Unlike string theory, which currently cannot be tested, new lasers might tell us if our universe could limit itself to two dimensions—or even one—at extremely high energies. "The problems arise from the standard model of particle physics, which successfully explains most of the universe but breaks down as it reaches the high energies that existed shortly after the Big Bang. The standard model still can’t explain why the expansion of the universe is accelerating, for example, or how to knit together the physics of extremely large and extremely small objects."