From Likutei Sichos, Vol. 35, pg. 74:
Before the world was created, God created another spiritual world, a world that collapsed. It collapsed because the components of that spiritual world — the world of Tohu — were highly charged free radicals that would not interact.
In principle, that intensity was good, for it was a powerhouse of spirituality. In practice, however, it failed.
Nevertheless, in the future redemption, the intensity of Tohu will once again be revealed, and this time, it will not collapse. This is because man’s good deeds throughout history will act as receptacles to bind with the intense free radicals of Tohu.
Sodom was a manifestation of the failed world of Tohu. The city was destroyed because its citizens were free-radicals who refused to pay attention to anybody else but themselves. Therefore, in the Messianic era, Sodom will be inhabited once again, for then the world will be a stable environment for the high-charged free radicals of Tohu.
