p. 217 We have found a strange footprint: Arthur Eddington, Space, Time and Gravitation (Cambridge: Cambridge University Press, 1921), p. 201.
p. 223 There were timelines branching: Larry Niven, All the Myriad Ways (New York: Ballantine Books, 1971), p. 1.
p. 224 empirically testable: Max Tegmark, “Parallel Universes,” Science and Ultimate Reality: From Quantum to Cosmos, J. D. Barrow, P. C. W. Davies, and C. L. Harper, eds. (Cambridge: Cambridge University Press, 2003), p. 21.
p. 224 Is there another copy: Ibid.
p. 230 Observation: Arthur Eddington, The Philosophy of Physical Science, p. 9.