Cross-post from EA Forum.
Recall the importance-tractability-neglectedness (ITN) framework for estimating cost-effectiveness:
The product of all three factors gives us utility gained / extra $, the cost-effectiveness of spending more resources on the problem. By replacing $ with another resource like researcher-hours, we get the marginal effectiveness of adding more of that resource.
In the 80,000 Hours page on ITN, scale ranges 8 orders of magnitude, neglectedness 6 orders of magnitude, and tractability (which 80k calls solvability) only 4. In practice, I think tractability actually only spans around 2-3 orders of magnitude for problems we spend time analyzing, except in specific circumstances.
Tractability is defined as the expected fraction of a given problem that would be solved with a doubling of resources devoted to that problem. The ITN framework suggests something like logarithmic returns: each additional doubling will solve a similar fraction of the problem, in expectation. Let the "baseline" level of tractability be a 10% chance to be solved with one doubling of resources.
For a problem to be 10x less tractable than the baseline, it would have to take 10 more doublings (1000x the resources) to solve an expected 10% of the problem. Most problems that can be solved in theory are at least as tractable as this; I think with 1000x the resources, humanity could have way better than 10% chance of starting a Mars colony, solving the Riemann hypothesis, and doing other really difficult things.
For a problem to be 10x more tractable than the baseline, it would be ~100% solved by doubling resources. It's rare that we find an opportunity more tractable than this that also has reasonably good scale and neglectedness.
Therefore, if we assume logarithmic returns, most problems under consideration are within 10x of the tractability baseline, and thus fall within a 100x tractability range.
The three outstanding problems in physics, in a certain sense, were never worked on while I was at Bell Labs. By important I mean guaranteed a Nobel Prize and any sum of money you want to mention. We didn't work on (1) time travel, (2) teleportation, and (3) antigravity. They are not important problems because we do not have an attack.
-- Richard Hamming
Some problems are highly intractable. In this case, one of the following is usually true:
I think the logarithmic assumption is reasonable for many types of problems. Why is largely out of scope of this post, but owencb writes about why logarithmic returns are often a good approximation here. Also, the distribution of proof times of mathematical conjectures says a roughly constant percentage of conjectures are proved annually; the number of mathematicians has been increasing roughly exponentially, so the returns to more math effort is roughly logarithmic.
Elon Musk thinks a self-sustaining Mars colony is possible by launching 3 Starships per day, which is <1000x our current launch capacity.