I like the metric system and would love to see the US switch to the metric system, but this comment is just wrong on so many levels. One litre of water only ap

I like the metric system and would love to see the US switch to the metric system, but this comment is just wrong on so many levels. One litre of water only approximately weighs 1kg and density is relative to temperature and pressure. Further, the "standard pressure" density is measured in isn't equivalent to average sea level pressure. Celsius is as much a SI derived unit as Fahrenheit is. The official unit is Kelvin and water freezes at 273.15K. Not such a beautiful number, but still based on the scientifically more significant definition of temperature.