Originally Posted by pdurrant
Also known as "The Day After Tomorrow" (thanks, alansplace), and I think I have read it under that title, but a vey long time ago.
It's Heinlein's first novel, on an outline by John W Campbell. An interesting early work, but definitely with its roots in the pulp super-science era. I enjoyed it, but perhaps more for the Heinlein insights rather than the story itself.
If you enjoyed it for that reason, I'd recommend "Assignment in Eternity", also by published by Baen. It too is very early Heinlein (a collection of a couple of novellas and a couple of long-ish short stories).