Wikipedia:Reference desk/Archives/Science/2016 August 17

= August 17 =

Have both the special relativity and general relativity concrete applications?
If we had just special relativity, but had not generalized it to general relativity, would things like GPS be possible still? Llaanngg (talk) 19:08, 17 August 2016 (UTC)


 * Yes, we would certainly be able to set up a working system. There would only be a theoretical problem about how to interpret the time dilations that are caused by the gravitational potential. In the end it wouldn't be much different from people knowing about Planck's black-body spectrum and the energy levels of atoms before quantum mechanics was developed. Count Iblis (talk) 20:46, 17 August 2016 (UTC)


 * We discussed this in October, 2014.  "None of the major engineering or political challenges, as enumerated by (Bradford Parkinson) - who our Wikipedia article credits as the inventor of GPS - have anything to do with the effects of special- or general- relativity."  (I cited extensive sources for these statements in that discussion, including a lecture presented by this key figure, "GPS for Humanity" from the Stanford Engineering Hero Lecture series).
 * As far as I am concerned, most of the stories you hear about the importance of general relativity to the design and implementation of GPS are largely apocryphal.
 * But you don't have to take my word for it - you can check the GPS textbook. The effects of relativity are discussed in the chapter on time references; and when these effects are quantitatively compared to other sources of error, the effects of relativity can be essentially ignored.
 * Nimur (talk) 20:55, 17 August 2016 (UTC)