Physicist Steve Sims is wandering around a very desolate USA after nuclear bombs have destroyed everything. While wandering, has also been working on a treatise on the “Paradox of Indeterminacy.” He finds other survivors, particularly a girl named Frances. Together with a guy called “Lucky” the start using science to take back the country from the unamed enemy. Best invention: a ray gun. I haven’t finished yet, but this story is good.
Murray Leinster is an award winning science fiction author and inventor. Read the wikipedia article here. Can’t wait to finish this one!