I have in mind thought experiment where physicist is in elevator falling towards the Earth. Question would be if he is not allowed to look outside, how would he detect the presence of the planet? Let's not take in consideration tidal forces and assume he is taking local measurements during small time intervals. And whole experiment is in vacuum. Is there a way he can detect Earth under these conditions before he crashes into it? The way I see things, there are only two conceptually different ways that our physicist can detect the Earth. Either by taking a peek outside of the elevator, or by crashing. These are two different ways we can transfer/register information from one point in space to another. Interesting thing is that first method has to do with constant velocity, and second with acceleration. Let’s notice one more thing. First method of information transfer has its maximum, speed of light. Should the second one have its maximum? Should there be maximal possible acceleration/force in nature? Why would non-inertial reference frames be any special compared to inertial, and don’t have the property of maximal information transfer?