Does one really have to consider having a co-author to avoid being considered as a nerd? I have just graduated in B.A.Sc. Within my undergraduate studies, I had been considerably active in research, such that I succeeded to publish a paper on my own at a well-known conference.

At the conference and after the presentation, a very experienced professor asked me to present him some more details about the applied methodology into the paper. His tendency to my research paper fully diminished, as hew saw the list of authors and realized that I am the sole author. He advised me that such of research might not be so noticeable and the community may take such authors as nerd people. Furthermore, he explained that such research reports would not consist of coherent enough accomplishments, due to the lack of any effect of the idea cooking that could be acquired by co-operation with the other researchers. The ironic stuff is that, before he found that the paper has just one author, his attitude regarding the paper and its content was gratifying, deservedly!

My questions are:


Is this viewpoint an overall and widespread idea among researchers?
If the ideas, simulations, manufacturing and the other stuff for a paper were done by a single person, should this person consider faking some co-authorship for the paper to avoid presenting themselves as a nerd to others?
There are reasons to be more careful about sole-author papers from young investigators, but pretty much none of them are the ones this professor told you.

I would be more cautious when considering a sole-author work from a young investigator simply because inexperience plus lack of supervision means there are more likely to be mistakes.  These might be in the technical work, the scoping of the problem, the design of the investigation, or the interpretation of results.  On the other hand, if your paper went through meaningful peer review, that's a pretty good initial filter for simple mistakes, and that means I'm likely to take the paper as seriously as any other that's made it through peer review (i.e., still with significant skepticism, but assuming basic sanity).

None of this, however, has anything to do with gratuitously insulting an undergraduate investigator.  I would consider the professor you describe to be both a fool and a bully. Perhaps this attitude is widespread in the community where you published, perhaps it is not; certainly, there are toxic scientific communities.  

I would thus advise you, if you want to continue working in that area, to keep doing so and meeting more investigators.  If you find they are more constructive in their criticism, then ignore the first, nasty person that you interacted with.  If you find the first scientist was representative in their attitude, then find a better scientific community to participate in.