Post

Question for space people: My son asked, if an ocean were suddenly to be teleported to space, whether the fish would survive. I think yes, since there would still be oxygen in the water (at least until the water froze or boiled?). Is that right?

32 reposts312 likes

I think only very briefly. Without either gravity or atmospheric pressure, that ocean is boiling off in to the vacuum of space very quickly. And while there are deep areas that would be several miles thick after being teleported, they still won’t last more than…minutes?

To me the more interesting question is how the ocean is gotten into space. Maybe involve the Five Chinese Brothers—specifically the one who can swallow the sea. Timing has to be bang bang—he sucks it up from Cape Canaveral, then gets choppered to the rocket already in countdown on the launchpad...

I think to a first approximation all of the fish die in seconds to minutes. I visualize it as the earth disappearing. You have a thin film of water shaped like the global ocean, but a huge void where the earth/continents are With the earth and atmosphere gone you get a violent decompression.

I am not sure how fast that propagates through the water, but it’s very fast. I can’t imagine it’s more than a few minutes before something really violent happens to the fish, especially from the deep ocean.

The mass would still presumably be spinning from earths rotation. I can’t imagine that it can collapse under its own gravity. That is a lot of angular momentum and it would all fling outwards from the center, causing even more violence, only this is instant.

Maybe some millions of small ice asteroids eventually reform. I don’t think they are gravitationally bound to each other in any meaningful way. Maybe some bacteria survive all of this and inhabit these asteroids.

The water is not moving at orbital velocity so it immediately begins falling back to earth resulting in global catastrophe and the fish are not gonna have a good time hitting the ocean floor with a billion tons of water falling on them

This is correct answer (the others assume 100% liquid or solid in the ocean). It would be like instantly opening a huge bottle of soda. There would be a few blobs of water with life in them left over, but not for long. bsky.app/profile/simo...

Simon #8647@simonkp.bsky.social

My partner makes a great point. The vapor pressure of the air in the water will have nothing to push back on it, and absent gravity, the mass of the water will not have any force on the vapor in the water, ego the oxygen and other gases will escape rather fast

With no gravity and no atmosphere, there’s nothing to give the water any pressure. When water has little to no pressure, it quickly turns to vapor. It would explode outwards and the fish would not have long to live, I’m afraid.

The ocean does not simply explode or instantly boil away; exposed surfaces are destroyed thermodynamically, while a sufficiently massive self-gravitating interior may remain liquid and temporarily habitable. Fish survival is conditional and short-lived for most fish, but not impossible for all fish.

Yes I guess the hypothetical needs some details. If we’re talking a whole ocean, I guess gravity would hold it together for a while but it would be pealing off rapidly at the edges and the ocean is quite tiny relative to the scale of the earth.

But given the huge area vs. the relatively tiny depth, what impact is the gravity going to have? Whether it forms a big sphere or not, I'm guessing no place would be liveable because of either pressure or temperature in short order.

Not a space person, just going by my advanced high-school chemisty from over 4 decades ago, I'm pretty sure any gravity from the much smaller mass of water would be insufficient to keep the oxygen dissolved in the water and would boil away. The fish would therefore die pretty quickly.

While I appreciate all the physics conjectures, the parenting answer is - you don't have to give the right answer to your son. One wise parent said: of your child asks a question, ask them what their answer would be. And the important part is not the *right* answer, but the dialogue.

Especially considering that the right answer is too complex for - you and most of the commenters, let alone the child. Why is the sky blue? A1: the atmosphere diffracts the light. End of conversation. A2: thar's a great question. Why did you think it is blue?

Where in space and what kind of fish? He'll want to send the ocean toward the sun so as not to have it freeze without an atmosphere. But not a lot inward so as not to create a wet runaway greenhouse. He'll want a fish that can burp and to put them ~30x deeper than where he found them.

But it's metastable. Nutrient cycling will be limited as some of the fish poop sinks and freezes into exotic ices on the planetoid's core. You'll need to add a lot of nutrient rich meteors to keep it viable. Milankovich cycles will eventually turn it into a snowball. Solar flares will ablate it.

You all seem to have solved what would happen to the ocean transported into space. What would happen here once some large percentage of the planet’s liquid water suddenly went away? Aside from the catastrophic retreat of the rest of the world’s oceans.

You will understand that I’ve never given this question much thought ever before. I think the physics of the oceans suddenly being transported to space are fascinating. Ask XKCD?

My partner makes a great point. The vapor pressure of the air in the water will have nothing to push back on it, and absent gravity, the mass of the water will not have any force on the vapor in the water, ego the oxygen and other gases will escape rather fast

A fascinating question from your son, that as a planetary designer myself I would be remiss not to address! I think first and foremost, you have to ask how and where the ocean will be teleported into space. Setting aside where for the moment, let's think about the how question...

... If you were vanish the whole ocean off of the Earth and instantly teleport it elsewhere in the Solar System in its original shape, the result would definitely not be good! The average thickness of the water shell would only be 3.86 km, and the combined processes of boiling off at the surface...

... and freezing beneath the surface due to adiabatic cooling would evaporate hundreds of meters of water off of the surface in short order, freezing the next couple of hundred meters solid in the process. That would of course still leave a couple of km of liquid water in the middle, but...

...that's not the end of your problems! Soon after that humongous, super-thin shell of water appeared in space, it would start to collapse under its own gravity, falling very slowly at first, but steadily accelerating as it collapses inwards almost 4,000 miles toward its aggregate center of mass....

The issue with the ocean being suddenly transported to space is one of gravity. If there is not sufficient mass to hold the water together, it would likely vaporize very quickly. If it were a sphere to start, the outer layer would either vaporize or freeze and later sublimate.

As an example, the reason there is very little atmosphere on Mars is that it is small. It doesn't have enough gravity to keep gases from escaping. (The escape velocity of Mars is about half of Earth's). The moon has no atmosphere because of its relatively small mass.

This relatively small amount of water, it is about 10 times smaller than the mass of the moon, can't keep the water from boiling away. Even if the outer shell freezes, it will sublimate away. How fast that happens likely takes more math than I want to do right now.

As the water dissipates, the life in the water likely will feel a drop in pressure. This might cause the dissolved gasses in the water to start bubbling out, as in a bottle of soda when the cap is opened. That might result in the deoxination of the water. So the life might suffocate, ironically.

Seeing a lot of interesting comments, but I haven't seen anyone ask "where in space?" Inside the orbit of Mercury? In the path of a coronal mass ejection? "Behind" the earth in shadow? In the Oort cloud? The long term answer is probably still no, but the shortest term answers may vary...

I haven't actually done the math. But my guess is that the ocean would boil off before its gravity could even pull it into a sphere. With no pressure, boil-off would be extremely fast. And most Aquatic Life lives near the top or bottom of the ocean, the parts that would boil off quickest.

The simplest math question is whether the water in the oceans would provide enough gravity to create enough pressure for the water to remain liquid. Again I haven't done that math but my instinct says it wouldn't come close.

Another math question has to do with the compressibility of water. Even though conventional wisdom says water doesn't compress it does actually just not very much. But that's small amount still wouldn't make it act like a spring trying to fling itself apart. The math here is spring versus gravity.

wouldn't the sudden reduction in pressure cause the fishes blood to "boil" just like ours does? if they were in the center of the water ball, they'd still be under some pressure, i guess, but the pressure of water density kinda relies on earth gravity

Lots of great replies! I’m going to urge anyone reading this to buy Randal Monroe’s “What If?” books. Fantastic bedtime reading but your significant other may tire of you excitedly describing the latest cool thing you just read. 🙈

Technically there are some "moss piglets" on the moon right now. Good chance they are dead dead at this point though - it's been years.

Wouldn’t it instantly boil (and freeze)? No pressure so its boiling point would be extremely low. I guess it’d boil off from the outside in though so if you were a fish a mile deep in the middle of the ocean you’d have a little time

I suspect that the depressurization wave would travel at he speed of sound, but of course that speed itself *varies with pressure .* Still, I would guess that the wave would move faster than a mile per minute. Definitely second tagging in @xkcd.com here.

Makes sense. After all the oceans are all currently in space. This is the same question then as ‘what would happen to the fish if all the rocks and air on earth were teleported away’ - and the answer is probably like most XKCD What-If? answers: ‘At first not much, but later, nothing good’

Is this from Star Trek IV: What About Those Whales?!?, where Scotty beams up two whales and a whole bunch of ocean to a relatively small Klingon warbird? Or are we sending an ocean into space itself, where it would lose all cohesion and spread out to infinity in the vast, frozen emptiness?

Yes, but not for long. The ocean would start "coming apart" quickly as strong expansion waves would travel from the outside vacuum inwards at the speed of sound in water, which is fast.

I assume the water in the deep oceans also contains sufficient quantities of dissolved gas to cause an explosion of the ocean to a cloud of small droplets and a bunch of fish flying through the cloud to their demise as the droplets evaporate/sublime around them.

Fish: Vacuum exposure → no oxygen exchange + immediate hypoxia → decompression injury (swim bladder/gases expand) → surface/body fluids begin to boil at low pressure + rapid evaporative cooling → rapid freezing → long-term desiccation (freeze-drying via sublimation) → radiation damage over time

Water: Vacuum (near-zero pressure) → flash boiling/evaporation → strong latent-heat cooling → surface freezing (ice shell) → ongoing sublimation + vapor escape → radiative cooling to deep-space temperature → self‑gravity reshapes into near-sphere → long-term frozen “ocean world” with slow mass loss

I really just wanted to say how delightful this discussion is among all the dark news. My college science reaction: The pressure difference would disrupt everything, including organisms’ structures.

The combined mass of the Earth's oceans would have enough gravitational pull to counteract that. Some vaporization would occur at the surface at first, but the rest of it would freeze. Basically I believe you'd end up with a comet.

I could be wrong, but the Pacific Ocean has mass 7e17 kg, Earth has mass 6e24 kg, the spherical Pacific Ocean would have radius 553 km, and Earth has radius 6,371 km, so the spherical Pacific Ocean would have 2e-5 times as much gravity of the Earth at its edge. Is that enough to hold it together?

Yes - we have had fish on the ISS, and I believe JAXA has done it too. Can get you more info if he’s still curious. (These fish are all small/tiny, no big creatures)