A surfer dude with no fixed address may be this century's Einstein.

A. Garrett Lisi, a physicist who divides his time between surfing in Maui and teaching snowboarding in Lake Tahoe, has come up with what may be the Grand Unified Theory.

That's the "holy grail" of physics that scientists have been searching for ever since Albert Einstein presented his General Theory of Relativity nearly 100 years ago.

Even more remarkable is that Lisi, who has a Ph.D. but no permanent university affiliation, solves the problem without resorting to exotic dimensions, string theory or exceptionally complex mathematics.

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A successful Grand Unified Theory would use a series of equations to show how the four fundamental forces of nature — gravity, electromagnetism and the strong and weak nuclear forces — relate to each other.

Electromagnetism and the weak nuclear force, which controls radioactivity, were linked more than 30 years ago, and some progress has been made with linking them to the strong nuclear force, which binds protons together in the atomic nucleus.

• Click here for Lisi's images of himself surfing, snowboarding, skateboarding and hang gliding.

But gravity has always been an outlier. Not only have all attempts to link gravity to the other three forces failed, but physicists still can't agree on what gravity actually is or how it works.

Lisi solves this by using the E8 lattice, an eight-dimensional structure visualized earlier this year in a widely circulated paper.

• Click here to read more about the E8 lattice.

He noticed that several of the equations used to describe the lattice matched those he'd come up with trying to resolve the four fundamental forces.

"The moment this happened my brain exploded with the implications and the beauty of the thing," Lisi tells New Scientist magazine. "I thought: 'Holy crap, that's it!'"

• Click here to read a formal presentation of the theory, if you dare.

By mapping known subatomic particles, plus 20 imaginary ones, onto the 248 points of the E8 lattice, and then rotating the lattice in a computer model, Lisi shows how the particles elegantly combine to form three of the four forces.

The imaginary ones combine to form gravity, for which subatomic particles have only been theorized.

• Click here to watch a video of the lattice being rotated.

"Some incredibly beautiful stuff falls out of Lisi's theory," David Ritz Finkelstein of Georgia Tech tells New Scientist. "I think that this must be more than coincidence and he really is touching on something profound."

But Professor Marcus du Sautoy of Oxford tells Britain's Daily Telegraph that "there seem to be a lot of things still to fill in."

For his part, Lisi self-mockingly calls his finding "An Exceptionally Simple Theory of Everything," and downplays the suggestion that it may be the Grand Unified Theory.

"The theory is very young, and still in development," he tells the Daily Telegraph. "Right now, I'd assign a low (but not tiny) likelihood to this prediction."

He hopes the Large Hadron Collider, or LHC, currently being built on the Swiss-French border will find some of his 20 imaginary gravity-related particles.

"This is an all-or-nothing kind of theory — it's either going to be exactly right, or spectacularly wrong," Lisi tells New Scientist. "I'm the first to admit this is a long shot. But it ain't over till the LHC sings."

• Click here for the New Scientist story, and here for the Daily Telegraph version.