Quote:
Originally Posted by jammies
There are only so many ways it is physically possible to gather information about the environment around you. "Eyes", in the sense of organs able to detect radiant energy, are likely to be nearly universal answers to this problem.
The idea that some unknown force exists that might substitute for vision (leaving aside echolocation, touch or scent, which are niche methods of primarily observing the environment and are hardly outside human comprehension) implies our understanding of physics is not just incomplete, but utterly mistaken. Further, organs that can detect this hypothetical unknown force would essentially be eyes anyway, not much different that being able to see infrared or x-rays or 5g wireless instead of "visible" light.
In short, aliens might be wildly different from humans, but not because they have inconceivable sensory organs.
PS: Binocular vision is very useful for predators, who need to gauge the precise distance to prey animals and resolve details at range. Eyes on either side of the head are better for herbivores, where field of vision to detect the approach of predators is more useful (close enough to see is usually too close already). Efficiency is what drive evolution, and three or four or more eyes gives marginal benefit over two, so again it is unlikely that aliens would have more than two eyes unless there were specific environment factors that made the expenditure of energy a net benefit. Maybe something like an amphibious species that has specialized eyes for multiple environments might qualify, but even then eyes with multiple functions make more evolutionary sense, just like we use different receptors in the eye for low-light vision. not another set of special night-eyes.
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I don't disagree with any of that, and used to look at it similarly. The need to 'see' the environment around you, seems a pretty universal necessity towards developing sentience.
But I am trying to keep my imagination open.
Some type of sonar or radar type of sensory perception could be possible (imagine a world where the atmosphere is cloudy and opaque).
Or maybe a creature's entire exo-material is opaque (like jelly fish and such), and they don't even need to develop a tool to see.
Also, your basic premise was once again built upon earth-centric premises: hunting other prey. Bifocular vision is wildly useful for chasing a prey across the Serengeti. But if your diet is entirely plant-based (and always was, throughout your species' evolution), or you don't need to eat at all (because nutrients are absorbed from the atmosphere), eyes aren't as necessary.