The thing about the Manhattan project is that they had solid physics and maths underpinnings to their theory, and what they invested in was techniques. The sun stood as evidence at scale and Rutherford's experiment had proved atom splitting was possible. Radiation existed. Predictable and precisely measured states of matter were understood.

Theory of mind right now and the last 50 years are speculative and we have no real insight beyond connectionist views and some neuron models. Statistics can emulate aspects of vision and language but to call it "comprehension" is a stretch.

The Manhattan scientists worried they might miss the mark but that mark existed as a certainty. AI is where a metaphorical take on the nuclear age is: one of the scientists had a lump of "wood" and a match, and asked people to set it on fire: it was petrified wood. He used that as the metaphorical mountain they had to climb.

Ai doesn't even have the match yet.

A Manhattan project is a goal seeking investment by state actors to a highly specific endpoint. HIV vaccination, polio eradication, fusion energy.

What we have is DARPA engineering funding to outsider project breakthroughs. It's three orders of magnitude less certainty and funding is commensurate.