> The Friends have a complex scheme, which does not include a simple military return-and-rescue – the 1,500-year technology gap makes this "risible". From the Wigner thought experiment they have postulated an unusual theory on the ultimate destiny of life in the universe. They believe that quantum wave-functions do not collapse like the Copenhagen interpretation holds, nor that each collapse actually buds off separate universes (like the quantum multiverse hypothesis holds) but rather that the universe is a participatory universe: the entire universe exists as a single massive quantum superposition, and that at the end of time (in the open universe of the Xeelee Sequence, time and space are unbounded, or more precisely, bounded only at the Cauchy boundaries of "Time-like infinity" and "Space-like infinity"), when intelligent life has collected all information (compare the Final anthropic principle and the Omega Point), and transformed into an "Ultimate Observer", who will make the "Final observation", the observation which collapses all the possible entangled wave-functions generated since the beginning of the universe. They believe further that the Ultimate Observer will not merely observe, but choose which world line will be the true world-line, and that it will choose the one in which humanity suffers no Squeem or Qax occupations. However, the Ultimate Observer cannot choose between worldlines if no information survives to its era to distinguish worldlines- if the UO never knows of humanity, it cannot choose a worldline favourable to it. In other words, some way is needed to securely send information forward in time.