Peter Davies

The hypothesis that life’s rapid appearance on Earth justifies the belief that life is widespread in the universe has been investigated mathematically by Lineweaver and Davis (Astrobiol- ogy 2002;2:293–304). However, a rapid appearance could also be interpreted as evidence for a nonterrestrial origin. I attempt to quantify the relative probabilities for a non-indigenous ver- sus indigenous origin, on the assumption that biogenesis involves one or more highly im- probable steps, using a generalization of Carter’s well-known observer-selection argument. The analysis is specifically applied to a Martian origin of life, with subsequent transfer to Earth within impact ejecta. My main result is that the relatively greater probability of a Mar- tian origin rises sharply as a function of the number of difficult steps involved in biogene- sis. The actual numerical factor depends on what is assumed about conditions on early Mars, but for a wide range of assumptions a Martian origin of life is decisively favored. By con- trast, an extrasolar origin seems unlikely using the same analysis. These results complement those of Lineweaver and Davis. Key Words: Origin of life—Mars—Probability theory— Carter—Transpermia. Astrobiology 3, 673–679.

Recent advances in string theory and inflationary cosmology have led to a surge of interest in the possible existence of an ensemble of cosmic regions, or “universes”, among the members of which key physical parameters, such as the masses of elementary particles and the coupling constants, might assume different values. The observed values in our cosmic region are then attributed to an observer selection effect (the so-called anthropic principle). The assemblage of universes has been dubbed “the multiverse”. In this paper we review the multiverse concept and the criticisms that have been advanced against it on both scientific and philosophical grounds.

There have been many claims that quantum mechanics plays a key role in the origin and/or operation of biological organisms, beyond merely providing the basis for the shapes and sizes of biological molecules and their chemical affinities. These range from Schr¨odinger’s suggestion that quantum fluctuations produce mutations, to Hameroff and Penrose’s conjecture that quantum coherence in microtubules is linked to consciousness. I review some of these claims in this paper, and discuss the serious problem of decoherence. I advance some further conjectures about quantum information processing in bio-systems. Some possible experiments are suggested. © 2004 Elsevier Ireland Ltd. All rights reserved.

Analyses of market-based reforms of state schooling have occasionally acknowledged positional elements in parental demand, but none has fully examined their nature and implications. Contrary to the normal predictions of orthodox economic analysis, competition in positional markets can result in inefficient outcomes. Predominantly relying upon recent British experience, we examine the extent to which compulsory schooling can be viewed as a positional good and explore its implications for policy. In particular, we consider whether policies targeting increases in parental choice assist a rise in the overall level of educational attainment.