If the universe was fine tuned for our life...

[Heywood]

No I think the burden of proof is the other way around. You imagine a space and give it rules. Now you say it is a real space. I ask in what way? You say it is real if viewed from the inside. But there is nothing inside to do the viewing. The burden of proof that it is more than just imagination is yours. Your sub-realities are nothing more than rules and descriptions of outcomes of those rules. They don't create anything real.

Presumably nobody is viewing the far side of Pluto right now....yet you and I would both agree that the far side of Pluto is not imaginary. Why? because potentially we could put an observer there and view it. Perspective is what determines what is real and that perspective exists whether or not a conscious observer exists. Our entire understanding of reality is formulated on this idea that what is real is determined by perspective.

Imagine you are in a space ship positioned in space. You see me pass you in my space ship traveling at the speed of light. You observe a clock on my space ship and see it is stopped. Is time really not passing for me? From your perspective there is no flow of time for me. Now from my perspective reality is completely different. From my perspective I see you passing me at the speed of light. From my perspective your clock is stopped and for you there is no flow of time.

Does the flow of time exist for me? Well it exists and it doesn't exist. It all depends on perspective. Sub realities exist and they don't exist...it all depends on perspective. How can something exist and not exist? The notion is nonsensical. I resolve the nonsense by thinking about it this way. If something can be observed to exist from at least one perspective, then that thing can be said to exist. Since a sub reality is real and has physicality from the perspective of the things they contain, I can credibly say sub realities exist....even if they lack physicality from my perspective. I can credibly say the flow of time exists for you even though it doesn't from my perspective.

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@Heywood

If I create a 'sub reality' does that necessarily infer that it is intelligent?

You can create a sub reality that has no potential for the emergence of intelligence. If you did that sub reality could not be a parent of its own sub reality. It would be a dead end.