My difficulty is in how even to describe the “number of computational steps” that reality takes
Probably the best way is to simply define a “step” in some easily measurable way, and then sit there with a stopwatch and try a few experiments. (For protein folding, the ‘stopwatch’ may need to be a fairly sophisticated piece of scientific timing instrumentation, of course, and observing the protein as it folds is rather tricky).
Another way is to take advantage of the universal speed limit to get a theoretical upper bound to the speed that reality runs at; assume that the protein molecule folds in a brute-force search pattern that never ends until it hits the right state, and assume that at any point in that process, the fastest-moving part of the molecule moves at the speed of light (it won’t have to move far, which helps) and that the sudden, intense acceleration doesn’t hurt the molecule. It’s pretty certain to be slower than that, so if this calculation says it takes longer than an hour, then it’s pretty clear that the brute force approach is not what the protein is using.
Probably the best way is to simply define a “step” in some easily measurable way, and then sit there with a stopwatch and try a few experiments. (For protein folding, the ‘stopwatch’ may need to be a fairly sophisticated piece of scientific timing instrumentation, of course, and observing the protein as it folds is rather tricky).
Another way is to take advantage of the universal speed limit to get a theoretical upper bound to the speed that reality runs at; assume that the protein molecule folds in a brute-force search pattern that never ends until it hits the right state, and assume that at any point in that process, the fastest-moving part of the molecule moves at the speed of light (it won’t have to move far, which helps) and that the sudden, intense acceleration doesn’t hurt the molecule. It’s pretty certain to be slower than that, so if this calculation says it takes longer than an hour, then it’s pretty clear that the brute force approach is not what the protein is using.