How old is the Earth?

[TheDarkestOfAngels]

Well if the Earth is really 4.5 billion years old then you cannot "observe" that decay rates are constant because yoru observation is vastly too small and insignificant compared to the whole time period. Even if you could observe it for 100 years it would still only be 2.2X10^-11 percent of the total time. Even a curved line looks straight when you only observe an insignificant portion of it. So you're going to have to provide some other backing as to how you know those rates are constant.

This reminds me of the arguements people used to make around here that unless someone was around during the big bang event then I could never truely prove that it happened.
Either way, the concept is ridiculous. Given the sheer volume of radioactive material on the planet and the fact that the laws of physics have been consistent throughout the entirety of human experience and beyond (since we can actually see billions of years into the past by simply looking up into the sky) we can easily tell that radioactive decay is consistent with mathmatical precision simply for the same reason that all radiation, everywhere, throughout human history has been consistent and not just with one material but all materials at their individual decay rates. Not only that, but people who measure these things can calculate the decay rate of a material to an insignificant fraction of a second.

If radioactive materials were inconsistent or could change to any degree over any length of time, it would have been spotted long, long ago by someone from somewhere around the planet because that kind of flaw would be obvious to anyone who makes their career around such concepts and it would affect many other areas of science.