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A less brain melting way to imagine the "expansion without edge" thing is the classic balloon system. Imagine your entire universe exists across the plain of a
by tidenly 7y ago
A less brain melting way to imagine the "expansion without edge" thing is the classic balloon system. Imagine your entire universe exists across the plain of a semi-deflated balloon and then someone slowly begins to blow it up. The "space" in your 2D world is expanding, but there are no edges.
- e12e 7y agoWhich leads to the follow up question: if you travel far enough in one direction do you end up where you started? (well, no, not if space expands faster than c).
- Filligree 7y agoIf it wasn't for the expansion, and if the universe had positive curvature, then yes. As it stands, there's not only the expansion, but the universe also seems to be flat -- meaning it's spatially infinite, not just borderless. That observation is also compatible with a very, very small curvature, but in that case the size would still be so large that it wouldn't be practically possible to circumnavigate even if it wasn't expanding.