There is no evidence to suggest that the universe has an end or edge, and therefore it's not surrounded by anything.
The observable universe, which is the portion we can see from Earth, extends uniformly in all directions as far as our telescopes can reach – over 10 billion light-years, equating to roughly 6 billion trillion miles. However, this doesn't mean the universe stops there.
Here's a breakdown of why we believe this:
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Lack of an Edge: We haven't observed any sort of boundary or drop-off in the distribution of galaxies or other celestial objects that would indicate an edge.
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The Observable vs. The Entire Universe: It's crucial to understand the distinction between the observable universe and the entire universe. The observable universe is limited by the distance light has had time to travel to us since the Big Bang. The entire universe could be far larger, potentially even infinite.
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Possible Topologies: Scientists have proposed various models for the universe's topology (its overall shape and structure). Some models suggest the universe is finite but without an edge, similar to how the surface of a sphere is finite but has no boundary. Other models propose an infinite universe.
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What lies "Beyond": If the universe does extend beyond what we can observe (and current models suggest it likely does), then it would continue to be filled with more of the same stuff – galaxies, dark matter, dark energy, and possibly regions with different physical laws. Thinking about what it's "surrounded by" is conceptually difficult because it implies an outside, and the universe, by definition, encompasses everything.
In essence, the question of what lies "beyond" the observable universe is a fundamental mystery in cosmology, and current evidence indicates the universe either continues indefinitely or is shaped in a way that doesn't permit an "outside."
