Units of Measurement

[Pyan]

The distance between Earth and Pluto is constantly changing.

In fact, between 1979 and 1999, Pluto was closer to the Earth than Neptune, so the outer planets went Jupiter, Saturn, Uranus, Pluto, Neptune.

Is Pluto or Neptune farthest from the Sun?

 

[JunkMonkey]

Sorry. My Cynical Sarcasm Font wasn't working.
But what other explanation could there be. When measuring distances in AU does anyone really care about a few thousand km one way or the other?

Someone once said the same thing about cash: "A million here, a million there... soon you're talking about real money."

 

[Pyan]

Someone once said the same thing about cash: "A million here, a million there... soon you're talking about real money."

How do you become a millionaire? Start off a billionaire and buy Twitter...

 

[Christine Wheelwright]

I think I've mentioned this before, but there is an important distinction to be made regarding the general use of units and the use of units in science!

When it comes to buying a pound of potatoes or a pint of beer, it really doesn't matter much about the quaint traditional units. BUT......when doing proper science or engineering, the SI system of units is hugely advantageous. Essential really. And it isn't just about being "metric". The SI system of units is carefully designed to make complex calculations simpler and remove the need for constants (multipliers) in fundamental equations. Hence, for a rotating machine, power = torque x speed (kW, Nm and radians-per-second being the SI units). Or, if you prefer, you could use silly (arbitrary/traditional) units in which case power (horsepower) = torque (foot-pounds) x speed (rpm) x some godawful constant that you will have to look up.

Of all the nations in the world, the US is the only one I've worked in where folks routinely attempt to do real engineering using antiquated units and well-thumbed books of constants. I think it is changing, but slowly.

 

[Wayne Mack]

The SI system of units is carefully designed to make complex calculations simpler and remove the need for constants (multipliers) in fundamental equations.

Hence all the roadway signs listing maximum speed in km/3.6 ksec.

 

[Christine Wheelwright]

Hence all the roadway signs listing maximum speed in km/3.6 ksec.

Right, but if you actually had to do some calculations (I dunno, maybe for crash tests involving kinetic energy and momentum) you would want to convert speed to m/s and vehicle mass to kg and then proceed from there. I would hope, anyway.

 

[Venusian Broon]

So, when The Proclaimers walked Five Hundred miles; we still don't have a clue how far away they actually got to.

To be fair, it says they would walk 500 miles. They didn't say they actually did it.

Also

"And I would walk 500 more
Just to be the man who walks a thousand miles
To fall down at your door"

Which raises a few questions. Are they actually 1000 miles away when singing this? And therefore they need to walk 1000 miles to get to her door?

Are they talking about a woman outside Scotland? Or are they going to walk 500 miles one way, then turn back and get back?

Luckily people have been doing research on this (although I think they used international standard miles - if you are using Smiles then it would be slightly bigger) :

Finally, falling down at her door would probably be the thing to do, if you do 1000 miles (whatever the distance is) in one sitting, you will be pretty tired, so that checks out.

 

[Cthulhu.Science]

Douglas Adams may have had his math off a bit:

Cosmological models are built on a simple, century-old idea, but new observations demand a radical rethink​

Our ideas about the universe are based on a century-old simplification known as the cosmological principle. It suggests that when averaged on large scales, the Cosmos is homogeneous and matter is distributed evenly throughout.

This allows a mathematical description of space-time that simplifies the application of Einstein's general theory of relativity to the universe as a whole.

Our cosmological models are based on this assumption. But as new telescopes, both on Earth and in space, deliver ever more precise images, and astronomers discover massive objects such as the giant arc of quasars, this foundation is increasingly challenged.

In our recent review published in Classical and Quantum Gravity, we discuss how these new discoveries force us to radically re-examine our assumptions and change our understanding of the universe.

Cosmological models are built on a simple, century-old idea, but new observations demand a radical rethink

Our ideas about the universe are based on a century-old simplification known as the cosmological principle. It suggests that when averaged on large scales, the Cosmos is homogeneous and matter is distributed evenly throughout.

phys.org

 

[Harpo]

It’s just occurred to me that we say “wafer thin” and “feather light” without considering wafers or feathers to be unusual at all.

 

[Dave]

we say “wafer thin” and “feather light”

We also don't consider what kind of wafer or feather. There is a huge different between the feathers of an Ostrich and a Wren.

What about "the final straw" ("last straw")?

Precisely how many "straws" are too many?
A Bactrian camel or a Dromedary?
And wouldn't this pasturage-based limit depend upon the average mass, width and length of the straws, the surface area of the camel's back, the Camel's health and bone density, and the size, age and strength of the camel that was used to carry out the test?

 

[farntfar]

Certainly it would, if we were having to do a sum of all the straws involved.
However, we are only really concerned with the last straw; the one that broke the camel's back. All the other straws, and the type of camel, it's previous history of back problems etc; are mere incidental details to the story.
Had the camel just walked 500 miles, for instance, with or without all the other straws?
Who cares.
It is only that last straw which can be blamed for breaking the unfortunate beast's back. The rest are entirely blameless.

 

[Dave]

Except that it's a point or level beyond which we do not, or may not be permitted to, extend or pass, and so it does matter if you don't want to exceed the ceiling.

You could say, "Sorry officer, but I only exceeded the speed limit back there in the last few miles per hour, the other 30 miles per hour were perfectly fine!" but I doubt it would help. However, if you didn't have a speedometer, and you had no way to tell how fast you were actually travelling, then that would be a problem. Or, if the speed limit was randomly imposed at a different value each day, with no signage to tell you what it was, then that would be a problem too.

 

[Harpo]

Can the straw camel pass though the eye of a 500-mile needle?

 

[Dave]

Possibly, but not 500 more!

 

[Ursa major]

The only thing we need to know about the last straw is that, whatever its weight, it was great than the difference between what was already on the camel's back and the maximum weight that the camel's back could support without breaking.

 

[Cthulhu.Science]

I thought The Last Straw was a journal about building homes out of straw bales.

 

[Cthulhu.Science]

For those who were wondering about needles in haystacks...from Life Magazine 1938...not clear if that is total "man-hours" or clock hours for the entire team searching.

 

[farntfar]

It depends on the punctuation.

It may signal the return of the camel, following the indication of the breaking of a particular straw.

The straw that broke.
The camel's back.

 

[Dave]

For those who were wondering about needles in haystacks...

So, assuming that it is man-hours, that means 106.33 needles in a haystack = 1 year

 

[Ursa major]

I thought The Last Straw was a journal about building homes out of straw bales.

It can't be the last straw, not when it sounds as if there'd be an immediate bail-out.