How Likely to Arise by Chance?
nShortest virus is 101 bytes
nThere are 10243 possible files of length 101 bytes.
nIf we have all 100 million PCs in world run full-time, making only 101-byte files at 1000/sec:
nProbability (hist univ) = 4 x 10-214
nIf every elementary particle in universe such a PC, then Probability = 6 x 10-100