Maddenation
Gold leaf
This story on the regilding of the Golden Dome, which was sent to me by my friend Cappy, piqued my interest. First, I was struck by how little of the total cost goes into buying gold. At, say 500$/oz, 8 ounces is only about 4k$ of the 300k$ cost. (I know, troy ounces aren’t the same as “regular” ounces, but they’re close, and it won’t change the conclusion.) Second, I smelled something fishy in the calculations. I know gold leaf is a lot thinner than 1 millimeter. It’s more like a few millionths of an inch thick. This source indicates it’s about 0.1 micrometers thick. Using this thickness, I calculate (you can check me) that almost a pound and a half of gold would be required. So maybe the gold leaf used on the Dome is thinner. Except that my third concern was that the writer may have misstated the amount of gold required. He says 8 oz. amounts to “a fistful.” My calcs say that’s a sphere roughly an inch in diameter. Is that a fistful? It’s certainly not a handful, but maybe that’s the point.
Overall, I come away from this article a bit dissatisfied and even disillusioned. Sure, the basic point that it only takes a little bit of gold to cover a large area comes through. And who cares exactly how much or precisely how thick it is? Even I don’t really care. It’s just that I knew immediately that the numbers didn’t fit, even before I could begin to remind myself that it didn’t matter much. And knowing that the numbers were inconsistent marred the credibility of the whole article. The author didn’t spend the time/effort to confirm his calculations. Other people reading this will remember the “fact” that gold leaf is a millimeter thick, and propagate this error. And what the heck is a “fistful”? A fistful of dollars is presumably how many you can grab in one hand (I didn’t see the movie, so I can’t say for sure.) A fistful of sand would be roughly equal to a handful of sand, which I contend would be more than a spherical inch (but I have big hands). Anyway, isn’t it easier to visualize an inch-diameter ball (a superball?) than a fistful? A golden golf ball would be too much. The golden goose egg would probably be enough to do 3 Domes. The regilding of the Golden Dome is an occasion worth reporting because it is an opportunity to demystify and elucidate a beautiful, magical, and automatically interesting process. Doing it right takes more than William Gilroy was apparently willing to give.
Dad • Observations • 03/08/05 • 4 comments
Comments
David • 03/10/05 • 10:34 PM:I didn’t see where it said gold leaf is a millimeter. The article says the gold used is 3 microns thick. Whatchu talkin’ about, Willis?
Dad • 03/10/05 • 11:18 PM:I sent an email to ND news yesterday and they changed the article. Trust me, it did say 1 millimeter in the original story. Even at 3 microns it doesn’t work out right. Go ahead and check my calcs. It’s a good exercise in units and scientific notation. I think you should also use it as a bell ringer for your kids. You can even give them the density of gold if you like.
I think gold is the most malleable metal. Didn’t Rutherford use gold leaf in his experiments to discover that atoms had nuclei?
David • 03/10/05 • 11:57 PM:Au is the most malleable metal. And yes, it’s what Ernest used in his experiment. That experiment is one of my favorites all time.
Speaking of Rutherford. Check out this picture (I use it in class all the time - you’ll need to scroll down a little bit). Tell me he wasn’t separated at birth from Cliff from Cheers.
Dad • 03/11/05 • 11:47 PM:No question, John Ratzenberger has to play Rutherford when Hollywood does his biography.
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