this post was submitted on 08 Mar 2024
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Showerthoughts

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A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The best ones are thoughts that many people can relate to and they find something funny or interesting in regular stuff.

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How come people say 5,000 km and not 5 Mm?
why not just say millions of meters or Mega meters?

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[–] [email protected] 1 points 6 months ago (1 children)

I've seen megameters used in the context of astronomical distances, but not terrestrial ones. I think terrestrially, the familiarity of kilometers helps with a sense of scale.

[–] [email protected] 1 points 6 months ago

The beauty of the metric system is you don't lose a sense of scale from using a higher unit because you can intuitively know 1Mm is 1000km.

[–] [email protected] 3 points 6 months ago (1 children)

Not much need to use Mm, it doesn't come up very often. So when it does it's easier to use thousands of km so as to not confuse people with "another" measurement.

[–] [email protected] 2 points 6 months ago (1 children)

We routinely count vehicle odometers in thousands of kilometers, AKA Megameters. I'd say it's a common enough measurement to popularize Megameters

[–] [email protected] 1 points 6 months ago

That really doesn't come up often enough.

[–] [email protected] 5 points 6 months ago

We already have this in Sweden. 10km in Sweden is 1 mil (Swedish mile).

When we sell/buy used cars and other types of vehicles we always count the mileage in Swedish miles.

Kilometers work but is just absurd when you start talking about 100k+ kms.

[–] [email protected] 6 points 6 months ago

Aside of kilometers there used to be "myriameter" (a myriad meters = 10,000 m = 10 km).

Fun thing, in Sweden they use mil for 10 km. In Finland there's peninkulma for 10 km, but it's very archaic.

[–] [email protected] 3 points 6 months ago* (last edited 6 months ago) (1 children)

In our primary schools, we learn our children mili, deci, centi, deca, hecto and kilo, and how to calculate between them.

Beyond that or below that is used either in science classes or specific usecases and not known by the whole population at large.

Since people use what they know, they'd never use mega as a common way of measuring. We mostly use km for distance, and only in specific cases we might use, say, hectometers or decameters.

5 megameter is not wrong, but I don't call 34 cm 3,4 decimeters either(unless decimeters make sense of course :p)

[–] [email protected] 1 points 6 months ago

Here i learn mega, giga, tera. But show up in computer which is like place you most commonly see them.

[–] [email protected] 1 points 6 months ago
[–] [email protected] 2 points 6 months ago (1 children)

Yeah but the real question is how many is a Brazilian?

[–] [email protected] 1 points 6 months ago
[–] [email protected] 9 points 6 months ago

Jokes on you elite dangerous uses Mm/s for lowest speeds in supercruise before it changes to "c" for relative to light speed

[–] [email protected] 5 points 6 months ago* (last edited 6 months ago) (2 children)

Scientific notation for everything: 5 x 10^6 m. Seriously though, I think it would be easier to think about it in megameters or gigameters if it were more standard to do so.

[–] [email protected] 2 points 6 months ago

Can we do 5E6 like on the calculators? Is that common enough?

[–] [email protected] 1 points 6 months ago

yeah but sadly not enough people know how to read that. sadface.

[–] [email protected] 1 points 6 months ago (1 children)

How many petameters is that?

[–] [email protected] 2 points 6 months ago (1 children)

This sounds like some electronic device they'd roll out in the UK used to detect pedophiles.

[–] [email protected] 1 points 6 months ago

No need to worry, it us just your everyday AI system

[–] [email protected] 9 points 6 months ago (1 children)

Well mainly because where we might need to use these units, we have more standard non si units, we use AU, Light years and Parsecs where Megameters, Gm, TM etc would be useful

[–] [email protected] 5 points 6 months ago

There's also scientific notation which eliminates having to use these prefixes so you can more easily compare and manipulate numbers.

[–] [email protected] 17 points 6 months ago

Megameters sounds scary and I don't want to alarm the people I'm talking to.

[–] [email protected] 4 points 6 months ago (5 children)

Main reason is nearly no one needs to measure things in megameters. Megameters would be a unit to measure the diameter of planets in, maybe the orbital altitudes of some moons. Our moon for example is ~384Mm away. Distances between planets, distances between stars, and distance between galaxies are many, many orders of magnitude farther than that.

As most of us rarely travel more than 1,000 kilometers very often, it's the biggest unit most people are familiar with on an intuitive level.

I'm still convinced people don't actually use the metric system's power of ten design. Like no one uses centigrams or kiloliters either. They've picked out units that are pretty close to the ones in the Imperial/Customary system, kilograms are used instead of pounds, grams are used instead of ounces, kilometers are used instead of miles, meters are used instead of yards, centimeters are used instead of inches, millimeters are used instead of sixteenths of an inch and so on. Want to confuse a European? Draw up some blueprints in hectometers.

[–] [email protected] 1 points 6 months ago* (last edited 6 months ago)

Actually, size of a plot of land is often talked about in hm2.

So no, it would not confuse a European. Because the system is easy to use.

[–] [email protected] 1 points 6 months ago

Yeah, the everyday usage is limited to, well, everyday sizes.
As you pointed out there is no difference in everyday usage. But for anything outside of the most trivial of comparisons, the imperial system breaks down hard.

The advantage of the metric system is the possibility to scale both bigger and smaller when you need it, and always does so with a consistent factor. Sure, not needed when you want to know how many 8 cm strips are needed to cover 50cm. But for 1m? With inches and yards you already have to handle two conversation factors. How many sixteenth of an inch do you need to cover a foot? 192. Possible to calculate, but not nice and you'll approximate with 200 if you need to do some calculations in your head. How many feet are in a mile? 5280. And yards? 1760. Do you really know these conversation factors? Do you want to calculate "there's a street light every 30 yards, the street is 2 miles long, that's xx streetlights? Or "there's a street light every 30 meters, the street is 3.2km long, that's 3200/30 = 107 streetlights"?

Oh, and the weird units do actually get used when it is a convenient size.
Cooking uses lots of in-between units for example. Centiliters (cl) are common in cocktail recipes or for shots, in some cookbooks you will find dekagrams, etc.
Hectare is commonly used to give area measurements (it's origin is hekto-are, and "are" in turn is hekto-square meters, though "are" is not commonly used.). Want to convert hectare to square kilometers? Simply divide the number by 100! 3000hectare of forest burned down? That's 30km^2, so 5kmx6km. Easy to visualize. The US customary system makes such conversations really really really hard. How many square feet, yards or miles are in an acre? I just looked at the Wikipedia page and there is no way anyone will be able to convert an area given in acre into "well, it's approximately x by z miles". Or "my house have xx square foot of living space, so that's yy acres".

Btw, no one uses kiloliters, because that's equivalent to cubic meters. Easy conversions!

[–] [email protected] 1 points 6 months ago

When measuring lengths and time, metric units are super useful. Micrometers, Millimeters, Centimeters, Meters and Kilometres are easily and often converted in a lot of technical jobs.

Same with nanoseconds, milliseconds and seconds when dealing with time in simulations or other computer programs (e.g. game development).

Milliliters, Centiliters and Liters are commonly used in cooking.

What's wrong with hectometers? I don't know how often they're used but dealing with a factor of 10 or 100 to the next "regular" unit (meters or kilometers) is no big deal.

[–] [email protected] 3 points 6 months ago (1 children)

Your assumption that an imperial system is some kind of default tells us more about your limited worldview than about measurement units.

[–] [email protected] 0 points 6 months ago (1 children)

It's a default because its older.

[–] [email protected] 1 points 6 months ago (1 children)

That's quite the anglocentric view

[–] [email protected] 0 points 6 months ago (1 children)

What language are we speaking right now?

[–] [email protected] 0 points 6 months ago

You think that's some kind of gotcha, gringo?

[–] [email protected] 1 points 6 months ago

oh I'll have to do that at some time

[–] [email protected] 16 points 6 months ago* (last edited 6 months ago)

I do. Unfortunately, I don't have many opportunities to do so. Which may be the reason why people don't say megameter.

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