<p>Do I have lower chances if I ask LOR from a research adviser whose work is quite irrelevant to the program that I'm applying? For example, LOR from biological related field but applying to applied physics (bioconc.).
Do they want to see research work that is directly relevant to the program that I'm applying?
Thanks</p>
<p>A letter from someone who knows you well is always the best. No one expects you to continue your research from undergraduate to a graduate program so it really does not matter. Presumably your physics ability is reflected in your academic performance anyway.</p>