THE MINIMUM LIGHT SPAN OF CREATION
The Hubble radius (1028 centimeters) may be viewed as the maximum light span of the visible universe. It represents the largest distance that real light—the type of light that can be observed empirically—can travel through space.
Its microscopic counterpart corresponds to the scale of grand unification (10-29 centimeters), which can be viewed as the minimum light span of the visible universe. It represents the smallest distance that real light can travel through space. These two limits are set by the twenty-ninth layers above and below the half measure, respectively.The same principles can be applied to the scales of the thirty-third layers above and below the half measure. Yet the thirty-three layers pertain to virtual, not real, light. In this case, the radius of the cosmic egg (1032 centimeters) represents the maximum span of virtual light within the universe—the largest distance that virtual light can travel through space. Its microscopic counterpart, which corresponds to the Planck scale, or the scale of superunification (10-33 centimeters), therefore represents the smallest span of virtual light within the universe, and the smallest distance that virtual light can travel through space.
Whether light is virtual or real, it is limited by the speed of light. Generally, a speed can be represented as a ratio of space and time. In this regard it should be pointed out that the Planck scale represents not only a minimum distance scale, given by the length Lp = 1.616... ? 10-33 centimeters, but also a minimum time scale, given by the time Tp = 5.37... ? 10–44 seconds. It turns out that the ratio of space and time of the Planck length and Planck time is exactly equal to the speed of light: Lp/Tp = c.
This illustrates what we mean by a light span: The Planck length represents literally the distance that light will travel during the Planck time. Because the Planck length and Planck time represent the minimum units of length and time that can be inferred on the basis of the fundamental constants, the Planck length may be understood as the minimum light span in the superuniverse.
In actuality, it is impossible for us to observe empirically an electromagnetic wave with a wavelength on the order of the Planck length or a period on the order of the Planck time. As a result, the Planck length must be viewed as the minimum span of virtual light in the superuniverse, and not the minimum span of real light.