Re:How Can a Star Be Older Than the Universe?
by tidenly on Wednesday October 16, 2019 @09:42PM
(#21278192)
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.
[ Parent
| on HN ]
Re:How Can a Star Be Older Than the Universe?
by e12e on Thursday October 17, 2019 @03:34AM
(#21279748)
Which 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).
Re:How Can a Star Be Older Than the Universe?
by Filligree on Thursday October 17, 2019 @08:09AM
(#21281132)
If 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.