Several authors (including myself) have made claims, none of which has been convincingly rebutted, that the flatness problem, as formulated by Dicke and Peebles, is not really a problem but rather a misunderstanding. In particular, we all agree that no fine-tuning in the early Universe is needed in order to explain the fact that there is no strong departure from flatness, neither in the early Universe nor now. Nevertheless, the flatness problem is still widely perceived to be real, since it is still routinely mentioned as an outstanding (in both senses) problem in cosmology in papers and books. Most of the arguments against the idea of a flatness problem are based on the change with time of the density parameter \(\varOmega \) and normalized cosmological constant \(\lambda \) (often assumed to be zero before there was strong evidence that it has a non-negligible positive value) and, since the Hubble constant H is not considered, are independent of time scale. In addition, taking the time scale into account, it is sometimes claimed that fine-tuning is required in order to produce a Universe which neither collapsed after a short time nor expanded so quickly that no structure formation could take place. None of those claims is correct, whether or not the cosmological constant is assumed to be zero. I briefly review the literature disputing the existence of the flatness problem, which is not as well known as it should be, compare it with some similar persistent misunderstandings, and wonder about the source of confusion.

一些作者（包括我本人）声称，由Dicke和Peebles提出的平坦度问题并不是一个真正的问题，而是一种误解，但没有一个令人信服地被驳斥。尤其是，我们所有人都同意，不需要在早期的宇宙中进行微调就可以解释这样一个事实，即无论是在早期的宇宙中还是现在的宇宙，都没有强烈偏离平坦性的事实。尽管如此，平坦性问题仍然被广泛认为是真实的，因为在纸质和书籍的宇宙学中仍然经常提到它是一个突出的（从两个方面来看）问题。大多数反对平面度问题的论据都是基于密度参数\（\ varOmega \）和归一化宇宙学常数\（\ lambda \）随时间的变化（在有力的证据表明它具有不可忽略的正值之前，通常假定为零），并且由于未考虑哈勃常数H，因此与时标无关。另外，考虑到时间尺度，有时声称需要进行微调才能产生一个在短时间后既不坍塌也不迅速膨胀以至于不会发生结构形成的宇宙。无论宇宙常数是否假定为零，这些主张均不正确。我简要回顾一下有关平坦性问题的存在的文献，该问题并不像应该那样广为人知，将其与一些类似的持续误解相比较，并想知道混淆的根源。