Temporal Anisotropy . In a short video clip showing two billiard balls bouncing off each other, forward and backward in time are indistinguishable if one ignores friction and inelasticity. In a longer video of a billiards break, the future is the end in which the balls are no longer in a nicely ordered triangle. If causes can be attributed to effects as easily as effects can be attributed to causes, then causal laws do not distinguish past and future, and the future for an event is the direction of increasing disorder in the system. Traces and memories of the past are a localized increase in order at the expense of an increase in system-wide disorder. Due to statistical considerations, some systems can cycle between order and disorder. In such systems the direction locally considered to be future can vary over the timeline of the system.
On 4 September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GC&CS.  Specifying the bombe was the first of five major cryptanalytical advances that Turing made during the war. The others were: deducing the indicator procedure used by the German navy; developing a statistical procedure for making much more efficient use of the bombes dubbed Banburismus ; developing a procedure for working out the cam settings of the wheels of the Lorenz SZ 40/42 ( Tunny ) dubbed Turingery and, towards the end of the war, the development of a portable secure voice scrambler at Hanslope Park that was codenamed Delilah .
An interesting question is whether the computation model represented by concrete programming languages is Turing equivalent. While the computation of a real computer is based on finite states and thus not capable to simulate a Turing machine, programming languages themselves do not necessarily have this limitation. Kirner et al., 2009 have shown that among the general-purpose programming languages some are Turing complete while others are not. For example, ANSI C is not Turing-equivalent, as all instantiations of ANSI C (different instantiations are possible as the standard deliberately leaves certain behaviour undefined for legacy reasons) imply a finite-space memory. This is because the size of memory reference data types is accessible inside the language. However, other programming languages like Pascal do not have this feature, which allows them to be Turing complete in principle. It is just Turing complete in principle, as memory allocation in a programming language is allowed to fail, which means the programming language can be Turing complete when ignoring failed memory allocations, but the compiled programs executable on a real computer cannot.