light.
4. We can only see parts of the universe whose light has had time to reach us.
5. The observable universe is a sphere centered on us.
6. The observable universe has a radius of 45 billion light years.
7. The observable universe contains around 200 billion galaxies.
8. Each galaxy in the observable universe contains hundreds of billions of stars.
9. If the universe is finite, it could be a hypersphere where 3D space is curled on itself.
10. A hyperspherical universe would have no borders or outside.
11. If the universe is a hypersphere, it could be at least 1,000 times bigger than our observable part.
12. Another possible shape for the universe is a hyper donut.
13. In a hyper donut universe, traveling in a straight line would eventually bring you back to your starting point.
14. A hyper donut universe could have different amounts of stuff in every direction.
15. Light from far away galaxies would do strange things in a hyper donut universe, creating a cosmic Hall of Mirrors effect.
16. An infinite universe would have no borders anywhere.
17. If the universe is infinite, it would contain an infinite number of combinations of particles.
18. In an infinite universe, every combination of particles could reasonably occur an infinite number of times.
19. An infinite universe would be full of things in all directions forever.
20. Cosmic expansion means that the distance between galaxies is growing with time.
21. Even an infinite space can become bigger through cosmic expansion.
Note that some of these points may be subject to interpretation or debate, but I have tried to extract the most objective and factual information from the text.