Of course we measure space!
In computational complexity theory "space" means "memory". The unit for measuring memory is bit (classically) or qubit (quantum).
In computer science, the space complexity of an algorithm or a computer program is the amount of memory space required to solve an instance of the computational problem as a function of the size of the input. It is the memory required by an algorithm to execute a program and produce output
Which is why all algorithms (mental models of reality) are subject to the space-time trade-off
Some algorithms take long time to execute (but require little memory)
Some algorithms take short time to execute (but require a lot of memory)
https://en.wikipedia.org/wiki/Space%E2% ... ff#History
Biological usage of time–memory tradeoffs can be seen in the earlier stages of animal behavior. Using stored knowledge or encoding stimuli reactions as "instincts" in the DNA avoids the need for "calculation" in time-critical situations.