• IndictEvolution@lemmy.world
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    1 year ago

    So, I understand that because water is not compressible, animals without air in their bodies are safe at such high pressures in the deep sea, but what I’m wondering is what would it look like if a human in the deep sea was suddenly exposed to those pressures, as would happen if a submarine rapidly pressurizes? I know the lungs would collapse and whatnot because the air would be pressurized into I’m guessing a liquid, like how propane sloshes when under pressure in a tank, but what else? What causes the instant death? Maybe the water shoots into nose/mouth so fast it acts like a bullet and applies a bunch of force to the walls internally?

    • assassinatedbyCIA@lemmy.world
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      1 year ago

      During the implosion you’ll have to contend with the walls of the sub and the water rushing it at a high percentage of mach 1 if not at supersonic speeds. That includes shards of carbon fibre and the big heavy titanium end plates. The air bubble inside will also be compressed to well above 400 atmospheres as the inertia of the incoming water causes an over pressure scenario. This compression heats up that air bubble to temperatures were a plasma is formed and for a brief moment the imploding sub would be the only visible light source down there. Basically anyone in there at the time is converted to a red mist. Think A-train running through that chick at the start of the boys, or that kid flying through that sheriff in brightburn for an idea of the result.

    • Windexhammer@lemmy.world
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      1 year ago

      If it was truly a rapid implosion as described by the Navy, then the whole thing will have crumpled like a steam implosion in which case, everyone inside is likely immediately dead from blunt force trauma.

      • Reliant1087@lemmy.world
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        1 year ago

        I wonder if this is truly correct. By default human body is mostly water and made of things deniser than water. If water rapidly flows into the submersible, that might compress the air inside and cause the lungs to explode basically from the pressure differential in the chest cavity? Styrofoam in contrast is less dense and compressible.

        • WolfhoundRO@lemmy.world
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          1 year ago

          You can take this with a pinch of salt, but I believe that, based on your mention that the human body is mostly water, our bodies, down to our last cells, also have this internal pressure from the water in our bodies. The water is not compressible, but tissue is. And that would mean that not only our lungs will explode, but our entire cellular structures. It would be like squeezing oranges or lemons

          • FinnFooted@lemmy.worldOP
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            1 year ago

            But tissue is mostly water with some solutes and a lipid membrane. I don’t think the cellular structure would implode. There are gelatinous animals in the deep sea with cells and such. But any cavity would implode. Lungs, thoracic cavity, digestive system, abdominal cavity, even the small pores in your bones if they aren’t packed full of equally dense liquid (not sure on this).

        • talldangry@lemmy.world
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          1 year ago

          Do take what I say with a grain of salt, but my late night napkin math says that (assuming a now rectangular human that’s 16 inches wide and 72 inches tall) a person should have a frontal surface area of 1100 inches, under 6000psi, that’d be about 6,800,000 pounds of pressure on them - instant death.

      • Skylake08@lemmy.world
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        1 year ago

        Holy shit and all of that happens within 2 nanoseconds I think? So that’s why the victims in that submarine wouldn’t even know it already happened because our brain takes 4 nanoseconds before we could process that pain.

        • ComeScoglio@lemmy.world
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          1 year ago

          There’s a big chance they’ve all passed out from lack of oxygen by the time this happened. It’s instant death either way.

        • heili@lemmy.world
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          1 year ago

          The velocity of a catastrophic implosion like that would exceed Mach 2 (686 m/s). Nerve conduction is about 50-60 m/s. Dead before they knew anything was going wrong.

    • TitanLaGrange@lemmy.world
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      1 year ago

      what I’m wondering is what would it look like if a human in the deep sea was suddenly exposed to those pressures, as would happen if a submarine rapidly pressurizes?

      Kinda depends on how fast ‘rapid’ is. Consider that the pressure difference between the outside and the inside volume of the sub represents a potential energy. At a depth of 4km for a sub that size you’re talking about the energy equivalent of about 50 kilos of TNT (thanks to Scott Manley’s live stream for the estimate ).

      That’s a lot of energy even if the release is relatively slow, which means that the forces pushing things around as everything comes to equilibrium are quite large. There might be a rate at which the forces are low enough to not significantly damage a human body, but also fast enough that the people won’t drown before the target pressure has been reached. As a guess, an average untrained person under normal conditions could probably last at most 2 to 3 minutes before beginning to drown (an extremely well-prepared person can last 24 minutes 37.36 seconds, the current underwater breath hold record), so that’s like 22 psi per second (equivalent to a descent rate of about 45 feet per second or 30 mph, pretty damn fast).

      I’m skeptical that this would be survivable, and at a minimum it would be extremely painful. As the pressure increases the air in the lungs would compress collapsing the lungs. That alone isn’t a huge problem, breath-holding free divers experience that. However, as the air is compressed the volumes in the skull (nasal sinuses and inner ears) could no longer be pressure-equalized by forcing air into them, so the surrounding tissues would be pressed into them. As anyone who’s flown while congested can tell you even a few pounds of pressure is extraordinarily painful. At 22 psi per second I suspect the forces would at least tear nasal sinus and inner ear tissues, and possibly crack skull bone.