The Time Ships is a sequel to the Time Machine, written by Stephen Baxter and authorized by H. G. Wells estate.
The book starts upon the return of the Traveller; who is full of guilt and self reproach after abandoning the Eloi Weena to the Morlocks. He vows to return to the far future and rescue her, leaving almost as soon as he arrives. But what he doesn't realise is that by making his original trip to the future, he has changed that future.
His discovery that his original journey has caused the future to contain a Dyson Sphere around the sun, (much as a flap of a butterfly can cause a hurricane) nearly drives him insane. His continued travellings backwards and forwards through time, eventually lead to him witnessing the ultimate mastery of life over the entire universe.
Again Baxter's work leaves you gasping, using concepts from cosmology and quantum mechanics to show you what a civilisation advanced enough to make a time machine, would actually do with it.