Hubble+/- 4.3%, is the constant "constant"? Why is the Hubble constant assumed to be "constant"? Just to keep things simple a la Occam's razor? Or is there a lot more to it than that? With further increases in the accuracy of its measurement, and a few centuries to make repeated measurements, is anyone placing bets yet on its value turning out to NOT be a constant rate of acceleration? I.e. the rate of acceleration is either increasing or decreasing at a constant rate. Or, the rate of acceleration is a function of some as yet undetermined factor that changes subtly over time.