The key is .. can someone read your paper and reproduce your experiment and the results. If not, it's not valid; it's just a paper.
More prosaically, some things can be verified even when a chemical process cannot be reproduced. Protein crystallization is a tricky process with many irreducible results. Yet if you have a crystal, and can use the crystal to determine the protein structure, then you can verify that the crystal indeed contains that protein - even if you are unable to reproduce the chemical process used to create the crystal in the first place. Others can use the same sample to re-verify the resulting x-ray structure even though they also might be unable to reproduce the crystallization step.
There are a lot of projects (and I won't name names, because I've got friends here who work on them) whose results cannot be reproduced, because they ran on some weird-ass combination of a weird libc, using a weird build system, running on weird hardware environments (especially common in HPC), with weird one-off data sets.
They report the results using this setup, and then the setup is gone forever. The code is probably not kept correctly in source control, and generally the community just takes them at their word that the results they get are authentic.
When you run millions of iterations on some crazy quantum solver, it's hard to spot if you're wrong. If others can't at least run the same result, science becomes a matter of anecdote.
People complain that published papers are full of incorrect results, but they don't understand that this is just part of the process. Incorrect results will be forgotten because they will never be validated. Correct results will be validated and used (cited) by new scientists as they try discover even more complicated things.
There are a good number of scientists (myself included) who spend at least part of the time making applications for other researchers; it's best when the products are multi-platform, because there are a lot of scientists who only use one platform. These application can be anything from plotting and basic analysis tools to simulators of various sorts. They're more specialized than Evernote or something but are still designed to be installed and used by members of the community, because it's a waste of time for everyone to write their own finite element models (even if everyone knew how).
When done right, not only are these tools enabling but they become very widely cited. For instance, in my field (geoscience) a tool called GMT (Generic Mapping Tools) has over 6000 citations, even though I'd estimate 70% of papers that have used it in some form don't cite it. This is an enormous number of citations in the geosciences; most very famous and influential papers have ~1-2000.
Maybe it's different in CS; I have heard that much of the software is illustrating a new algorithm or something.