In the Friedmann models, the answer is tied to the average density of matter: a high-density universe will collapse, whereas a low-density universe will expand eternally.

• 在佛里特曼的模型中，这个问题的答案和物质的平均密度有关：高密度的宇宙会塌陷，而低密度的宇宙则会持续膨胀。