Is there a specific size range for intelligent life under biological constraints, or could smart aliens be as much smaller than bugs or much larger than whales?

Question

I read a long time ago an essay by Asimov that described what elements could support life as a building block and why most elements cannot. I didn’t fully understand that at the time but it was interesting to see why carbon based makes sense and some other random element does not work.

Similarly, I wonder if under different planetary conditions, smart alien life (so not single cell life) can be very tiny or very large, or if there are biological constraints that would restrict that size range regardless of basic setup.

In: 324

Answer 1

While everyone else here is looking at earth-like biology, if we assume creatures could exist in all sorts of exotic forms throughout the universe there are still hard physics constraints on how much volume is required for a certain level of computational power

The [Bekenstein Bound](https://en.wikipedia.org/wiki/Bekenstein_bound) defines the maximum amount of information that can be stored in a given space

The [Bremermann’s Limit](https://en.wikipedia.org/wiki/Bremermann%27s_limit) defines the maximum processing speed in a given space

It may be possible for a human level intelligence to exist at bug size but as you get further down in size you’ll bump into those hard limits.