<p>If your math is good enough that you can do competitive math and astrophysics research, I don’t see not having multivariable calc or lin algebra destroying your application. That is, of course, assuming that you’ve taken everything else in math/physics and excelled in those classes and that you’re accomplished in your research and competitions. Granted, that could probably said of most RSI applicants and I most certainly haven’t sat in on an RSI admissions committee, so my word should be taken with a particularly large crystal of sodium chloride …</p>