This always seems like a logical error to me and perhaps someone can explain:
To measure a constant, you need something constant, but you do not know if something is constant if you do not have something constant to measure it against. (False premise?)
I believe we can only assume things are constant, but they only appear constant.
I you read the work of the physicist Julian Barbour regarding time I think you will be in for some remarkable insights. "Time arises out of change".
It's okay to measure one thing with something else that's variable. For example let's say I want to determine aluminum's coefficient of thermal expansion. I have a block of aluminum which I am measuring with a steel ruler. Both objects will change size if I vary the temperature, but by measuring both at several temperatures I can determine the ratio of their coefficients of thermal expansion. Funnily enough, if I'm using a mercury thermometer I'm really measuring everything relative to mercury's coefficient of thermal expansion.
To measure a constant, you need something constant, but you do not know if something is constant if you do not have something constant to measure it against. (False premise?)
I believe we can only assume things are constant, but they only appear constant.
I you read the work of the physicist Julian Barbour regarding time I think you will be in for some remarkable insights. "Time arises out of change".
https://www.youtube.com/watch?v=GoTeGW2csPk