Shrink a quarter to the size of a dime | Hacker News Reader

Shrink a quarter to the size of a dime

intellectualventureslab.com

32 pointsshard14 comments

I must admit I am a bit surprised: can you just change they way the atoms in the coin are packed, so that they take up less space? Or is something being squeezed out of the coin to make up for the lost space? Or is it actually the same size as before, only now it is thicker and less wide?

I just didn't think that the packing of atoms could easily be changed - wouldn't that be a completely new material?

It's just putting a great deal of pressure on it. The coin becomes much thicker.

Better pictures: http://205.243.100.155/frames/shrinkergallery.html

Thanks - so the title is misleading, because the size of the coin does not really change, nor is it being shrunk.

in metalworking, decreasing surface area by increasing thickness is called shrinking.

the opposite, smooshing something out, is called stretching.

the terms make sense when you think in terms of the surface area shrinking or stretching.

"A shrunken coin weighs exactly the same as before, and its density also remains unchanged. The coin becomes thicker as its diameter is reduced, but the overall volume of the coins stays the same."

http://capturedlightning.com/frames/shrinker.html

OK, so I'm wondering how fast would the quarter have to travel to actually shrink to the size of a dime, based on special relativity?

The FitzGerald contraction would only shrink it in one dimension.

What would happen if the quarter was rotated on its disk at relativistic speeds?

http://math.ucr.edu/home/baez/physics/Relativity/SR/rigid_di...

http://en.wikipedia.org/wiki/Ehrenfest_paradox

Which is the best I could find for the question of shortening a quarter to the size of a dime using relativity.

The best "What if?"s always come from science geeks, I swear.

This is not happening in this case, but some materials do indeed have different crystal phases that can exist at the same temperature and pressure for extended periods of time, and some of them have different densities, like steel (search http://en.wikipedia.org/wiki/Martensite for "density") and quartz (search http://en.wikipedia.org/wiki/Coesite for "volume"). The property in general is called "polymorphism", see http://en.wikipedia.org/wiki/Polymorphism_(materials_science....

(And of course glasses do not in general have the same density as crystalline forms of the same materials.)

A few years back (5? 7?) there was a startup working on a new memory technology based on polymorphic crystallization. To update a bit, you would melt the material in a cell on the chip, and then let it cool over some period of time; I think the number was something like 2 ns for a 0, 5 ns for a 1, resulting in one of two different polymorphs. The two polymorphs of the material had a difference in some electrical property (permittivity? resistivity?) that permitted you to tell which form had been crystallized. (I was told about the technology under "friend NDA", but I'm pretty sure that this is both late enough and vague enough to be okay.)

(I'm not a materials scientist; I'm just interested in stuff.)

I dont know if is the same person, but a guy sells these on ebay: http://cgi3.ebay.com/ws/eBayISAPI.dll?ViewUserPage&useri... I bought one as a Christmas present for my dad a couple years ago.

Seeing the title I assumed they were talking about making a dime-sized coin with the value of a quarter. It's probably more now, given the increase in value of precious metals, but the last time I checked, about 3-4 years ago, a silver dime was worth a quarter.

inflation from the credit crunch should achieve this for all quarters in the US over the next decade... ;-)

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