Wrote a paper, supervisor couldn't respond I wrote a paper based on research done with my supervisor, and sent it to them.
They haven't yet confirmed they saw it. It's been some time, and I sent a followup.
What happens if they never reply? I am an undergrad; this would be my first paper.
I am aware I cannot submit it on my own, and I don't know where to submit anyway. But may I post it on arxiv?
No, publishing it in any form without all authors (and their consent) is misconduct. But you don't yet know that you are being blocked, and I doubt that you are, since it is pretty rare.
You don't say how much time has passed but if it is less than, say, a month, there may not be any problem. People have other things to do. Email gets lost or misfiled. Lots of things might cause this &quot;issue&quot; for you.
But you might be able to discover, by contacting the department whether the professor is available or if there is something causing the delay. You might not learn what it is, but you might be assured that it is just a delay. Illness happens, for example as do family issues, travel, and all the rest.
But some third party might be able to give you some assurance if not the actual reason. And it might just be patience that is needed.