There is one thing that every young earth science denier needs to understand.
“Assumptions” are NOT a get out of jail free card.
You cannot just hand-wave away scientific findings that you don’t like simply because they “make assumptions.” In order to challenge a scientific theory on the grounds that it makes assumptions, there are three things that you must do.
- State precisely and accurately what the assumptions are.
- Make sure that it really does make the assumptions that you are claiming that it makes, and that it hasn’t been superseded by a more up to date method that has found a way to side-step those assumptions.
- Provide a credible, evidence-based mechanism by which those assumptions could have been violated in such a way as to give the exact same results that we see in reality, right down to the precise measurements and the mathematical correlations between those measurements.
So for example, when we see that radiometric dating results increase linearly with distance in places such as the Hawaiian islands, and the rate matches very closely with direct modern day readings of continental drift measured through GPS satellites, you have to provide a credible explanation as to how nuclear decay rates and continental drift could have varied in exact lock-step with each other, by a factor of a billion. Without generating so much heat that it would have vaporised the earth’s crust many times over in the process.
And what you have pointed out demonstrates that you don’t know what the word “repeatable” means.
“Repeatable” simply means that when two or more methods give the same results despite their assumptions being different (for example, with nuclear decay rates and continental drift), it is evidence that those assumptions were in fact correct. You don’t have to have “been there to see it happen” to carry out cross checks such as these. So in the example I gave above, when radiometric dating gives a rate of continental drift that matches closely with modern direct measurements from GPS satellites, that is repeatability.
And no you can’t just hand-wave them away as “both making the same assumptions of uniformitarianism.” Repeatability is a test of assumptions, and tests of assumptions are not assumptions themselves.