&gt;To me the litmus test is now this: do you need a particle accelerator (or equivalents) to conduct research in your field? If not, don&#x27;t do a PhD.<p>As someone that did research outside of academia my litmus test was:<p>Do I need a mentor to train me to be a great researcher? After doing research on my own for a while I discovered that yes I needed such a mentor. I optimized my search around finding the best mentor possible.