On: 0 degrees celsius + 0 degrees celsius -

[Retric]

No, swapping them gives the same value.

http://www.google.com/search?hl=en&q=0+degrees+celsius+%...

Google always convert temperatures to Kelvin for this stuff.

http://www.google.com/search?hl=en&q=0+degrees+celsius++...

The assumption is if your doing math with temperature you are using it in a physics context.