Less than 4 milliseconds. They didn’t feel a thing.
this post was submitted on 30 Jun 2023
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Explain Like I'm Five
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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.
I just take solace in the fact that they probably just snapped out of existence instead of having to slowly die in a dark tube over a few days.
I had seen a comment saying human to salsa in 4 milliseconds. ಠ_ಠ
And because what failed was the carbon fibre composite pressure vessel, it probably didn't even give any warnings to make them worried. It would be like squeezing a glass bottle, everything will be perfectly fine until it just instantly shatters.
Sometimes glass will give a 'click' as a crack starts. Not sure about carbon fibre though.
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.
How did you get this number?
Physics and math. J/k. I’ve seen similar numbers thrown about. Here is a link to a Quora question What happens to the human body when a submarine implodes from 2 years ago that may be of interest.
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.
Do you think they died from the water rushing in and hitting them unconscious?
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.
Put another way: The matter that made up their bodies was very quickly rearranged into other chemicals; much quicker than the long chain-reactions that make up human thought.
I know a diesel engine works off compression, but it has a fuel. All fires must have oxygen, fuel, and heat. What fuel would they have in the titan to ignite?
Everything (including the passengers) inside the sub could have been fuel for combustion had there been time for the reaction to take place. If I remember correctly the interior of the sub could have temporarily been hotter than the surface of the sun during the implosion. Pretty sure just about everything burns at those temps. But the collapse and gas release from the hull happened so quickly I doubt there was time for anything to ignite.
If you compress a gas enough it will get hot enough to ignite. Google “fire pistons”.
It's also why airplane tires are filled with nitrogen instead of air. On landing, the high pressure and heat can cause the oxygen in air to combust.
On landing, the high pressure and heat can cause the oxygen in air to combust.
Phew. Imagine being the pilot to find that out.
Ex-people, plastic and so on. With a small room's worth of air it wouldn't have burned long, though.
More significant is just how hot it would get as it collapses. When you suddenly compress an an ideal gas (which air is a lot like) it gets hotter in proportion to it's previous absolute temperature. Room temperature is already 273K, and the pressure down there is hundreds of time larger than at the surface. At some point the law would break down on the way, but you get the basic idea. It was probably as hot as the sun without any help from combustion
Water contains oxygen. With enough heat that oxygen becomes free.
"Rushing" implies something like a wave. The thing crushed flat like the plastic tube it was, and would have done so too fast to even visually track.
If you were to slowly lower an open glass into the ocean, it would gradually fill with water. So i just think its the same with the sub, albeit faster?
Sure, but "faster" here means around the speed of sound, and that's fundamentally a different thing from the playful streams we're used to. The thing was waaay down there when it went.
If there was a tiny little hole somewhere that wasn't getting larger, maybe it would slow down enough to just gradually fill the vessel. In that case, though, it would not have imploded. They found it in pieces and the US Navy heard the pop.
Yeah I guess if you think of the fact it actually went 'boom' you can imagine the water didnt really flow in but rather flew in very fast. There was probably a huge shockwave that killed them instantly
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
The primary cause I'm hearing is the window. It was rated for a dive depth of 1500m, and the sub would routinely dive to 4000m.
I also heard the carbon fiber skin wasn’t appropriate for so many massive pressure changes it underwent with each dove.
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.
I really don't get this. The CEO knows that the window is so seriously under-speced, yet he still doesn't hesitate to jump into the sub himself.
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.
He may have thought along these lines... So the window is rated for 1500m interesting usually engineers use a 3x safety factor when they rate something that'd be....(sound of slowly grinding gears) 4500m! But I'm only going about 4000m meters down?
Jackpot! I'm not going to waste my time certifying the window to some silly extra strong standard! Take that you nerds!
I don't think the lesson had time to sink in
Oh, you.
It was arguably in poor taste, but I'm glad someone noticed regardless.
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.
But cautiously saying half is probably better.
https://youtube.com/watch?v=8tW4zfTeJqM&feature=sharea
On the topic— interesting slowmo of a miniature titanium sub imploding. Its hard to even imagine the forces a sub can go through.
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
Here's another way to think about it.
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
https://www.youtube.com/watch?v=Zz95_VvTxZM
You see the way this tank imploded?
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?
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:
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
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