Quitting is a little bit better than not getting in to begin with. Getting an MS is getting an MS - loads of people "quit" grad school this way and it's rare th

Quitting is a little bit better than not getting in to begin with. Getting an MS is getting an MS - loads of people "quit" grad school this way and it's rare that anyone outside sees it as more than you having an MS. Also, try talking to your graduate school about whether you can switch to a different program. This is not always possible, but it may pose an alternative to getting your ass kicked by graduate-level theoretical mechanics.