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Sciama’s argument on life in a random universe and distinguishing apples from oranges

Nature Astronomy volume 7, pages 755–756 (2023)Cite this article

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Dennis Sciama has argued that the existence of life depends on many quantities—the fundamental constants—so in a random universe life should be highly unlikely. However, without full knowledge of these constants, his argument implies a universe that could appear to be ‘intelligently designed’.

Dennis Sciama, considered to be one of the fathers of modern cosmology, argued that if our Universe were random, it would almost certainly have a low probability for life as we know it1. In his argument, Sciama assumed that the feature distinguishing different potential universes was the set of specific values for the fundamental constants, with the underlying physical laws themselves being fixed. We can then envision the set of universes compatible with human life as an ‘island’ within a ‘sea’ of more general possibilities. Each point on the island or in the sea describes a unique universe that is described by a distinct set of fundamental constants. The dimensionality of this space of points is naively given by the number of fundamental constants. Thus the human-compatible island of universes corresponds to some shape in a high-dimensional space. The shoreline of the island corresponds to the boundary separating those universes that have a chance to produce human life from those in which this is impossible. So the shoreline itself will be made up of universes with an exactly vanishing probability for such life. Assuming continuity, as one moves inland, this probability will increase.

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Fig. 1: A counterintuitive consequence of concentration-of-measure phenomena.

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Authors and Affiliations

  1. College of Physics, Jilin University, Changchun, People’s Republic of China

    Zhi-Wei Wang

  2. Department of Physics, University of Warwick, Coventry, UK

    Zhi-Wei Wang

  3. Computer Science, University of York, York, UK

    Samuel L. Braunstein

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  1. Zhi-Wei Wang
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  2. Samuel L. Braunstein
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Correspondence to Zhi-Wei Wang or Samuel L. Braunstein.

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Wang, ZW., Braunstein, S.L. Sciama’s argument on life in a random universe and distinguishing apples from oranges. Nat Astron 7, 755–756 (2023). https://doi.org/10.1038/s41550-023-02014-9

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