Complex Numbers

And It Was All Yellow

Well, here we are: the worst month of the year. At least it's shorter than other months. Wait, this is a leap year? Rats.

No sense dwelling on it. I'll just pick another site from my queue to blog about, and move on.

One perfectly legitimate reason to avoid having kids, besides the obvious ones, is that, at some stages, they ask awkward questions that may be hard to answer in an age-appropriate manner.

Like this one.

    Why is Gold yellow? Spoiler alert: Einstein again  
It turns out you don't have to look further than gold jewelry to experience Einstein's relativity.

I don't think I ever asked my dad that particular question, but I did ask the classic "why is the sky blue" one, and his lengthy scientific explanation went right over Kid Me's little head. I think I might even have fallen asleep.

Eventually, I understood the reason for the effect, at least to some degree. And I've often wondered why gold appears, well, gold-colored, when most other metals (with some obvious exceptions, like copper) are various shades of gray. Just haven't wondered enough to be arsed to look it up. Then this article somehow got my attention.

You’ve probably not given it much thought, but the reason why gold is yellow (or rather, golden) is deeply ingrained in its atomic structure — and it’s because of something called relativistic quantum chemistry.

Now, here's the thing: Generally (pun intended), relativity deals with large-scale things, while quantum mechanics deals mostly with the smallest. I'm told the two theories are both well-supported; that is, predictions they make turn out to match observed evidence. And yet, they're incompatible with each other (again, just going by what I've heard, here). So for me, the phrase "relativistic quantum chemistry" is itself a shiny gold thing that I just have to pick up.

Simply put, because it’s a very large atom, gold’s electrons move so fast that they exhibit relativistic contraction, shifting the wavelength of light absorbed to blue and reflecting the opposite color: golden yellow.

And there you have it: the answer. Refreshing to see that at the beginning of an article. Of course, it goes on to explain that shit further, which is also good.

Incidentally, this is an entirely different phenomenon from why the sky is blue, but I can't help but notice the parallels: blue light from the sun gets preferentially scattered by air molecules, turning the sky blue and making the sun appear yellower.

Read on for a more in-depth look into the fascinating chemistry that gives this symbol of wealth and luxury its prized color.

At this point, it's less a symbol of wealth and luxury than one of overindulgence and greed. Still pretty, but come the apocalypse, all that gold you've been hoarding will be mostly useless. It's not like any survivors will need it for its amazing electrical conductivity.

Anyway. I won't bore you with too much from the rest of the article. I do think it's very accessible—probably too much for a toddler, but not for a teen or a grown-ass adult—so give it a look if, like me, you want to finally get that stubborn curiosity looked at.