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.

[–] [email protected] 7 points 1 week ago* (last edited 1 week ago) (1 children)

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!

[–] [email protected] 1 points 1 week ago* (last edited 1 week ago) (1 children)

Yes, that would work. But imagine the swelling, to give Godzilla that much buoyancy.

[–] [email protected] 2 points 1 week ago* (last edited 1 week ago) (1 children)

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.

[–] [email protected] 3 points 1 week ago

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.

[–] Darkmuch 7 points 1 week ago (1 children)

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.

[–] [email protected] -2 points 1 week ago* (last edited 1 week ago)

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.

[–] mossy_ 1 points 1 week ago (1 children)

I hope you get cited when they put this dialog in the next movie

[–] [email protected] 0 points 1 week ago

I just don't know why I'm getting booed, I'm right.