XKCD: It's more than a comic

And it may give us an edge at fighting them.

New comic. Titled "Kilogram" and found here.

Imagine the chaos that would ensure if the kilogram was redefined to equal the Imperial Pound, rather than the other way around.

Hehe. That's a play on the fact that we did just redefine the kilogram in terms of the Planck constant rather than a physical reference standard, meaning that all SI units now have definitions based on fundamental constants. We no longer have to worry that someone will accidentally drop the kilogram and cause all our physics and chemistry to change.

Edited by Fighteer on Nov 17th 2018 at 11:46:21 AM

Incidentally, the pound's official legal definition is 0.45359237 kilograms.

So if, like in the comic, the kilogram tried to define itself as 1 pound, you'd end up with a situation where 1 kilogram = 0.45359237 kilograms.

I have no idea what this would actually mean in practice, but I'm fairly certain it would horrifically break the metric system.

Let's do it...

I think they did measurements comparing The Kilogram to records of what it weighed decades ago, and it had very slightly changed. Like, I think they had kilogram masses made of different materials that had been weighed against The Kilogram a long time ago and they were more like each other than like The Kilogram now.

Of course, the Kilogram can be defined from the meter and a set of temperature and pressure.

It is, after all, the weight of a cubic decimeter of water (but is that water supposed to be pure H₂O?).

Edited by Medinoc on Nov 16th 2018 at 6:47:29 PM

Mass of a cubic decimeter of pure water at standard temperature and pressure.

But you can't define a pressure without the kilogram...

Well, Monsieur Kilo was known to occasionally fluctuate due to dust and atoms spontaneously migrating off of it...

I worked in metrology a while back, and the factors you have to deal with at that level of precision are insane. You have to factor in your elevation (because gravity varies) and air density (everything is buoyant outside of a vacuum, although seldom enough to actually float) for example.

Physicists like precise definitions. The original definition of a kilogram was the mass of 1000 cm3 of water at 4 C and atmospheric pressure. The problem is that these conditions are very difficult to reproduce, so they made the Kilogram in the 1880s. It was much later that they redefined it using fundamental physical constants that are known to a very high precision. Not that anybody needs to measure mass with that precision, not in the kilogram scale anyway.

The kilogram is actually not the only unit whose definition is changing. There's also the ampere (the current definition is based on specific experimental conditions), the kelvin (based on the properties of water) and the mole (based on a specific isotope of carbon). The new definitions are all based on fundamental constants.

And then one day, the constants changed...

If an engineering degree has made one thing clear, it's that there's far too many different units and nobody is going to stop using them.

Also for the sake of earlier conversation, just saw a Tumblr post that was Indirect Detection to a T (a very weird opinion on gay bars I can't succinctly summarize)

Edited by FerrousMaelstom on Nov 17th 2018 at 9:48:31 AM

Well, the good news is that if any of the fundamental constants changed we'd probably all die instantly and this won't be a problem anymore.

Oh good, no need to worry about that anymore.

There's nothing that could possibly be accomplished by worrying about it, so...

Airplanes and Spaceships

What's the next frontier, though?

If you follow the evolution of the U.S. Air Force's motto, it's Cyberspace.

The comic's a saddening commentary on the decreasing rate of technological progress.

We're a lot closer to the '50s in terms of technology than the '50s were to 1900 or than 1900 was to 1850. If a time machine brought a person from 1900 into 1950, they'd be bewildered. (Passenger jets! Appliances! Freeways! Public santation! Widespread use of vaccines!) If one brought a person from the 1950s to the present day, they'd still see a world that they essentially recognized.

The Internet's cool, but it's not fundamentally life-transforming in the way that electricity or the internal combustion engine were.

Edited by Galadriel on Nov 19th 2018 at 12:17:33 PM

If our experience is any guide, the solution to the Fermi Paradox may be that all advanced civilizations turn inward into virtual worlds rather than outward into space, and that's why we haven't seen any. The future of intelligent life may be a Lotus-Eater Machine.

I think that the differences between between 1850 and 1900 are less than between 1900 and 1950. I noticed a similar trend in information technology around the millenium. Advancement in computers slowed down significantly since the late 2000s. Actually, it was the fastest in the '90s and early '00s.

I'd say the internet has been just as life-changing (and infrastructure changing) as the internal combustion engine, it's just less visible at a glance.

Edited by Clarste on Nov 19th 2018 at 10:55:38 AM