Did Townsend Brown know – early in the 2oth century – what scientists in the 21st century are just figuring out?
Sadly, I feel that the answer to that question is "no".
First, General Relativity is not new. It's a theory from 1915. LIGO has made no change to this theory; they just built a lot of hardware and sensitive detectors and put some very powerful computers and algorithms on top to filter out all signals which are not in keeping with the predictions of this 1915 theory.
(Okay, there was a bit of maths and theory added in the 1950s/1960s General Relativity Renaissance, and perhaps some assumptions overlaid on top of GR which Einstein himself might not have approved of. Einstein, for example, did not believe in black holes, and saw singularities as a mistake in GR, so any theory of the production of GR-compliant gravitational radiation which depends on merging black holes, is something that's quite alien to Einstein's idea of what GR was about back when he was creating it. But, I think he was more open to the idea of propagating waves in spacetime.)
So scientists are not just now figuring out the ideas that LIGO is based on. All the figuring out was done by 1915. They are just now getting
data that appears to confirm century-old ideas which, for multiple generations now, physicists have always expected to be true.
Second, Townsend Brown claimed to be producing and detecting a form of radiation which is completely unlike GR radiation, and that's why he was never taken seriously by the students of General Relativity: his ideas simply were not compatible with Einstein. Or at least with the contemporary interpretation of Einstein.
Townsend's idea of gravitational radiation was variously:
a) a static/repulsive/anti-gravitational force coming from empty space that could be "a push not a pull". A form of Le Sage gravity, which a little glance at Wikipedia reminds me yes, is still considered extremely non-mainstream. (
https://en.wikipedia.org/wiki/Le_Sage%2 ... ravitation ) That's not GR waves. At best, in a GR framework, that's something a little like the "cosmological constant" which Einstein thought of as his greatest mistake.
b) a radiation perhaps like (a) but which - based on Charles Brush's idea of "thermogravity" that also goes back to Michael Faraday - might cause anomalous heat buildup inside massive objects such as rocks. This again is not something predicted by Einstein in GR, and is not accepted by the current GR community.
c) in Structure of Space, a longitudinal as opposed to transverse mechanical wave in a very real mechanical spatial ether (GR in the modern sense doesn't allow speaking of an ether at all) produced at radio frequencies by a dipole antenna facing forward, which he expected to produce mechanical oscillations in an antenna. This seems essentially the same as Tom Bearden's 1980s idea of "scalar radiation" or "longitudinal EM waves" and may have also been something Tesla claimed to produce and detect. There has been, as far as I'm aware, no verified detection of longitudinal waves, but it's possible that that's because the subject might be classified.
e) in his 1950s "gravity radio", radiation produced by a (small, desk-sized, not city-sized) massive high-K radio antenna, which might or might not be the same thing as (c). If in fact the Gravity Radio really worked as Townsend described it in his letters, it certainly didn't need a black hole to produce this radiation or a detector the size of LIGO to receive it.
e) in his 1930s-1950s "differential electrometer" and his 1970s-1980s "petrovoltiacs", not even an actual "radiation" but rather just an abstract statistical correlation between a slowly time-varying electric field in a detector, and with various astronomical alignments of the Earth with the Sun, moon, and stars. The electrical signals that were correlated with the stars specifically being assumed to be caused by "sidereal radiation" - radiation from either the stars or the space between the stars. And if from the space between the stars, then that
might be the same thing as (a) or (b). Note that GR does
not predict any form of gravitational radiation
from space itself - the radiation in GR travels
through space, but has to originate from a point source of very rapidly moving matter or very rapidly changing energy.
I'm a Townsend fan, and I very much
want to believe that he detected something strange and real which the GR community completely missed, and which is, perhaps, being put to use in some classified military communications system. But I don't think it helps our case at all to confuse his very specific and idiosyncratic - and very pre-Einsteinian - ideas about gravity, with what Einstein and Einstein's followers in the GR community actually taught and predicted and are now, after over a hundred years of being soaked in Einstein's ideas, claiming to have detected.
If Townsend Brown's ideas of gravitational radiation
are compatible with Einstein's GR, then we now have the quite large problem of explaining why the post-1950s GR Renaissance community - with military sponsorship and the top scientific brains in the world, in multiple countries on both sides of the Cold War - apparently came to the conclusion that GR forbids these ideas.
Regards, Nate