<ol>
<li><p>Yes, it is possible to double major in something and mathematics. I’ve known quite a few people who go the math/econ, math/science, math/engineering routes. [I’ve also met a math/English, but that was mostly out of interest than practicality.] It generally helps [and makes things easier] if the two majors complement each other and have some overlap though.</p></li>
<li><p>It is my understanding that a PhD in mathematics can lead to many things. You say that you enjoy theory, would you consider research? [There are still Millennium Prize Problems to be solved, gogo!] </p></li>
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<p>Also, I’m pretty sure that you can be an engineer without having to actually build things. I’ve heard from some people that they spend the majority of their time doing calculations. Since I probably didn’t help much, I have websites.</p>
<p>[Careers</a> in Mathematics](<a href=“http://www.toroidalsnark.net/mathcareers.html]Careers”>Careers in Mathematics)
[AMS</a> - Career Information](<a href=“http://www.ams.org/careers/]AMS”>AMS :: Career Information)
[Student</a> Careers](<a href=“http://www.maa.org/careers/]Student”>Careers in Math Home | MAA Math Career Resource Center)</p>
<p>Also, the theories and ideas don’t own anything.</p>