Scientists believe that gravity, electromagnetic force, strong nuclear force and weak nuclear force are the Four Basic Forces of the universe.

科学家们认为，万有引力、电磁力、弱力和强力是宇宙中的四种基本作用力。

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Only gravity and a phenomenon called the weak nuclear force, which governs some types of radioactive decay, can bind them—hence the term “weakly interacting”.

只有重力和一种可以支配某些放射性衰变的弱核力能够使其聚集凝固，“弱反应”这一术语由此得名。

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Compared with the other three forces in the universe (electromagnetism, the weak nuclear force and the strong nuclear force), gravity is relatively feeble, making gravitational waves hard to detect.

和宇宙中的其他三种力(电磁力、弱核力、强核力)相比，重力就微弱得多了，所以引力波很难被观测。

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Compared with the other three forces in the universe (electromagnetism, the weak nuclear force and the strong nuclear force), gravity is relatively feeble, making gravitational waves hard to detect.

和宇宙中的其他三种力(电磁力、弱核力、强核力)相比，重力就微弱得多了，所以引力波很难被观测。

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