It is note worthy that most of physics (at least high energy physics) ist published on arxiv.org and open access.
I don't know if sci hub bothers with publications that are available freely from an official source.
I don't know if sci hub bothers with publications that are available freely from an official source.
Don't use the term "open access" like this. A paper published on arXiv is free to read, and was freely published. "Open access" is a scam by the big publishers, where they don't take money from the readers, but make the authors pay. Or, putting it another way, anyone can pay their way in those journals and publish (sometimes sub par) papers.
"gold open access" is where you publish to a peer-reviewed open-access journal, which may or may not involve the author paying for the privilege.
"green open access" is where you publish to any peer-reviewed journal, and then the author self-archives the paper somewhere, like an institutional website, arXiv (as a "post-print", not a pre-print), or even Sci-Hub.
There are discussions involved about copyright and license and so on, but that's the gist of it.
Either way, we don't pay anyone any fee to publish on arxiv.
"arXiv (pronounced "archive"—the X represents the Greek letter chi [χ])[1] is an open-access repository of electronic preprints and postprints[...] "
https://openaccess.mpg.de/Berlin-Declaration
Publishers do misuse the concept though. They try to stay clear of using the term when they do. They use terms like Free Access or some of the more dubious colour variants of OA that doesn't provide all the freedoms that the Berlin Declaration of OA defines.
Interestingly articles uploaded to arXiv with the arXiv.org perpetual non-exclusive license are not OA as the reader is not allowed to redistribute the paper.
This is not true and comments like this are damaging to science.
Open Access papers are still peer-reviewed and by far not all of them make it into the journal. You can't pay your way into those journals.
Of course there are shady pseudo-journals which just cash in on the fee, do not carry out peer review and just dump the paper on the internet. But any scientist should be able to tell such scam journals from serious ones.
True, some journals, like many of the Frontiers series or PLOS One, make it very hard to be rejected in peer review. As long as your paper is reasonably well written and doesn't contain falsehoods it will almost certainly make it to publication. Still, you don't "pay your way into those journals".
Granted, many of papers in those journals report mere incremental progress. But these journals are still attractive for scientists to publish in, for obvious reasons. Publishers like PLOS use those journals as cash cows to fund their higher-tier offerings.
It is fair that the author pays for publication in those journals, since the most benefit is often for the author, not the reader. For the progress of science these offerings are not so useful, unfortunately.