Possibly the most stupendously useless thing I've ever done. It's a UTM, running on an (infinitely long, lazily initialized) tape, which encodes a description of the UTM + the same tape.

The "L0" machine has been running for about 1.5 months, taking about 1B steps/sec.

The L1 machine it's simulating has been taking about a dozen steps/sec.

The L2 machine it's simulating takes about one step/hour.

In ~2070, the L3 machine will take its first step.