From: Jan Langer (jan_at_[hidden])
Date: 2003-10-16 17:04:08
Jan Van Dijk wrote:
> Unfortunately the algebra (the transformation properties) is not linear. Just
> consider conversion from the temperature-'base vector' K (kelvin) to C
> (Celsius), C=K-273.15.
> In technical terms: obviously the K->C base transformation cannot be described
> with a (metric) 00-tensor (or scalar) M via the linear transformation
> relation C=MK.
> This is a nasty habit of temperature units, it seems: the seem goes for the
> Fahrenheit and the (less well-known) Rheamur. I don't know of units for any
> other dimension than 'temperature' with this non-linearity property. It shows
> that people quantified the concept of temperature in an era in which they did
> not have a clue about its true meaning :-)
when thinking about it, i cannot imagine a case where this is important.
it makes imho no sense to add °C to °F or something similar. what is the
result of 20°C plus 10°C? 30°C or (293.17+283.17)°K or just 30 Kelvin?
it is difficult to calculate with units which cannot be used as
differences. and if they can be used as differences they are linear. IMHO.
-- jan langer ... jan_at_[hidden] "pi ist genau drei"
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