` ::Thanks.  Re ``penultimate`` etc, either is fine really.  I was thinking of the Overmind as the end point in my choice of word, but ``last`` may be clearer, especially as we will have readers who are not very familiar with English.  I suppose I imagine the children were still physically, superficially, human despite their empty facial affect.  Of course Karellen or Rashaverak had explicitly stated they were ``no longer human`` much earlier, even before the tsunami.  I thought the biographical material was good and interesting, except for two sentences not very germane to CE: ``Clarke enrolled at King's College London .... editor for Science Abstracts.``  Perhaps those should be moved to the ACC article.  (I think all of the bio info should be incorporated into the ACC article as well, if it is not there already.)  Are the links to time dilation and special relativity sufficient for the physics explanation you wanted?  Strictly speaking I suppose references outside Wikipedia would be better, but we would need to find something that is easily available, ``reliable``, permanent, and at an elementary, tutorial level. There should be good ones in the relativity articles, but I have not looked around yet. Cheers,   `