Pressure at that depth is about 5800 psi. Imagine 3 ton, 1 cubic inch cubes being dropped on every square inch of your body from every side all at once and you'll have your answer.

Yeah but the pressure equalization happens so fast you’d almost certainly feel nothing.

Hmm, but human body is mostly solids and liquids, not very compressible. Their lungs and airways, sure, would be compressed to nothing, but what of the rest of their bodies?

Eg I'd imagine the poor souls on the Titanic next door are not crushed by the pressure, for the same reason.

Or with scuba diving, deep scuba is complicated and dangerous for many reasons, but the pressure compressing the body is not one of them.

i'd assume the air forced into various cavities (especially the skull) would send shock waves into neighbouring tissue ripping everything apart upon surge of pressure. also probably lots of turbulence creating shearing forces also ripping everything apart. so, everybody ripped apart. titanic victims sank slowly allowing for continuous evacuation of cavities. air streaming out and water in.

Think about why a parachute works. It’s the same concept.

Their bodies are also pressurized at 1 atms, after being exposed to 400 atms they instantly died. My guess is that they were effectively vaporized/liquified.

Much better way to go then suffocate in darkness.

It's a good guess.

https://en.wikipedia.org/wiki/Byford_Dolphin

> Investigation by forensic pathologists determined that Hellevik, being exposed to the highest pressure gradient and in the process of moving to secure the inner door, was forced through the crescent-shaped opening measuring 60 centimetres (24 in) long created by the jammed interior trunk door. With the escaping air and pressure, it included bisection of his thoracoabdominal cavity, which resulted in fragmentation of his body, followed by expulsion of all of the internal organs of his chest and abdomen, except the trachea and a section of small intestine, and of the thoracic spine. These were projected some distance, one section being found 10 metres (30 ft) vertically above the exterior pressure door.

That's with a nine atmosphere pressure differential. The Titanic is at about 400 atmospheres.

That wiki page describes a decompression injury, which AFAIU is the opposite of implosion:

> This resulted in the chamber being explosively decompressed from a pressure of nine atmospheres to the one atmosphere of the unsealed chamber system.

Whereas an analogous description of the submarine implosion would describe the opposite, i.e. "explosively compressed from a pressure of one atmosphere to 400 atmospheres."

The point is the extreme, rapid force involved.

Imploding or exploding, nine atmospheres is gonna suck. 400 atmospheres is... like standing under a nuclear bomb. The good news is it doesn't hurt, at all.

Someone else on the thread posted a video of a one atmosphere implosion (https://www.youtube.com/watch?v=Zz95_VvTxZM). 400x the pressure here.

Indeed. I'd be curious if there would even be a body to find. I have to imagine it'd be compressed into paste. It's very disturbing to think about, but also a preferable way to die compared to suffering through 96 hours of uncertainty before slowly asphyxiating.

I tried to find [1] how much pressure explosion of a grenade would cause. It would take a lot of grenades to get to 400 atmospheres...

- [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514183/#:~:tex...

I wonder if you even could, given the fact that that stuff is trying to get away from each other you'd have to get the timing right to a ridiculous degree of precision.

Why are people assuming this? How about a leak that fills the sub with water? Is a leak impossible to keep stable at those depths?

A slow leak that filled the sub would not necessarily have lead to the vessel's destruction.

That said, you can get leaks. I participated on a research cruise with a French submersible, and there was talk of small leaks with the main hatch seal occurring during descent. The "fix" was to go deeper so the pressure would essentially seal the hatch shut.

At 5800PSI, A leak with an area of 1/100th of a square inch would have 58 pounds of force behind the water coming in and a flow rate of about a half-a-gallon per second.

Sure I get that. A hole will be like a water cutter.

I was thinking more like a screw with resistance along the threads such that the pressure goes from 5800 psi to say 20 psi at the last thread or whatever. Then you might get a stable leak.

At that point, you're counting on the material that thread is sunk into to be capable of withstanding that pressure without brittle fracture, and from the wrong side.

A screw is there to resist being pulled out. If water got to those screw threads as you posit, that'd basically be like reversing the forces to which that fastener was meant to resist. You go from "big chunk of material to hold in screw" to "little triangular threadforms trying to stay joined to the material around them in spite of 5800 psi trying to transit a pressure gradient insisting otherwise."

I'm not saying it's impossible, I'm just saying if I remotely thought it was possible to end up in that situation, I'd be going back to the drawing board to try to rule out that possibility. My brain just shows me visions of a screw turned into a bullet that barely gets slowed down going through a human body after threadforms crush like tortilla chips, a water cutter blasting through somebody into the opposite ablating a hole and causing a cascaded failure that then shortly thereafter becomes diesel thoomp.

If you'll excuse me, I'm abandoning this train of thought.

It depends on the depth.

But if the leak is noticed at say 20m they would have surfaced.

A leak with the amount of pressure at 1000m would cause a high speed jet like from a water cutter. That in turn would cause the material around the leak to be ground away.

This is really bad for the structural integrity and boom the whole thing implodes in a fraction of a second.

> Why are people assuming this? How about a leak that fills the sub with water? Is a leak impossible to keep stable at those depths?

Part of this is the use of carbon fibre, which is a very brittle material. In bike frame failures, for example, carbon fibre doesn't tend to rip a little or bend, it often fractures greatly or even shatters.

Add the enormous pressure difference, and this is why most people assume instant catastrophic failure.

A leak at 400 atmospheres doesn't stay a leak.

That highly depends on the source of the leak. But if it does start to leak you better surface pdq.

They found a debris field. That's pretty conclusively not a slow leak.

i think any small breach is an instant implosion at 400 atm

Probably combusted? At 400 atms their biomass would compress into a gelatinous hydrocarbon fat blob with the oxygen present, resulting in automatic combustion. The amount of compression their bodies would experience is an order of magnitude greater than a diesel engine cylinder. The explosion would immediately be quenched by the surrounding water and the only thing remaining of the occupants would be ash.

This would happen on the order of milliseconds.

When it happened in that accident referred to elsewhere in the thread the water temp was elevated massively in that area (enclosed so measurable).

Their blood would combust instantly.

They found cooked blood after that accident too.

Edit: https://en.wikipedia.org/wiki/Byford_Dolphin

That accident was only 132 psi. A diesel engine causes combustion at around 300-500 psi. This accident was 3000-6000 psi, so I think it's safe to assume that the organic matter would combust almost instantly.

Why would anything, except possibly something particularly easy to ignite on a surface, ignite? The only thing being heated dramatically is the air, and a whole lot of cool water would be spraying everywhere at the same time.

Same way bubbles imploding have localised temps hotter than the sun, just that writ larger and at 400 times atmosphere.

This: https://www.dailyrecord.co.uk/news/uk-world-news/divers-bloo...

was 'only' at nine atmospheres the titanic is at four hundred!

Went to see titanic only to get turned into diesel, horrible fate

Someone put Mythbusters on the case

Yeah, it would be curious (if morbid) to see what happens to something like an animal carcass. In most cases of submarine failure at depth e.g. the USS Scorpion no bodies are ever found.

They sorta did one like this ...

https://www.youtube.com/watch?v=LEY3fN4N3D8

Adiabatic compression of air to 400 bar increases the absolute temperature by about a factor of 5.5, which would be the temperature of a flame.

Water, fat, etc are not nearly as compressible as air, and the thermal mass of the air involved would be a couple orders of magnitude lower than everything else.

400 bar is (from some quick searching) fairly mild for industrial hydraulic systems, and hydraulic fluid doesn’t get especially hot while in use.

On the other hand, a leak in a pressurized hydraulic system is extremely dangerous if you’re around it due to the extreme velocity of ejected fluid.

Hydraulics don't get hot while in use unless you introduce air into the system, in which case they do get hot and explosive. This is called hydraulic dieseling and microdieseling. The passengers would have been surrounded by oxygen and CO2 gas, and the oxygen tank would rupture as soon as the capsule imploded.

Someone on reddit did out the math- they were crushed before they had any idea what happened.

There's obvious differences between the Oceangate sub and this (1 atm difference, this is a thinner steel(?) railroad tanker not a sub), but I think it effectively demonstrates how violent and quick an implosion would be:

https://www.youtube.com/watch?v=Zz95_VvTxZM

Video contents: An experiment where the vacuum safety valves were removed from an oil tanker railroad car, and a vacuum was placed inside the car, resulting in it crumpling in an implosion. There is no gore or other specific disturbing content

The sub wasn't steel, it was a carbon fibre weave. The tiniest crack would have caused catastrophic shattering of the hull.

For every ten meters of descent, pressure increases by 1 atmosphere. At 4000 meters, that's 400 atm, or ~40 Mega Pascals, which is significantly higher than the pressure caused by the bomb that leveled a building in Oklahoma.

The hull shattered catastrophically, and the pressure wave liquified the occupants instantly. It's horrifying, but at least it was painless.

Yup - and if someone had been inside the tank in that YouTube video they’d likely have been dead almost instantly too when it imploded. (Even if we forget about the vacuum)

Probably the fastest and least painful way to die, short of sitting on a 2000 lb bomb or the like when it goes off.

Interesting a commenter on the video notes the pressure there is equivalent to only 10 meters underwater. Imagine the force 2 miles below

I am probably too stupid, but how is that possible? A lot of divers go 10 meters underwater and don't die of pressure, right?

Pressure equalizes as they descend slowly. It's different from descending 4000m inside an armoured can and have it all released upon you in a split second.

Humans are less compressible than an empty steel tank (being mostly water) and when they dive they don't teleport from 0 to 10 meters in an instant.

Well, sea level is at 1 atm already, so an increase to 2 atm isn't immediately catastrophic. However, if you took that tank filled entirely with sea level air and shoved it down 30 feet under the water the same thing would happen. It instantly crumples because its hollow. We're full of water with some air in a couple places. We'd crumple too if we were just a layer of skin over an air sac. But as it stands, the human body can withstand that pressure alright

10 meters of water is one atmosphere, so they're right - 0 on the inside and 1 on the outside is a pressure differential of one atmosphere.

"almost 4000 meters of water" is "almost 400 atmospheres". About 2.7 tons per square inch. I find that that absolutely unimaginable. - I can't find any equivalence that my brain can make sense of.

When death occurs faster than nerve impulses can travel to/in the brain, yeah.

For context, some numbers I saw estimated the implosion would take about 1ms, and it takes about 25ms for signals to travel from nerve endings to the brain.

So what you're saying is, there is a reliable means of death that is, in all likelihood, more humane than any practiced by states with capital punishment?

It's a good question, I was wondering the same. Do we even have any sort of artificial means for generating that kind of pressure? I suppose we could drop someone into a trash compactor, but it might be difficult to convince people that's more humane than a simple injection, even if it technically is.

Explosives.

but your brain is in fluid and fluid isn't compressible much at that pressure

The extremely rapid pressure change would shred everything into fine pulp instantly.

No time to drown, when the pressure vessel failed they basically found themselves in a hydraulic press. The entire thing would have imploded as the pressure inside the vessel went from 1 to 400atm.

Instantly too, as carbon fibre is brittle, this would not have been a progressive process.

I am wondering the same. Everyone is talking about the rapid implosion of the sub, but can we assume that the bodies just got instantly crushed into nothing?

> can we assume that the bodies just got instantly crushed into nothing?

Bodies are mostly water, which is not compressible. So not really. But all the voids would have filled very quickly: the sinuses, ears, trachea, and lungs would have collapsed instantly. The bodies would also have been "pasted" against the opposite bulkhead to the failure, as unlike water the air around them would have been very compressible indeed.

Depending on your definition of 'instantly' and 'crushed' yes.

Milliseconds, at most.

I think "before realization, fear, or even pain set in" is well within everyone's definition of instant death.

Yes, that was the point. You wouldn't even know what happened. That cargo wagon depressurization and implosion video linked from elsewhere in this thread is a very nice demo, but it only has one atmosphere to work with. And I can't even see the state change on the frame-by-frame, just a very brief hint that something is about to happen (slight deformation), and in the next frame it's all crumpled up and bent.

Well, if you had to die, that's sure a nice way to go about it.

Not that anyone had to die.

I'll watch the drone footage of the deep ocean, thanks.

It's explosives-induced explosion level of pressure. Big explosion

Lets put it this way.

If it was structurally compromised, the implosion would be so fast, a combustion event a la what happens in diesel engines would have occurred.

There would be no bodies. There would only be shreds of pressure hull.

The titanium hemispheres may have maintained their shape. There is a slight chance it may have been a pinhole leak, and someone had a second to go "Uh..." before the rest of the structure started giving way.

It is clear that even these "strain gauges and microphones" to detect compromise of the structure were useless, or that the issure ultimately rested on the window in the front.

The main point to keep in mind is that short of finding the two hemispheres in the next day or so, we'll likely not know the full details with regard to the course of events of the unmaking of the vehicle.

The Sea has claimed them, and she is wont to give up her dead. Hubris, met by the cold hard edge of reality, has proven to be an insufficient aegis once again.

May they rest in peace.

Update: they found the two ends.

Implying the middle carbon fiber imploded.

Not finding the CF cylinder really does seem like the most telling part here. Given they've found the front, the back, and the bottom, you'd think the single largest component would be laying around in the same area. Unless ..

Source/link?

Oof. Just heard. At least it was quick.