Mathematically, the issue is that in order to do any science before about 10k years ago, we must make assumptions about the physical forces int he universe. If the measurements then were different from the measurements now, then any computations could be wrong. And we have no way to check those measurement. Now, scientists argue that change of measurements would show in geology or various other ways, but this is wrong and they know it, as everyone agrees that time dilates as you go over the radius of a black hole, and that there is no way those on the space ship could know they are doing this.