rate is still two units.<br /><br />So you've got seconds per....what?<br /><br />Time is a fundamental unit, not a derived one, like velocity (meters per second) which uses two fundamental units, meters and seconds, to obtain it.<br /><br />Relativity says the size of the unit of time changes. People get together and agree on how long a second is. However, even by using the same definition (period of a pendulum under specific conditions, atomic vibrations, whatever), once people start moving at different relative velocities, they no longer agree on that length.<br /><br />E.g. say everyone believes a second is the period of a pendulum of a certain design, in standard earth gravity (1g).<br /><br />Now, using the same design, and same gravity, people measure it, but they have one difference: They're moving. On trains, in spacecraft etc. All other conditions are identicle, and so the pendulum will have the same period (it is not, and cannot be, coupled to velocity, as that's entirely relative).<br /><br />Despite that, when the observers look at eachother's experiments, they will disagree. They'll say eachother's pendulums are moving slower than the physcists report. I.e. the person w/ the pendulum will still say 1 second. The person outside, looking in (and moving at a different speed) will say it takes longer.<br /><br />However, changing the duration of a given unit of time is not a rate. It may be a ratio, and we know how it shifts, but it is not a rate, nor a speed. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>