Search - The Peace War (Peace War)

While not Vinge’s most impressive novel (I’ll give ‘A Fire Upon the Deep’ that designation), The Peace War is a very competent, effective post-apocalyptic/science fiction novel.
Some years ago, at the outbreak of international war, someone invented the ‘bobble’ – spherical containment fields which could eliminate threats by creating an unbreakable barrier around a weapon, or battalion…
The war was terribly destructive anyway, and now a level of reduced technology is enforced by mob-style governments. However, a technological underground resistance exists – including the brilliant scientist who invented this field. When he finds a ghetto urchin who may be a natural math genius, he finally agrees to take on an apprentice.
But the situation is becoming more hazardous for the underground, because it seems that someone else has discovered the secret of the bobble…