Another alternative was proposed by Hawking &amp; Hertog (Phys Rev D, 2006, see below): walk the present values surface back to a superposition of possible universes and study the mechanisms that generate probabilities near one.  That then is their way of asking about the degree of fine-tuning, with the anthropic principle being recasta as a constraint on the set of possible consistent histories.<p>H&amp;H spend a lot of time comparing themselves to the approach of selecting an initial values surface in the early universe and marching it forward; they more or less do the same but flip the direction of the arrow of time and arrive at a superposed state.  Re-flipping the arrow of time leads to relic fields like the CMB carrying evidence for the superposition.<p>Essentially this is just taking time-reversibility of local microscopic physics seriously (great), and absorbing the difference in degrees of freedom in macroscopic physics into a superposition (uh, ok).   The problem of setting up a values surface remains pretty much the same.   &quot;Fine tuning&quot; is just a way of saying that the system is sensitive to the values it evolves from (or to).<p>I&#x27;m not really convinced that that a present-day spacelike hypersurface is easier to write down than an early-time initial values surface.<p>ArXiv version: <a href="http:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;hep-th&#x2F;0602091" rel="nofollow">http:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;hep-th&#x2F;0602091</a>