Lightness and Trouble describe current thinking about the most fundamental physics questions--the underlying nature of space and matter. Ten years ago such books might well have emphasized string efforts in that direction. These books do not. They are in that sense post-string popular accounts of fundamental physics. How they do on the market is an indicator of how readers see research progressing in deep-foundations physics. It is interesting to track, and check for signs of a shift in public perceptions. I will track both books and try to predict how their salesrank ratios do compared to the average salesrank of the five most popular stringy books on any given day. Readings of Amazon salesranks will be at noon pacific time. Today 21 December the five most popular stringy books were fabric, elegant hardbound, blackhole, parallel and hyperspace---salesranks 1886, 2347, 2493, 3001, 4006, for a benchmark average of 2746.6. Lightness ranked 2506, so the ratio was 1.1---it was doing slightly better than par. Trouble ranked 5647, with ratio 0.5---it was performing only about 50 percent of par. Let's try to predict the larger of the two ratios as of noon 1 February. I think the larger will be Lightness, so I look at this as forecasting Lightness' ratio. But I could be wrong and Smolin's book might move ahead, so we'll take whichever ratio is larger to allow for that possibility. Closest guess wins. As a help in predicting, here are past performance ratios: https://www.physicsforums.com/showpost.php?p=1986028&postcount=13 For some reviews and current information here are the Amazon pages for the two books: https://www.amazon.com/Lightness-Being-Ether-Unification-Forces/dp/0465003214 https://www.amazon.com/Trouble-Physics-String-Theory-Science/dp/061891868X ======================= Update: As of 22 December both books' ratios were 1.1, they were both doing slightly better than stringy par. The five most popular stringies were parallel, blackhole, fabric, elegant hardbound, and hyperspace, with an average rank of 3999.8. Smolin's Trouble with Physics ranked 3537 and Wilczek's Lightness of Being ranked 3631. This may seem quite ordinary if you didn't happen to notice what happened to string and non-string market share two years ago (2006) at the Christmas season. Right before Christmas it seemed like all the parents were buying their kids string books---or kids were especially asking for Brian Greene and Lisa Randall books. They dominated the physics bestseller list and Smolin's book was temporarily wiped out. This year, in the Christmas present book market, the non-string theory books seem momentarily at least to be holding their own. There's a marked difference. Also another straw in the wind: the blackhole book that is doing quite well has nothing about strings until the last quarter, when it talks about applying string to speculating about black holes. I include it with books by, for example, by Brian Greene, but it is not primarily of that genre.