Superstring theory has long been criticized for being unverifiable. It unites the theory of relativity and quantum mechanics, the 2 horsemen of mutual incompatibility, and it matches current observations to a T, but for every problem, there is a solution that is simple, elegant, and wrong, and extraordinary claims require extraordinary proof. Superstring theory makes some extraordinary claims indeed -- that the universe has 11 dimensions, for example, most of which are too small to see (it's complicated), and -- more relevantly -- that space-time is pixellated into tiny discrete units. Tiny discrete units.
How tiny? On the order of 1.6160 x 10-35 meters, the Planck length. If a hydrogen atom were the size of the known universe (close to 30 billion light years across), the Plank Length would be a couple dozen feet.
This poses problems.
Generally, when dealing with the microscopic, the smaller the area that you wish to probe (and probing is necessary, by whatever method, be it jabbing your finger at something or bouncing a photon off it), the greater the energy requried; that's why the superconducting super collider (good name for a superhero) would have been so much better than your average cyclotron. To probe into the Planck length by brute force, you'd need about 1028 electron volts -- you'd need a particle accellerator the size of the solar system.
And now the monster of scientific criticism rears its party-pooping head. If a theory makes no testable predictions, it asks, why does it exist at all? Sure, superstring theory is cool. So is the idea that there's an invisible, noisless, hand-dodging hamster sitting on top of my monitor. The question science needs to ask is, is superstring theory right, or just mathematical masturbation? An important question, because superstring theory is a theory of everything. And thus, whether the universe has granularity is important (doubly so, because it probably would have been anyway).
Fortunately, nature may have probed its own depths and left the results plastered across the cosmos. Shortly after the big bang, the universe was itself tiny -- if pixellated, then only pixels across*; accordingly, the energy would have varied (and still vary) from point to point jaggedly, not in a smooth sweep. When the fabric of spacetime began to expand inflationally, with ludicrous speed, those pixel-caused jags would have expanded, themselves, and if there wasn't quite time for the energy to diffuse completely before leaving its imprint, for it to reorient to the new, spacious 1024x768 resolution, an echo of that low-res image should be dimly visible, tremendously magnified by inflation, each pixel light years and light years across.
For this reason, a new, more intensive survey of the microwave background radiation is scheduled to begin some months from now. Let's hope it reveals a faint, pixellated overlay. That would be so damn cool.
That's a bit of an oversimplification, sidestepping the possibility of an infinite universe. It really doesn't matter how big the primordial cosmos were, just how dense.