I just used Google to convert -8ºC into Fahrenheit.
I type in -8c in f and get the answer:
I noticed Google put the brackets in. Hmm, I thought, what happens if I put the brackets in a different place?
So I type in -(8C) in f and get…
What the hell? That’s cold. At first I wondered if maybe it was working out 8ºC below absolute zero or something, but no… absolute zero is only -459ºF or so.
What is Google working out, exactly?
Okay, so I figured out what it’s doing.
8ºC (in absolute temperature terms) is 281.15 ºC above absolute zero.
And 281.15 ºC below absolute zero would be -554.3 ºC.
And -554.3 ºC equals -965.74 ºF (or would, if such a temperature existed).
But why on Earth does Google interpret it like that?
I think it’s a side effect of internal conversion to Kelvin, but it does make sense in a bizarre kind of way. Celsius is not strictly a unit but rather a scale adjustment combined with a unit (a kelvin) – Celsius, Kelvin and Fahrenheit 0 points do not match up. So just because X degrees Celsius is Y degrees Fahrenheit, -X degrees Celsius is not necessarily -Y degrees Fahrenheit. So not only your unit is different, your scale is different as well. In a way when you write 8 C you are specifying relative temperature interval, it just happens to be relative to a fixed well defined point. -8 C is the same amount in the different direction from that point. Temperature has a relatively well defined 0, and that just happens to not match up with centigrade 0, so -(8 C) is the negative of the temperature above the physical zero, not the relative zero because you are negating your scale as well as your scalar.
:smack: I think I just made it more confusing.
I suspect that there’s also some other google calculator routines that are getting called, having nothing to do with unit conversion as such, but triggered by the -( ) notation… first evaulate whatever’s inside the brackets, and then take the absolute negative of it.