Aliens?

[Elmo]

After the Valar, who before were the Ainur of the Great Song, entered into Ea, those who were the noblest among them understood most of the mind of Illuvatar sought amid the measurable regions of the Beginning for that place where they should establish the Kingdom of Arda in time to come. And when they had chosen that point and region where it should be, they began the labours that were needed. Others there were, countless to our thought though known each and numbered in the mind of Illuvatar, whose labour lay elsewhere and in other regions and histories of the Great Tale, amid stars remote and worlds beyond the reach of the furthest thought. But of these we know nothing and cannot know, though the Valar of Arda, maybe, remember them all.

This quote form Myths Transformed I find very intriguing due to the mention of other worlds. This reminds me of all those worlds in the Magician's Nephew and they throw up many questions even though Tolkien says we cannot know anything about them. Is Tolkien implying that there are 'aliens' in his imaginary world? Are these beings Children of Illuvatar as well as Elves and Men? Or are there Elves and Men in these distant worlds? Perhaps even more intriguing is the fact that Melkor did not exist in these worlds as Myths Transformed mentions he concentrated all his power on Arda. Are these worlds therefore free of evil?