ELI5: How does the universe not have an edge? If the Big Bang was the start of all space, expanding from an infinitely small point, in what did that expansion take place? And what is the universe expanding in?

I?ve heard the raisin bread analogy, but to me that makes little sense because the raisin bread is expanding INSIDE the oven. My mind goes to thinking that the universe is expanding inside something. Based off our most likely understanding of the universe, I just can?t comprehend the idea of the universe not having an edge or being inside something.


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