What Properties Might Light of Millennia Past Have that Today's Doesn't?

Hi Foreveryoung,You are kind of correct; if the earth is "orders of magnitude younger than 4.56 billions years old", then it logically follows that something is badly wrong with radiometric dating. Accelerated decay would be a reasonable suggestion to explain the discrepancy.But how do you know that the Earth is young?That is the un-evidenced bit in your formula. That's where you need to provide evidence. And please don't say that you know the earth to be young because radiometric dating is wrong...Mutate and Survive