What does this equation mean?

so the horizon that can be sustained at a target success rate $\tau$ is $n_{\max} \approx \frac{\ln \tau}{\ln q}$. The derivative of $n_{\max}$ with respect to q is steep near q = 1 , which is the good news — small per-step gains buy disproportionate horizon. The bad news is the same expression read the other way: sustaining an order of magnitude more steps requires driving per-step error down by an order of magnitude, and every one of the six problems above is a term in that per-step error which scale is not reducing. Verification, calibration, and memory are precisely the mechanisms that break the exponential by resetting accumulated uncertainty. Without them, capability gains are spent buying a slowly lengthening horizon rather than a qualitatively longer one.