The writers would know the definitive answer, but in mathematics and economics, an initial condition (such as a starting price in a comparative statics model) would be labeled P and a later condition would be labeled P' (pronounced P prime). Typically one would not call the initial state P alpha, but alpha often denotes the "first" in a series. For example, the probability of a Type 1 error in statistics is denoted Alpha and the probability of a Type 2 error is denoted Beta.
A similar set of notation would label an initial state P subscript/superscript 0 (P naught or P sub zero) and the later state P subscript/superscript 1 (P sub one).
Thus it appears that the writers are reaching into scientific notation to make a science fiction show sound more sciency about a scientific phenomenon.