>>>>Naomi,
>>>>
>>>>>For water it's 1m*1m*1m = 1kg, if my memory serves me right.
>>>>
>>>>The original definition of a kilogram = the mass of 1 liter of water at 0 degrees C.
>>>WRONG!
>>>It's at 4 degrees Celsius! at that temp the water is the lightest. :-)
>>
>>Not lightest: heaviest, or, more accurately, densest.
>You are absollutely correct! I answered too quickly, concentrating on the degrees and not more. This is naturally one of those anomalies of water which makes life on earth possible. <g>
>
>Peter

because the densest is max and then the densest gradient is 0
this minimize the error measure.