# Confused about proper time on a worldline

1. Nov 12, 2014

### zwoodrow

Is the use of proper time just for ease of simple equations? ie you could define velocity and acceleration with any reference time you want but all other choices are arbitrary other than proper time- proper time is the only time that is special.

It seems to me that if you use proper time then you are able to shift all of the transformation machinery over to spatial components- ie when you see partial derivatives appearing you know they are tied to the spatial components and not to the time part.

To put it another way - If you picked a time other proper time you would see partial derivatives floating around that might have to do with time or/and might have to do with spatial components.

2. Nov 12, 2014

### ghwellsjr

Yes, Proper Time is the time displayed on and kept track of by real clocks so that makes it not only special but the time that any theory must explain when the clocks are moved around. The coordinates that you use to keep track of how those clocks move around are arbitrary but no one has found a simpler method than Einstein's so that is why it is used.

You can try but I don't think you will succeed.

Coordinate Time is a time other than Proper Time and it works quite well with spatial components.

What is the problem that you think needs to be solved?