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1 year ago in Cosmology By Himanshu

If the universe is expanding, what’s it expanding into?

Okay, I get that galaxies are moving apart. But what's on the other side of the edge? What is the universe expanding into?

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By Usha K Answered 2 months ago

This is the most common and most frustrating question in cosmology because the answer is counterintuitive. The universe isn't expanding into anything. It is all of space itself that is stretching. The classic analogy: dots on a balloon. As you inflate it, the dots move apart, but not because they're racing toward an edge. The surface itself is growing. There is no "outside" in the model. New space is created between galaxies, inheriting the same three dimensions. There's no void it's spilling into. Just more universe.

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