I cannot believe there's any argument about this. There are literally thousands of references. Below, are links to the first few references that I found. Note

I cannot believe there's any argument about this. There are literally thousands of references. Below, are links to the first few references that I found. Note: you'll see that in the first link in item #5 the comment about the strategic nature of this information, that means don't expect to get how-to-do-it plans from the military but you can bet your house to a brick that the military is deeply involved in gravity detection (specifically because, like inertial navigation, it's silent and doesn't broadcast its presence). Also note the dates, this stuff goes back to even before the 1970s, the technology is now very mature. "Google only brings up gravity wave detectors." See Google's patent in item #5. ___ Links as requested: 1. General Information/Overview https://en.wikipedia.org/wiki/Gravity_anomaly https://en.wikipedia.org/wiki/Gravity_anomaly https://en.wikipedia.org/wiki/Gravity_gradiometry https://en.wikipedia.org/wiki/Gravity_gradiometry https://csegrecorder.com/articles/view/magnetic-and-gravity-methods-in-mineral-exploration https://csegrecorder.com/articles/view/magnetic-and-gravity-... https://www.911metallurgist.com/blog/wp-content/uploads/2015/10/Airborne-Gravity-Gradiometry-in-The-Search-for-Mineral-Deposits.pdf https://www.911metallurgist.com/blog/wp-content/uploads/2015... http://www.ga.gov.au/pdf/RR0027.pdf http://www.ga.gov.au/pdf/RR0027.pdf 2. Commercial https://www.geologyforinvestors.com/gravity-surveys/ https://www.geologyforinvestors.com/gravity-surveys/ 3. Underwater https://www.whoi.edu/cms/files/08oceans-1_41284.pdf https://www.whoi.edu/cms/files/08oceans-1_41284.pdf https://www.sciencedirect.com/science/article/abs/pii/S0029801815002516 https://www.sciencedirect.com/science/article/abs/pii/S00298... https://library.seg.org/doi/10.1190/geo2018-0090.1 https://library.seg.org/doi/10.1190/geo2018-0090.1 4. Military specific https://www.navysbir.com/n09_1/N091-092.htm https://www.navysbir.com/n09_1/N091-092.htm [Note the comment re the strategic nature of this information.] https://apps.dtic.mil/dtic/tr/fulltext/u2/1012150.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/1012150.pdf https://slate.com/culture/2013/10/the-hunt-for-red-october-movie-revealed-classified-information-about-u-s-submarines-because-tom-clancy-knew-his-stuff.html https://slate.com/culture/2013/10/the-hunt-for-red-october-m... 5. Even Google has a patent! https://patents.google.com/patent/US5339684A/en https://patents.google.com/patent/US5339684A/en ____ Edit: Just found this very specific reference too, but it's not free: https://pubs.geoscienceworld.org/tle/article-abstract/34/12/1498/136542/How-do-submarines-use-gravity-gradients-to-avoid https://pubs.geoscienceworld.org/tle/article-abstract/34/12/...