<p>yeah, Terry is a decent backup.</p>
<p>happyentropy and neapol1s have given a really superb summary of everything. The undergrads at Caltech are probably better than many of the grad students in math, which helps get attention from faculty. It's much easier to get research opportunities early than at H, P, or Chicago, (i.e. get money and advising) -- and needless to say about two orders of magnitude easier than at Berkeley. Caltech undergrads are on average somewhat smarter than Chicago undergrads, so your peers will be better at Caltech, but Chicago has a somewhat better faculty. A committed student can get more resources out of Caltech than pretty much at any other top university.</p>
<p>In both students and faculty, Caltech math falls a little below the critical mass of what is needed to have a really superb department. There are individuals who can absolutely beat the pants off anybody in the world -- both on the student and faculty side -- but Harvard, Princeton or MIT have math communities that seem more vibrant. If you want to be a professional mathematician, those places are probably better purely on that dimension.</p>
<p>Caltech has turned out some great pure mathematicians over the years, but it has tended to be better at producing very strongly trained pure math undergraduates (and even grad students, c.f. Don Knuth) who go on to be big in related mathematical fields -- applied mathematics, control and dynamical systems, computer science, theoretical economics, theoretical physics, finance (academic and applied) and the like. One reason is that profs in other departments eagerly grab math undergrads for theoretical projects, and then people get interested and go off and do other things. Especially because other departments seem to have a more active culture than math.</p>
<p>In any case, one thing to observe apropos of the discussion is that an academic mathematician (in general) is a pretty unpleasant thing to be. The job market is very slow, people have to hang around in postdocs longer and longer due to inability to find a good assistant professorship (5+ years is not uncommon). Salaries and stipends are among the lowest of the non-humanities and the specialization is so extreme that the audience for the average paper is miniscule even compared to other balkanized fields. So the question of why you are sufficiently nutty to want to be a professional mathematician in the first place is one you should be asking yourself.</p>
<p>Incidentally, I chose Caltech over Harvard and Princeton to study math (full disclosure: money was one factor) and haven't regretted it. The training is very strong and the opportunities for the committed student are vast. The top few Caltech undergrads who choose to stay in math virtually always get into the very top graduate programs. The best publish research before they graduate at a rate comparable or higher than that of MIT or Harvard or Princeton. </p>
<p>So that's that... obviously, strength of math is not the sole dimension you should be considering. Hopefully the above praise/quibbles have given you some idea of where Caltech fits in and you can factor that one dimension in appropriately as you consider others.</p>