Communications of legitimate physics ideas
In physics, there are principly two means of communicating one's ideas to others in the field. The first and most common means is via publishing one's work in a peer-reviewed journal. The other is via a presentation at one of the many conferences/workshops held throughout the world. I will discuss the former.
For a physicist, there are three most prestigous journals for one's work to be published: Nature, Science, and Physical Review Letters. These journals not only require that the work submitted to be of significant importance and quality, but also have wide-ranging impact beyond just a small, specialized area. This is especially true for Nature and Science where both journals tend to only publish papers that will have a high impact value.
It means that getting one's work to be published in one of these three journals is not that easy. Nature and Science have editors that are actively involved in weeding out all the submitted papers. My guess is that between 50% to 60% of all papers submitted to these two journals never made it past the editors. These editors sometime consult ranking physicists in the appropriate fields to see if a submitted paper has enough of an impact for it to continue to the next stage. Of the remaining papers that did get through and went on to be reviewed by selected referees (typically 2 or 3 referees for each paper), only about less than half that actually got approved for publication. This process is similar for Physical Review Letters, except the editors tend to be more liberal in letting the papers go to the refereeing stage (they still weed out the obvious quackeries, which from what I gather, they receive almost everyday). However, the referees are as strict and demanding as those for Nature and Science.
Why are these three journals that prestigous? First of all, because everyone in the field knows how difficult it is to have a paper published in those journals, it means that having one is a sign of accomplishments. Many funding agencies look favorably if someone has work appearing in these high-impact journals. Secondly, these journals have their own public relations people that advertize and produce press releases of select papers in their journals. This makes some work widely known and cited both within the field and in the public media. Having one's work published in one of these journals is a sign of very high achievement.
If those three are what I consider to be the top tier journals, the next in line would be the Physical Review series of journals (i.e. Physical Review A,B,C,D, and E), the Journal of Applied Physics series and Applied Physics Letters. It needs to be emphasized here that just because these journals are of a lower tier than the first three, it doesn't mean they are of any less importance or less impact. Often, the Physical Review journals serve to expand the work published in the Physical Review Letters (PRL), since PRL has a limit of 4 typeset pages for each paper. Other than certain specialized sections, the Physical Review journals have no length limitations. The papers published here also tend to be more specialized for people working in a particular field, i.e. it doesn't have that "wide-ranging" impact that Nature, Science, and PRL require.
The next tier of journals would include European Physical Review, Journal of Physics series, Europhysics Letters, and Physica journal series. Again, there have been very important papers being published in these journals, even though in terms of prestige, they are not typically considered as high-impact journals.
The level of refereeing also tends to be commensurate with the prestige of the journals. One tends to see a more liberal refereeing for a lower tier journal, and maybe each submitted paper might have only one referee, as opposed to 2,3, and up to 5 referees for papers submitted to Science, Nature, or PRL.
To end this, here's a very sobering fact. Since the establishement of peer-reviewed journals in the scientific field (let's say since 1900), there have been NO instances of any work or ideas making a significant contribution fo the body of knowledge in physics that have not appeared in a peer-reviewed publication. Now think about this for a second. If you have a discovery, theory, ideas, etc., and you have not or unable to have it accepted and published in a peer-reviewed journal, you have an ABSOLUTE ZERO chance of having any impact or contributing to the body of knowledge in physics. PERIOD! This is what the history of science has shown. It means that if one only has one's theory appearing on some website and/or discussion areas, and these are the ONLY avenue for such an idea to see the light of day, there is a 100% chance that such an idea will go nowhere, do nothing, and will disappear into obscure-land. Having one's work appearing in a peer-reviewed journal is a NECESSARY criteria, although not a necessary AND sufficient criteria, for having any impact and making a contribution to physics.