Nehaveigur

It didn’t have to be this way. The laws of nature could’ve been different so that life wouldn’t have emerged, humans wouldn’t have evolved, and there’d be no-one to wonder why things turned out this way.

Yet we exist, and think, and observe the universe. Therefore, the universe could only be the way it is, or at least similar enough to support sentient life. This is the anthropic principle.

Slight deviation from physical constants would’ve resulted in a universe incompatible with life. For example, if the strong interaction binding subatomic particles together were only slightly different, stars as we know them wouldn’t exist. While it is true that physical constants appear fine-tuned to allow life to emerge, the mystery is bigger than this.

There could’ve been nothing instead of something. The universe could’ve been completely chaotic, without any natural laws. There could’ve been a different number of space or time dimensions, none of them conductive to life. The universe could’ve been too small to support life, or not complex enough.

But even assuming that the laws of nature and physical constants could only be the way they are, this doesn’t necessarily lead to the emergence of life. We know it did emerge, but in a sense, this was not a foregone conclusion. The only way to find out if a universe that appears fine-tuned can actually support life is to wait until life actually emerges. The emergence of life is likely to be computationally irreducible.

Could there be a universe whose physical constants appear to be fine-tuned to life but that doesn’t allow for evolution? This is hard to imagine, since emergence and evolution to me seem more fundamental than physical constants. Maybe in any sufficiently complex universe evolution is inevitable. Or maybe we are confusing cause and effect. Is the universe fine-tuned to life, or life fine-tuned to the universe, as has been argued by Stephen Jay Gould?

But even once life exists, there is no reason why it would necessarily evolve towards sentience. There could’ve been only one dominant life form, or at least much less biological diversity. Life could’ve remained unicellular, as it did for a long time on Earth. Life could’ve never gotten around to evolving minds, or sentience.

But even if sentience had emerged, there is no reason why that would necessarily lead to civilization. How did natural selection prepare the human mind for civilization before civilization existed? There could’ve been only one dominant and static civilization. It could’ve been that no civilization ever developed advanced technology. There could’ve been civilization but without play, beauty and art.

Alternatively, a sentience with god-like abilities could’ve arisen somewhere in the universe, subsuming everything within its light cone. If this is possible, why hasn’t it happened, given the scale of the universe? Is the universe somehow arranged to prevent it? For example, we could imagine a small universe with only a single planet, but that there are so many worlds with so much distance between them suggests the universe is fine-tuned to prevent domination by a single agent.

The unifying feature of all of the above, and maybe therefore of everything, is that the universe doesn’t just appear to be fine-tuned to support life but fine-tuned to maximize possibilities.