In 1916, Einstein proposed the theory of general relativity, which solved the problem of stellar evolution. However, even Einstein was wrong about whether the universe is static. He believed the universe was stationary, but Hubble's observations in 1929 proved that the universe is expanding. This leads us to ponder whether the universe truly exists and what it actually looks like.
What does the universe look like? Currently, there is no definitive answer. Stephen Hawking suggested a viewpoint: the universe is finite yet unbounded, having more dimensions than Earth. Just like our planet, regardless of whether you travel from the South Pole to the North Pole or vice versa, you will never find its boundary, yet it is evidently finite. The same applies to the universe.
So, how do we understand that the universe has more dimensions than Earth? Imagine a small ball rolling into a hole. If we are three-dimensional beings, we would see the ball still inside the hole. However, for two-dimensional beings, the ball seems to have disappeared. This is because they can only comprehend two-dimensional phenomena and cannot grasp the three-dimensional world. Similarly, we live in a three-dimensional world, making it difficult to fully understand a universe with several more dimensions.
Why can't we comprehend the true nature of the universe? Our cognition is limited to three-dimensional space, and for higher-dimensional worlds, we can only speculate through theory. This is precisely why the question of "what does the universe look like" is so challenging to answer.
