the way things seem to be

light, spinning at a frequency. oscillating many times --- # of cycles per second. the rate determines the density. Slow/very dense. High number of cycles/second = Light. Different frequencies throw off different colors. Alternating current IS a frequency. So does magnetism have frequency. Holographic. A hologram 3-D photograph made with a laser. .... holograms encode/decode frequencies.

Fundamentals of Time and Frequency