To add context here, it takes your brain somewhere around 100ms to detect and then another 250 to process pain. So 4ms is not only fast, it's absurdly fast.
To get a sense of how fast it is, go ahead and stub your toe, the time it took to feel it is 100 times longer.
Did some math based on that number since it seemed pretty insane. That would mean that each side of the outer hull would have been moving inward at about 425mph by my estimate. Seems slower than I would expect by that number, but 4ms is hella fast.
When a submarine hull collapses, it moves inward at about 1,500 miles per hour - that’s 2,200 feet per second. A modern nuclear submarine’s hull radius is about 20 feet. So the time required for complete collapse is 20 / 2,200 seconds = about 1 millisecond.
A human brain responds instinctually to stimulus at about 25 milliseconds. Human rational response (sense→reason→act) is at best 150 milliseconds.
The air inside a sub has a fairly high concentration of hydrocarbon vapors. When the hull collapses it behaves like a very large piston on a very large Diesel engine. The air auto-ignites and an explosion follows the initial rapid implosion. Large blobs of fat (that would be humans) incinerate and are turned to ash and dust quicker than you can blink your eye.
They died by being crushed with enough pressure such that the air inside the sub ignited ie compressed so much it essentially exploded. Death was instant.
I don't think anyone has any real data on the failure point, which is the needed info to know how long it would take to die. There has been lots of speculation that the carbon fiber used (rejected by Boeing as being out-of-spec) or the use of dissimilar materials each with different thermal expansion and contraction coefficients, to the "bubble window" being way under spec because the CEO didn't want to pay for a proper spec one.
Without those we don't know exactly how fast. We don't know if they passengers had any indication of a problem (sounds?) or if it started leaking before it imploded or if it was an instant catastrophic failure.
I believe they have found parts of the wreckage. I wonder if we will get any clues to how it happened. I guess either way they wouldn't have survived long
I think based on the reported sounds from US Navy and James Cameron (what a weird sentence), we are actually pretty sure it was a rapid, catastrophic and instantaneous implosion.
Specs aren't a universal constant. They're defined by humans. Expert humans, but humans. He must have thought he knew better than the experts. He was wrong, but I don't think the lesson had time to sink in.
There’s no such thing as a slow implosion death. That’s just called being crushed. It’s sorta like how you can’t have a slow explosion death, but even less likely because in an explosion you can be thrown clear with slowly fatal injuries
This is all kinda blind speculation and there will be a formal report eventually, but as a general outline:
-When carbon fiber fails, it tends to fail spectacularly: completely and suddenly. So you can think of it not as "crushing a tin can" but more "smashing a glass lightbulb, but from all sides at once".
-If we randomly assume they were halfway down (no idea on where they actually were but as a blind guess 50% is a good starting point) that's about 200 atm of pressure. 1atm = ~15 psi, so thats about 3,000 psi. For comparison, a typical firehose is roughly 100 psi. And that can do serious damage to people: if a badly threaded cover pops off a charged hydrant, there is enough force behind that to break bones. If you were sitting next to the hydrant it'd hit you faster than you could react - you'd only know it after you'd been hit. The water outside the sub is at 30x that pressure.
-Lets assume just as an arbitrary approximation that in the first instant of the carbon fiber failing catastrophically, an area roughly equivalent to a 3ft diameter circle fails (it probably actually fails by buckling in a line then milliseconds later splitting and shattering, but we're just approximating). This means that the water that flows through is pushed by 30x as much pressure as a firehose, and that pressure is coming in across 200 times as much area as a firehose (which are typically 2.5in diameter), so there are basically 200 of those 30x-power-firehoses coming through at once.
-A 2.5in firehose will do ~300 gpm. 6000 firehoses would be 1.8 million gpm. The internal volume of a 2m diameter/4m long cylinder is about 2,500 gal. That would be completely full of water in 0.001 seconds. Of course in reality water doesn't hit full speed instantly, fluid flow is far more complex than just multiplying through like this, etc. But this just drives home that we're talking very very small fractions of a second.
-Yes, compression = heating and when its super fast there isn't much time for heat transfer so its adiabatic: wikipedia has an example under "adiabatic compression" for 10:1 compression going to about 500dec C (in an engine) and this is more like 200:1. But remember that air has low specific heat capacity and also doesn't weigh much. The specific heat capacity of water (i.e. humans, plus those 6,000 firehoses worth of water) is ~4x that of air, and the density is ~1000x as much. So if you have equal volumes of air and person, and you heat the air by 4,000 deg C, that contains roughly enough energy to heat the person by 1 deg C. And also refer back to "there isn't much time for heat transfer". So chances that this actually matters beyond detailed physics calculations are slim.
Bottom line: completely obliterated by the force of so much water under so much pressure. By the time any water entered the sub it should have been over faster than a human could perceive. No explosions or incineration though, just force.
Also, common misconception: pressure alone doesn't hurt you. You would not be directly hurt by spending time anywhere from the complete vacuum of space (0atm) to the challenger deep (1,000 atm). Obviously there are other little complications like you can't breath in 0atm and that'll kill you quickly, but the pressure itself won't. Conversely at high pressures oxygen becomes toxic which isn't great for staying alive, but the pressure itself isn't the issue. Very rapid and therefore very violent pressure CHANGE, however, can and will kill you in many horrible ways.
If we randomly assume they were halfway down (no idea on where they actually were but as a blind guess 50% is a good starting point)
The wreck was found 500m away from the wreck of the Titanic, the Titan descends in a curve and not straight downwards, gives pretty good indication that they were near the depth of the ocean floor. Combine that with the fact that they descended faster than anticipated and that they lost communication right around the time they were supposed to reach the lowet point, I think they were close to the ocean floor.
I can't find where I saw it, but the friction of the water as it poured into the submarine at those depths would have been so strong that it would have heated the internal components hotter than the surface of the sun. Supposedly they cooked to death before they were crushed. But damn I can't find the link anymore, lol. Someone with better google-fu please link to the article
This is a good example, it's a hydrophone recording of a glass sphere imploding, the level of sound and echo should give you a good idea of the kind of forces we're dealing with:
Wow. So those echoes are literally the sound waves propagating to the surface and reflecting back to the hydrophone on the bottom at 2.62km of depth, a round trip of 5.24km for each echo. That's also a really great example of how much faster sound propagates in water.
We can calculate what the change in volume of the chamber would be based on the difference in pressure when it collapsed.
Initially, at atmospheric pressure, the interior chamber contained about 5.6 cubic meters of volume. At the depth of the sub prior to implosion, the external pressure was about 3,000 psi. Once the walls failed, the interior volume was suddenly compressed from 5.6 cubic meters down to a miniscule 0.06 cubic meters.
Basically, the interior walls slammed in, compressing everything inside from the size of a small minivan down to the size of a very small fishtank
What if the titan was the same implosion, albeit stronger/faster, but the way the edges/ends of the cylinder didnt really collapse, only the middle? What if you were sitting on the end parts?
Even if they "only" died as fast as that shows, if you are on the inside, you get crushed by the pressure on your body so fast you likely wouldn't realize anything.