Professor Friedlander's research concerns cosmic rays and related infrared and gamma ray astronomy.
His earlier experimental work related to the the properties of the 'strange' particles produced in the collisions of high energy cosmic ray particles. This included the discovery of the beta decay of the kaon and the first precision measurement of the mass of the lambda-zero hyperon. Friedlander has been interested in finding a common ground among these apparently separate topics as well as radio astronomy from which it is known that many celestial objects display non-thermal spectra indicating the presence of high energy electrons. He investigated the effects of cosmic ray particles in dust and gas surrounding Eta Carinae, an extremely luminous object that may well also be a source of energetic particles.
Friedlander is also interested in the interface between science and society and in the structure of science. He has taught courses in the history of science and in the contrast between science and pseudoscience, and has written two books in this area.