Farsight, I don’t know what physicsforums policies are about what merits banning, but if what you say is true they are draconian and probably stifle potentially fruitful discussions. My guess, though, is that they probably get a lot of genuinely disruptive posters insisting that some out-of-mainstream idea is going to revolutionize physics, and that as a result they are hyper-sensitive to removing those posters before they become a problem. The “crackpot index” that Xunzian regretfully employed is further evidence that whatever the frequency of suppression in physics, there is certainly no shortage of people who are just wrong. (I’d also like to clarify that, thankfully for everyone involved, Xunzian is only a temporary moderator while TheStumps is on leave. He is also a drunken old coot who’s comments shouldn’t be given too much weight. )
As for anecdotes about people being encouraged not to do anything radical, I have a few thoughts. First, they are anecdotes and, even those from Nobel Laureates (Farsight, I assume the second link was supposed to go to the article by Josephson?), while suggestive of a strain of thought within the physics community, are not necessarily evidence that it is a major strain, let alone the predominant strain.
James, none of the theories you propose are part of accepted science. They’re all proposed theories to account for various observed phenomena, and though they haven’t been disproven, most are as yet untested (mostly because a test has not been devised that is practical and that would distinguish between competing theories). The theories make assumptions, but that is not a problem in science when the assumption is acknowledge, is made about a legitimately undecided question, and is used to make predictions which could potentially be tested.
Nor are these theories being “force fed to children in public schools.” Superstring theory, if it mentioned at all, they are mentioned as a footnotes to get kids exciting about interesting questions currently facing science (which is certainly what these theories represent). Anecdotally, my own formal physics education, which began in public school and went up through college-level modern physics, never dealt with any of these theories, except the 4th dimension (when dealing with spacetime in special relativity). Especially considering the recent test-centric shift in public education, I would be shocked if any part of the curriculum in mandatory public education dealt with anything more involved than non-quantum electricity and magnetism.
One thing I think it’s important to keep in mind is that it’s very easy to come up with radically divergent proposed theories in any discipline of science, and that almost all of them will be wrong. Again, I think the attribution of malice and intentional suppression, even of significant closed-mindedness, doesn’t take into account the probable volume of actually inane theories. Even if, for example, the review process for posting on arXiv.org is extremely accurate, and the reviewers are reasonably open to challenges to some foundational tenet of a discipline, the flow of truly useless theories could quite easily be so large that some legitimate proposals would be lost in the deluge. Most of the time, when the scientific bureaucracy attempts to “defend [s]cience against the crackpots,” they will be right to do so, because most theories labeled ‘crackpot’ are truly not scientifically interesting in the least. (This point is to say nothing of theories presented here, rather it is meant generally of the entire landscape of conceivable ‘radical’ theories)