[ExI] david statue coincidence

Sun Aug 21 21:11:53 UTC 2016

On Sun, Aug 21, 2016 at 12:45 PM, spike <spike66 at att.net <mailto:spike66 at att.net> > wrote:

>… buddies coming by, Hey Mike!  Whaddya doing dude?  He would say something like: chipping away everything that isn’t David.  …  Every chip contained smaller replicas of the big guy, ja?  So how does he figure they weren’t also rock encrusted Davids?  And each chip of each smaller David would itself contain still smaller Davids and way more of them, all the way down to the calcium carbonate…spike

The more I think about this, the more it bothers me.  Sure this went off on a rather lighthearted… eh… make that absurd note.  But what if… David did topple one day and spoil the day of perhaps dozens of admiring proles?

Since this is an engineering-oriented discussion, let us go that route and do some BOTECs, shall we?

I have heard that David is about a triple scale if you assume the model was a big guy, and a big guy is about 100 kg and the volume of a solid scales as the cube of the linear dimension and so 3, 9, 27 times the volume of the 100kg guy and marble has a density of about 2.7 compared to humans’ paltry 1 g/cc, so David would have a mass of about 7000 kg?  Are you getting about that number?  7 tons of David?

OK then, we can do the same trick to estimate the cross sectional area of the ankles, so a big guy might be about 10 cm by about 8 in roughly an ellipse (no not that part, I meant the ankle), so about 60 cm^2, triple and squared, we get around 500 cm^2 area per ankle times two ankles so about 1000 cm^2 supporting about 7 tons of David or about 70 kN on about a tenth of a square meter, so about 700 kPa, ja?  Ha! Really a mere 700 kPa?  To stone that kind of pressure is child’s play!  Rather for stone that would be pebble’s play!

Or would it?

If you sat thru engineering school and didn’t learn about stress concentration in ceramic materials, you weren’t listening, in a really dangerous way.  Two things I thought of: marble isn’t really very good as a structural material.  It is great for sculptures because of its beauty and… it is easy to carve.  Whyzat?  Because it is relatively soft.  Being stone, stress concentration is a big deal.  With a five meter lever arm between ankles and neck, and an area moment of intertia small enough to obviate my even bothering to post BOTECs, you can see it would be easy to create sufficient stress concentrations to result in catastrophic structural failure at his ankles. 

Once we have those numbers we can estimate how easy it would be for three or four fidels to throw a rope over his neck and intentionally topple the artwork.  Perhaps they would see internet images of infidels walking around, admiring it, women with heads uncovered, committing idolatry!  This is offensive of course, people walking in circles around a stone, and it must be stopped.  

Keith’s evolutionary psychology-based theory on human behavior predicts that fidels might be motivated to destroy an idol if it gave them status in the eyes of their compatriots.  The compatriot to adversary ratio increases steadily and will likely do so for the foreseeable future in Helsinki Italy.  Conclusion: as few as three or four fellers with ropes and AKs could show up, use the latter to slay everyone in the joint, use the former to topple the accursed idol and flee.  The risk of this grim scenario increases annually, with no credible end point other than David on the pavement, marble microshards by the millions, each containing countless nano-Davids which will remain forever encrusted in calcium carbonate.

If the good guys can imagine this scenario, the bad guys can think of them far more easily.  If such a thing occurs, I will be dismayed but not surprised.

The article goes on about the risk of David taking a dive by natural factors but doesn’t say a word about what looks like a far bigger risk of his perishing by unnatural causes.

My apologies for harshing your Sunday buzz.

spike

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20160821/16ca0fad/attachment.html>