Reading more from the excerpt which you quoted,
When I was a child, I had a personal conflict over my beliefs. My parents were raised in the Buddhist tradition. But I attended Sunday school every week, where I loved hearing the biblical stories about whales, arks, pillars of salt, ribs, and apples.
Perhaps that answers your question, "What's his religion?"
I suppose that the following helps explain why he describes the "11th dimension" as "Nirvana":
These creatio ex nihilo myths stand in marked contrast to the cosmology according to Buddhism and certain forms of Hinduism. In these mythologies, the universe is timeless, with no beginning or end. There are many levels of existence, but the highest is Nirvana, which is eternal and can be attained only by the purest meditation. In the Hindu Mahapurana, it is written, "If God created the world, where was He before Creation? . . . Know that the world is uncreated, as time itself is, without beginning and end."
In Buddhism, "Nirvana" is I think described as a state which is:
- Unconditioned (i.e. it doesn't depend on or come into being as a result of other things as its condition)
- Timeless (perhaps also translated as "ever-present" or "eternal")
He's saying that the "11 dimensions" described in one of the theories of Physics has similar properties, i.e. it exists without a cause (perhaps unlike "this universe", which I take it is presumed to be embedded within those 11 dimensions, and which has a cause e.g. the "Big Bang").
There's also this sentence:
What is gradually emerging from the data is a grand synthesis of these two opposing mythologies. Perhaps, scientists speculate, Genesis occurs repeatedly in a timeless ocean of Nirvana.
I don't think that means he literally believes in the Biblical story of Genesis. Its in a section of the chapter titled, "Baby Pictures of the Universe". I think the phrase "Genesis occurs repeatedly in a timeless ocean of Nirvana" is meant as, and should be understand as, "something-created (I guess/presume he's talkig about 'four-dimensional space-time' there) occurs repeatedly (or maybe 'fluctuates') within a timeless higher-dimensional space", and he's using pseudo-religious phraseology.
My personal opinion is that it's a pointless (meaningless and unhelpful) analogy.
A similar tendency exists elsewhere, e.g. Quantum mysticism suggests a link between quantum theory and consciousness ... whereas this guy suggests we equate his cosmological/mathematical theory with Nirvana (or with certain characteristics/descriptions of Nirvana taken out of context).
It may or may not (depending on your preconceptions) be a helpful description/analogy of 11 dimensions ... I guess it's an idiosyncratic description of his ... and I'd guess it's not a good description (not a canonical description) of the Buddhist Nirvana.