Carr, Bernard (red.), 2007- Universe or Multiverse?

We considered both the ‘weak’ anthropic principle – which accepts the laws of nature and physical constants as given and claims that the existence of observers then imposes a selection effect on where and when we observe the Universe – and the ‘strong’ anthropic principle – which (in the sense we used the term) suggests that the existence of observers imposes constraints on the physical constants themselves.

Indeed, since we necessarily reside in one of the life-conducive universes, the multiverse picture reduces the strong anthropic principle to an aspect of the weak one. For this reason, many physicists would regard the multiverse proposal as providing the most natural explanation of the anthropic fine-tunings.

We do not know how to calculate these, but the most natural value would be the Planck density (which is 120 orders of magnitude larger than the observed value). […] The observed value therefore seems implausibly small.

The reason is clear: the idea is highly speculative and, from both a cosmological and a particle physics perspective, the reality of a multiverse is currently untestable. Indeed, it may always remain so […].

In fact, the dichotomy in attributing anthropic fine-tunings to God or the multiverse is too simplistic. While the fine-tunings certainly do not provide unequivocal evidence for God, nor would the existence of a multiverse preclude God since […] there is no reason why a Creator should not act through the multiverse.

[…] it seems unlikely that – even in the extended form required to accommodate the multiverse – science will ever prove or disprove the existence of God. Some people may see in the physical world some hint of the divine, but this can only provide what John Polkinghorne describes as ‘nudge’ factors.

Any assumptions we make about it will necessarily be made on philosophical grounds. However well justified these may be, other possibilities will remain open. Lacking any observational or experimental restrictions, the theory can take any form we like and may be used to justify any conclusion.

[…] any ensemble proposal is not a final explanation; it just pushes the ultimate question back one stage Fiszki źródłowe • Carr / Chaberek • doktorat further. For if one assumes the existence of a multiverse, the deeper issue then becomes: Why this multiverse rather than another one? Why an ensemble that allows life rather than one that does not?

The existence of multiverses is neither established nor scientifically establishable. The concept is justified by philosophy rather than science. They have explanatory power, but the philosophical nature of their justification must be appreciated.

Accounting for the existence and specific character of our multiverse requires an adequate generating process or principle, which must explain the particular distribution function specifying it. This may itself require fine-tuning.

Science can neither support nor exclude such a conclusion. It cannot even adjudicate the question. However, in going beyond the sciences, we must avoid putting God in the ‘scientific gaps’. […] We should ensure that the divine agent is always a primary or ultimate cause – not one that could conceivably be filled by some unknown secondary or created cause.

[…] the ‘core version’ of the argument essentially involves claiming that the existence of intelligent-life-permitting values for the constants of physics is not surprising under theism, but highly surprising under the non-design, non-multiverse hypothesis […].

The multiverse-generator itself […] seems to need to be ‘well designed’ in order to produce life-sustaining universes. […] invoking some sort of multiverse-generator as an explanation of the fine-tuning serves to kick the issue of design up one level […].

[…] the physics of the Universe is extremely special, inasmuch as it is both simple and comprehensible to the human mind.

If there is a ‘law of laws’ describing how parameter values are assigned as one slips from one universe to the next, then we have only shifted the problem of cosmic biophilicity up one level. […] we need to explain where the law of laws comes from.

Life is incredibly complex but the laws of physics are, in the algorithmic sense, simple. So life cannot be contained in the laws of physics. […] one could not predict the structure of, say, a bacterium, nor even its genome sequence, from the laws of physics, because the genome has very high information content.