Full disclosure: I’m high, but what exactly is expanding in the universe? Like I read something at some point that said that galaxies and cosmological bodies aren’t actually moving away from us faster than light, the space between them is just expanding. They made a distinction somehow but now, a long time after reading that, I’m sitting here wondering what it is that’s expanding… and wouldn’t whatever it is be expanding faster than light? I hope someone can help because I’m starting to spiral out.
In: Physics
Imagine you have an elastic band line and you put two points on it close by. As you stretch the band, it expands, however the two points close together barely move apart.
Another example is a crowd of people, if the space between all the people grows by a foot, then the whole crowd will grow quite a bit, but individuals haven’t moved much.
So in the universe, the space between everything is growing. Gravity, electromagnetism, and the strong and weak nuclear forces keep things together, however when you have very very long distances where gravity is tiny, such as between galaxies, this expansion is noticeable.
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