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I haven't heard the cupcake version. It does have something to recommend it, though raisins don't crawl. So that may make it harder to visualize the differenc

by btilly 8y ago

I haven't heard the cupcake version. It does have something to recommend it, though raisins don't crawl. So that may make it harder to visualize the difference between how fast you're expanding versus how fast you're moving versus local space. Which is the whole point.

mehrdadn 8y ago
Good point, I guess they're good for illustrating different things :)
vanderZwan 8y ago
What I find confusing is that the space inside the ants/raisins should expand as well. Why do we not experience this expansion locally?
- function_seven 8y ago
  Space is expanding everywhere, but the matter that resides within it is bonded to other matter, or gravitationaly attracted together, so it holds. Back to the balloon analogy, the surface of the balloon is expanding, even under the ant's feet. But the ant doesn't grow.
  - acqq 8y ago
    And since the even the whole groups of galaxies are gravitationally bound, it seems that the galaxies, including our own galaxy, are not "stretching" but remain the same size. And, based on the same principle, everything inside of them also, including us. So back to the cupcake analogy, the raisins are the whole galaxy groups. Also: https://medium.com/starts-with-a-bang/this-is-why-we-arent-expanding-even-if-the-universe-is-d8c770531082 https://medium.com/starts-with-a-bang/this-is-why-we-arent-e... "As physicist Richard Price once put it, “Your waistline may be spreading, but you can’t blame it on the expansion of the universe.”" https://www.newscientist.com/article/dn8082-cosmic-expansion-is-not-to-blame-for-expanding-waistlines/ https://www.newscientist.com/article/dn8082-cosmic-expansion... https://arxiv.org/abs/gr-qc/0508052 https://arxiv.org/abs/gr-qc/0508052
  - caf 8y ago
    Here "bonded to other matter" means "electrostatically attracted together".
- gregdunn 8y ago
  It's not strong enough to overcome the forces keeping us together. But that might not be the case for forever: https://en.wikipedia.org/wiki/Big_Rip https://en.wikipedia.org/wiki/Big_Rip

by btilly 8y ago

mehrdadn 8y ago

Good point, I guess they're good for illustrating different things :)

vanderZwan 8y ago

What I find confusing is that the space inside the ants/raisins should expand as well. Why do we not experience this expansion locally?

function_seven 8y ago
Space is expanding everywhere, but the matter that resides within it is bonded to other matter, or gravitationaly attracted together, so it holds. Back to the balloon analogy, the surface of the balloon is expanding, even under the ant's feet. But the ant doesn't grow.
- acqq 8y ago
  And since the even the whole groups of galaxies are gravitationally bound, it seems that the galaxies, including our own galaxy, are not "stretching" but remain the same size. And, based on the same principle, everything inside of them also, including us. So back to the cupcake analogy, the raisins are the whole galaxy groups. Also: https://medium.com/starts-with-a-bang/this-is-why-we-arent-expanding-even-if-the-universe-is-d8c770531082 https://medium.com/starts-with-a-bang/this-is-why-we-arent-e... "As physicist Richard Price once put it, “Your waistline may be spreading, but you can’t blame it on the expansion of the universe.”" https://www.newscientist.com/article/dn8082-cosmic-expansion-is-not-to-blame-for-expanding-waistlines/ https://www.newscientist.com/article/dn8082-cosmic-expansion... https://arxiv.org/abs/gr-qc/0508052 https://arxiv.org/abs/gr-qc/0508052
- caf 8y ago
  Here "bonded to other matter" means "electrostatically attracted together".
gregdunn 8y ago
It's not strong enough to overcome the forces keeping us together. But that might not be the case for forever: https://en.wikipedia.org/wiki/Big_Rip https://en.wikipedia.org/wiki/Big_Rip