translation - Does くだく mean “destroy”? What does いい mean at the beginning of a line?

Would the following be a good translation of the text in the above two speech bubbles?

"Everything in this universe is composed of atoms. Destroying something is equivalent to destroying the atoms that compose it"

Also, I'm especially interested in knowing if the Japanese text is implying that atoms are completely destroyed/annihilated or if the atoms are separated or pulverized (but not literally/completely destroyed). I'm having troubles on my own... =/

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Here is a transcription of the two speech bubbles, in case you can't see the images:

「この
　大宇宙にあるもの
　すべてが
　原子でできている
　のよ」

「いい　破壊する
　ということの
　根本は　原子を
　くだく
　ということなの」