"High explosives" doesn't just mean "bigger boom" 

Steve is extremely qualified as an explosives engineer, but thankfully after what he says here, not as a firefighter.

I feel like this series is going to end with Tom Scott standing underneath parliament saying "now we've covered all of that"

Go pro stuck the landing

Can we take a moment to appreciate a GoPro standing literally an arm's length away from 40g of Semtex going off and just doing some nifty backflips? It's incredible how tough they have become.

Fun fact: Semtex and boot sole checking were both invented in the Czechoslovakian Republic, the boot sole checking because someone tried to pass SEMTEX through airport security

Tom Scott: "You know what's a good socially distanced safe activity to make a video of? Blowing up the English countryside."

Tom has finally figured out how to perfect RU-vid: just make videos with explosions

EOD tech here. I'm so glad you qualified that. Side note: whilst secondary explosives are generally safer and more powerful, if they do catch fire and become contained it can lead from deflagration to detonation. This is where they burn, but the containment results in that runaway energy propagation where the gas isn't released fast enough. If it burns hard and fast enough, the positive feedback loop builds enough energy to generate a shockwave and it detonates.

It's worth mentioning that modern smokeless gunpowder is a low explosive and that's why barrel lengths matter with firearms, cause as long as there is propellant to burn the bullet will continue to accelerate to a point, and the brass case expands to keep the gasses contained while it burns. That's actually where I learned the difference, interesting stuff

I like how unlike the thousands of "don't try this at home" warnings we see on youtube videos of people doing stupid stuff, you actually hired an expert.

“In fact, you’re actually allowed to have 50 kilos of high explosives in your car.” That’s what my recruiter told me.

"High explosives won't go off ... unless you want them to." Although this depends on the explosive: nitroglycerine in particular is *notorious* for going off simply by dropping it.

I remember in the Gulf War the Marines let me absolutely vaporize a metal oil drum with a pound of C-4 (via detonator). They they showed me how you could take a piece of C-4, light it with a match, and use it to heat a cup of water. Mind-blowing.

Tom sounds like he’s planning for a Tom Scott movie.

Why does the high explosive look so delicious

For those who may be wondering, "6,000 to 9,000 m/s" roughly equates to Mach 17 to Mach 26 (at sea level in standard temperature and pressure). To put that in perspective, the "High Hypersonic" speed regime is considered to start at Mach 10, and "Reentry speed" starts at Mach 25.

"In fact, you are allowed to have 50kg of high explosives in your car" IRA: How about that Brit's car?

Tom is slowly getting very interested in explosives. Next week, we'll see Tom exploding computers by overheating them.

The biggest takeaway is that GoPros are way stronger than we give them credit for, even Tom and Stephen didn't expect that.

For those wondering, the tool that explosives engineer Stephen Miller uses to cut semtex is a Leatherman Pulse.

R. I. P. Table, thank you for educating thousands of people 😔

Tom's recent videos during lockdown have been about pieces of land (and villages) disappearing and now, two on explosives. What are you planning, Tom? Also, are you recruiting?

There are also explosives that don't rely on oxidisation, but rather on molecular strain, the molecule just simply doesn't want to be in that shape. Generally these are quite unstable, and will quite happily detonate violently by small energy inputs, such as heat or light impacts.

0:11 that reminded me to google the etymology of "parapet," a word i look at every time i leave the library, intend to look up, and then forget to by the time i get home. thank you.

tom: that is a high explosive me, an intellectual: forbidden bubblegum

I love his slow confident walk away from the test zone every time

Nicely done. Now I am getting into finer points. Not all high explosives are molecular explosive, like TNT or PETN, with the fuel and oxidizer all in one molecule. Some are mixtures such as ANFO (ammonium nitrate-fuel oil) - no chemistry happens when these are mixed. Similarly smokeless powder, usually considered a low explosive, is primarily composed of nitrocellulose which does have a fuel and oxidizer in one molecule. The defining difference is the speed of the reaction. High explosives detonate at a supersonic speed while low explosive deflagrates at a subsonic speed.

0:57 Steve is slowly walking away from the explosion, not even looking at it - like a badass from an action movie.

An example of what Tom's talking about at the start: it took me years to realise 'massive' has the word 'mass' in it - having a lot of mass.

I find it fascinating and terrifying that many high explosives look like Play-Doh or clay

I had a similar realisation 2 years ago with Low Treason, and yes, it's a thing. Oddly enough, I worked for many years for the country's major explosives manufacturer.

the way that Steve just walks away after lighting the fuse shows how experienced he is. He cut the cord, he knows exactly how long it will take to blow up, so he knows how long he can take to get to safety.

I swear, Steve just looks like the engineer from tf2 went to university, got in shape, and got a degree in explosives.

*Tom is becoming an explosive channel and I'm all here for it.*

Not all explosives are fuel oxidiser reactions though he's describing binary explosives (generally a metal oxidiser reaction) although alot of them these days are actually to do with bond strain, high heat of formation etc in a single chemical (RDX, any of the azides, NTI classic examples) it's not just a really mixed low explosive. It's also catagorized by detonation velocity. The channel explosions and fire explains this really well

I gotta say, thank you VERY much for all your stuff being subtitled! My HEARING is fine, but my brain processes sensory information a little weirdly, so it can be hard to follow speech if there's literally any other noise happening, or if it's been more than ten seconds so I get distracted even if something is interesting. Thankfully I'm way better at reading text.

Reminds me of how I always just thought of pipe cleaners as craft supplies until I saw a bag of them next to a pipe my dad bought. I had just never processed that the name was descriptive of the function.

The ring of smoke rising from the firecracker is looking gorgeous.

2:40 burns like a ping-pong ball

Props to the camera for surviving 4 reactions of 2 different kind of explosive masses being demonstrated while being in close proximity.

"One dead GoPro..." "Yup..." Was I the only person hoping that the closing second or so would be of Tom's face looming over the upset GoPro, and exclaiming some variation on "...actually, no!" ?

Too bad there isn't Tom Scott grinning with an explosion in the background on this one.

it's always worth trawling through old tom scott videos to find the ones you've missed.

Well, today I learned something again. High explosives really show that in order to create a runaway reaction, you need high pressure, either by containing it, or by its own shockwave. Thank you, Tom!

It happened literally yesterday. The Norwegian word for apron is "forkle", and I've never realized it stands for "for"(as is pre/in front of something) + "-kle"(Clothing), so "forkle" literally stands for 'in front of your clothing', which makes a lot of sense.

I had one of those obvious moments: I was in spanish class and I learned that monday is Lunes in spanish, which got me wondering. Why don’t we have a day for the moon in english. My reasoning being we have a sunday why don’t we have a moonday? And then I realized...

0:02 - For me I had a moment like that a few months ago, I realized I had been Mishearing "For all intents and purposes" as "For all intensive purposes" for 20 years and somehow missed it.

I was absolutely stunned by the idea after seeing a visual demonstration of it. It's fascinating to think about and I had never heard of it before.

This should be a series called "wait a minute" or "why does that make sense".

My guy really just walks away from the explosives like a badass

Thank you. Your video helped me trying to explain to someone that bomb damage is not always only the fire caused by the explosion but the force of the explosion itself cause the damage.

This was so incredibly informational and easy to understand. That guy is good.

I love those little brain jolts you can get. I had one when I realised that "soft drinks" - lemonade, coke, etcetc - are called soft in contrast to "hard drinks" - alcohol!

Tom Scott's vlogs are more informative than some educational programs. Dude is a legend. I would watch him sit in a high class english styled study, and drink tea to classic music. Nothing else. Just that.

Cool to see this in such controlled environments, with the exact same weight in each example and the differences in effect and explanations of why by a professional.

Yes, that is actually what I imagine an explosives expert to looks and sounds like. How does Tom keep finding the platonic ideals of experts?

The smoke ring from that explosion (1:47) was so cool!

I love seeing this. I would suggest having a diagram to illustrate Steve's explanation of the layering of high explosives though as that would make it a lot easier to understand

I was aware of most of this, but it was still cool to see it all demonstrated so well! Thanks! 😀👍😀

I had this particular realization when I was 15 and I watched a British documentary on explosives, and it changed my life/world. It began me on a journey to become a chemical engineer after it got me super interested in chemistry.

I never knew I needed to see a guy cut an explosive with a knife before, but here we are.

This was an excellent mini documentary. Thank you for sharing.

Tom scott i love your videos so much .. please never stop :')

- Oh no! That track is on fire! - Don't worry, it's just a high explosives - Oh, ok then. Btw what do you think about weather today?

3:58 RIP GoPro. Thank you for your service.

Very simple and concise, yet illuminating explanation, really liked it.

It's like that story of soldiers burning high explosives to heat water/cook food because they had nothing else and it was almost perfectly safe to use.

I just explained this distinction to a few people last week in response to their misuse of the term "high explosive". Unfortunately, my explanation was vastly inferior because it didn't go boom. Time to send some links and fix that.

It's worth noting that what Tom says at the end about high explosive being inert applies only to modern high explosives like semtex that are specifically engineered to be so. There are plenty of compounds that are high explosive and are also unstable and extremely dangerous to store and handle - a relevant historical example being nitroglycerin (a precursor to TNT) that before the invention of the relatively safer TNT was used as an explosive by itself, and caused numerous injuries and deaths due to how hazardous it is.

Been watching one guy named Tom do energetics chemistry, and now I see the other Tom learning about the results of energetics.

That is really interesting! I truly never thought of if low explosives was a thing! The gopro getting doing a backflip was a good touch!

I very recently realised "shepherd" comes from "sheep herd". Why has it taken me decades to add one letter and make this connection?

As the GoPro laughs: "Is THAT all you got?!!?"

THAT was one of your best episodes yet!

Clear. Concise. Explained so the layman can understand. This was excellent.

This is a really good topic example of "things we thought we already knew"

We used to use C-4 (similar to the Semtex in your video) as fireplace lighter. Wet wood was no problem, because the intense heat from the burning C-4 would dry it enough to catch fire.

I remember doing national service here in Sweden. We were trained on how to use plastic explosives, including putting the fuse into the primer, and crimping the primer onto the fuse. The NCO told us that you can do the crimping by biting down on the primer. But don't do that. Use these pliers instead. And be sure to keep the primer and the fuse and the pliers out beside your hip, keeping them away from your crotch. And look away, to save your eyes. Just in case you accidentally set off the primer. I still wonder to this day what would have happened to my fingers, if I had messed up. Apparently, the primer is scary dangerous on its own.

There’s a lot of top shelf knowledge in this video, I appreciate it

"I didn't even realise that "low explosives" were a thing;" Glad I'm not the only one.

Hey Tom, please give a compliment to that guy explaining the explosions! He’s the MVP of these episodes!

1:39 Tom: "The gas that it releases expands and builds up pressure and then.." My headphones: "Battery low"

Love your short informative videos, thank you!

Tom Scott finally converted to the cult of making things explode for fun.

2:34 I am definitely not allowed to have 50 kilos of high explosives in my car.

R.I.P. GoPro, You did your job really well.

Mrs Richards: " I paid for a room with a view!" Basil: (pointing to the lovely view) "That is Torquay, Madam." Mrs Richards: "It's not good enough!" Basil: "May I ask what you were expecting to see out of a Torquay hotel bedroom window? Sydney Opera House, perhaps? the Hanging Gardens of Babylon? Herds of wildebeest sweeping majestically past?..." Mrs Richards: "Don't be silly! I expect to be able to see the sea!" Basil: "You can see the sea, it's over there between the land and the sky." Mrs Richards: "I'm not satisfied. But I shall stay. But I expect a reduction." Basil: "Why?! Because Krakatoa's not erupting at the moment?

"Chartered Explosive Engineer"; that's something great to have on a business card. Wow, that deflagration produced a really nice smoke-ring. Also, that was a great shot from the Go-Pro.

So is no one going to mention that vortex ring? That was amazing.

Fascinating. I never realized that the term was technical. The more you know.

Thanks for the explanation. I thought the difference between high and low explosives was that low explosives ignite below the speed of sound and high explosives do that faster than the speed of sound. Thanks for clearing this up.

This is actually a fantastic ad for GoPro cameras.

Most people in lockdown: I played some DnD online and put on ten kilos. Tom Scott: I made friends with an explosives expert...

1:02 I love how the dude just casually walks away from the explosive.

Tom scott is the guy that answers all the random questions you asked to your dad back in the day

Meanwhile, the GoPro says in a little squeaky voice "I'm not dead yet".

You missed the desclaimer "no cameras were hurt during production of this movie"... Ok, maybe it was hurt a little bit

Literally a death cam at the end. Marvelous

Coming to everyone from southern Kentucky here. Our version of high explosives is called Tannerite. It's made up of ammonium nitrate and aluminum powder. Totally safe, unless you shoot it with a gun (which does the same job as the detonator). Can be made at home very easily.

That giant smoke ring was awesome! 1:42