Cosmic endowment

The ‘cosmic endowment’ comprises the \(\approx 4 \times 10^{20}\) estimated stars that could potentially be reached by probes originating from modern Earth, before the expanding universe carries those stars over the cosmological horizon. It has been estimated that simply surrounding a star with solar panels would yield on the order of enough energy to perform \(\approx 10^{42}\) computer operations per second. Using 100 billion neurons x 1000 synapses per neuron x 100 operations per synapse per second as a standard handwavy estimate of the computing power required to support a human-equivalent existence—although it is doubtful that humans are using this computational power very efficiently, or that 100 ops/​second could faithfully simulate one synapse—this suggests that a star could support, at minimum, \(\approx 10^{25}\) human-equivalent sapient lives. Glossing a star’s lifetime as 1 billion years, and assuming the quality of posthuman existence to count for no more than 1 Quality-Adjusted Life Year (QALY), this suggests that the cosmic endowment could be used (extreme handwaving) to realize at least \(\approx 10^{54}\) QALYs.