Paint What You See
Around 1948 or ‘49, I was four or five laying on my back on our lawn in South Gate, looking straight into the sky, I saw patterns filling my vision. Undulating. As I looked they moved, faster and more complicated. Looking higher, the surface of the patterns filled the space between distant blue and me on the ground. It felt like I was reversed, I was falling into the deep sky.
Somewhat later, maybe ’52 or 3, a neighbor friend my age taught me to grab tight my folded legs as I sat on the grass, pulling my knees to my chest, forcing panting breaths until I collapsed unconscious on my back. As I regained consciousness, my vision was filled with flashing intricate patterns like 3D wire forms, kaleidoscopic colors. The powerful show dimmed and was gone in a minute.
Cosmologists refer to a "surface of last scattering" when the photons last hit matter; after that, the universe was too big.
At some point, photons ceased to scatter at all and began to propagate freely through the Universe. These photons reach present-day observers as the cosmic microwave background radiation. This radiation appears to come from a spherical surface around the observer. This surface is what is called the last scattering surface or "The Surface of the Last Scattering.”