Part 4/10:
The debate hinges on whether these dimensions behave as theorized when the universe is filled with energy. Typical string theory proponents argue that these extra dimensions cannot vibrate at observable energies because the energy needed—at the Planck scale—is extraordinarily high. As Penrose points out, however, the total energy present in our universe—such as the energy output from the sun—far exceeds these theoretical thresholds. If these extra dimensions could indeed vibrate at such energies, should we not have observed such effects? The lack of empirical evidence calls into question how and whether these extra dimensions actually influence the universe.