This question is a followup on the question about DNA algorithms asked by Aadita Mehra.
In comments there, Joe Fitzsimmons said, in part:
[T]he radius of the system must scale proportionately to the mass to avoid this. The computational power scales at most linearly in the mass. Thus your exponential amount of machinery has an exponential radius. Since you can't signal faster than light, a signal from one side to another takes an exponentially long time to reach the other side, and so if all the machinery contribute to the answer, it is impossible to solve the problem in less than exponential time.
My question has two parts.
(1) What is the best way/ways to formalize a statement like, "The computational power scales at most linearly in the mass" ? Is this statement really not up for debate?
(2) Suppose the statement is true. Even so, could nature already have done an exponential amount of preprocessing that we might be able to make use of, for example evolution's creation of vision systems through "brute force randomization."
I've heard and read a fair number of soft (pseudoscientific) answers to questions of this sort, and I'd be grateful for any answers here, but I'm most interested in how (1) and (2) can be recast in TCS rigor.