How did Neptune form to be more dense than Uranus?

This is a question that arose from another question I asked earlier today, but why is Neptune more dense than Uranus despite being close to the same size, but further from the sun? As I understand it, heavier elements should have been concentrated closer to the sun during the formation of the planets. The only... show more This is a question that arose from another question I asked earlier today, but why is Neptune more dense than Uranus despite being close to the same size, but further from the sun? As I understand it, heavier elements should have been concentrated closer to the sun during the formation of the planets. The only theory I have heard is that Neptune somehow formed closer to the sun than Uranus, and drifted to a further orbit, but I received no explanation as to how that would happen.
Update: Lionheart, I do not know if there is a god or not, but couldn't your answer also be used in respect to religion? That it is just a story people choose to swear by? I have nothing against religion, but I would just like answers that help lead to a clear understanding.
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