Here is the discussion, which was interesting but inconclusive about the merits of this rubber sheet model:  <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=8542244" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=8542244</a>