# Space time interval

1. Jul 31, 2009

### Amith2006

1. The problem statement, all variables and given/known data

I am bit confused about the expression for finding the space time intervel. Some books say it is,
(spacetime intervel)$$^{2}$$=(time intervel)$$^{2}$$ - (space intervel)$$^{2}$$
while some books say it is,
(spacetime intervel)$$^{2}$$=(space intervel)$$^{2}$$ - (time intervel)$$^{2}$$
2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jul 31, 2009

### Cyosis

It's just a convention, pick one and stick to it. The physics will be the same.

3. Aug 1, 2009

### LithiumHelios

As mentioned above it's just based on the adopted convention. http://en.wikipedia.org/wiki/Sign_convention#relativity - This wiki article on the sign conventions employed may help clear things up. It is something of an arbitrary choice though as long as you remain consistent.

Last edited: Aug 1, 2009
4. Aug 1, 2009

### Amith2006

The criteria for an intervel being time like or space like just get interchanged. Maybe it is not a universal fact as u say. Anyway, thanx guys.