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submitted 3 weeks ago by xkcdbot@lemmy.world to c/xkcd@lemmy.world

xkcd #3115: Unsolved Physics Problems

Title text:

'Tin pest' makes more sense to me. Tin just doesn't want to be locked down in a shape like that. I get it. But why would any metal want to grow hair??

Transcript:

Transcript will show once it’s been added to explainxkcd.com

Source: https://xkcd.com/3115/

explainxkcd for #3115

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[-] Quazatron@lemmy.world 131 points 3 weeks ago

I thought long hair was a requisite for metal, especially headbanging.

[-] Diplomjodler3@lemmy.world 49 points 3 weeks ago

That settles it. Nobel prize incoming.

[-] Successful_Try543@feddit.org 56 points 3 weeks ago

A colleague of me did his PhD exactly on the last topic.

[-] BartyDeCanter@lemmy.sdf.org 41 points 3 weeks ago

And does he know why? I've had to deal with it too often and it would be really nice to be able to expand RoHS to aerospace.

[-] Successful_Try543@feddit.org 63 points 3 weeks ago

Deep in the coating, where the Cu6Sn5 [Remark: intermetallic phase of Sn coating and Cu substrate] is present, the deviatoric strain was high. This indicates that the growth of the intermetallic phase causes plastic deformation of the tin coating.
[...]
A short (4 micrometre) radial gradient in hydrostatic stress was observed around the root of the whisker. This gradient together with long-range diffusion from specific regions could provide the driving force for whisker growth.

https://portal.research.lu.se/en/publications/tin-whiskers-experiments-and-modelling

[-] cmgvd3lw@discuss.tchncs.de 17 points 3 weeks ago

Did he found a cure for baldness?

[-] Successful_Try543@feddit.org 27 points 3 weeks ago

Well, if you are willing to coat your head with copper and some tin on top, you can grow yourself some tin whiskers. Yet, I don't know if they make a good replacement for hair.

[-] mojofrododojo@lemmy.world 2 points 3 weeks ago

shaving is gonna be an adventure

[-] Honytawk@feddit.nl 7 points 3 weeks ago

No, but those zinc ingots now have great mustaches!

[-] elucubra@sopuli.xyz 2 points 3 weeks ago

There is no cure for baldness, else Bezos would have a mane.

[-] markovs_gun@lemmy.world 1 points 3 weeks ago

Elon has hair plugs that admittedly look pretty good. I think Bezoa just lost his hair too quickly to fool anyone.

[-] bstix@feddit.dk 2 points 3 weeks ago

hair plugs that admittedly look pretty good.

Nah, it also doesn't fool anyone. it looks like a toupee, except that he can't take it off.

[-] elucubra@sopuli.xyz 28 points 3 weeks ago

It's missing the mistery of why it's necessary to try three or more times to insert an USB A, when it only has two possible positions.

[-] Hamartiogonic@sopuli.xyz 24 points 3 weeks ago

That’s a mathematics problem. Current theory of probability doesn’t account for cases where the probabilities are actively fighting against you. Once you’ve formulated the axioms of antagonistic conditional probability, you should be able to understand how USB-A ports work.

[-] elucubra@sopuli.xyz 8 points 3 weeks ago

I'm more inclined to blame gremlins.

[-] Hamartiogonic@sopuli.xyz 2 points 3 weeks ago

In Nordic folklore, there’s a concept for a household spirit (nisse/tomte) that may do mischievous tricks if you don’t treat it appropriately. If mathematics can’t solve this puzzle, it has to be a computer tomte that isn’t happy with your taste in RGB or how infrequently you run software updates.

[-] dumples@midwest.social 2 points 3 weeks ago

Or you haven't poured enough milk and porridge into your computer. Depends on the tomte

[-] Hamartiogonic@sopuli.xyz 2 points 3 weeks ago

If you see sparks and smoke coming from the computer, you can be pretty sure you’re doing something wrong.

[-] VindictiveJudge@lemmy.world 1 points 3 weeks ago

So you're saying that if I stop feeding my mogwai after midnight I should be able to plug in my USB devices on the first try?

[-] MyNameIsRichard@lemmy.ml 18 points 3 weeks ago

USB A actually has three positions, right side up, wrong side up, and fuck you.

[-] toynbee@lemmy.world 11 points 3 weeks ago

That's important and accurate information, Richard. Thank you.

[-] Tar_alcaran@sh.itjust.works 13 points 3 weeks ago

Similarly, ice spikes. You can make em at home, and we really don't understand how or why they form.

[-] BreadOven@lemmy.world 18 points 3 weeks ago

I think it's been figured out for a while now? Essentially most of the surface freezes, except for a small hole. The spike forms from that hole since the water is pushed out before freezing (on the outside) leaving a hollow spike.

The rate of freezing is similar to the rate of extrusion, a spike can form.

[-] Ageroth@reddthat.com 12 points 3 weeks ago

I thought there was a relatively good explanation for ice spikes having to do with the volumetric expansion of water as it transitions phases from liquid to solid. Basically as an ice cube freezes there is a shell formed over the top surface and under the right circumstances it forms from the outside edges in leaving a hole, but then instead of the hole closing over ice starts forming downward into the bulk of the cube, pushing liquid water out of the hole which is then frozen into a protrusion

https://en.m.wikipedia.org/wiki/Ice_spike

[-] whotookkarl@lemmy.dbzer0.com 7 points 3 weeks ago* (last edited 3 weeks ago)

Cursed unsolved math problems sounding like the beginning of a horror story:

You're lost in a forest without a map and compass...

Does generalized moonshine exist?

What's the longest snake you can jam into an n-dimensional hypercube?

[-] obstbert@feddit.org 2 points 3 weeks ago

I'm interested. Please elaborate!

[-] whotookkarl@lemmy.dbzer0.com 2 points 3 weeks ago

Bellman's lost in a forest problem: https://en.wikipedia.org/wiki/Bellman%27s_lost-in-a-forest_problem

Generalized moonshine: https://en.wikipedia.org/wiki/Monstrous_moonshine#Generalized_moonshine if the moonshine phenomena also exists outside the monster group

Snake in a box problem: https://en.wikipedia.org/wiki/Snake-in-the-box

this post was submitted on 15 Jul 2025
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