Satellite navigation (Global Positioning System) uses the accuracy of atomic clocks to calculate your position. Some of those clocks are on satellites orbiting at about 20,000 km (12,540 mi) above the earth, and they all need to keep time to billionths of a second to calculate your position to an accuracy of 5 meters. This precision shouldn’t be a problem because the atomic clocks used are much more accurate than required. However, Einstein came up with the idea that speed and gravity affect time (Special and General Relativity). He predicted that moving the clock into orbit where it is moving faster than the earth’s surface would result in it running slower than its twin on the earth. Einstein made this worse by also predicting that time is affected by gravity, and because gravity is lower for the clocks in orbit, they will run faster. The net result is that Einstein’s theories of Special and General Relativity predict that, “the satellites’ clocks tick faster by about 38 microseconds each day.” (NASA)
For most people, Einstein’s ideas contradict their everyday experience. Watches do not run slower when you are driving. His theories defy common sense, are mathematical, and it is easy to decide because you don't understand them they must be wrong and ignore them. You are not responsible for creating the GPS system and therefore your decision does not matter. In everyday life, people are not concerned about Einstein's theories, but they are concerned about accurate navigation. They want to get to their destination and therefore need the GPS to be accurate to 5 meters or so. GPS systems have Relativity correction built into them but imagine that the designers decided to add a switch so that you could choose to switch it on or off. Now you have the choice but you also the consequences of that choice. If you believe Einstein was wrong, then you should switch Relativity correction off, and if you are right, the GPS should be more accurate because it is not adding an unneeded false error correction. If you did this according to NASA “position errors would accumulate so quickly that the system would be useless for navigation in a matter of minutes.” The consequence of applying your belief and switching off the Relativity correction is that GPS becomes unusable. You might still reject the Einstein’s theories, but now your desire for a usable GPS system pushes you to accept them. You might not want to believe in them, but they make the system more accurate. It becomes much more challenging to dismiss them because if they weren’t correct why would they make the system more accurate.
When you have a goal like building a GPS system accurate to 5 meters you need to use ideas that will progress you towards that accuracy. You might not want to believe some of those ideas are true but if they deliver then your goal forces you to. The moral of all this is that to make progress; you need truth. Having a goal like "accurate to 5 meters" forces you to test ideas and apply ideas that help you towards your goal and reject those that don't.