it is growing at a pace close to exponential.

I wonder how he (or anybody else) measures growth of knowledge. Are there any sensible metrics beside amount of paper created? I understand that published pages is a measure as is number of patents but I don't think these are useful proxies for knowledge.

What other measures might be used?

• Complexity measures of the created knowledge: Depth of the gratph of citations between papers (assuming each citation adds something; might be weithed by the number of outgoing refs)

• Complexity of the created artifacts (programs, machines). E.g. number of abstraction layers. Or other standard complexity measures thereof.

• Speedup achieved by the methods when applying them to optimize tasks. (Exponential speedups in this domain could result from self-optimization and are dangerous and I really hope that those are not implied by the OP).

• Ability of the research work (persons or software) to acurately describe/model real-world phenomena of a given (and exponentially growing) size. This I think is the most likely candidate.

• More simple quantities: Number of researchers in a field, number of conferences, number of mails exchanged about a topic

• And of course subjective complexity. I guess we are bound to label anything exponential that grows faster than we can keep track of.