I was thinking about this, when someone in that dating forum said that Creationists don't have our own dating methods, and it occurred to me that the one that makes most sense is extrapolate back in time using things, or factors, that make sense today, and see where they stop making sense. I'm talking stuff like gravity, the solar wind eroding the atmosphere, the moon's orbit, and the like.
Most of all, what comes to mind for me is the speed of light. Its speed has been observed to be slowing consistently since first observed in the 19th century, (as has the rate with which it's done so) and beyond that, I think it's pretty clear that it's aging on a curved, non-linear line, and as the present is the key to the past, we can presume it aged in the same way long before contemporary scientists started measuring it.
The question is, just how steep was the curve? Do we know enough to chart its trajectory? Millions of years ago, even if we extrapolate linearly, the effects of light from yesterday must not be the same as today. Light from distant stars back then, which take thoasands of years to get here would not have needed to, would they? How quickly are we talking? What would be the other effects? How about on life, here? In a younger, more energized light, just what would all the differences be?
Can we collaborate our measurements of light with other forms of energy, and see if we can't find corroborating evidence? Has gravity weakened over time, like light? How about electricity? How strong would it be, compared with today, millions of years ago? Would it make sense? Why, why not?
Basically, when did the Point of Erosion start? Where does math, observation, and common sense best point towards? (I would expect creationists and evolutionists to differ in their assumptions, but I think this is an interesting question.)
PS: I was debating in another forum, and wanted to learn more about current dating methods. I was arguing elsewhere with someone, and as a result, I am looking for evidence against current dating techniques. If someone could send me some links, or point me to a book or two, that would be nice, but also, if you wish to point me in the direction of stuff refuting that, I will be open to such, also.