Why It Was Almost Impossible to Make the Blue LED

I was watching a YouTube video from a Scottish YouTuber recently and heard him refer to a light as being a LED bulb. He, however, pronounced LED as if it were the element lead. I, an American, pronounce those bulbs as their three separate letters El Ee Dee, like an acronym. 

Neither, of course, is correct, nor is it at all relevant to this video.

This video, just over half an hour long and produced by Dr Derek of Veritasium, goes through the quantum mechanic explanation of how semiconductors conduct at room temperature which also explains how LEDs produce light and - eventually in the video - how LEDs can be tuned to produce different colors.

This video is also a great exploration of how doped semiconductors conduct electricity. 

I'm really happy that I don't have to teach this concept in my chemistry - or material science - classes because this really pushes my understanding of quantum mechanics and electronics. I didn't thoroughly understand it when I first heard about it back in 1993 or 1994, and I don't entirely understand it now. I do, however, fully accept that there are people who do understand these concepts and that we owe those people a massive debt because the widespread use of LEDs has been a huge revolution in energy savings for our world.

Plus it lets people wrap their cars in Christmas lights.

How Japanese Masters Turn Sand Into Swords

This isn't a replacement for the Nova episode "Secrets of the Samurai Sword". 

...but the Nova episode tends to appear and disappear from YouTube and DailyMotion with fair frequency, so you might need another video that goes through the ancient art of creating samurai swords from the initial collecting and smelting of iron-rich sand through to the slicing of tatami mats to demonstrate the sword's quality and the sword wielder's technique.

This video's contents...

• 2:00 - why bronze was used for sword and was eventually replaced
• 3:00 - cyanobacteria creating oxygen that precipitated iron from ancient oceans
• 6:30 - carbon + iron = steel, initial interstitial positions shown...why alloys are harder than pure metals
• 10:30 - slag formation and removal from the 'ancient' forge
• 13:30 - forging the steel by master swordsmiths
• 14:30 - folding the steel - how and why
• 16:15 - how carbon atoms migrate to different positions and form ferrite, cementite, perlite, and martensite
• 18:30 - differential cooling rates via clay thickness creating different steel types and the distinct blade shape

Another great video from Veritasium and one that shows that he's got a team of folks making videos with/for him at this point...and it's short enough at about half an hour - to get through in a single class period, unlike the Nova episode.

This is the natural disaster to worry about

Forty-one minutes...that's the length of this video from Veritasium about the transformation of raw rubber into the amazing modern material we have today - primarily through the development of vulcanization by Charles Goodyear in the late 1800s.

In those forty-one minutes, Dr Derek explores - with seemingly a co-host for the first time that I've seen - the science behind rubber's stretchiness, the efforts to find an additive that can improve rubber's less useful properties, and a fungi that threatens the millions of rubber trees currently supplying our world's rubber needs.

But it's still forty-one minutes long...and that's without a whole lot of stretching.

Sorry...I'll see myself out.

Why Lithium Is Dangerous But PERFECT For Batteries

Our chemistry book has a diagram of a battery in the electrochemistry chapter, and I discuss that battery for a bit before explaining to my students that the basics of ACME (anode, cathode, metallic path, electrolyte) hold for every battery but that the engineering of modern lithium-ion batteries is far different from the diagram in the book.

This video - again leaning into the algorithm-rewarded longer and longer format - explains some battery basics involving the activity series, the history of the development of the lithium-ion battery, and the methods of fiery failure when the battery overheats.

This is, as Dr Derek says, a technology that has allowed our modern, battery-dependent world.

How One Company Secretly Poisoned the Planet

At some point in my material science and chemistry courses, I speak bluntly to my students that most research suggests that man-made polymers are bad for us.

Some are worse than others, but most research on the effects of polymers on humans seems to suggest that there are bad effects from most man-made polymers. Some are minorly bad, but others - like the family of PFAS - are more obviously and persistently bad.

The video above is short and has a direct message: DuPont is bad (or has acted badly).

The longer video below - from Veritasium - is far longer but is much, much more informative.

If this sounds familiar, you might've seen a semi-recent movie about this story, Dark Waters.

People said this experiment was impossible, so I tried it

As promised last week, here's the first Veritasium video about thermite. 

I'm not thrilled that Dr Derek's titles seem to be getting more clickbaity and less informative. Again this week, the video's title isn't really what the video is about. It's a minor part of the video - here addressed in about six minutes in the middle of the video - and doesn't really cover the bulk of the video's content.

With that being said, seeing thermite in slow motion and through glass is pretty stunning.

Great video...bad title...

Why don't railroads need expansion joints?

The title of this video - which might change since I'm writing this up just a day after it was posted to YouTube - is a bit misleading. The actual question in the title - why don't railroads need expansion joints - is only answered in the last half minute or so of the video and is answered more thoroughly in a Practical Engineering video that I'll post after a jump.

The bulk of the video is spent explaining how railroad welds using thermite work. The video explains the nuances far better than other thermite videos I've posted before, explaining why the rails must be aligned and peaked, why the rails must be preheated (including a nice demonstration of heat treating), how the crystal structure changes as a result of the weld, and eventually why the rails don't need expansion joints.

This is the second of at least three thermite videos from Dr Derek. I thought I'd posted the first video to both blogs, but I can't seem to find it, so it'll likely show up next week.

The Most Important Material Ever Made

Glass is pretty awesome.

Here Dr Derek explores the history of glassmaking through modern glass like Gorilla Glass including how modern glass is made stronger, how it's tested, why glass is transparent for light, and lots more.

Explaining concrete while getting buried in it

I ranted last week about the lack of 5-10 minute YouTube videos, so I won't rehash that grumble pile this week.

Instead I'll mention that there's an urban myth (frequently disproven) that construction workers on the Hoover Dam either fell into an couldn't get out of or were purposefully dumped into the un-set concrete used to create the dam itself.

"No, they weren't," is the short answer. The long answer has to do with the inhumanity of such a practice, the long set time of concrete, and - as this video above shows - the high density of wet concrete.

Today's video sees Dr Derek in a wetsuit trying to fill a sphere with himself and a batch of wet concrete while cutting back and forth to various explanations as to the science of concrete, the most widely used material we have and the underlying backbone of our modern world.

And at about 9:30 we get the clear explanation as to why bodies were never sunken in concrete: bodies float in concrete. 

Yes, the rest of the video is well done, explaining the history of concrete - primarily around the Roman discovery, the science of concrete setting, slump testing, ingredients in different concrete batches, clunkers, the environmental effects of concrete production, cement v concrete, and much more.

It's a great, great video.

The Genius of 3D Printed Rockets

There's a part of me that looks at this video's tour guide like he's from the Parks and Rec Grizzyl offices. I know he's probably brilliant - his wikipedia article certainly suggests so - but it's like Dr Derek is getting a tour around a rocket factory from a teenager. 

This is another video where I spent much of the time with my mouth agape once I realized how revolutionary this method of production could be if they get all the hiccups worked out. The process seems like an extreme of the 'build it fast and wrong, then build it again and better' style of prototyping and manufacturing.

If you have the time, compare this video in which rockets bodies and engine parts are 3d printed from aluminum and alloys to the old-school rocket manufacturing tour from Smarter Every Day. I don't know which is better, but they show radically different approaches.

Why Metals Spontaneously Fuse Together In Space

There is nothing cooler than space.

Nothing...

I'm willing to watch just about the most mundane bit of nothing if it's being done in space because nothing happens in space the same way that it happens here on the surface of Earth.

On Earth, two metals put next to each other stay fairly distinct from each other. (I don't want to hear about your dendritic growth causing shorts.)

In space, however, metals spontaneously weld to each other if the metals are in close enough contact because any sort of oxide layer - immediately formed here on Earth pretty much no matter how well we polish the two surfaces - simply doesn't form. As Dr Derek paraphrases from Richard Feynman's lecture, "when the atoms in contact are all of the same kind, there is no way for the atoms to 'know' that they are in different pieces of [metal]." 

Seriously, space is so totally foreign to our experiences.

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.