Self-Healing Material

Self-healing materials could be pretty cool if we get them figured out.

I appreciate the brief dalliance into cold welding between metallic pieces in space - something I've posted about before.

And I appreciate Steve Mould, of course, who sadly keeps his humour (British, natch) mostly in check for this video.

Weird metal that's also glass is insanely bouncy

I've been looking for an amorphous metal demonstrator off and on for a few years but with no success.

There are some samples of amorphous metals available on ebay, but I really don't have any idea of what those metals actually are, whether they're really the zirconium-beryllium-titanium-copper-nickel alloy that Steve describes at 7:10 in this above video.

This video sees Steve explore how to optimize the bounces - which material should the ball bearing be made from, how big should the ball bearing be, how can you measure the number of bounces most easily - which is cute, but the big payoff in the video comes after around 10:00 when Steve explains how materials plastically deform and why amorphous metals don't easily deform plastically.

That's absolutely fascinating, and I even more desperately want one of these atomic trampoline demonstrators.

Feel free to hunt one down and buy me one for Christmas. I'll happily give you my address if you do get ahold of one.

Now I'm curious how an amorphous metal would respond to a hardness test. Would it be much tougher to create a traditional 'dent' from a hardness tester?

(In hunting down more info on amorphous metals, I might've found a preliminary answer to that one on the LiquidMetal website, scroll down partway to find hardness data.)

Here's more info about amorphous metals and a video from Grand Illusions, from whom Steve borrowed his atomic trampoline demonstrator.

• MRSEC at UWisconsin - amorphous metal page
• LiquidMetal - the trade name under which the amorphous metal is available
• A white paper about the Atomic Trampoline from UWisconsin & Arthur Ellis
• LiquidMetal's wikipedia article
• "The Case for Bulk Metallic Glass" paper from Science Direct
• A white paper from Taylor Edge electronics about metallic glasses and the atomic trampoline demonstrator
• Information about vitreloy, a different commercial name under which metallic glass has been available

World Record Chain Fountain? The Mould Effect Explained

I don't need more disagreement science videos between YouTube posters.

I feel like they're just cross promotional crap, and they annoy me.

I do like Steve Mould's videos as a general rule, but after watching only one Mehdi video, I'm certainly not a fan yet.

For the most part I don't see that Mould's explanation is significantly different from the Biggins and Warner video that I posted previously.

Piezoelectricity - why hitting crystals makes electricity

Heya, Steve. Good to see you back again.

The part of this video that I think I most appreciate is the actual look at the guts of a piezo electric safety lighter. I've used them for a long time and never quite been sure how they work on the inside.

I also appreciate Steve's comments on quarts 'healing crystals' around 1:40. "Don't know if you take it orally or..."

And then we get into the fact that piezoelectricity is dependent on the electronegativity differences in a quart crystal (admittedly simplified in Steve's peanut-butter-jar model). I'm totally duplicating this post for my chem blog because of that explanation.

What happens when you heat a plastic cup?

Shrinky dinks!

Well, it's the same science as shrinky dinks, anyway. 

Today we see Steve Mould heating up polystyrene cups (recycling code 6) and allowing them to shrink back toward their original, flat shape.

Fun times...

My YouTube subscriptions

In case you were wondering which science- or material science-themed YouTube channels I subscribed to, you could probably just skim back through and see which video sources I post from most frequently.

But I thought I could put together a list in case you wanted to subscribe to them, too. So, in no particular order...

• Smarter Every Day - Hands down, my favorite channel on YouTube. Destin Sandlin is an engineer turned YouTuber who covers a whole host of science topics both high brow - How Do We Land on the Moon - to low brow - How Do You Harvest Pecans - and covers them all with a humility, curiosity, and ease of communication that is infectious. Occasionally he gets a little too excited about things (check his collaborations with Mark Robert, for example), but most of the time his tone is spot on, and I learn something from nearly every video that he makes. Most tend to be ten to twenty minutes, but occasionally he post forty-five minute to an hour videos and takes a far deeper dive into a topic - take his nuclear sub series, for example. You could easily turn his videos into a year-long science course. I'd take it. He also has a second channel of slightly less polished videos and lots of behind the scenes footage. Destin also spoke at Skepticon about balancing his faith and his science. It's a great talk. His TED talk isn't bad, either. (equally for both blogs)
  
  
• Real Engineering - Initially this channel from Brian James McManus (yes, he's Irish) focused mostly on the rudiments and basics of engineering and used a lot of white on blueprint paper background animation. He's upped his video quality and started using a whole lot more licensed footage over the years, and he now tackles some pretty deep dives into engineering topics (solar panels, renewably powered ships, tesla's battery challenges, colonizing the moon, digital vs vinyl sound, etc). Videos tend to be in the 15-25 minute range anymore. We almost never see Brian, himself, though there have been a couple of videos where we did. I learn a TON from his videos at this point. Initially, I didn't learn nearly as much. (more for MatSci blog)
  
  
• Practical Engineering - Grady Hillhouse reports from his house in San Antonio and makes civil and mechanical engineering incredibly understandable. Some of the best parts in his videos are his small-scale, homemade demonstration aids to help him explain the video's concepts. He's built tiny rivers to show how weirs function, made rebar-reinforced concrete cylinders to show how they improve concrete's resistance to cracking, crafted complex pipe systems to show water hammer, and much more. His videos stick to the 8-12 minute range, and are great explanations of basic engineering concepts. (more for MatSci blog)
  
  
• Veritasium -  Dr Derek Muller hosts - and probably writes - the veritasium channel videos. He originally did all the work himself, but one of his more recent videos celebrating his tenth anniversary on YouTube talked a bit about his increasing team helping him make videos of higher and higher quality. Muller comes out of Canada by way of Australia and is all over the map as far as topics go. His videos are about optical illusions, origami engineering, calculating the speed of light, close packing with shade balls, and - my absolute favorite video of his - how trees get their mass. He covers chemistry, biology, engineering, physics, and general philosophy of science. (equally for both blogs)

• Steve Mould - Steve's videos are far less focused on any one area of science (or of math). He covers everything from "I calculated absolute zero with vodka" to "Tree tumors are GMOs but not made by humans" to "Self driving cars are dangerously confused by LED lights" to "Does Canadian money really smell like maple syrup?". He's a bit of all over the place, in other words, wandering pretty much anywhere that his curiosity happens to take him. The initial videos were pretty low-budget and short (1-4 minutes long), but the quality of video made a pretty big jump about five years ago. The videos have gotten longer over time, some of them wandering to the fifteen minute range, though he still makes a decent number of videos that are in four or five minutes long or shorter. (equally for both blogs)
  
  
• Mark Rober - Mark's all about building bigger, more theatrical versions of everyday things. He's build a scaled up SuperSoaker, filled a pool with jello, and set up the world's largest elephant toothpaste (or devil's toothpaste). He's also built machines to skip stones better than humanly possible, squirrel obstacle courses, and a liquid sand hot tub. Admittedly, most of his videos could be cut by about 25% of their length by eliminating the over-reaction shots. I think his best videos are the most focused. I particularly recommend the rock skipping video.

Mystery blue & white beads

The blue and white bead bottle up there might look familiar to a lot of science teachers, especially the ones who have taken our ASM summer camps. The bottle can be bought from Educational Innovations or from Flinn Scientific (though Flinn's version is green and white).

The bottle is a spectacular demonstration of density and of solubility, both of which are explained by Steve Mould in the above video.

We do a similar activity in a lab in our material science course at Princeton (one we certainly didn't develop but have tweeked to our needs) using preforms and polymer pellets. An extension we particularly like is related to the food coloring demo that Mould mentions in passing near the end. I especially recommend green food coloring. The effects are far more dramatic than the red that Mould shows.

Another extension involves shining ultraviolet light at the bottle. It turns out that - as one of our Utah campers pointed out to me after I'd had the bottle for a decade or so - that the white beads are actually the UV beads that Ed Inn sells. Apparently having a classroom with no windows blocked me from seeing that happen until she pointed it out to me.

I did also find a video showing how you can make one of your own - without the UV beads, however. The YouTuber's full instructions with quantities can be found in the video description.

I'll copy the video description, however, in case the video experiences link rot...

"Sorry for the spelling mistake in one sentence!

Water and Isopropyl alcohol are SOLUBLE with each other. (solvable is wrong word)

Poly Density Bottle

Take any size bottle, divide number of ounces of the bottle into half. Half number of ounces distilled water and half number of ounces 91% Isopropyl alcohol.

I used 50oz bottle.

So I added 23oz water and 23oz Isopropyl alcohol.

Salt 1tsp for 1oz of water.

So I mixed 23tsps of Salt in water.

Not filling the bottle completely and leaving some space for air at the top is a good idea.

Easy to shake and mix liquids.

Beads 260 of each kind.

You can add or minus number of beads according to the size of the bottle."

Self organising steel balls explain metal heat treatment

TL;DW - Top video great, absolutely show in class...second video mathematical diversion, not efficient use of class time, good math...third video between the two - more mathy but more tightly edited and efficient and material-science-course tied)

I'm posting all three of these videos together because they're part of a series that Steve Mould made (with help on the lower two) exploring ball bearings and ball-pit balls as crystalline modeling tools.

In the above one, Mould makes a really fancy version of our ASM BB board (we use CD cases and airsoft pellets - he uses plexiglass and metal bb's, more akin to the Atomix toy of yesteryear). If you want to make something like his fancy version, here are a couple of links to check out.

Mould uses the BB board the same way we use it in class: to discuss grains, grain boundaries, heat treating etc in crystalline metals. He places the BB board on a shaker to model adding energy via heat (and there's a brilliant view of vacancy defects moving through the crystal at 2:27 and again at 2:35). Mould then discusses how the crystalline structure he's modeling affects the macroscopic properties (hardness, toughness, strength, etc) of the metal.

Honestly, it's a great explanation of about half a day of summer camp, even admitting that his model is limited in exactly how accurate it is compared to more complicated reality. He mentions a couple of videos that go further. I've already posted one and will look at the other.



The second video is Mould and Matt Parker going through to find the most efficient packing for spheres - using ball pit balls. They then shift from tetrahedral packing to a more square packing - which turns out to be exactly the same (check the below video to see that they're the same). 

I'll warn you that the second video is a lot less professionally laid out and more heavily math-leaning. (There's a slightly more organized video that shows about the same content.) But Mould and Parker do cut a whole bunch of oranges trying to calculate the percentage of space occupied in the face centered cubic packing. (It an IRL version of a computer animation that we use in class and that I'm STUNNED to see I haven't posted on the blog before - coming in two weeks now.) We include a mathematical version of the proof at 16:55 in our summer camp powerpoint (at least Becky and I do - check slides 85 & 86) and you can find the math laid out here, too.

The last video is back to Steve Mould's channel and shows - using ball pit balls and a cardboard box - hexagonal (and face centered cubic) packing. They use that to demonstrate stacking faults (maybe defects, maybe disolcations, maybe grain boundaries - I need to figure out which term is most correct there), brilliantly shown with the color-coded balls from about 6:00-8:00.

The idea that the face centered cubic lattice is really and A-B-C (repeat) hexagonal arrangement whereas hexagonal close packing is A-B (repeat) is kind of mind blowing and so brilliantly well shown with the ball arrangement. The ABC diagram is a little weird to me and very much a mathematical diagram, something I wouldn't get into in class.

Fountains of Chain: Science Take: The New York Times

I've never tried to demonstrate the bead chain demonstration (available from Educational Innovation for about $20, though I'll admit that I'm looking for longer, cheaper beaded chains) from more than a couple of feet off the ground. That height gives a jump out of the beaker of about five inches or so. Supposedly, though, a longer drop (from a balcony, a second or third story, even) will provide an even higher jump out of the container.

Why, however, does it provide that jump above the lip of the container? That's a little more complicated.

The video above says it explains that jump, but I got a heck of a lot more out of the video below.

Amazing bead chain experiment in slow motion - Slo Mo #19 - Earth Unplugged

The beaded polymer chain demonstration - from Educational Innovations - is one of our go-to demonstrations in the summer, year one workshops. In all honesty, though, I think it's a better demonstration of kinetic and potential energy, momentum, and acceleration.

Sure, it's a long chain, and so are most polymers, but if that's all we're showing, then we wouldn't need the mug or the running of the chain out from that mug.