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strbean 2 days ago

Except the various disasters caused by assuming the wrong units (Mars Climate Orbiter, for example).

monster_truck 2 days ago | parent | next [-]

The team that wrote their code in English units instead of Metric defied specifications, that has nothing to do with this.

> The Software Interface Specification (SIS), used to define the format of the AMD file, specifies the units associated with the impulse bit to be Newton-seconds (N-s). Newton seconds are the proper units for impulse (Force x Time) for metric units. The AMD software installed on the spacecraft used metric units for the computation and was correct. In the case of the ground software, the impulse bit reported to the AMD file was in English units of pounds (force)-seconds (lbf-s) rather than the metric units specified.

From https://llis.nasa.gov/llis_lib/pdf/1009464main1_0641-mr.pdf

seanhunter a day ago | parent [-]

Hey don't blame the English for that. I would be prepared to wager you couldn't find a single English engineer who uses lbfs or anything similar. Everyone in physics or engineering uses metric for everything to do with forces even those who might use mph for a speed informally.

monster_truck 12 hours ago | parent [-]

Nobody is blaming the english for anything, those are simply the units they used.

drob518 2 days ago | parent | prev [-]

Which proves what? That misunderstandings happen? Yes they do. Get over it. But most amplifiers and recordings don’t crash and burn, so there’s your counter proof. Use units when they might be ambiguous. But in many fields they aren’t.

Nevermark a day ago | parent | next [-]

> But in many fields they aren’t.

I am lost. What fields you are talking about?

1. I am unaware of any field operating within its own echo/context chamber using unit-less numeric notation for anything but actual unit-less quantities. Except for informal slap-dash arithmetic, on trivial calculations.

2. Units indicate the dimension being measured, not just the relative magnitude within that dimension. Nobody is going to know from any shared context, except in person, what a bare number measures.

3. Virtually every measurable quantity has multiple possible units of different relative magnitude, depending on micro context, so even people within a field, who agree on the dimension measured, still need units. Meters, light years, AU, angstroms?

4. You cannot apply standard formulas of physics, or anything else, without specific units. Formulas operate on dimensions, but to interpret and calculate any numbers, you need to know the specific unit being used for each dimension.

(In any context, but a late night napkin argument between two well acquainted colleagues in a bar, units are universally used. And in that case, the opportunity for serious misunderstandings is more likely to be from missing units, than the quantity of scotch each has imbibed, or how much they have spilled on the napkin.)

drob518 a day ago | parent [-]

You’re arguing both sides. If nobody does it then it’s not a problem.

ashoeafoot 2 days ago | parent | prev [-]

No, this are the sounds of underspecification.