Thrity fables about thirty different realms of time.
It's an original work. More like a short sotry collection than a novel though. They're tied together by occasional brief interludes featuring Einstein in Switzerland in 1905, not long before his theory of relativity was finalized. But without those brief, unnecessary interludes it could have been called Lightman's Dreams.
They're stories of ideas. What if...? What will this guy come up with next? His writing lacks both the eloquence of a Nabokov and the insider's details of a Hemingway. But he deserves credit for thinking in different directions, different ways.