I just finished Starquake, the sequel to Dragon's Egg, and damn, what a great book. I loved the first one, but this one had me hooked even more.
The cheela have to be some of the most fascinating aliens in science fiction. They're about the size of sesame seeds and live on the surface of a neutron star where gravity is 67 billion times stronger than Earth's. They also live roughly a million times faster than we do. While the humans in orbit are having a conversation, generations of cheela can be born, live their lives, and die.
What really got me was everything that happened after the starquake. Their civilization is practically wiped out, leaving only four survivors on the surface. They try to rebuild, and somehow it all ends up under a barbarian tyrant. That whole part was hard to put down.
Meanwhile, the cheela in space are trying to find a way back down to save their people. I liked that the humans and cheela still needed each other, even after the cheela had raced past humanity in nearly every branch of science.
Forward was a physicist, and you can tell. Some of the science went right over my head, but honestly, that was part of the fun. The book makes you stop and wonder how life could work under conditions that are almost impossible to picture.
If you like hard science fiction and haven't read Dragon's Egg and Starquake, you're missing out. Read them in order.
I really wish Forward had written a third one.
Wayfarer