If you haven't read anything by Isaac Asimov yet, there's probably no better place to start. Originally written as three consecutive short stories, and available as a single novel now, The Gods Themselves is one of Asimov's best work, at par with the Foundation Series. Like a lot of his other works, The Gods Themselves deals with aliens who live in a world very different from ours. This particular species inhabits a dying parallel universe whose last hope for generating energy leads to catastrophic results on Earth. In case you're not sure about investing time to read an entire novel, just read the short story 'Nightfall' and you won't be able to stop yourself.
Contributed by Anshul Awasthi