Re: What is time
See my comment about dog years below (when it gets posted, post-time is not in sync with real time).
My point is, that to be useful as a measure of change, delta-t at the earths surface has to be equal to delta-t at the core. Because the earths core and earths crust regularly interact, and its silly to have each layer of the earth in a different time scales.
@"proper times because that is the physical time determining the evolution of everything"
Proper? Well no, we could define change in all manner of parameters, so for example if I throw a ball its path is parabolic, i.e. y = ax + bx^2, a parabolic curve defined as a function of x. That equation is not actually true, it treats gravity as fixed and constant, if we'd defined it properly, we'd have a much longer equation.
Then when we parameterize that equation for a 'change' value the correctly deals with gravity, (which we'll call tReal ), we then have a definition which we could then use BOTH at the crust, AND at the center of the earth and everywhere inbetween. There's nothing special about our perception of time that makes it the proper perception. But all that physics *we* defined in terms of t, where t is time defined in terms of our incorrect perception of it.
Why is it incorrect?
Put it this way, the dog years thing:
I was there at the birth of my dog. My dog is older than me in dog-years. This is because dog-years is not a real measure of change, its an arbitrary scaling of my dogs years as a measure of how old it is in human age terms. Which leads to impossible faults like me being at its birth and it being older than me. Or like the earths core being younger than the earth. The fault, (which Jake below notices but doesn't understand the implications) is such a major flaw in a parameter intended to be the measure of change.
Hence using t, a human perception of time, is an incorrect measure of change.
The earths core really isn't younger than the crust, its just the incorrect way we defined t.