Comment Re:stupid comparison (Score 1) 501
mixing them should be a capital crime.
Bollocks - I regularly mix units, because it sometimes makes a lot of sense. I've described something as a metre by a yard (it wasn't quite square). Similarly, I've described items in feet or inches in area, but thickness in millimetres (it tends to be anything less than 1/4 inch).
Before you complain that not everyone knows basic conversions (not everyone's an engineer), it helps if you do any amount of travelling, especially if you're from the US or UK. Also, this topic is physics/engineering, so it usual to see mixed units - we see them when talking about rocket payloads all the time. Similarly, would you complain about the mixing of AUs, light years, millions of km/miles in an article about astrophysics or astronomy.
Even you would not be so stupid as to mix units when directly comparing two things. You would never say something like "Alpha C is 4.3 light years away, while the voyager spacecraft has already traveled 18.2 billion kilometers! The stars are ours, if we take the time!" You wouldn't do that because the vast majority of your audience would not be able to make the comparison without a fair bit of work. Sure, using mm to describe the thickness of something who's other dimensions are described in other units could be appropriate, but using mm to describe the thickness of one thing, then comparing it to the thickness of something else in thousandths of an inch is just stupid. Your "metre by a yard" comparison is cute, but relying on people to know that a metre is about 3 inches more than a yard certainly is something that can lead to troubles.