I'm applying to graduate school for physics and am wondering what to do about recommendations. It has been more than 10 years since I received my undergraduate degrees in math and physics and since then I've bounced around between the military, writing software, and doing system administration. Do the recommendations need to be from academics sources or can I have my most recent employers write them? If they must be from former teachers is it acceptable to request them from professors from long ago? Any help would be appreciated.