I'm in physics where the order of authors is meaningful. The first author is the lead author and the last author is the principal investigator. I am an undergraduate who has collaborated on a topic with two post docs and a professor. We are nearly ready to submit the paper to a top journal (Nature physics).
I proposed the topic after I discovered a huge idea in the field. I proved a variety of theorems and generated the supporting data independently. I used post doc 1s previous work in the paper - but it has already been published. Post doc 2 made a very small contribution, the other has contributed significantly more. I wrote the "main results", "applications" and "technical discussion" section. Post doc 1 wrote the intro, conclusion, abstract and a minor background section. The appendix is very long and I wrote 90% of it. The proof techniques and methods are my own creation with no input from any one else. Post doc 1 has helped greatly in improving my presentation since he has far more experience than me in writing papers (I have never written one). Post doc 1 made a lot of edits and helped restructure some arguments for clarity of presentation.
The paper has just been posted online to Arxiv. I am second to last author. Post doc 1 made himself first author. I have read a number of articles on the topic and since I contributed the most I believe I should be first author. What is the best way for me to approach the situation? I really feel like I am being ripped off. 3rd author could be given to any undergrad and I imagine the difference for grad school/future career could be substantial. Thanks!