I know him. We've both been involved with the American Linear Collider Working Group. He's a sharp guy, and a hell of a speaker.
What the article leaves out is the physics motivation behind large extra dimensions. The purpose is to solve what's known as the "hierarchy problem". Gravity, you see, is many orders of magnitude weaker than the other forces, which is one of the reasons why it's so hard to unify with the others. Let's suppose, however, that our 4-dimensional spacetime is but one slice of a higher-dimensional space, and suppose further that the strong, weak and electromagnetic forces were constrained to operate on that slice. If gravity alone were permitted to operate throughout the entire higher-dimensional space (often called the "bulk"), its effect as seen from the slice could be diluted to an arbitrary weakness, even though the actual strength of the interaction would be comparable to those of the other interactions.
One of the interesting consequences of Nima's theory is that electrons of different polarization would be displaced slightly from each other in the extra dimension. The displacement is energy-dependent, so two sufficiently high-energy polarized electron beams (as would be produced in a linear collider) could pass right through each other, missing each other, as it were, in the 5th dimension.
I pointed out to him once that this is almost exactly the physics behind the Oscillation Overthruster in The Adventures of Buckaroo Banzai Across the Eighth Dimension. He'd never heard of it.
Meanwhile, back here on the ranch, we gotta feed the chickens and milk the cows. Cows go mooo. Just so you know.
But, what about the red leptons?
So would each dimension have it's own displacement signature?
The Adventures of Buckaroo Banzai Across the Eighth Dimension.
Yep, that's definitely what comes to mind, monkey-boy!
My science fiction side wants to know that if these dimensions exist, and are extremely small, and exist outside of our space and time, if they could be entered and exited by something other than subatomic particles, could this be a way to move objects in our space without actually moving through our space and time?
It would seem to me that if you enter a parallel dimension, and subsequently leave it, you may not be where you started, in either space or time. If you were, that in itself would be unusual.
Here comes the headache....
Are there any guesses as to why gravity is monopolar?
"Laugh while you can, monkey boy!"
Brush with fame: I saw John Lithgow at Holiday Valley Skiing (just south of Buffalo) Just before "Third Rock.." became a big hit. Told Him Buckaroo Bonzai is one of my all-time faves and he laughed.