Terrell-Penrose controversy

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In the 1950s, James Terrell wrote a paper with the slightly startling conclusion that part of special relativity as it was being taught was wrong. Under most theories, the concept of an "observer" relates to a perfect observer, who simply sees and records without overly interpreting or superimposing their own beliefs onto the data. Special relativity's observers were different, they took measurements calibrated according to certain belief ("I know that the speed of light is globally fixed in my own frame"), and then reported the results of their interpreted calculation as being observations.

Special relativity said that for any given observer, any "moving" bodies would seem to be length-contracted by the Lorentz ratio, and many people seem to have taken this to mean that observers see moving bodies to be length contracted. In fact, with special relativity, as with pretty much any other theory, visible, photographable lengths change by the same ratio as the visible frequency-shift, so if we see a receding object whose Doppler shift halves the frequency of its signals, it should appear visibly shortened by a factor of two (regardless of theory), whereas if we see an approaching object's signals to be doubled by the Doppler effect, we should see its visible length appear doubled, too.

What the special theory said that an observer observed was not necessarily the same as what the theory said they should see.

Publication problems

Terrell had trouble getting his paper published, and after getting versions rejected by multiple journals over a period of years, finally got the paper accepted for publication in Physical Review in 1959.

At around this time, the well-known mathematician Roger Penrose submitted a paper on a similar theme to a non-peer-reviewed newsletter of a local mathematical society, who published it before Terrell's piece appeared in print – this meant that Penrose got credit for the discovery, which started being referred to as "The Penrose Effect".

This episode raised profound questions over the legitimacy of the peer-review process and how we assigned credit. From Terrell's point of view he was a struggling "nobody", the scientific community had appeared to be blocking his work because he appeared to be critiicising their level of expertise, and right at the last minute, when he had been about to "win" and they could no longer find any credible excuse not to publish, they'd rescued the situation by ensuring that "one of their own" got the credit, by slipping a similar paper to some of his friends, who'd then published it without going through the same peer-review process.

It probably looked to Terrell as if the community had joined ranks against him, and finally conspired to make sure that one of the existing "big names" got the credit instead of him.

To make matters worse, since Penrose was actually a sort of authority on odd geometrical questions, it was entirely conceivablee that one of the several referees for the journals that Terrell had sent his paper to might have shown it to Penrose ... it might even have been that a journal had sent a copy to Penrose himself ... but the confidentiality rules regarding peer-review said that even if this had been the case, they'd be obliged not to disclose it.

This created at least the appearance of a potentially corrupt and self-serving system that protected its own interests, looked after its own friends, and "saw off" troublemakers by blocking their work and then making sure that they were starved of credit. The system as it was would allow a prestigious authority figure to be confidentially sent a copy of a potentially important paper written by a newcomer, reject it, then mull over the problem, write their own (obviously superior) paper, and then slip it into print, bypassing the system that had let them block the original paper, be officially recognised as the person who had published the idea first ... and get away with it.

Regardless of whether or not this was what actually happened in the Terrell/Penrose dispute, it became clear to onlookers that the system would have allowed this to happen, and that the system didn't allow us to investigate and demonstrate that it hadn't happened. Reviewer confidentiality meant that if Terrell had been screwed over he'd never be able to prove it, and that if Penrose had never seen Terrell's paper, he'd never be able to establish his innocence by demontrating the he hadn't been a reviewer and that he and his friends had never been given an advance copy of Terrell's work by the journals.


What happened next was that the American Journal of Physics printed a paper arguing Terrell's case for priority for the "Terrell-Penrose" effect, given that Terrell had only lost publication priority because he'd correctly gone through all the proper channels, whereas Penrose had bypassed peer review. It would be bad for peer-reviewed journals if people knew that the best way to to win a priority dispute was to publish elsewhere. "Am.J.Phys" published a rash of further papers on the optical appearance of moving bodies, inspired by the Terrell and Penrose pieces, and Terrell's paper became well-known to (and well-cited by) anyone working in that subject.

The dispute helped to change some of the ways that we assign credit: Later priority disputes tended to be solved by assigning priority based on the date of submission rather than the date of publication, and a number of public "preprint and e-print" internet document servers appeared (notably the arXiv.org server), which allowed researchers to upload a public timestamped record of the work that they were submitting to journals.

Terrell, though seemed to have had enough, and quit physics.