A message can survive losing pieces of itself

Reed–Solomon codes add extra symbols so a receiver can rebuild ones that were erased or corrupted. Voyager used them. A compact disc uses them. A scratch need not be a click.

Irving Reed and Gustave Solomon, in 1960, constructed codes over finite fields in which any portion of the received word, if long enough, determines the original. You may lose symbols up to a budget. Past the budget the reconstruction fails cleanly rather than almost working. The Voyager probes, photographing the outer planets on a transmitter of tens of watts, leaned on this and on a convolutional code wrapped around it. The pictures were not a stronger radio. They were a code that tolerated a vicious channel.

On a compact disc the same idea, cross-interleaved so that a scratch ruins many short stretches instead of one fatal one, turns a gouge into samples the player can interpolate or conceal. The silence where a scratch would have been is the code spending its budget. There is a budget. A bad enough disc still wins.