Extra dimensions -beyond length, width, height- seem the stuff of science fiction. What would extra dimensions be like? Is time the fourth dimension? Could deep reality be so strange? And, anyway, why would we care? Featuring interviews with Lawrence Krauss, Michio Kaku, David Gross, Nima Arkani-Hamed, Juan Maldacena, and Roger Penrose.

Of course, if we like, we can see time as half a dimension (forward only). Okay. But…

Beyond that, one way of looking at these controversies is to begin by asking what difference it would make.

I (O’Leary for News) remember, in high school, reading a book that calculated how many 11-dimensional baseballs would fit into a nine-dimensional box, or something like that. Not being, at best, gifted at math, I quickly lost the thread of the discussion.

One can’t help wondering what the notion of many additional dimensions is supposed to do.

Some resources:

“One recent string theory suggests that the reason we only experience the three spatial dimensions is that all universes with higher dimensions got into some cosmic car accident and destroyed each other, leaving our measly three-dimensional brane untouched.”

“Current versions of string theory require 10 dimensions total, while an even more hypothetical über-string theory known as M-theory requires 11. But when we look around the universe, we only ever see the usual three spatial dimensions plus the dimension of time. We’re pretty sure that if the universe had more than four dimensions, we would’ve noticed by now. … Thankfully, string theorists were able to point to a historical antecedent for this seemingly radical notion.”

“It turns out that in order to encompass both of these two forces, we have to add another five dimensions to our mathematical description. There’s no a priori reason it should be five; and, again, none of these additional dimensions relates directly to our sensory experience. They are just there in the mathematics. So this gets us to the 10 dimensions of string theory. Here there are the four large-scale dimensions of spacetime (described by general relativity), plus an extra six ‘compact’ dimensions (one for electromagnetism and five for the nuclear forces), all curled up in some fiendishly complex, scrunched-up, geometric structure.”

By now, you probably get the picture. The side door to “Anything we want to believe is true.”