I am sorry for my incompetence. I am new in Quantitive Finance, so I read an article about the relationship between Alpha and Portfolio Risk and I can not understand what is the meaning behind the orthogonality in Finance. For example, I met these sentences: "Alpha is the search of sources of risk and return that are ideally orthogonal from the manager is using already."Maybe here "orthogonal" means different? And: "Alpha must be orthogonal to widely-known factors and to other alphas in portfolio". What does it mean?
Thanks a lot!