Special Relativity. Lifetime.

[John 6IX Breezy]

Special Relativity is very specific about what it does and does not apply to and it requires velocity. Not just speed, but velocity (speed plus direction). If you try and use frequency the units don't cancel and you simply can't calculate your Lorentz transformations. Its like asking "A train leaves Philadelphia travelling at 40 km/s and a clock is ticking at 17 Hz in Boston. If it's a 600 km long trip, where on the tracks do they meet?" The answer is that if it's on the tracks the train runs over the clock in Boston station 15 hours later because it have a velocity of sweet bugger all regardless of its frequency.

When I began reading your train/clock question I thought you were going to make a point on relativity. Many examples of time dilation for the non-specialist begin with some kind of moving object (train) and a clock. Of course, I understood you were just demonstrating the clock's lack of velocity. However, I found it interesting you described the clock as ticking at 17 Hz. I don't necessarily know what that means, but a constant rate of any kind be it the ticking of a clock or firing of a neuron, can be used to keep time. Isn't this rate or fequency what gets affected by velocity in relativity? In other words, there still seems to be something that ties frequency and velocity together, if not categorically, then at least causally, within relativity.

(I should mention that my views on time are influenced by psychology; as such I view time as an abstraction derived from the perception of change, not an actual space in which change occurs. I'm ignorant of how physicists view or define time)