Bethel displayed his ignorance in this American Spectator article, where he suggested that Einstein's special theory of relativity "may have to be discarded because the logical consequences of its postulates do not correspond to experimental results." Bethell's book Questioning Einstein might provide something resembling a proof of this assertion, but his article falls far short even for the scientific layperson. For example, Bethell quotes from page 9 of Stephen Hawking's The Universe in a Nutshell, perhaps not reading far enough to see that Hawking was supporting Einstein:
...the theory of relativity is now completely accepted by the scientific community, and its predictions have been verified in countless applications. (The Universe in a Nutshell, p. 11)
Barr's response in First Things noted that "The world is full of people who think they know something about physics, but haven't even the barest inkling of what it is that they don't know," and suggests that Bethell "should stick to subjects he knows something about." Bethell attacked Barr in the comments:
He shows no understanding of relativity at all. I mean really none. Maybe he took a course on it once but maybe he already forgot it. On the basis of his post, I doubt if he could be teaching the subject. [...] I don't think he knows the FIRST THING about science. And that includes physics.
Barr, however, has a much stronger hand to play:
For the record, I teach a one-semester course in General Relativity for advanced graduate students every two or three years. I also teach Special Relativity at the graduate level (as part of a course in Classical Electrodynamics) almost yearly. [...] I neither had nor have any intention of "disputing" with [Bethell] about relativity theory. One cannot have an intelligent dispute with someone who lacks even a rudimentary knowledge or understanding of the subject. [...] The problem with you is not your lack of credentials, but that you quite literally don't know what you are talking about.
A commenter from an earlier thread suggested a possible reason for Bethell's antipathy toward science other than generating a controversy in order to sell his book:
It could be part of the young-Earth creationist campaign. One problem they'll always have is the fact that their 6,000-year-old universe contains a whole lot of stuff that's more than 6,000 light years away. But if they can "prove" that light doesn't have a constant speed, then they can explain away all those 13-billion-year-old galaxies with the idea that the light just got held up in the aether and merely "looks old."
On the basis of Bethell's work, it appears that the "P" in GOP does not stand for "Physicists."