# Ds^{2} invariant interval as + or - proper time increment

1. Feb 18, 2015

### binbagsss

Some sources have $ds^{2}=d\tau^{2}$, and others have $ds^{2}=-d\tau^{2}$,
Does the sign depend on the signature chosen for the metric?

2. Feb 18, 2015

### Staff: Mentor

Yes.

3. Feb 18, 2015

### binbagsss

Thanks, and just to confirm a $(+,-,-,-)$ signature has $ds^{2}=d\tau^{2}$ and a $(-,+,+,+)$ signature has $ds^{2}=-d\tau^{2}$?

4. Feb 18, 2015

### Staff: Mentor

Yes. I prefer the second convention. (-+++)