Change is least likely in the physical medium of books.
书的物理介质不太可能发生变化。
The spatial relationships that are brought into being by knowledge of writing are constrained by physics, of course — after all, writing is a physical medium — but they are in no way grounded on it.
因为写作内容而形成的空间联系虽然受限于物理条件（毕竟写作是一种物理媒介），但却肯定不是以物理条件为基础形成的。
They imagined the existence of a physical medium - the ether - filling all of space.
他们想象存在一种充满整个空间的物理介质——以太。
They imagined the existence of a physical medium - the ether - filling all of space.
他们想象存在一种充满整个空间的物理介质——以太。
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