The human brain has on the order of 1e11 neurons. The galaxy has on the order of 1e11 stars.
Now, would we confidently predict that we could "solve" the galaxy in less than 100 to 500 years, say? And yet we make very, very aggressive estimates of how quickly we might unravel the secrets of the brain.
Biology is just monstrously, monstrously complex!
The hope is that it may actually be easier to build a useful thinking machine than to fully reverse-engineer the brain.
If we can really build a neural lace in the sense that Iain Banks originated the term, then we've probably also solved cancer and the rest of biology. Imagine the fine-grained control you'd need to manufacture a molecular-scale structure in-situ.
I'm intrigued by the difference between "understanding" a population, in aggregate, and having a fine-grained view of each individual while also knowing how each individual relates to the whole.
So, what might we learn about the galaxy if we knew what / where / when every single bright spot of star-ish size is, that we would not learn from an aggregated simulation? Rhetorical question, obviously.
I don't even know how many people live within 5km of me. How many are human-trafficked, held against their will? etc. We can make approximations, but there's a lot of interesting information at the margins.
While you don't know how many humans are within 5km of you, that's certainly easier to verify with confidence N than it is to verify how many humans within 5 light years.
1) How soon do you think we'll be able to tap every neuron?
2) How soon do you think we'll understand the galaxy in terms of each and every individual constituent star (not aggregates).
We can hand-wave estimates for the number of constituents in each of these systems. But it's interesting that we don't really know how many neurons there are in your individual brain, or in mine, etc. We can't yet look across the scales required to e.g. count and localize every single cell in your brain. Also, at what time? It changes. Just interesting questions when you get to a fine scale...
If it's doable but the computer can't tell the difference between my attempts to command it and my daydreams, maybe still no.