“… It was (in part) Gross’s excessive enthusiasm for string theory in the mid-80s that drove me (as an impressionable grad student at Princeton) away from theoretical physics (and into astronomy). String theory may have been a beautiful idea, but it made no predictions that could be tested experimentally in the then-foreseeable future. That’s not science. 
A quarter century later and the theoretical physics community has yet to wake up and realize that there is new physics right under their noses – just not the new physics they’ve been expecting (GUTs, strings, membranes, etc.). Galaxy dynamics are consistent with a single, universal force law, but this unexpected behavior has largely been ignored because it doesn’t fit with particle theorists’ dreams of super symmetric dark matter particles. That we do not understand the observed behavior makes it more interesting than the “expected” (but unobserved) new physics: who ordered this?”