[jcfrei]

Counterpoint: Alien life will probably look very similar to life on earth. If you look at evolution then countless species have evolved into something crab-like: https://www.youtube.com/watch?v=wvfR3XLXPvw Turns out that their form is pretty good for survival. While biology can take on a myriad of forms, the competitive nature of life will weed out a lot of them. And since the rules for biochemistry are the same across the universe similar traits that are beneficial here will probably be beneficial there.

[heavyset_go]

> Turns out that their form is pretty good for survival

Their form is pretty good for survival on Earth, we don't know if they're good forms for survival elsewhere or in general.

[cactusplant7374]

I agree with this but would the intelligent beings on other planets be the same size as humans? Could there be giant creatures that are just as intelligent as us?

[dmurray]

There are some square/cube laws that put a rough cap on how big an efficient animal can be with Earth biology. But if you change some parameters (lower gravity, energy-rich environment, stronger building materials than bone) you could get hundreds of times bigger than humans. Even on Earth, intelligent dinosaurs would have been completely possible.

[dmurray]

And I forgot to even mention whales.

[jcfrei]

There's a natural limit to size due to the square-cube law. An increase in height leads to a cubed increase in mass which means they are pretty quickly too large and require too much energy to sustain themselves.

[kevin_thibedeau]

There's no reason to believe other sentient life will be in any way relatable to us. Most significantly, there's no reason their perception of time is on the same order as ours. We could be glacially slow or impossibly fast for them to engage in any meaningful way.