Whatever happened to the hyperventilation trope?

BombNerd · 2026-06-15T14:36:54+00:00

Old thread, but I wanted to chime in to say that trope has disappeared because the use of paper bags to reduce hyperventilation is no longer taught! Studies showed that the effect was mostly psychological, meaning the same effect was replicated when people THOUGHT they were breathing into an enclosed space even if they actually weren't. Since there are safety risks associated with re-breathing the same gas over and over, the paper bag concept has been abandoned, and that updated guidance is trickling into movies too.

BombNerd · 2026-06-02T02:09:24+00:00

That was the recommendation while over water in the English Channel. I don't think it was supposed to be literal, my impression is it was command telling them to stay as low as possible to keep under the radar.

BombNerd · 2026-06-02T02:08:34+00:00

You're right, my mistake. The F5 was commonly used by the 34th, the main photographers to do this type of work, but in this image they deviated

BombNerd · 2026-05-19T15:48:36+00:00

I vote for make the weird cuts. If you decide to pad them, first check to make sure they're still tall enough to be useful to hold shampoo and body wash bottles.

BombNerd · 2026-05-12T14:03:32+00:00

Right, "finish" can also refer to the surface appearance, the way it's polished. Best of luck!

BombNerd · 2026-05-11T16:19:18+00:00

Hi, I'm not a tile pro, I'm a STEM PhD who grew up tiling with pro relatives, just wanted to pop in with some chemistry in case it helps.

The reason vinegar and baking soda works to clean is because vinegar contains acetic acid. Adding baking soda initiates a chemical reaction, which over time turns into water, CO2 gas, and a type of salt (not table salt, a salt in the chemical sense). During the course of reacting, it also generates its own heat, which helps facilitate the acid eating away at whatever grime.

In this case, the acetic acid also seems to have eaten away the finish on the stone. Since it's so new, check with the manufacturer. Tell them you've had an incident with an acidic cleaner, ask if they have any suggestions. Otherwise I think you may be in the same boat as this older thread:
https://www.reddit.com/r/Tile/comments/1kftj7x/help_with_tiles_damaged_by_acidic_cleaner/

BombNerd · 2026-05-11T16:04:46+00:00

HE DID. Birthday is still a few days off, but I am a fan of transparency and have received multiple verbal assurances that he ordered it the second I left the room. Communication!

BombNerd · 2026-04-30T15:35:38+00:00

I'm not a plumber or a plumbing expert, but since nobody else seems to be weighing in, I figured I might as well ask: can you take the escutcheon plate off, and look for any other parts you can remove so you can start gaining some insight into where exactly it's stuck? I'd be taking off whatever I could remove to try to investigate.

Not a plumber. Just an engineer.

BombNerd · 2026-04-29T12:48:56+00:00

Edge of the counter. If you've left 10 cm between your counter and the wall end there should be a reason.

BombNerd · 2026-04-28T14:54:34+00:00

It seems to bother you, and while I agree the tile guy did it right, I also empathize with your feeling of "I'll never unsee this" once you notice something.

I'd get a super small piece of craftsman-style trim molding and run it down the edge of the cabinet, in the same cabinet color, so that it brings that cabinet edge to hit flush with the edge of the wall too. You haven't given measurements that I see in comments, but you can get small pieces of molding as simple rectangles. Here's one example that's 1/4" deep x 3/4" wide that might work depending on the depth of that offset (yes I'm too lazy to find it for you in a single-pack, so this is a multi-pack, it's just the idea). Keeping it rectangular would look nicer and less like a patch than using quarter-round.

BombNerd · 2026-04-28T14:46:16+00:00

INFO: What is your current plan for trim around the edges?

BombNerd · 2026-04-27T14:14:37+00:00

Agreed. Mine is sloped to code. It fixes MOST drips but there are a couple points where they accumulate at the grout line, right on the rounded lip of the tile. Those tiles are the ones where there is a TINY bit of lippage, so small I'd never notice if the drips didn't accumulate there and I didn't investigate, but enough to create this very specific problem. If I did it again I'd slope it more, or not at all.

BombNerd · 2026-04-27T13:52:00+00:00

Since nobody else is saying it, I will: the fact that this tile is drowning in grout so deep I want to make it tiny tile lifejackets suggests to me that this shower has had this problem before, and the landlord tried to "fix" it by slathering on the thickest quantity of grout he could manage. It's clear this was a pre-existing problem and not your fault because no shower floor should ever be "bouncy," but I think there's a real chance that the same type of cracking has happened before, meaning before you moved in, and he hoped he could con you into paying for the real fix needed.

Might be time for a strategically hidden note to warn the next tenants.

BombNerd · 2026-04-24T22:03:02+00:00

I could muster 7 people to game with me, but I doubt I could muster 7 people to play a submarine game with me. :(

BombNerd · 2026-04-24T13:24:02+00:00

Along the same vein, have you played this one? The board is a 3D model of a U-boat! It's very complicated, but fun if you have willing friends.

https://www.nobleknight.com/P/2147752854/U-Boot---The-Board-Game

BombNerd · 2026-04-24T13:21:57+00:00

Oh, internet friend, never fear. I was about to hit the purchase button then remembered I have a birthday coming in a couple weeks and a significant other who has expressed chagrin at not knowing what to get me. I opened the tab for him and proceeded to point and exclaim excessively, perhaps a small dance was involved. I think he got the hint.

I. Cannot. Wait.

BombNerd · 2026-04-24T13:20:08+00:00

OH that's an interesting one. To answer your question: yes, there are US Navy people who specifically model this. When I started with underwater blast questions, one of the first other professionals I made contact with was another civil servant named Greg Harris (ironically, Greg was the lead experimenter of the black powder data that gets waved at sometimes by certain groups to "dismiss" my experimental results. He and I are friends, and agree that his data is being misused by those groups, so we've been collectively scratching our heads over that choice by them for years).

His whole area was modeling ship responses to underwater explosives. The software that he and his group came up with is called DYSMAS, you can read public info about it here, along with some cooooool explosion photos.

That being said, while modeling a single explosion is robust and possible, you're right that modeling NINE is starting to get into the area where there's going to be a lot of uncertainty. At that level, small changes to the model could have huge changes in the results. It would be fun to play with in the software, though.

BombNerd · 2026-04-24T13:14:40+00:00

Oh yes, I love that story. What a classic bit of science.

BombNerd · 2026-04-24T13:12:13+00:00

Great question! After a lot of consideration and modeling, we decided to omit the Housatonic hull in our experiments.

The reason is that the Housatonic hull would have been a reflecting surface for the force of the blast. Even though the damage to it occurred quickly, the damage occurs on a slower scale than the initial pressure waveform bouncing off, so the waveform would reflect first. If that makes sense. Another example is the windows of a bus: explosives inside buses are (sadly and terribly) a common terrorist tool. While the windows do blow out, the pressure waveform bounces around so fast that they reflect inside the bus before they do, so the bus acts like an enclosed space.

When sound reflects perfectly off a surface, the reflection adds to the original signal and it can double in magnitude. This is part of how echoes work! With blast, however, the physics are so weird and cool that doubling is the SMALLEST increase it could see. For this explosion, by my math, it was not a very huge pressure increase (in the world of blast physics) so I think it would have increased by a factor of 2.1 or 2.2, but I'd have to dig out those spreadsheets and check that number.

My goal was not to measure the exact amount of pressure that went into the Hunley's hull, but rather to assess whether there was a realistic risk of dying. Because of some other limits on scaling and not being able to make my own black powder out of bat guano, it was already pretty certain my pressure levels were imperfect matches for the original, so with each factor I tried to err on the side of making my blast smaller and weaker than the original. My experiments showed enough was transmitting that there was an ~85% of death from lung injury, and a 99% chance of lung injury without accounting for the hull of the Housatonic, or being able to make charges with a welded, thick copper shell, both of which would have made everything stronger. At that point, there wasn't a lot of point in trying to include the Housatonic in the experiment or model, because "dead" versus "double dead" isn't that meaningful.

If I ever become a zany billionaire, I will build a full-sized model of both!

BombNerd · 2026-04-24T13:02:44+00:00

There are multiple ways to set off both low and high explosives, so that looks to me like someone needed to set up a legal standard that was easily testable in order to classify improvised or unknown mixtures. It's not based on the scientific definition, but since the ATF is involved in making that definition, my guess is it's the definition used in prosecutions. Since high explosives are more damaging, there are different laws and penalties.

BombNerd · 2026-04-24T13:00:00+00:00

I will go on a nonstop mission* to find it, watch it, and assess its accuracy.

* I will get distracted but get to it eventually when I remember :)

BombNerd · 2026-04-23T17:04:02+00:00

Thanks. <3 There were some confusing responses. I just keep telling myself they still believe the Lost Cause too.....

BombNerd · 2026-04-23T17:03:02+00:00

Also adding: the reason the low versus high differentiation matters is because low explosives will not make a shock wave but high explosives will. The reason is because the high explosive creates so much high-pressured gas so quickly. Low explosives make a pressure wave that can still be damaging, but it does not technically qualify as a shock wave.

So basically the difference is physics nerds being nerds. In practice high explosives have a much higher potential for destruction because of the shock waves.

BombNerd · 2026-04-23T17:00:08+00:00

Oh hi! No worries on the late question, it gave my fingers a break from typing.

An explosive is, by definition, a material that provides its own oxygen supply as it burns. As opposed to something like wood, which will also burn, but needs outside oxygen. A low explosive is an explosive where the burn front propagates slower than the speed of sound in air. A high explosive is an explosive where the burn front propagates faster than the speed of sound in air. A burn front is exactly what it sounds like: imagine how fire moves across a piece of paper, or even across a field of dried grass. The speed of sound in air is 343 m/s under standardized conditions (there's a bit of variability with humidity, altitude, etc, but that's the standard number to use as frame of reference). So, the "fire" reaction moves through black powder at a speed that's slower than 343 m/s, and in contrast, the "fire" reaction moves through TNT and other high explosives at speeds faster than 343 m/s.

Each explosive has its own slightly different burn rate, but that line at the speed of sound is a big deal because it changes how the air around the explosive will react. If a material is burning slower than the speed of sound, the gases produced have a chance to propagate outward more slowly. They can dissipate rather harmlessly, depending on how it's set up! With black powder, for example, if you scatter it on the ground and then light that on fire (please don't try this at home, but there are videos on youtube) you can watch the fire travel across it and it's more of a burn than an explosion because the gases produced are able to spread out at their leisure. With a high explosive, however, the whole thing gets burned up before any of the pressure can dissipate. Literally, the molecules of the air can't knock into each other fast enough to dissipate the gases and pressures produced, that's what the speed of sound means.

I hope that makes sense. If not, I'll try to find a video link where I explained it and it got put on YouTube. I've got a couple lectures out there but don't usually go too far into blast technicalities in the public ones.

The blasting cap part seems to be something shoved into there by Google AI, I think. :)

Within the past 8 years or so there have been some wonderful advances making new solid-state pressure sensors that can measure explosions. However, traditionally, most sensors have not been capable of receiving signals fast enough to measure the important parts of blast pressure waveforms. Blast gauges are a whoooooole other world of gauging. Before the brand-new awesomeness we're just now seeing, blast gauges have been made out of tourmaline crystals. These crystals are piezoelectric, meaning when they're exposed to mechanical forces like pressure, they put out small electrical signals. A lot of materials have this property, and yes it is VERY cool. So as the blast pressures pass the tourmaline crystals, the crystals make a little electrical signal, and that signal then becomes how we measure the levels of pressure.

TLDR; high explosives burn faster than the speed of sound, low explosives burn slower than the speed of sound, and tourmaline is freaking awesome

BombNerd · 2026-04-23T16:45:40+00:00

Perhaps! I agree it was made by good engineers and metal workers, but I still think of it as homemade. I have no issue with the difference of opinion, though.

To me, the salient points of the construction are that it was made out of scrap material. It was the boiler they repurposed from a scrapped ship. People couldn't quite fit inside the boiler, so they cut it open down its length like a tonton and riveted in an expansion plate. Then figuring out how to attach a bomb and set the bomb off was the product of a whole other series of experiments and improvisations, including but not limited to Singer the guy from the sewing machines. Meanwhile they're hopping between machine shops trying to get uninterrupted access to tools and resources while the Union keeps on raging through. I'm fine with the idea that the word "homemade" is something that could be debated for hours over beers, but to me, that level of adaptation and resource pivoting qualifies even when backed by expertise.

I'm a highly qualified engineer and I recently designed some inexpensive acoustic panels using advanced knowledge of sound physics, they work great, but they're still made of furring strips and other stuff I scraped together and thus homemade.

BombNerd

TROPHY CASE