<p>I heard that many graduate schools way grades very lightly, and care more about research opp and letters of rec. How true is this? Especially for, say, a physics program.</p>
<p>it's probably much more true for physics and other hard sciences than it is for humanities and social sciences.</p>
<p>Research experience and letters of recommendation are probably the most important factors in science admissions. That's not, of course, to say that grades don't matter, just that really great research and LORs can get you forgiven for a good-but-not-great GPA.</p>
<p>I'd say that letters of recommendation can trump almost anything, but are usually tied very closely to good/great undergraduate research. </p>
<p>However grades, like your GRE scores, won't get you into a school, but they can certainly keep you out. Just remember that you're competing with people who probably also have great recommendation letters AND great GPAs.</p>