Definition of "theorist"

Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains.

2012 January, Michael Riordan, “Tackling Infinity”, in American Scientist‎, volume 100, number 1, archived from the original on 30 April 2013, page 86