6mo ago

Another mystery solved.

You're viewing a single thread.

62 comments

He's just one big buoyant boy.
- He looks badass from the top, but under the water his lil legs are paddling at full speed.
  
  That's a paddlin'!
- My head canon for sea-based Kaiju is they have a sack of muscles somewhere inside their body that can expand a cavity, kind of like the diaphragm expands the lungs, except instead of taking in air or water it just creates a volume of vacuum inside of them. This makes them extremely bouyant relative to the surrounding sea pressure, so they rapidly ascend and can casually float like a boat near the surface.
  But if they ever want to dive again, they just let that cavity collapse and all their bouyancy goes away.
  
  My head canon for sea-based Kaiju is they have a sack
  That's all the explanation I need
  
  I dunno. Seems a little unrealistic!
  
  💯 This is the true answer
  
  To get unnecessarily scientific here, that wouldn't change the overall density of the body, no? Even if there's now a cavity with vacuum, the matter that was occupying that space just moved somewhere else within the volumes of the body and the overall density remained the same.
  Now, if it pushed some matter out, air or water, and created a vacuum cavity, that might work. But I'm not an engineer, so correct me if I'm wrong.
  
  A hundred ton steel ship floats, a hundred ton steel block does not. Density equals weight per volume. If you increase the volume without increasing the weight, the density will go down.
  
  Exactly my point, the volume doesn't change in the example provided. Weight and volume stayed the same. We either need to expand Godzilla or it needs to eject some mass.
  
  In the example he gave, he mentioned lungs expanding, so volume IS changing. Godzilla can shoot lasers in current lore. He could easily have some super compressed ballast tanks as organs that release pressure changing a whole slew of variables.
  If Submarines have ballast tanks of 600 pounds of air at 3000 PSI, Godzilla can have his own magic organs that do crazy stuff.
  
  Expansion of lungs makes us float because our whole body expands significantly, relative to our small volume.
  In the examples mentioned above, the organs creating vacuum are said to be "somewhere inside" the body. Vacuum or not, Godzilla needs to visibly swell to increase its volume and buoyancy, which we don't observe.
  The air in submarines is used for pushing the water out of tanks, so the principle is ejecting matter. If Godzilla were to use that approach, as I said before, it needs to eject something.
  
  I think that it’s implicit that the volume of Godzilla would increase; we need to assume that the bounding layer has a degree of elasticity and that that the matter displaced by the flotation cavity will expand into that, reducing the net density.
  Mighty Godzilla, with power untold
  Rises through the waves; his powers unfold
  Hidden muscles in clever design
  Create a new chamber as they realign
  Inflating his body, a titanic display
  Defying the depths, he floats up and away
  No long bound by the oceans’s might
  Godzilla soars, a triumphant sight!
  
  Yes, that would work. But imagine the swelling, to give Godzilla that much buoyancy.
  
  Ordinary biomatter is very close to the density of water to begin with. That's why having a little air in your lungs is enough to be the difference between sinking and floating.
  If Godzilla's biomatter under 1atm of pressure has a density close to water then being able to compress or expand an empty chamber inside his body by even just a tiny percentage of his ordinary overall volume could be the difference between floating at sea level or sinking to extreme depths.
  Or if you prefer we can imagine that Godzilla gives himself a big ole booty when he needs to come up to the surface and make a mess of things.
  
  First, let's address the expansion of lungs, because you say "little air", but in terms of volume, lungs are very big. On average, the volume of a human body is about 65 liters. When person fully exhales, the lung capacity is at about 1-1.5L; when expanded, it's about 5-6L. Interpreted charitably, that's roughly 8% percent of the entire human body volume. So realistically, expansion of the body by 8% is the difference between slowly sinking, and floating with the top of your skull (or roughly 1% of your body volume) peaking out of water.
  Now, Godzilla, on the other hand, has like 80% of his body above water. Can you imagine, the amount of expansion that needs to happen for that much buoyancy? That's pufferfish territory.
  So no, a "tiny percentage" increase in body volume driven by empty chamber "inside" his body would not be enough.
  
  I hope you get cited when they put this dialog in the next movie
  
  I just don't know why I'm getting booed, I'm right.
  
  You'd be right if the cavity is only compressing other organs inside the body without changing the overall volume, but I don't know why you seem to insist on making that assumption.
  I thought it would be clear from my original description, via the analogy with lungs, that the cavity would not squish the internal organs but rather expand the overall volume of the body.
  
  This is further proof that for every statement made, no matter how whimsical, there exists at least one person online who will tell you that you're wrong.
  -The Earth revolves around the sun.
  -Ackchyually, they all revolve around the galactic center...
  -Godzilla floats by increasing his volume.
  -Ackchyualllllly, his volume doesn't increase because lungs are on the outside... (Wtf?!)
  -Cotton candy is my favorite fair food.
  -Ackkkkkkchyualllllllllly, my review of the last three years of your comment history proves your favorite fair food is not, in fact, cotton candy. I have gathered and will prove this with ten points. Point one: your childhood experience with Geoffrey the Giraffe suggests...
  
  Whimsical or not, there was a scientific misconception used in the statement, that I myself used to have as well. My only goal was to help dispel the misconception. Usually, Lemmy is quite welcoming to correction of scientific inconsistencies in sci-fi discussions. Idk what happened in this particular thread, but it went off the rails. All my statement got misconstrued and downvoted, despite me engaging in the discussion in good faith and being factually correct. Several people showed up, making incorrect or irrelevant statements and got upvoted.
  Like your "lungs are on the outside" comment. Maybe you can explain to me, why am I being antagonized and intentionally misunderstood? Obviously I didn't mean that lungs are on the outside, context matters. And I explained the context in another comment.
  
  I made that assumption because lungs aren't really inside, they are pretty close to the surface, so they are easy to expand. If they were inside, they would have to push other organs away.
  And regarding increasing the overall volume of the body, I addressed that in another comment. Basically, Godzilla would have to visibly swell by a lot, to have that much buoyancy.
  It could be that the swelling is only in the underwater part, but then Godzilla would tip over with any slight movement, because the center of mass would be way above water.
  
  "Lungs aren't really inside" is not an argument that I thought I'd be confronted with.
  If you find that your lungs are not inside your body then I urge you to seek immediate medical attention.
  
  At this point, you're just trying to ridicule me over my choice of words and not actually trying to interpret them in the context that you yourself set:
  they have a sack of muscles somewhere inside their body
  Why mention "inside their body" if you didn't mean "deep" inside? All organs are "inside" the body. Therefore, I interpreted your words meaning truly "internal" organs, that that don't manifest themselves on visual inspection, like heart or bladder. Lungs, while technically inside, are peripheral and visibly expand - a critical distinction in this context.
  So you specify "inside" and then mock my adherence to that framing, instead of addressing the core biomechanical issues being discussed.
  
  Ducks and other waterfowl have the majority of their weight above the waterline. So do boats.
  
  Yes, but birds are very light in general. Most of their volume is feathers and they have a low bone density to boot. As the result, they have a very hard time diving, and have to either dive at high speed or paddle really hard to stay underwater.
  And regarding boats, it depends. Do you mean completely empty passenger boats? Then yes, their density is very low by design, because they are mostly empty on the inside. When fully loaded, a commercial cargo vessel, is 80-90% under water.
  
  You can't prove that Godzilla's bones aren't hollow ballast tanks that can be emptied and filled as needed.
  
  I can't, and I wasn't going to. My argument was never about what Godzilla can or can't do, it was about physics. Specifically, that you can't move stuff around internally, without changing volume significantly, to change buoyancy.
  Deballasting bone cavities is definitely an option. But to achieve the levels of buoyancy displayed by Godzilla, they'd need to be truly massive. Or he's using paddling in tandem to help itself stay above water, akin to what dolphins do to hold most of their body above water.
  Also, you can't squeeze bones, so Godzilla needs an organ that would force discharge that ballast. Like sacks of highly compressed air, which are used to push out the water completely. This is similar to what submarines do.
  Instead of bones, we could also just use your approach with organs. Emptying sacks of water and filling them with air. But either way, we need to discharge ballast, as I was saying originally. It's a limitation of law of physics, and not a limitation of Godzilla's abilities.
  Source: I have a bachelor's degree in Maritime Transportation and Navigation. Which is basically a BSc on "how to buoyancy right".
  
  When fully loaded, a commercial cargo vessel, is 80-90% under water.
  Hahaha, no.
  While I can't find a comparable article for cargo ships, cruise ships are 10% underwater. A fully loaded cargo ship can't be more than 30% as they tend to be stacked far higher than the ship's sides. Ocean waves would easily swamp a ship that was 80-90% underwater.
  
  Don't know what to tell you, man. You sound very confident, but I literally have a bachelor’s degree in Maritime Transportation and Navigation, and have served on several cargo vessels, as well as a couple of passenger ferries. I might have exaggerated with 90%, I'll give you that, so take it down to 80%.
  cruise ships are 10% underwater
  As I said, those are usually mostly above water, to prioritize comfort. But even those are at least 30% underwater, with very low center of gravity. You can't have a ship 90% above water; it would keel over. Except some heavyweight barges that have big surface area, I suppose.
  A fully loaded cargo ship can’t be more than 30%
  In fact, that's about the least an empty cargo ship is underwater. Because when empty, cargo ships take ballast to prevent capsizing. Also the propeller is designed to be at least a few meters below water to be effective.
  they tend to be stacked far higher than the ship’s sides
  I think you're focused specifically on container vessels. Those still have way more massive holds than the containers you see on deck.
  Ocean waves would easily swamp a ship that was 80-90% underwater
  Depending on the season and projected weather conditions, ships are leaded to a different extents. They have load lines for winter and summer. In summer, for certain cargo ships, the freeboard can sometimes be measured in centiliters. I remember being able to kneel on deck and reach the water with my hand. In heavy seas, the waves are constantly on the deck and the ship can handle it fine; you just don't go there.
  Ships often look deceptive about their draft, because you almost never see a ship truly empty. Even when not carrying load, they have a lot of ballast.
- It's spelled 'buoy'

62 comments