Anthropic Principle (Wikipedia)
Wheeler's Delayed Choice Experiment (Wikipedia)
Delayed Choice Quantum Eraser (Wikipedia)
A New Theory of the Universe (Robert Lanza, The American Scholar)
The Simulation Argument (Nick Bostrom, Oxford University)
Constraints on the Universe as a Numerical Simulation (Silas R. Beane et al, Cornell University Library Archive)
Why does the universe exist? (UIUC Department of Physics; interesting read though it begs the question posed here)
Conspiratorial cosmology – the case against the Universe (Jörg P. Rachen, Ute G. Gahlings, Cornell University Library Archive)
Is 'reality' unreal? Scientists work on a way to find out (Joel N. Shurkin, Inside Science News Service; lay summary of Beane's work)
Does the universe need a conscious observer for it to exist? (Quora discussion)