The Manhattan Project

The K-25 gaseous diffusion plant: the single largest and most expensive Manhattan Project site.

Roberta's been watching Manhattan on the tube, which got me to wondering if anyone had done a timeline on the project and of course, this being the internet and all, several people have. I like the one on Atomic Archive.
    When WW2 started, there were only a few crackpots (like Albert E.) who thought it might be possible to build an atomic bomb. Basically, they knew almost nothing about the subatomic world. Oh, they knew about neutrons and protons and electrons, but they only had vaguest ideas about how all these things played together. That little bit of knowledge and the idea that a bomb might be possible along with the impetus of war was enough for the powers to be to jump in with both feet. Okay, they started with one toe, but it quickly ramped up.

Expenditures for the Manhattan Project sites, through the end of 1945

    The biggest investment, money wise, as you can see from the graph above, was for the construction of the uranium isotope separators in Oak Ridge, Tennessee. Y-12 wasn't started until February 1943 and K-25, the big one, wasn't started until September. They didn't know if they would work, and they still didn't know if they could make a workable bomb from the stuff these plants produced, but they charged on anyway.
    They dropped the bombs in the August of 1945, two and one-half years after they started construction of the biggest factories in the world.

I am having a hard time getting my head around the idea that these guys went ahead with this project to the tune of billions of dollars when they didn't even know if it would work. I guess we can chalk one up for science, and the religion thereof.

P.S. Why are some people writing Manhattan with the 2nd A in parentheses, like this: Manh(A)ttan? Is that supposed to look like a bomb? Several sites have done this, but no one has offered an explanation. I think it's dumb. YMMV.