Letter | Published:

Should Hubble's constant be doubled?

Naturevolume 274pages449450 (1978) | Download Citation



LYNDEN-BELL1 has argued that Hubble's constant H0 should be doubled, from its present notional value of 55 km s−1 Mpc−1 to 110 km s−1 Mpc−1. He claims that with this value of H0 the apparent superluminal expansions in compact radio sources can be explained in a more consistent manner than previously, by means of his model of the expansion based on the old ‘light echo’ theory used to explain the Nova Persei phenomenon of 1901. Lynden-Bell's conclusion is heavily dependent on his special interpretation of the expansion phenomena in the source 3C120. Here I revert to the interpretation previously presented by Cohen et al.2 and use a more general ‘energy echo’ model that allows the primary energy ejected from the source nucleus to be propagated with a speed vc, with Lynden-Bell's case v = c as a limiting possibility. The primary energy may therefore be in the form of relativistic particles, plasmoids, shock waves or photons.

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    Lynden-Bell, D. Nature 270, 396 (1977).

  2. 2

    Cohen, M. H. et al. Nature 268, 405 (1977).

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    Longair, M. S., Ryle, M. & Scheuer, P. A. G. Mon. Not. R. astr. Soc. 164, 243 (1973).

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    Present address: Astronomy Centre, University of Sussex, Falmer, Brighton, UK


  1. University of Otago, Dunedin, New Zealand



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