prove a negative

you can't prove a negative nor recreate history to show what might have been.

没人能用反证法或者重造历史来说服大众——说明某事也许会发生。

Since it is logically impossible to prove a universal negative, science will never be able to prove that creatures like Bigfoot and the Loch Ness monster do not exist, and it is possible that these mysterious beasts lurk far from prying eyes.

要证明一个全称否定判断从逻辑上说是不可能的，因此科学将永远不能证明“大脚”和尼斯湖怪兽之类的东西不存在。也有可能，这些神秘莫测的生物的确潜藏在人们好奇视线之外的远处。

in science, you can't "prove" a negative (e. g that a chemical won't be dangerous).

在自然科学中，我们不能“证明”一个否定的观点。

it's very hard to prove a negative.

要证明问题不存在非常难。

i was trying to prove a negative.

我尽力证明什么都没有。

Although the cohesion tension theory has been well established for more than a century, some problems have stood in the way of its complete acceptance because its corollary is difficult to prove: large negative pressures exist in xylem conduits.

虽然内聚力-张力学说已经建立了一个多世纪，但要完全接受它仍有一些问题，因为它的一个推论是很难证实的，即木质部导管中存在大的负压。