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The raisin bread is a 3D expansion in 3D space. So from the viewpoint of a specific raisin the others are moving differently depending on what direction you loo
by jecel 6y ago
The raisin bread is a 3D expansion in 3D space. So from the viewpoint of a specific raisin the others are moving differently depending on what direction you look and you can use that to determine where the center of the bread is.
The balloon is a 2D expansion in 3D space, which is a better analogy for our 3D universe expanding in 4D space. From the viewpoint of a particular dot you see the exact same thing no matter what 2D direction you look. There is no center.
I agree that the balloon is more confusing, but it is more correct in that it doesn't lead to ideas like "the point where the big bang happened".
- anigbrowl 6y agoIs the a term for the 4-dimensional coordinate of the 'inflationary center', like there a 3d coordinate for the center of the balloon (inaccessible from the flat universe on its surface)?
- svachalek 6y agoImagine that the balloon is actually completely flat and (to all intents and purposes) stretches infinitely in X and Y directions without wrapping around. As I understand it, we currently believe we're in a 3D version of that: https://en.wikipedia.org/wiki/Shape_of_the_universe https://en.wikipedia.org/wiki/Shape_of_the_universe
- solstice 6y agoYour last point resonates with me. I had neither previously considered where the big bang might have taken place, nor that this would somehow be an erroneous concept. I scrolled through a bunch of disjointed answers on Quora that left me more confused than before. Could you point me to some good resource on that topic?