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A new pyramid-like shape always lands the same side up

quantamagazine.org

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Re: A new pyramid-like shape always lands the same side up

#111

Post by bigDinosaur »

p0w3n3d wrote: post #107
schiffern wrote: post #99

Earlier quoted context omitted.

>useful as a tamper detector If anyone's actually looking for this, check out tilt and shock indicators made for fragile packages. https://www.uline.com/Cls_10/Damage-Indicators https://www.youtube.com/watch?v=M9hHHt-S9kY

These shock watches and tilt watchers are quite expensive. I wonder how much must be the package worth to be feasible to use this kind of protection

It may not just be monetary value. Shipping something that could be ruined by being thrown around (e.g. IIRC there were issues with covid-19 vaccine suspensions and sudden shocks ruining it) that just won't work may need this indicator even if the actual monetary value is otherwise low.

Re: A new pyramid-like shape always lands the same side up

#112

Post by Someone »

p0w3n3d wrote: post #107
schiffern wrote: post #99

Earlier quoted context omitted.

>useful as a tamper detector If anyone's actually looking for this, check out tilt and shock indicators made for fragile packages. https://www.uline.com/Cls_10/Damage-Indicators https://www.youtube.com/watch?v=M9hHHt-S9kY

These shock watches and tilt watchers are quite expensive. I wonder how much must be the package worth to be feasible to use this kind of protection

Did you notice the column indicating number of items per box/carton?

Shockwatch is $170 for 50 items, for example, and the label $75 for 200.

Not dirt cheap, but I guess that’s because of the size of the market.

Re: A new pyramid-like shape always lands the same side up

#113

Post by lloeki »

ortusdux wrote: post #39
ChuckMcM wrote: post #16

Worst D-4 ever! But more seriously, I wonder how closely you could get to an non-uniform mass polyhedra which had 'knife edge' type balance. Which is to say; 1) Construct a polyhedra with uneven weight distribution which is stable on exactly two faces. 2) Make one of those faces much more stable than the other, so if it is on the limited stability face and disturbed, it will switch to the high stability face. A struc…

You jest, but I knew a DND player with a dice addicting that loved showing off his D-1 Mobius strip dice - https://www.awesomedice.com/products/awd101?variant=45578687... For some reason he did not like my suggestion that he get a #1 billard ball.

There's a link to a D2, where prior to clicking I was thinking "well that's a coin, right?" until I realised a coin is technically a (very biased) D3.

Re: A new pyramid-like shape always lands the same side up

#114

Post by lloeki »

gerdesj wrote: post #51
ortusdux wrote: post #39

Earlier quoted context omitted.

You jest, but I knew a DND player with a dice addicting that loved showing off his D-1 Mobius strip dice - https://www.awesomedice.com/products/awd101?variant=45578687... For some reason he did not like my suggestion that he get a #1 billard ball.

Love it - any sphere will do. A ping pong ball would be great - the DM/GM could throw it at a player for effect without braining them! (billiard)

Nitpick: one of the properties of dice is that they stop on one side (i.e they converge towards stable rest on even ground) and the typical rule is that when they come at rest because of something other than even ground then the throw is invalid.

So while a sphere has only one side it basically never comes at a stable enough rest unless stopped by uneven ground (invalid throw), and if it stops because of friction it is unstable rest where the slightest nudge would make it roll again.

Therefore in a sense a sphere only works as a 1D because you know the outcome before throwing.

Edge cases are fun.

Re: A new pyramid-like shape always lands the same side up

#115

Post by voidUpdate »

emporas wrote: post #79
boznz wrote: post #2

maybe they should build moon landers this shape :-)

They could do that, but a regular gomboc would be totally fine. There are no rules for spaceships that their corners cannot be rounded. Maybe exoskeletons for turtles could be more useful. Turtles with their short legs, require the bottom of their shell to be totally flat, and a gomboc has no flat surface. Vehicles that drive on slopes could benefit from that as well.

> There are no rules for spaceships that their corners cannot be rounded

If the inside is pressurized, its even beneficial for it to be a rounded shape, since the sharp corners are more likely to fail

Re: A new pyramid-like shape always lands the same side up

#116

Post by Etheryte »

Etheryte wrote: post #23
pizzathyme wrote: post #22

Couldn't you achieve this same result with a ball that has one weighted flat side? And then if it needs to be more polygonal, just reduce the vertices?

A ball that has one flat side can land on two sides: the round side and the flat side. You can easily verify this by cutting an apple in half and putting one half flat side down and the other flat side up.

Note: the GP comment didn't include the word "weighted" when I made my comment, their edit makes this comment look like nonsense.

Re: A new pyramid-like shape always lands the same side up

#117

Post by tlb »

ChuckMcM wrote: post #16

Worst D-4 ever! But more seriously, I wonder how closely you could get to an non-uniform mass polyhedra which had 'knife edge' type balance. Which is to say; 1) Construct a polyhedra with uneven weight distribution which is stable on exactly two faces. 2) Make one of those faces much more stable than the other, so if it is on the limited stability face and disturbed, it will switch to the high stability face. A struc…

If you're not limited to a polyhedron, a thin rod standing on end does the job.

A rod would fall over with a big clatter and bounce a few times. I wonder if there's a bistable polyhedron where the transition would be smooth enough that it wouldn't bounce. The original gomboc seemed to have its CG change smoothly enough that it wouldn't bounce under normal gravity.

Re: A new pyramid-like shape always lands the same side up

#118

Post by globular-toast »

eggy wrote: post #97

Great article! The excitement kind of ebbed early on with seeing the video and realizing it had a plate/weight on one face. "A few years later, the duo answered their own question, showing that this uniform monostable tetrahedron wasn’t possible. But what if you were allowed to distribute its weight unevenly?" But the article progressed and mentioned John Conway, I was back!

Initially I thought it was unimpressive because of the plate. But then I thought about it a bit: a regular tetrahedron wouldn't do that no matter how heavy one of the faces was.

Re: A new pyramid-like shape always lands the same side up

#119

Post by stavros »

lloeki wrote: post #113
ortusdux wrote: post #39

Earlier quoted context omitted.

You jest, but I knew a DND player with a dice addicting that loved showing off his D-1 Mobius strip dice - https://www.awesomedice.com/products/awd101?variant=45578687... For some reason he did not like my suggestion that he get a #1 billard ball.

There's a link to a D2, where prior to clicking I was thinking "well that's a coin, right?" until I realised a coin is technically a (very biased) D3.

Huh, now I'm curious, what did the D2 look like?
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